Introduction to VRF Technology

hey thanks for watching this video this is one class from the 2022 hvacr symposium in claremont florida we have the symposium every year and so to find out more information kind of upcoming go to hvacrschool.com symposium big thanks to our sponsors for this event which was accutools and truetech tools they're the two title sponsors that made the event possible [Music] this class is with john chavez john chavez is a past guest on the podcast he's done a lot in the ductless and vrf space and in this class he talks about some of the very basics of vrf for people who are interested in that segment of the industry good afternoon everyone thank you for coming to the class this class is uh introduction to vrf variable refrigerant flow and i've spoken to a few of you here um who by show of hands who has uh installed a vrf system previously all right what about service okay right on cool okay this class is non-commercialized as uh much as we possibly can i'll answer any of your questions so i may bring up uh some products but this is a discussion just about the technology in general my name is john chavez this is a little piece of my resume [Music] but i just want to call attention to these areas here so i've been a ductless aficionado for quite a while and you know anything to get me out of the attic right anything that can get me away from sheet metal you know and meat hooks so i fell in love with this uh technology pretty quickly and went from uh as a contractor went from ninety percent air side to ninety percent ductless in one year and never look back i'm here in the capacity of a licensed hvac consultant so [Music] during my time as a consultant customers call me for problem projects you know exclusively so that was kind of my niche you know imagine you having the most vexing problematic angry customer you know two three even four years in you know manufacturers called me owners call me attorneys have called me you know architects so it's kind of a special niche just to let you know you're in good hands today here's some of uh you know this is these are all guesstimates you know i mean i don't know how accurate is but um i've represented in the capacity of as a manufacturer's agent these products so i've had factory training uh from the factory not on the contractor side so feel free to ask any questions during this presentation we got plenty of time and anybody on linkedin you can find me here and uh you know we can continue i love talking shop so you can always just uh shoot me a dm or what have you alright today's discussion topics is what is a vrf vrv technology we'll talk about some of the manufacturers and key differences what are the essential features right of vr vrf variable refrigerant flow how do they work we're going to review the components applications and design advantages it's it's going to sound a little sales pitchy but don't worry i'm not trying to sell you anything if anything i'm just trying to sell the concept and then service and maintenance so there's a very short uh section on that just to get a general overview um typically i give this class uh this discussion for people that are not even in the air conditioning industry all right so vrf technology right we're used to understanding that you can hook up multi-zone systems with one outdoor unit and i gotta tell you it's not your typical heat pump and they're all heat pumps the capabilities of some of these systems are extraordinary you can achieve 100 cooling capacity down to maybe 10 negative 10 degrees maybe even negative 20 and have maybe 78 percent heating capacity down to negative 13 degrees there are some that can go 100 heating capacity that's without any supplemental uh electric heat this is just heat pump usually where you know if you've been in the industry uh you know that heat pumps usually fail that's a lot sooner than these numbers and uh just to you know i like to uh simplify things um as soon as i understand them i find that people like to [Music] make things more complicated than they are me being one of them if you ask me what time it is i'll tell you how to build a watch you know but i'm trying to refine that and this is one of the refinements you know it's just software driving the hardware that you already know does that help you know it's just software we're going to talk about the software a little bit but you know it still has a compressor it still has solenoids expansion valves accumulator temperature sensors pressure sensors so just a little background here the first installation for vrf was approximately in 1982 and uh there are i think this number is low actually it's hard to get a good number but there's more than 10 million installations worldwide as a matter of fact in third world countries many splits and multi zones are almost you know 100 percent maybe like 90 nobody likes to say 100 but you know 95 of how they get heating and cooling and in europe it's the adoption is something like 85 to 90. they call it chiller killers over there because in the 90s in the early 2000s chillers were going out the door and vrf was coming in the door and in asia it's 85 90 percent you can actually go in some third world cup uh countries and buy your milk and bread and a mini split all in the same place so if you're worried about uh adoption this is a brand new subject you're not sure uh you know about it you you don't know if you want it in your if you don't want to suggest it or recommend it um in 2012 ashrae the american society of heating refrigeration and air conditioning engineers which is our main institution published chapter 18. on revere variable refrigerant flow and uh they've every if if you know the ashrae publishes these books there are four books and there's a new one published every year so it's a four year adoption and you can go find it you could read it online i think there's actually a pdf available on there so you don't have to buy the whole book but if you wanted to you know learn more about it and uh instead of watching cartoons and eating cereal on saturday morning you know maybe you can uh understand more about the vrf technology because that's this you know our industry is going towards inverter driven