Boiler humming but no flame - our possible suspects..

[hosh]

Hello

Hoping you can help me understand that I am understanding this properly:

Our system is a boiler in the kitchen (Potterton Promax HE) and a tank in cupboard on the first floor, timer controls are also there for hot water and central heating - we had an issue earlier in the year with a two port motorised valve (acl Lifestyle) in the tank cupboard: the one controlling hot water wouldn`t close - so a plumber, as a quick solution, wired the hot water over to the central heating valve, as a result both would turn off and on simultaneously, all controlled by our heater thermostat. While this might not suit most people it works fine for us as the tank hot water is only used for the kitchen taps (our shower is electric).

Obviously the slight issue is in summer when the heaters are not needed at all - so my bright money-saver idea was that during the few months of summer, if we turn off each radiator valve we could run the boiler and still have hot water without a hot house. I ran this by the plumber at the time and he seemed to say it would work.

Now in Summer I have put the plan into action. It doesn`t work - reason being that the pilot light on the boiler has gone out; specifically when the thermostat is set to be on, the boiler hums softly but doesn`t fire up.
So the question is - is the boiler`s not firing up somehow connected to the fact that all the radiators are closed? Or is it just a coincidence: the boiler should work for hot water even if the radiators are turned off, but the boiler has a separate pilot light issue now?

If you could please help me understand this would be wonderful.

Many thanks

Mike

 

[Agile]

It sounds as if turning off the rads has caused a lack of circulation which has caused the boiler to overheat.

The obvious solution is to get the failed motor valve replaced. You don't seem to want to explain why you have not done that!

You said it was a quick solution whet the plumber did. That's reasonable but the proper repair should have followed soon afterwards!

Your questions are verging of the gas/combustion/safety aspects which we don't give DIY advice on.

Tony

 

[hosh]

Having asked the question I ran the test:
I turned on one radiator a bit and the boiler didn`t fire.
I then turned on this radiator full and the boiler fired.

So likely:
- my initial diagnosis of the pilot light being out was wrong - I deduced this by looking in the little black hole and seeing no light. (I will research this properly shortly)
- (more importantly) some radiators need to be open in order for the boiler to properly fire up. I hadn`t expected this but it seems to be the fact.

While the boiler did fire up (I could see the flame in the little black hole) - it didn`t last long.... and now about 15 minutes later if has fired up good and proper. During the interval I fiddled with the radiator opening valves again and realise I don`t really get how these work (what is fully open etc), I research this now.

Thank you in advance if you are able to offer any insights.

Mike

 

[hosh]

Tony:

Thank you for the response.

You might be right about the boiler overheating, to be honest I don`t really know how these things work. I did touch the box to confirm humming was coming from the boiler when it was`t firing up, and it wasn`t hot.

As for not having the work done properly its mostly austerity I am afraid, also there was a second potential issue with an isolation valve that had potentially seized that would have doubled the cost. Otherwise it seemed to me to be cheaper and more convenient having the hot water controlled by the heater thermostat - in our current setup the timer controls are in a bedroom we let out and its not easily accessible due to where the bed is - I prefer not to disturb our tenants by needing to go into their room and shuffle about their bed to tinker with settings.

The question is now though - I gather knowledgeable readers can understand the set up we have and further understand why it doesn`t work. The deduction so far is that even though both the hot water and central heating are controlled by one two-port motorised valve, if the thermostat is on but the radiators are turned off, the boiler won`t fire up. Why not?

I have a feeling it has to do with the tap hot water in the tank not being the same water used for the central heating? If it was it should work, but the central heating has special water with other chemicals in it, so it would be different. If the central heating is on, but the radiators are closed, then the heater hot water is only being pumped around the circuit, and if its in summer especially it won`t cool down much, so the system won`t think anything needs heating up.

Once again, any insights to help would be great.

Mike

 

[CBF]

i hope you have an open vented cylinder & not an unvented one ?

 

[Agile]

The plain situation is that you have a faulty system that has been bodged as a temporary cure.

Because it has been bodged, the only good advice is to get it properly repaired. I usually charge about £212 to drain a system and replace a motor valve.

If you dont have it repaired then you cannot expect it to work correctly.

Your boiler does not have a pilot light and its reasonable modern. Pity to risk spoiling it by not having the system repaired.

Tony