No hot water - boiler not firing - cylinder temp 27 degrees

[Mark Hunter]

Hi all.

We have had a few issues with our boiler over a couple of years, which I'll try to keep concise. We have a condensing boiler in the kitchen, cylinder in a bedroom and water tanks in the loft. A running problem is that when the heating and hot water are on at the same time the hot water really suffers whilst the heating is fine. A couple of times there has been no hot water at all, to the point where it is now on continuously in all weathers. Yesterday however, with no heating on, the hot water was incredibly cold and the boiler wasn't firing. Plumbers came to look, turned the heating right down and replaced the thermostat on the cylinder which seemed to do the job (radiators were tested before and they were fine), but only hours later the water in the cylinder had dropped to 27 degrees and again the boiler wasn't firing. The plumbers say we need a new, larger cylinder for the size of house and an immersion heater too, although we stressed that, given finances, we're not worried about heating for the moment, just hot water. They still say we need these new items, but I want to see if anyone out there can suggest anything else that may be causing the hot water to fail. Pump and boiler have been tested and are working fine.

Any advice greatly received as we can't afford these new items but naturally need hot water.

Thanks!

Mark

 

[Simon F]

Hello Mark,:welcome:
if the boiler is not firing when there is a call for it,
suggests an issue with the wiring + controls - programmer /thermostat /motorised valve

 

[cjg]

motorised valve naff all to do with tank, its 90% chance just m/valve stuck or goosed, replace first, not a big job unless its hidden in the worste possible inacessable stupid place,

hope that helps
cjg

 

[Mark Hunter]

Thanks guys - I'll look into the areas you suggested and will read up on m/valves. Forgive my ignorance, would that solve the problem with the heating/hot water conflict or is that down to something more serious?

Mark

 

[JAP&H]

motorised valve naff all to do with tank, its 90% chance just m/valve stuck or goosed, replace first, not a big job unless its hidden in the worste possible inacessable stupid place,

hope that helps
cjg

Hi Mark

I agree with cjg probably valve problem (2 or 3 port). Motor, actuator or entire valve need to be checked possibly replaced.

Whether or not the cylinder is undersized has no bearing on water getting hot or not. Means you may run out of hot water if there are a few bathrooms and kitchen.

 

[cjg]

motorised valve controls the water flow, ie, ether to the tank only, or c/heating, if you have a 3 port then 1 tank 2 c/heating 3 both, not in that order .there should be a leaver on the motorised valve for manual control, but that may be stuck too! just have a look to see mybe you can (untill repair done ) use the manual leaver for a day or two regards cjg

 

[Mark Hunter]

Following a similar problem a year ago I actually had a look then at what I now realise is the m/valve but I don't know what it should ordinarily do. All I do know is that when I turned on/off the heating/hot water it made a noise like it was transferring from one 'flow' to the other but the little stick didn't move, it either locked in position where it was or was free to be manually moved. It didn't move automatically though, which I'm guessing it should.

Does that help clarify the problem?

Thanks,

Mark

 

[diamondgas]

Any chance of a picture Mark? Or is there 2 or three pipes attached to the valve in question? If two pipes there's a problem, three then it's working correctly

 

[Mark Hunter]

I'm at work but will take some pics this afternoon and post. According to the wife a 'family' plumber has come round and got it working by turning the boiler temp up and keeping the CH running but turning the radiators off and thermostat right down. He has also suggested to turn one particular radiator on if we encounter further problems and this should help. Can someone explain why this might work, given that we turned the CH off at the control panel and it didn't work? Not convinced that this resolution will last us until the autumn when we can look at larger-scale changes.

Thanks.

 

[diamondgas]

Really would benefit from knowing a bit more about your system designs and controls Mark! It could be as suggested a faulty 2 port motorized valve, 3 port valve or a wiring fault! Deffo nothing to do with the cylinder unless it had a blockage in the coil which isn't impossible ... All depends on pipework configuration for that one