compressors and so the more you can understand that the do's and don'ts chips tips and tricks the better off you'll be and potentially have some earning power um because if you don't know then you're either going to make a costly mistake or you're not going to be able to talk about it and your competitor will all right so for me how i like to learn is the words right what are the buzz words what are the key words and um that helps me understand whatever subject matter i'm happy to be learning so we're going to go over some terminology not too much but just enough so we can all be on the same page so the first one is vrf versus vrv there is no difference it's exactly the same as just a marketing term and vrv stands for variable refrigerant volume and there's one specific manufacturer who utilizes this terminology but it's exactly the same as variable refrigerant flow okay and we won't go through this whole list but the second one there eev and aliv there is one manufacturer that uses lav but it's an eev and by the way if you go to my linkedin page you can download this presentation so yeah there's really nothing here that is not already publicized out there widely available i just kind of collate it um heat recovery that's how you get simultaneous heating and cooling we're going to go over that in a section and then the variable aspect is you know equals modulating you can see the modulating compressor an eev is a stepper motor it modulates fan is a bldc motor a luscious brushless dc motor and you could have a multi-speed indoor fan there's some other basic terminology which will go over the single phase and the three-phase outdoor units but in uh our industry they call mini splits or single zones ductless duck free split dfs and asia they just call it a split or split clima you know so um and then a multi-zone or multi-head can typically this is in a residential application typically not commercial uh yeah maybe eight to one uh eight indoor units can be attached up to one uh eight indoor units to one in uh outdoor unit and then you have branch boxes uh so this system architecture so uh this is just a general overview of a narrative in how this system operates in very general terms so just look at it this way a system of singular or modular heat pumps more than one with indoor fan coils which are connected by a common system of control and a common set of refrigeration piping so common control common basically this is a typical diagram of a heat recovery system it gives you a very good kind of illustration of that the refrigerant is passed through a series of fan coils by means of a variable refrigerant a variable speed compressor and metered by an electronic expansion valve that regulates refrigerant flow to accommodate the comfort set point for individual zones so basically when you look at a multi-zone or a vr system each indoor unit is a single zone to the outdoor unit right each indoor unit is its own zone the variable speed compressor increases or decreases the system capacity to satisfy the individual load requirements resulting in uh lower electric electricity consumption so if you have a high load in a space the compressor is going to ramp up deliver refrigerant to that indoor head indoor head will satisfy the space as soon as the space is satisfied then the compressor will ramp down uh the refrigerant into that coil will be reduced and thus all that energy can either be put into a new uh into another uh indoor unit or uh the compressor will just ramp down to off and so that's how you can have uh full and part load efficiencies uh one manufacturer coined this term you know personalized comfort so personalized zone level comfort control that's that's how we can look at uh each indoor unit the software programming in the outdoor unit continually scans approximately 250 data points to meet predefined target temperatures and pressures okay these are already written and instead of saying software program we could say algorithms so what is an algorithm well basically it's just a set of instructions if this do that you know and um the best analogy i can give to that is actually the story i was called out on a eight-story hotel in dallas texas it was the summer that we had over 100 days with 100 degrees and the system wasn't keeping up the vrf system was cooling the common areas and so i got called out and looked at the remote control and it said 74 degrees so it was 74 degrees they had it they wanted it at 72. and you know it was a little it was a little uncomfortable slightly you know not not like the lobby and um so we made it the way to the roof and i saw a condenser farm of condensers walked towards them and as i walked towards them i walked past them and then looked from the rear and i saw a bunch of goosenecks laundry vents so as i approached the condensers i started they're usually blue but these were like a gray and sure enough all the lint was completely perfectly coated over the coil and you know you could just peel it off perfectly now imagine a typical air conditioning system coated with lint you know maybe half inch thick what would happen something right you wouldn't be cooling but because of the algorithms the software programming the discharge temperature is monitored and the system just lowered the compressor increased the fan motor to maintain that discharge temperature in its uh happy spot right um which can be you know somewhere between 160 and 220 degrees depending so uh was that a good kind of understanding of how the software can work set of instructions again just to kind of simplify it the software is a conductor in a sophisticated symphony there's a lot of stuff going on it's the components you know applied science and mechanical and electrical engineering all right so we have heat pump and then we have heat pump with heat recovery so with a heat pump you have three general components you have the outdoor unit and the indoor units and the controls pretty straightforward right you got one mode at a time but everybody has their own control so you have one mode at a time a first typically first mode wins there's a lot of strategies to manage the mode call we're not going to go over that today but there are but generally speaking uh