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Central Heating

Heat output to radiators from combi boiler dropped

Anonymous user 23/02/2024 - 3.27 PM

I have a Baxi combination boiler (105 HE) and it only used to only take an hour of use to heat up my house comfortably for the whole day. Then it broke down and when it was repaired, the heat output dropped considerably. Now if I put the heating on for an hour, all I get is a lukewarm heat from the radiators at best and the house will be cold after a couple of hours, even with all the settings turned to maximum. Can anyone give me any advice to get my heating back to the way it was. Thanks. Update: Thanks for the replies. In answer to what was wrong in the first place, the water pressure had dropped in the boiler. I think he said the PCB was broken and he replaced it with a new one. Hope this clarifies things.

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2 Answers

Conor Cunningham Plumbing and Heating

Rating: 4.6 out of 5

Castlewellan

First question would be what broke in first instance. It sounds like 1. the pump has air, 2. The pressure is down in boiler 3. A valve hasn't been opened properly since the repairs. You should get a service of the boiler, normally about £100 and will leave it working or if still a month since previous plumber was there report to him to resolve.

Answered28 October 2019

Heron Gas Services

Rating: 5 out of 5

Solihull

Hello, It depends what repair it was. It may be related or may be nothing to do with the last repair. Those boilers have a built-in filter near the isolation valves under the boiler. If that is sludged-up then it could cause your symptoms. Without visiting and seeing it's hard to say but I would say a restriction on the return FROM the heating is likely if the system is dirty inside. Failing that, a restriction in the flow TO the heating i.e. diverter valve area or heat exchanger. I think if the pump was really weak and struggling then it would probably affect the hot water operation too but maybe it could still work on hot water mode as it's just a small circuit. Failing all that, if the Printed Circuit Board (PCB) was messed with by the last Engineer, then he may have turned a potentiometer and left it in the wrong place, keeping the output far too low. I think they have a potentiometer or dip switches on the PCB to adjust the central heating output or burner pressure on central heating mode. One last thing - If the knobs on the front of the boiler were fitted when the PCB potentiometer was turned 180 degrees the wrong way, then what you think is maximum CH heat will be nearly minimum as the knob is not in the PCB correctly. Hard to explain but if the PCB was changed or taken out, the heating temperature control knob may have been inserted back in wrongly and does not correspond to the max and min on the front of the boiler. If that's the case, you could get the same Engineer back to put it right and would be non-chargeable if his error. He may not have tested the heating properly at the time if it was warmer weather. Now you are noticing the issue when the heat is needed. Thanks.

Answered28 October 2019