Combi boiler problem - can anyone make any sense of it?

JennyW_2

We have a Potterton Performa combi boiler. It's about 3 years old. We have been having problems with the hot water (or lack of it). It comes and goes and when it's not hot, its only warm. We've had an engineer around and have now had the temp sensor and heat exchanger changed. The Heat Exchanger was done Friday and on Friday we had lovely hot water - really really hot on a good flow so we obviously thought the HE was the cause of our problems. However this weekend it's gone back to warm water

This morning I tried the water 3 times and it was hot for all 3 times, however just before I left for work it had gone warm again. We're at our wits end and don't know what to change now My husband has spoken with the engineer who feels it could be an electrical problem - ie from the circuit board, perhaps a dry circuit. My husband is an electrican so will try and source it but god knows how you try and find a fault which comes and goes and is not there all the time. Anyone had a similar experience and suggest what we should change next? The diverter valve is working ok and we have no problems with the heating - that's working fine. Any help would be appreciated.

The engineer also rang Pottertons and explained the problem and they suggested the temp sensor and heat exchanger so we've changed what they suggested.

Mr_Proctalgia

There has been a lot of issues with Poxy Battertons and circuit boards, watchdog got involved and they have been swapping circit boards for free and refunding people who have paid. There is some information on this thread that may help you Here

Boilercare

The post regarding the Watchdog report is not related to the Potterton Prforma combination boiler, but the Potterton Suprima ordinary central heating boiler, and should be ignored.

I have been repairing combination boilers for more than 20yrs and can offer the following professional advice.

Firstly, the fact that the boiler starts up and produces warm water tells me that the majority of the boiler is working correctly, and therefore replacing the printed circuit board on this occasion will provide a solution.

Secondly, it is important to understand the basics. A boiler (combination or standard) simply creates heat. What you do with that heat (use it to heat hot water or central heating radiators) is irrelevant to the boiler. The main differences between hot water production and central heating within a combination boiler are;
1] what size flame does it require (we call this input rate)
2] which position is the divertor valve in (this is the device that changes where the heat goes to)
3] which temperature control circuit does it need to look at (these are internal controls within the boiler).

Get your installer to check the burner pressure and gas rate while a tap is running, and compare the figures to the "Data badge" on the boiler.

The most common cause for your symptoms is related to a divertor valve that has not shut off the central heating correctly. If this is the case, you can carry out a very simple test to confirm it (this DOES NOT require you to enter the boiler or use any tools)
Carry out this test with the central heating turned off, and the radiators cold. Simply run a hot water tap, and check the temperature of the pipes below the boiler by holding them with your hands. If the left hand pipes (22mm in size) gets hot whilst the tap is running, the boiler is sharing its heat with the central heating circuit, and will therefore result in reduced water temperature at the tap. In this instance, replacing the divertor valve will rectify the problem.

There are other technical reasons that are too complex for me to go into with you, but there is one other item that I have come across many times which resulted in poor hot water, and this is actually not the boiler that is causing it.
If you have a shower with a thermostatic mixing valve, this can allow cold water to feed backwards and mix with the heated water from the boiler even if the shower is not in use. To eliminate this, simply set the thermostat on the shower to cold and try the hot water again.

Dave Hickey

Lakrits

Thanks! I think I know what's wrong with our Potterton Performa 24 now. The hot water comes and goes and the left hand pipe gets hot when the hot water is turned on.

How much do you think this will cost us in total?

Many thanks again!