first mode call wins so if somebody gets there in the morning or turns on heat then it's going to be heat until specific criteria is met for it to do system changeover so a heat pump is a reverse cycle refrigeration system that provides cooling and heating from a single compressor the reverse operation is achieved by one key component called the reversing valve the reversing valve channels the refrigerant to be superheated or sub-cold at either the indoor unit or the outdoor unit most of us understand that in cool mode the indoor unit contains a superheated vapor and the outdoor unit contains subcool liquid and heat mode it's the reversed and so here's an illustration of a very typical refrigeration system this is not a heat pump this is just a refrigeration system the key however the achilles heels for a conventional heat pump system is its inability to provide heating or cooling at low outside air temperatures typically the heat pump will start to have diminished capacity around 55 degrees outside air however vrf vrv technology uses the reverse cycle heat pump and supercharges it by optimizing the following so each one of these components is monitored and manipulated by the software through this finely tuned refrigerant and electrical management vrf vrv systems are able to operate 100 capacity in either heat or cool mode at outside air temperatures ranging from negative five degrees to uh 115 degrees respectively there are other systems that can perform even greater um they were talking about a system that can do 100 cooling at negative 40. you know so these are just general numbers you know again i'm not talking about anyone specific but when you engage a sales engineer or an hvac designer about a vrf you're going to want to know what its capabilities are and then whatever that published data is that's what the manufacturer should guarantee heat recovery all vrf and vrv systems are heat pumps okay for heat recovery systems there is an added component which is required for the system to provide simultaneous heating and cooling with only one outdoor unit so you have one outdoor unit that can provide multiple indoor units and you get simultaneous you can have cool and heat in two different units with one outdoor unit so that added component is here so in a refrigeration system during the call for cooling the outdoor coil takes superheated saturated refrigerant gas and phase changes it to sub cooled liquid while sub cooling the gas into a liquid in this process the refrigerant gives off energy absorbed from the indoor coil during cooling and then transfers that to the condenser coil as a heated air right we all understand that or we're beginning to understand that well with the heat recovery system that potential heat energy which is normally ejected into the atmosphere is uh re-routed as sub-cooled liquid and can either be stored or used by the heat recovery box this re-routing of the refrigerant is achieved by a component by many names for now we'll just call it heat recovery box we'll go over the different names in a later section the heat pump the heat recovery box is uh directly controlled by the outdoor unit so if you have a heat recovery box the outdoor unit it's an extension of the outdoor unit it contains components such as a liquid gas separator thermistors solenoids ports eevs and manifolds all these components are monitored by the and controlled by the software so this is um illustration and these are the different names that different manufacturers use but it's the same thing they are constructed and designed differently but essentially they perform the same work and they're in this category of heat recovery there are two different styles you have a three pipe system and then you have a two pipe system so you could have two pipe heat recovery or three pipe recovery and there's a lot of arguments you know which one is better what have you it really depends on the job there's arguments for both both work generally speaking fine if you go with the top names but there are some some strong arguments that the two pipe heat recovery can save time and less first costs because typically with one manufacturer in particular that i know for sure is that you can run soft copper uh instead from after the first connection which uh soft copper is less expensive than acr you know by weight not by foot by weight and it's my understanding that if you have a three pipe it's all a very heavily engineered system and they do recommend if not require acr piping which means you have a lot more uh potential for leaks right because you have more raised connections so you know get with your designer sales engineer before making any of those decisions so what are the key features you can mix and match indoor units we're going to go over the different styles that are available for vrf inverter driven scroll compressors you know scroll has been very good to our industry it's very robust and reliable way to pump refrigerant and you can have up to 150 percent connected capacity so connected capacity what that is is that let's say you have a 10 ton outdoor unit you can connect in this case at 150 15 tons of indoor unit now it doesn't mean you're going to get 15 tons of energy out of it because you only have a 10 ton outdoor unit the connected capacity of that 15 tonnes is going to be that energy will be shared now my personal experience is that you really don't want to go any more than maybe 10 or 12 percent something like that but you really have to know your building well to [Music] strategize what is called diversity right because a building is not a hundred percent used all the time you know there's sections people move around houses right in the daytime in the night time people are in the bedrooms and nighttime people come out you know same thing with a commercial building so there are things that you can uh some assumptions that you can put into your design but like in phoenix arizona that you know there's no diversity it's just hot you know so be careful but one thing that you can have up to potentially 50 indoor units on one outdoor unit which would make it somewhere around uh maybe seven or eight thousand ptu indoor units you know i've personally never seen that