Is It Better To Leave The Heating On Constantly? Boilers & Heat Pumps | Consumer Advice

it's the age-old question do i heat my property all day low and slow or time it's come on and off as often as possible or even with heat pumps have it on all day and all night there's industry experts saying yes and then there's money saving expert and energy-saving trust websites which say absolutely not all with little explanation to back up what they say just anecdotes so should we leave the heating on well i'm here today to tell you the exact science behind it explain all the variables and exactly why they're all wrong welcome back to the consumer series where we advise you the consumer on everything heating and renewables and as with all of these things the actual answer is it depends there seems to be a problem in our industry and perhaps worldwide that the simplest explanation is always the one that's most believed and the most widespread everyone wants a yes or a no no one wants the reality of the grey that is the real world to find out what best suits your property and your lifestyle you'll need to look at things like your appliance type internal and external wall insulation levels the thermal mass of the property the property size and layout your emitter type your usage pattern if it's high or low or regular or irregular and the occupancy if that's high or low now one of these variables on its own won't just tell you whether you should or shouldn't heat your property entirely throughout the day or potentially night it's looking at all of the variables and adding them together that builds you the picture additionally it's not about just heating all the time or just heating in tiny little fragments it's how much of either one you want to do and also when your heating's off how much setback temperature which we'll come on to you want to use so the answer is a variable not just a binary yes or no unlike the decision to sub to this channel so what do we actually mean by leaving on heating all the time it doesn't necessarily mean set your thermostat to say 21 degrees permanently it means making the use of setback temperatures that is to say rather than your heating being time to just go off the target temperature for the room is just lowered slightly so at night time for example you might lower to 18 or 19 rather than just switching everything off or if you have weather compensation the flow temperature from your heat source might just lower a little bit to drip feed heat in overnight more on that later now how often this temperature has changed and how much it's changed by is what we should actually be looking at almost nobody wants their property at 21 degrees at night when they're trying to sleep but conversely if you turn your thermostat down to 16 overnight you're basically just turning the appliance off which prevents all these potential gains that i'm going to go into because it's not often that a building will actually drop below 16 overnight the second thing i've really got to drive home here and this is where the other advice is lacking is that heat loss is not the same as fuel consumption right so what do i mean by that let's say that you have 40 kilowatt hours of heat lost out of the building over a day that doesn't necessarily mean that you've used 40 kilowatt hours of gas from your gas boiler or 40 kilowatts of electricity from your heat pump in fact if your boiler has run at a consistent 85 efficiency you would have used 47 kilowatt hours of gas and if you can get a consistent 93 efficiency from the same boiler you will only use 43 kilowatts of gas and hearing lies the problem most of the arguments if not all that you see everywhere for turning the heating off are to prevent heat loss which is not the same as saving fuel and the difference between these two relies heavily on our very first variable that we need to check and that is what is our heat source if you have electric heating such as electric underfloor heating or infrared panels these work at 100 efficiency so if you lost 40 kilo hours of heat you would have input 40 kilowatt hours of electricity timing your heating to come on and off as often as possible will absolutely save energy here and you'll need it as heating with electricity at only 100 efficiency is by far the most expensive heating you could ever use now that might sound a little bit strange but bear in mind heat pumps are between 200 and 500 efficient if you've got an older non-condensing boiler your efficiency and output is basically fixed at between say 50 and 70 running them continuously adds absolutely no gains whatsoever so time away to your heart's content this day and age though most people have condensing boilers these can run at much lower temperatures which cause the fumes which normally blown outside to condense into water hence condensing boilers and that process extracts spare energy that was getting chucked outside and increases efficiency now the lower we can get our radiators and flow temperatures the lower the temperature of the fumes that we're going outside and the more of this condensing action we can make take place and again further increase efficiency lower temperatures of course means that the system will be slightly less responsive so the trade-off is it will have to be run lower and slower for longer periods of time however this is very often worth it depending on the other variables we're about to go through for more information on condensing and how that actually works check out our condensing theory article on heatgeek.com it's also worth noting that oil boilers only have around about half the condensing efficiency gains than gas boilers do if you have a heat pump the gains from running at lower temperatures are even more exaggerated here running at higher temperatures of say 55 degrees which is high for a heat pump to maximize the responsiveness of the system and switching the unit