Combi boiler hot water issues. Repaired and principals explained.

okay so here we have a main combi 25 eco customers the payment of no hot water upstairs in the bathroom the hot tap want two hot tap running upstairs boiler is running as hard as it can which I've proved I've guest rated the boiler and it's at 26 kilowatts on the 25 kilowatt boiler I've isolated the flow so I know that none of that heat is going into the heating system so we go upstairs now more time so this is the hot water in the bar it is thermostat and it's tempered and that those that is all the way on high now to prove it's not that thermostat there really easy way to do that I've got hot tap open here as well so now this hot tap was red-hot losing aesthetics and temperatures over there if this hot tap was red-hot and was coming out of there tepid you notice the thermostat on the wall so let me run through what so we have a boiler it's a 25 kilowatt boiler is running at twenty six kilowatt 26.6 net and if you look on the day of address fine that's what it's meant to be at so it's running at full power none of the heat is going into the heating system 4x I've isolated the flow so all of the power of that boilers going into the hot water and the hot water is tepid there's only one reason that hot water can be tepid and that is simply it's running through the boiler too fast so I'm going to set the boiler up to how it was from the factory with the liters per minute it was meant to have and I'm gonna recheck the war at these taps now I would say that's less than 42 it's probably about 30 degrees 35 maybe it's not it's nowhere near good enough to have a shower so oxide reset the flow rate okay so the boiler is uh running that 26.6 kilowatts [Music] 26.9 kilowatt [Music] running hard there's no way any of this heats going down the heating because it's still isolated here so we're now doing a differential temperature so we've got one plant on the coal train won't clamp on the hot outlet and this is what we've got cold rain is coming in at 7.2 it's leaving at 31.8 I told you about 30 degrees and the Delta Tina it's only twenty four point nine so the ball is only rising the temperature I was only raising the temperature buying up 25 degrees okay which is not good enough so this boiler will be designed and say hello it says specific flow rate 11.9 Lee is a minute that would be with a 35 degree temperature wise that'd be a full 10 degrees higher than what is providing them so the only way this boiler isn't providing that is because the waters running through it too fast that's it it's as simple as that so we can reduce down the flow rate of the boiler to mirror that 11 point line leads to a minute we should see that delta T which is that number there that should go up to 35 degrees it back when we get out to 35 then the boiler is operating as it should so that's what I'm gonna do now on the just down the flow rate to get that correct but just tweet that twenty-eight now I'll show you how I'm doing it anything this simply doing the healthy and I'll tweak this well slow it down slowly see that that says growing up you know that one that should be a 35-foot temperature-wise at eleven point nine litres a minute [Music] so if I get a 35 to attempt relies on there I know I should have 11.9 litres a minute that's hot to a brand new outdoor boiler that's how it should look right [Music] fool so the temperature at taps now blocks of 42 degrees a 4.6 that 4.7 [Music] so we've got 35 food temperature what I said Scott so this is obviously this is all matter okay I'm upstairs now that's hot water that's hot but right probably hot yeah is hopefully as hot the remember is going through a thermostat so that thumps that ask the blender some cold switch so I'll never be as good as this but if we turn this off if we turn this off and get the full hot potential go into this definitely does he still get to a thermostat which now remember you have no control over this so if I got this tap here red hot but this was still tempted you know is that much improved Nicole the most freezing cold now now the thermostat is blending it to a temperature here that isn't really very good so this now this situation here could be resolved probably by taking that handle off moving it around and putting it back on because we know we've got the flow right now you know you've got the right temperature going in okay so I'm gonna take that off and locally adjust that for this cost we'll get it working and that'll be it I'll put the borders work improve this I'm gonna do my flute just a little bit on there I wanna give this border of service I'll go through that while I'm here and hope y'all get this thumb settled fixed and the hot water all resolved ought to do the flow rate I'm gonna check the flow rate in a set go back again so I've adjusted in right but I've adjusted in a little bit more movement of this a few minutes now with a combi you have to remember you always get a glug of hot water within the boil and then it cools off and then it goes hot again so I on any convey when you run that hot tap and it's got preheat or not there's usually a little bit hot water in that boiler and then the boiler plays catch-up so you always get that once where it cools down before it comes back home and once it comes back up the second time it should be consistent and less something like this is causing the problem so we'll say I'll give you some minute or so and then I'll come back alright it's now done this is now a Maxwell ready to point them down probably a little bit more in fact I might just do that just tweak a little bit more okay quite simply this is how you adjust these things you've got a thing running football it's hot much hotter than it was but I need that little bit more adjustment so this handles at the stop for them as hot as it can be and you simply take this off let me take it off turn the orientation ever so slightly put it back on and now that gives this one bit of dough I'm going to adjust this until I'm happy with the maximum temperature coming out here like why that's what a nightmare is one o'clock top and then I'll tweak the best just attack this is an old phone so it doesn't have any of them and buttons on it to limit it to 37 degrees or any of that so I've got me carefully this subsidy there are kids in it or make sure this doesn't and not too hot that's just perfect where it is there so I'm going to make that the maximum and that's perfect that's perfect now it doesn't move that's plenty hot enough we can adjust it back and change the temperature so all usable temperature you start to cover back on this is all done there lady so I just got something to put the screw back in put this handle back on it's all done but in a seconds flow right now now the reason I'm doing up here on the bathroom tab which is all usually do it is because the kitchen tap is a high pressure air rated tap so it has a very small thin flexible tap connectors going into it so they reduce flow so I wouldn't be setting it correctly doing it off that so I'm going to set it here at eleven point let me point nine leaves per minute [Applause] so it is a little bit hatred okay so the final result of this job was to flow restrictor within this boiler had failed so allowed more mains water through the boiler than it should have which is why the temperature was decreased that happens to Wooster is quite a lot because it fair was behind the domestic cold water flow since he low the quantum of what is called now that little plastic piece that holds it fails so was just get high flow rate in the blow hole water performance so that was wonderful the thermistor in the shower upstairs which was the shower bath mix and he's it adjustment and the diverter valve in the boiler was letting boy just a little bit and if you look in their last pitch or we lost about three degrees of hot water temperature through let boy which is pretty minor and the customer didn't want to do anything about it so oil is all fixed and customers happy

Channel: HeatingGeek

Views: 94,234

Keywords: Combi boiler repair, no hot water, combi boiler faults, how to diagnose combi boiler

Id: z7cwuN-B5NU

Length: 13min 4sec (784 seconds)

Published: Thu Jan 25 2018