the most i've seen is maybe 36 something like that average maybe 20 to 25 some between outdoor units remember you're sharing that energy with the the space so uh the building load profile with the distributor capacity uh the refrigerant energy is shared among the indoor units so when one unit is satisfied the other units can make use of that energy there's also solar diversity you know so typically north facing buildings are going to require less heating less cooling than south facing so there's a lot to know about your application so there are two or three pipe systems two wire digital direct control network which is just um you know it could be shielded or unshielded cable and you just daisy chain and that's the communication system some manufacturers were are polarized so you have to land them at the specific terminals others are non-polar so it doesn't matter but it's all integrated and if you've ever built up a chiller system or uh built up a hvac system you you know you know that you need to buy all these disparate components and put them all together one of the benefits with vrf is that it's integrated so you get you know not only the heat and cooling power but the ddc network integrated controls which we'll go over and bacnet and lawn works so um i work on uh high-end homes i'm called into and you know everybody wants to do crestron or uh some uh you know new automated system and more and more they're choosing vrf systems to marry with their home automation system so individual zone control flexibility and design what's interesting about these systems is that there are ways you can manipulate the software by the use of dip switches and there's a number of times when you can do all the preparation that you want but when you get to the job something has changed and now that particular zone is not working as expected so by using dip switches you know i've got out of trouble i've got helped other people get out of trouble um just that uh your conventional systems just can't do that you know not yet anyways the other thing about the flexibility and design is that you can choose whatever different models that are available so in this case we're in this photograph we're looking at the one-way cassette but as we'll go over there are a number of um heads and sizes and then simultaneously and cooling so this is a uh just generalization you know this is not from any one manufacturer but typically speaking you can have you know maybe a combined 3 300 feet of piping on a single system with these vertical lifts this is where uh you know without practice uh you can make mistakes but luckily um we're gonna talk about the selection software and every manufacturer has some sort of selection software that can keep you out of trouble but these are some pretty incredible links wouldn't you agree so the scale of economy if you're looking at it in terms of roof space to the right here we have rtus and these are condensers here and this is a chiller system this is a air-cooled chiller water cool chiller and this is 80 tons of vrf at one time uh there was a outdoor unit and there may still be that con of this size of this chassis that can fit into an elevator and if you're doing a retrofit you know that could be pretty helpful but just to kind of understand the differences between refrigerant and air and water you can see here by this illustration how much physical space is needed to achieve the same work so in terms of transfer of heat abilities uh refrigerant r410a is 10 times more uh more has more heat transfer than chilled water and 190 times more heat transfer than air is that surprising to you no yeah everybody knew that so um the argument for reducing the total size of any building i mean i can't tell you i mean i've worked in beverly hills bel air austin atlanta you know [Music] upstate new york they always want us to put 10 pounds of rocks into a five pound bag if you're on residential um you know you're hard-pressed if you're going to get any kind of mechanical drawings you know and space is a huge concern but with vrf or ductless technology in general here you can see illustrated what is required and there is argument that if you have a 10 story tall building you may be to lose and not pay for one full story of it just because of the duct work that you're not installing here we have an example uh indoor unit that is about um eight inches tall this is a ducted unit medium static which is about 0.6 esp so lower structural costs this slide is you know admittingly for architects more than contractors but just gives you a kind of a dollar amount of what can be saved with vrf as your baseline so integrated controls like i said two-wire polar or non-polarized communication bus these integrated systems can con have the potential to control pumps and parking lights and uh other on and off um emergency lights uh maybe not fire safety but a lot of other things so it has that uh opportunity built in and then just the sound i mean [Music] you know where we're used to listening to anywhere from 75 to 85 decibels you know with the outdoor unit as a matter of fact this is this is at high these indoor units this decibel rating is at high fan and typically there's three to five fan speeds so at the lowest fan speed it's probably somewhere around 20 dbs and um you can with a couple of dip switches you can set the outdoor unit to be somewhere in the 50s you're reducing the capacity all you're doing is putting a governor on the compressor but it's possible so energy efficient system automatically matches the zone load adjusts the capacity and thereby energy consumption adjusts the compressor fan speed and and compressor and fan speed improves temperature control resulting in more comfortable spaces so soft starts you know if you have um or if you're working with any solar people this is one of the reasons why many splits are so popular with them because when you design a solar system you're you're looking at all the loads and the lock rotor induction motor is going to be a big load could be 30 of the load so solar guys love us um also for retrofit you know you may not have to update the um circuit breaker capacity you know that's a big deal right chiller versus vrf while the