on and off regularly will result in a very poor scope or efficiency of only 200 percent which is poor for a heat pump but running the unit as cool as possible year-round in a low and slow manner will result in more like 500 efficiency clearly even if you had the same fuel bill year round you'd much rather have a sustained one temperature throughout your property throughout the day rather than timing it on and off for no gains whatsoever and in fact it'll probably result in lower maintenance this is of course provided the systems installed and maintained by a properly trained engineer check out our finder heat geek map on heatgeek.com the important concept here is the lower the flow temperature or radiators the more efficiency that you'll gain out of these appliances and the lower your flow temperature the more low and slow your heating will have to be this is known as steady state heating and this is our main aim with the low and slow method or steady state heating we're trying to be much more gentle on condensing boilers and heat pumps and give it a chance to continually feed your property's thermal mass more on that later with higher efficiency low temperature heat rather than blasting high temperature inefficient heat at the property when you think you need it it's a little bit like saying i'm going to drive 100 miles an hour to the shops and get there in 30 seconds to save fuel because i'm only driving for 30 seconds if you drive there at five miles an hour and take three minutes you're definitely going to use less fuel all right it's been on longer but it's been running much more efficiently if you don't have a condensing boiler or heat pump though just don't bother just time it on and off all day although you may be less comfortable as the vast majority of the population now have condensing boilers or heat pumps that's what we're going to address for the rest of this video but before we go into the variables of what uses less fuel in your specific case for your property and your usage type you should also be aware of the other benefits of stable state heating you'll have lower corrosion rates in your system which will protect valves heat exchangers and all sorts of other things you'll have less thermal shock to the system to prevent things from breaking as easily it'll be better on your expansion vessel your expansion vessel something that normally expands and contracts that will expand and contract less and also be kept cooler the rubber membrane in there will be kept cooler it'll last longer when these normally fail it does also cause other issues down the chain it reduces cavitation at the pump and fittings there's less noise and creaking in the system there's increased comfort in your room through reduced heat gradient across the room there's increased comfort through steady emitter output and also increased radiant heat versus convective heat it's safer there's cleaner air within the house you'll find higher levels of comfort at lower air temperatures due to the radiant effect there's longer run times and less cycling at the appliance so the appliances break down less often and there's comfort at times when you're unexpectedly going to use the house so even if you do use a fraction more fuel by running all day the small amount of extra fuel may be worth the increased comfort and lower maintenance costs if anything i've just listed there is alien to you all of these benefits are listed in a lot more detail over on our article the benefits of low temperature heating over on heatgeek.com just give it a little google so outside of what your heat source is here's your first variable is your usage pattern high or low regular or irregular so if you come home to your property perhaps you're the only one that lives there and you get home for eight o'clock at night and let's say you're in bed by 10 and then you leave the house at 6 37 a.m five days a week and then you may be busy out of the property on the weekends as well heating all day is quite clearly going to be very very inefficient however if you're home more often perhaps you could even be retired you could be experiencing much higher levels of comfort throughout the day with all of those other benefits that i've just mentioned including potentially reduced fuel bills if yourself or other occupants are in and out of the house at random times for random lengths of time then again it might just be worth leaving the heating on so it's warm for whenever you come in or you may just want to use a slightly higher setback temperature but again we have to factor in the other variables that we're going to go through thermal mass our next variable is how much mass your property has to hold the heat a 1930s property with a brick in a skin and brick internal walls will have a high thermal mass a modern building with stud plasterboard internal walls will have a low thermal mass now the benefit of thermal mass is that it can store the heat and slowly release it back into the room after the heating's been turned off conversely though it'll also mean that when the heating's turned on it'll take a lot longer for the heating to heat up the building because those walls are drinking up that heat so a high mass property will have to turn on the heating a lot earlier and off the heating a lot earlier and have a big chunk of time where the temperature isn't either as cool as they want it or as warm as they want it which is obviously wasteful so this clearly would more suit a steady state heating obviously this is a very quick overview once again head over to heatgeek.com and we have a more in-depth article specifically on thermal mass the next variable is what emitters do you have emitters are just what puts heat into the room like radiators or underfloor heating now these have different response rates underfloor heating for example has a much slower response rate as it has to heat the floor before it