Combi boiler problem

[victoriamullett]

We have a Potterton Lynx 2 combi boiler. For some reason (only in winter) when running the hot water in the shower, it will run for about 5 minutes and then the boiler will shut down and the water will cold.

I have to get out of the shower to re-set the boiler. After a minute or so the water will run hot again, but after a few minutes the same thing will happen again and the boiler will shut down.

The central heating is fine, running hot water else where in the flat is fine, it's only a problem when running the bath or shower!

For info we have a mixer shower - not sure if that makes a difference - but I must admit that our boiler is starting to drive me mad!

If anyone can help it would be really appreciated!

 

[twgas]

I would suspect the low flow rate through the shower causes overheat, try running the basin tap whilst showering and see what happens.

 

[victoriamullett]

I tried turning on the bathroom sink tap and all it does is reduce the pressure of the water to the shower - it didn't solve the shower going cold.

I even tried the shower with the central heating off, but it's made no difference. What confuses me the most is that it only happens in the winter!

Any other thoughts or suggestions would be welcome!

 

[twgas]

Try filling a bucket from the shower, and timing it to check the flow rate.

 

[victoriamullett]

There is nothing wrong with the flow rate from the shower, that is fine and is quite powerfull, it never drops off.

The problem is that it goes cold frequently and we have to get out of the shower to re-set the boiler. But it only seem's to happen in winter.

We're at a bit of a loss - I have read some articles that point towards the fact that we have a mixer shower - could this be the cause?

 

[Agile]

You seem to be very sure whats not wrong with your boiler or shower.

You should try to understand that we have not seen your system and have no idea what you have or what the problem could be. You dont even say clearly how the boiler "shuts down" ! Is that an ignition lockout ?

I presume that you have never had the boiler serviced?

It seems to me that you are either going to have to carefully and completely answer all our questions or call a competent boiler engineer to diagnose and repair your boiler.

Tony

 

[hobhead]

See if you can turn off the cold supply to the combi, then open a hot tap. If you get any water out of the hot tap then the mixer is passing and will need a non return valve fitting on the hot feed to it.

 

[Agile]

The central heating is fine, running hot water else where in the flat is fine, it's only a problem when running the bath or shower!

Based on what she has said that does not seem to be the problem!

However, I would never assume that she has given us the correct information.

I am beginning to wonder if she is one of those people who think that all "plumbers" are naturally thick and stupid!

I have this feeling that if she telephoned me free on 0800 955 4454 I might discover that she has not actually correctly described the situation.

Tony