new chiller may require more energy right instead of using the existing two watt uh you know they have to bring something wire they have to bring in something more heavy duty that's a lot of money you may have to change the transformer these are all just considerations i'm not sure how many of you do sales in design but these are some of the conversations that are happening to promote vrf inverter driven compressor matches compressor speed to meet full or part load demand if you find me repeating myself is because i'm trying to drive home some key points you know off the charts energy efficiency when in part load conditions so we're all familiar with sear ratings right seasonal energy efficiency ratings yes yeah okay so that is a design condition a 95 outdoor 80 degrees dry bulb 67 wet bulb about 40 feet of duct and 25 feet of lang length with the outdoor indoor unit at a level plane now tell me what job have you installed with that condition anybody yeah neither have i i haven't seen it i haven't done it so when you get that seer rating it is a snapshot in time okay um so what happens when uh the compressor ramps down to half the hertz right half the speed what happens to the sear reading does it go down does it stay the same does it go up you tell me goes up uh they don't uh necessarily publish that in information on the residential side but on the commercial side there are some closer values and we'll go over a couple of those but that's why i wrote this off the charts so with the target discharge temperatures they ensure that the compressor has a long life right because it seems to me that all the refrigerant components and proper installation and maintenance and refrigerant charging of any particular refrigeration system whether it's a water cooler or a 10 000 a day industrial ice machine if all those things are to spec that the compressor is happy you know and so one of the ways to discover the the compressor's operating performance is managing and understanding the target discharge temperatures for that particular design so that's where that dallas story of this hotel came to mind so you've probably seen this before this is a very old kind of slide but um basically when the compressor starts it just turns on then room temperature starts to come down it ramps up it can go up to 120 hertz you know delivering that refrigerant very fast to the indoor coils then the temperature just um rides on that line and so the compressor goes down to half the speed and that's you know a little cartoon of uh what we're trying to promote in this space so this concept works with single zone uh mini splits to vrf as well and uh you know any uh inverter driven compressor you know whether it's conventional unitary systems or not this is what we're trying to achieve and save electricity so compressor is soft start you have a high power factor which is good and a low reactive factor reactive power which is great um compressor capacity reduction equals lower kilowatt usage precise temperature control nearly eliminates wild temperature springs so the only precise part of it is that the thermistors are fast reacting it will sense a load change very quickly and that could work for your disadvantage if it's installed incorrectly for instance if you install an indoor unit and it's a high a high wall unit and a certain part of the day the sun beats on it well it's going to over cool right because it thinks it's too hot you have to strategize where you're going to be sensing temperature with these systems you can sense temperature from the indoor unit you can sense temperature from the remote you can have a remote sensor so it's um you have a number of uh choices so in terms of the seer rating the seer rating for a commercial vrf is uh hri standard 2030 and it takes these conditions here and averages them and this is supposed to be a swath between uh you know all gen like four different climates so they're doing their best but it it tells a little better story than seer rating but it doesn't tell the whole story and you know what happens when uh you have a simultaneous heating cooling system and you have both heating and equal amount of heating and equal amount of cooling being called while there's uh system efficiencies with that and so um you have this uh curve here that you know people can [Music] design their system around their building and then uh utilizing an energy model um have some kind of predictive uh understanding of how much money they're going to spend over the lifetime of their equipment so i was attending an ashrae luncheon you know they have them once a month and they had a panel this is like 10 years ago a panel of a bunch of texas contractors and one thing that stood out to me is this statement here so mitsubishi uh that's my first manufacturer call out because it's the only one that i know for sure they published that they have a half a percent warranty return rate i mean that's what they tell people but if it's installed correctly it's bulletproof and that's from one of the largest texas contractors so a life cycle uh it's very much a lower life cycle costs are much more achieved with vrf why the cost of hvac system is more than just the cost of design equipment and installation it's you got to consider the operation the service the maintenance and replacement as part of the total cost vrf zone systems are more efficient easier design takes less time to install and require less maintenance and in our service and maintenance section you'll see why so how do they work this is called a block diagram typically used for designing controls so you have the indoor unit and you have the remote controller set point so it's not a thermostat it's a remote controller a remote controller does much much more than a thermostat thermostat's a 24 volt on off device typically and a remote controller can control vanes can port air messages error codes you know it does a lot more than just a typical thermostat but now that we understand what the difference is we can call it thermostat that's fine um so you set the set point and then you have the space air temperature and that delta that's what drives the system then you have the outdoor unit so the outdoor unit and this is for