heats the room radiators obviously have a much quicker relative heat up because they heat the air directly this really means that you should probably suit the emitter to the property type and the usage pattern of the property however that's obviously seldom done so you've got to work with what you've got anyone who has under floor heating knows that underfloor heating only really works with stable state heating and radiators are obviously more suited to the intermittent heating just to illustrate this a little bit further if you've got underfloor heating you can heat that underfloor heating with short blasts of high temperature less efficient heat the floor will then store that heat and slowly release it into the room and achieve a pretty steady temperature in that room throughout the entire day however why would you want to blast your floor with 88 efficient heat for two hours in the morning and 85 to 88 efficient heat for two hours in the evening when you can put a third of the power requirement in for a continuous 12 hours at 94 efficient heat the actual kilowatt hours emitted from that floor will be the same but the heat input will be lower and you'll get those other benefits that are listed again it's like doing 100 miles an hour to the shops twice a day for two hours versus driving 33 miles an hour for 12 hours you're going to cover the same distance but you're going to use a lot less fuel so the last variable is controls what controls you have by controls i mean sort of you know thermostats and what controls you're heating for me it's the misses [Laughter] if you only have a system that can operate at a fixed temperature and particularly a high temperature you're not really going to benefit from any of this low temperature steady state stuff i was talking about although perhaps pay to upgrade your system controls to ones that will operate at lower temperatures as this will lower your bills lower your maintenance costs and increase comfort whether you choose to do steady state heating or not if you do upgrade your controls to ones that have the ability to run at lower temperatures you'll want to decide whether you go down weather compensation route or room compensation route we have a very in-depth thoroughly interesting article on heatgeek.com called weather compensation versus room compensation it's very popular have a look through that and you can learn loads more about heating off the back of that as well so as i say in no way by answering one of these variables we do decide whether to do steady state heating or not but i think knowing what you know now you could probably make quite an informed decision yourself and remember the answer to this question is not binary it's not simple yes or no it's how much should you time your heating to come on and off and when it's off how much do we reduce our setback by if you're suited more to steady-state heating the closer you'll have your comfort temperature and your setback temperature together and the less times you'll put in and the more suited to intermittent heating you are the further you'll have your comfort and setback temperature and the more time drops that you'll put in notice i haven't mentioned heat loss or insulation levels now having a high heat loss is just the same as having a bigger house heat loss doesn't really affect this theory at all despite that being the main reason given on other sort of platforms what people are actually supposed to be on trying to refer to is thermal inertia thermal inertia is the balance between the thermal mass and the heat loss the variable is the thermal mass when you see people mentioning uh look at the heat loss just don't look at the variables that i've just mentioned here lastly people's idea of what continuous heating actually is is changing older style controls don't use setbacks they just use an on or off time but these controls are dying out and the idea of heating for two hours in the morning and two hours in the evening is two this can be a complicated subject uh i'm hoping that i've packaged this in a kind of a consumable easy to understand way if i've done that or not please let us know in the comments below if you however decided that actually this is quite complicated and you don't really want to do this yourself why don't you look for a heat geek on our heat geek map who knows all of this stuff and can help you decide how to best control your system and potentially what best controls to have if you want to upgrade of course everyone can experiment here and comment in the comment section if you found something interesting out if you have a heat pump what you'll generally find is in most scenarios is that you want a two or three degree setback and to heat all day most of the time if you're a little bit geeky like me and you question the maths and theory here look out for our why not to zone heat pumps video and that goes quite into detail about the maths that can be gained from running at lower temperatures and how that can be worth heating the whole house most of the time don't forget to sign up to our newsletter on heatgeek.com subscribe to the channel hit bell notifications and leave a like if you found this useful if you're a consumer and would like more advice on renewable heating check out our consumer series playlist here on heatgeek for all you need to know about renewable heating and energy

Channel: Heat Geek

Views: 510,950

Keywords: air source heat pump grants 2021, air source heat pump green homes grant, air source heat pump noise, air source heat pump system, air source heat pump water heater, boiler, clean heat grant scheme, condensing boiler, heat loss, heat pump, heat pumps, heat pumps explained, heating, how does a heat pump work, how heat pumps work, net zero carbon emissions, renewable energy, renewable heat incentive, thermal mass

Id: kGs_biFA87Q

Length: 16min 15sec (975 seconds)

Published: Thu Mar 03 2022