many uh multi zones as well single phase multi zones uh you have it's looking at the connected capacity thermistor readings the compressor hurts could have multiple compressors and the lev positions and it's targeting temperatures and pressures that's trying to achieve is that a pretty good simplified way of understanding any questions sir i'm sorry the light is shining in my eye yeah it's really cool but what about like control boards and stuff like all the that that make it open uh you're talking like an industrial area or residential yeah so beach okay i'm glad you said beach because uh the salt content of the air is going to destroy you know a lot a lot of things right i mean so uh what i would recommend is that um you know they clean the coils once a month with fresh water only because the coil already has a film on it and then as far as the controls you can pot the controls the pcb and potting the board means that you just put in like a paste on there a silicone and you have to remove it and then pot the back of it put it in the front and you can put some in the front too um but you know there's not a lot more you can do without yeah yeah but what i find interesting is that the installers when they put in a system and they run the line sets they don't cover that penetration well enough and so you get all kinds of critters and things and so and so what i've yes because i've traveled overseas for years yeah that in korea japan china they're manufacturers over that have a there water rated coating on their film this is usually black or is a heavier film yes and i guess because of the cost in our market they don't sell it here because up the price too much well yeah they also don't have ul so there's a lot of differences but right on the coast you can get that thank you for bringing it up i was done you can [Music] yeah and some manufacturers will sell you that coating but you're adding additional time because it's going to be a special order yeah and cost so you can also coat the coils there's a like an epoxy you have to take out disassemble the coil and dip it is the proper way if you spray it on it's going to last maybe two or three years so you have to come back and retreat it which may be a maintenance contract i don't know but if you dip it it's going to last a long longer when you're using a ceiling cassette do you have to worry about the heat in the attic on the crawl space um there is a foam that's about maybe an inch thick on there and it i i haven't seen him sweat so i would say no you don't have to worry about that um yeah is there tricks or do's and don'ts well yes um this is a rabbit hole who wants to talk about fresh air show of hands you got one two three all right we got enough all right so that has nothing to do with fresh air i didn't i didn't include fresh air is because it's a half hour minimum to an hour conversation but my recommendation based on my experience design experience and project experience would say you're probably better off with a separate ventilation system you absolutely got to be careful because i'll give you an example if if this is a cassette okay and i'm looking at the top of it and here's the bottom there's going to be one side that's going to have the incoming vent right it's going to be four inch or five inch something like that now that let's say that's raw air right it's filtered there's like some merv 8 filter somewhere and it's it's not drawing it in it has to be powered in and now this connection here we don't know where the pipe sensors are but that part of the coil is going to behave and react differently than the rest of the coil you know so it isn't evenly distributed because in a cassette it wraps the coil wraps around right now if you have a ducted unit right you have a return air duct you can install the vent the outside air ventilation air in the duct and it you know depending it may just be on one side of the coil but what if that side of the coil is uh in part load conditions you know see where i'm getting you know you can have too much air coming in too much temperature high temperature and the system is not going to respond well or if it's in part load then it may respond great in full load conditions but in part load it may not take care of the the air treatment that you need so i always recommend you know if you can afford it uh on a residential or a light commercial you know get a dedicated uh dehumidifier you know like april air or or santa fe something of that nature pre-treat it before introducing it into the air conditioning system or if you're a commercial then it would be like an erv or or and or a dedicated algebra system so basically this is just a very high overview of the electrical system and from the top left to right you have ac to dc and dc to ac right that's the inverter section so the ac voltage gets transferred transformed into dc voltage it's manipulated then it's converted from dc to ac once the voltage is controlled by the software the voltage frequency uh which in the u.s is 60 cycles per second or 60 hertz can either be increased or decreased to suit the demand so fun fact nearly all if not all single zone ductless mini splits or three-phase compressors who knew that single zone fun fact this is a single zone ductless mini split are typically all of them are three-phase compressors so yeah it uh one of the lines is a simulated uh third leg so um you know in though in the history of uh electricity and electronics uh a tremendous amount of manipulation has been part of it i mean it's uh electricity is just amazing and i highly recommend if you plan on staying in this industry for more than five years that you learn um computer terminology and electronic terminology because you're going to have to interface at some point with a system and if you don't understand the words or why they're there or what's going on uh you know it can cost you time and money and maybe even the customer's confidence i've seen it a lot so that's my recommendation for the day as far as treating the control board no sir so i know i could say this with some confidence that whatever manufacturer that you're working on okay so train is mitsubishi and i know for a fact that they have a recommended um tube of silicone that i don't know if you can buy it from them but i've replaced boards before and it came with it in the box this was clear but the white paste is the heat sink paste yeah that's i think that's different um but um i always you know even if i'm sure i always like to use whatever the manufacturer represents right i don't i'll improvise on things that have a very low probability of um coming back at me you know so um yeah i get with the manufacturer but a question sir are all this in interconnecting electronics do you have to worry about uh uh always but i mean like more than more no no if what florida is the most lightning okay in the u.s so lightning strikes so i've worked on two hotels with lighting strikes and it's um there is no rhyme or reason what happens to the components in a lightning strike we've had uh this particular project i'm thinking of had eight uh systems so they had eight outdoor units and uh is a four-story hotel and uh every room had either nothing wrong with it or something different wrong with it so it wasn't like a very it took them it took that contractor two months to to fix it they had to shut down for about six weeks you know um but you know had they had some light lightning arresting apparatus or perhaps maybe even a surge protector which is not the end-all be-all by no means but it's better than nothing they could have saved some some some trouble perhaps but i i i have not seen or heard you know in all my travels uh that vrf is any more or less susceptible or will cause an increase of lightning strikes all right so um pid pid has been around for decades manufacturers of whatever widget you know food manufacturers car manufacturers you know component manufacturers have used pid in getting their work done a lot of people use the analogy of a gas pedal so you have um and forgive me if i get this wrong but it should tell the story is that you have um the gas pedal itself which has a mechanism then you have the pressure of your foot right and then you have the resistance so all those things are accounted for in pid let's just say and um so when you look at service manuals or you you're seeing t1 t2 or tset or whatever you know it's part of the kind of language and don't get thrown off by it it's just an engineering way of communicating what to expect you know because remember an algorithm is a set of instructions to solve a problem here's a breakdown of a expansion valve you have typically a 12 volt power head 12 volt dc power head you have the valve body the stepper motor can go 500 steps or 2000 steps depending on what it's doing how big the system is where it isn't applied so you know if you think about a thermal expansion valve you know it's very slow responding and not very finite in its control would you agree with that statement so with a stepper motor you just have much more control then you have what can be referred to as a smart coil so some coils have up to three sensors in them an inlet and outlet and then a room uh temperature sensor that's constantly monitoring to keep target superheater sub cooling in line key word here is target and this yes sir uh no not like a regular heat pump it's much more refined uh depending on the manufacturer you can have a time defrost that's every eight hours uh some manufacturers will just look at the coil and says hmm we're a little frosty here let's go to defrost and it could be anywhere from two minutes to four minutes so i don't need to be snooty with your question but yes so the indoor coil fan stops yeah the system is very intelligent in turn if you want to turn this conversation into what happens when you first start it uh say if you have 20 degrees outside you don't want to blow cold right so the system will increase the compressor speed um which can heat up the refrigerant before it's delivered to the space and at a certain threshold then the indoor fan will turn on so at the get-go you're blowing warm air all right so let's go over the components we have air and water source heat pumps hybrid vrf which is already available overseas they've been talking about it for five years or more bringing it here heat recovery systems indoor fan coils indoor units zone control central control all right so typically you have a outdoor system that can be anywhere from 36 uh six to 36 tons um some manufacturers even have larger combined units somewhere the voltage 208 230 or 460 volts inverter driven scroll compressors sound ratings as low as 48 decibels connected units 50 to 1. and connect up to 130 percent of indoor unit capacity you may notice those who are paying attention that i'm changing these numbers it's intentionally i'm not trying to be consistent because you need to go out and whatever unit you're going to apply that's what you should be looking up if you're designing a system based on this presentation you're going to get in deep trouble right this is just all the introduction right essentials single phase heat pumps um are available in three four four and a half five and six tons there's one manufacturer i know it's making a six ton single phase vrf um so 230 volt uh single phase typically i'm sorry um inverter driven compressors and 12 to one um now there is one manufacturer out there that makes a single phase heat recovery so now any of you guys working on residential and you want to put in something real fancy that can delight you know the most uh uh you know demanding of customer uh maybe this is your product then we have water source heat pumps and heat recovery most major manufacturers have this product available so you can imagine that you have a chill a water system and instead of running it through your uh chiller and boiler you just run it through the vrf and if you have a ground source heat exchanger otherwise known as geothermal you can do that as well then you have uh what is touted as hybrid vrf which is basically using both water and refrigerant the green here in the illustration is refrigerant and then you have it can that heat recovery box can produce either cool chilled water or hot water so the heat recovery box this is a illustration of just one of the manufacturers that are available out there here's another illustration of a different one they all they come in different sizes you can have one or up to 16 indoor units connected here's project you can tell it's installed with zero clearance at the top i'm not saying that that's recommended but uh you know you want to read the installation manuals for your for your um prescribed clearances and this is what that a particular indoor heat recovery box looks like inside you have a tube and tube heat exchanger here your solenoid valves going to your ports your manifold block here then you have your lav and sensors i would advise that you don't be intimidated by this you know because uh these are there's a lot of people that have been doing this a long time good people that can help you get out of trouble and um you know it's just at the end of the day it's just a man-made device that does something pretty cool and if it's made by man then it can be fixed by man here's a very top level [Music] illustration of different heat recovery box strategies in this case uh you could have you know 16 indoor units with four boxes heat recovery boxes you could have one to ones or you could have many to one indoor units all right so you have the classic high wall mount ceiling suspended and the ceiling suspended the return is the bottom and the supply is this vein here and you have zero clearance at the top and it has a very long throw maybe 33 feet so if you have a narrow space this is a great solution you know for maybe schools or it room i'm not recommending vrf or ig or a vrf or ductless for crack rooms you know computer room air conditioning but you know it's going to get done whether or not i recommend it but this with a long room uh and it has a high heat load if you throw the air across then it will come back hot and now you are cycling that you're removing that heat from the space you know so if somebody's dead said i'm putting a vrf or a ductless in a computer room this is the one that you may want to look like look at especially if it's a long room then the floor standing these are great for radio replacements so in the northeast corridor of the united states is our number one is vrf and douglas number one market because they have very old buildings with no addicts you know and these are very popular there also with churches you can put some of these you can get a floor standing without the cover and install it into a wall and some you can put short ducts on there depending on the product so it can be hidden in the wall and if you imagine a church you know that has a lot of expensive mill work you know they don't want something sticking out so you put it in the wall and do you know get very good uh aesthetically pleasing uh application then you have um this is a four by four uh well three by three uh four-way cassette and here's a two by two four-way cassette so you can throw this in a t-bar seal a half of the t-bar ceiling you know this guy is pretty big so if your ceiling height is anything less than 10 feet you may want to go to this just because it's pretty big then the one-way cassette which is great and when i get a vrf in my house i'm using all the one-way cassettes now these all have built-in drain pumps typically these do not have built-in drain pumps you have to add it after but these have built-in drain pumps and ductless means no duct work for all these reasons no testing and balancing there's ducted systems medium static low profile low static and then the conventional classic air handling unit so you have a centralized controller that that groups uh zones together all in one interface so you maybe you have 250 indoor units 256 indoor units but with a web browser you can have up to 2000 units all in one one uh computer so the number one thing that you should remember about service the number most important thing when you're approaching a system is the gap to have patience all right if you've never worked on these systems before um you're going to need if you think it's going to take an hour schedule three also get the manuals the manuals are your key roadmap you're going to need a dc volt meter with 600k ohms if you're working on vrf you're going to need a computer because you're going to be interfacing with the computer some service tools are better looking than others this is just an example and please leave your gauges in your truck please leave your gauges in the truck don't bring your vr or ductless really leave your gauges you can't control the superheated soap calling so i don't know what you're looking at here are the players names you know these are the main players in my opinion and you know five years from now there's probably going to be chinese names here well thank you very much for your time thanks for watching this video again to find out everything we have going on you can download the free hvac school app on android or on iphone or go to hvacrschool.com and then specifically up in the top you'll see events to find out more about upcoming symposiums hope to see you there thanks for watching our video if you enjoyed it and got something out of it if you wouldn't mind hitting the thumbs up button to like the video subscribe to the channel and click the notifications bell to be notified when new videos come out hvac school is far more than a youtube channel you can find out more by going to hvacrschool.com which is our website and hub for all of our content including tech tips videos podcasts and so much more you can also subscribe to the podcast on any podcast app of your choosing you can also join our facebook group if you want to weigh in on the conversation yourself thanks again for watching [Music] you

Channel: HVAC School

Views: 64,794

Keywords: hvac, hvac school, Introduction, to, VRF, Technology, VRV, technology class, HVACR Training Symposium, John Chavez, commercial structures, ASHRAE, heat pumps, cooling capacity, heating capacity, HVAC system, refrigerant flow, variable refrigerant flow, variable refrigerant volume, heat recovery box, EEV, high-wall, ceiling-suspended, floor-standing, drain pumps, vrf system explained, vrf ac system, what is vrf, variable refrigerant flow systems, vrf cooling system, Vrf installation

Id: Jh0_zCayS6c

Length: 70min 39sec (4239 seconds)

Published: Mon May 09 2022