Potterton Puma 80e DHW temperature/flow problem

[tooltime79]

Hi all,

I have a problem with my boiler...the CH is working fine and gets hot, but recently the temperature of the HW has fallen so that the water is only lukewarm, the manual control is turned upto the maximum and the boiler pressure is normal. When the hot water is on, the CH pipes remain cold so I assume the diverter is ok?

If you let the flow rate decrease then the temperature of the water does get hot. My initial thoughts are that either one of the sensors has failed or that the heat exchanger has got scaled up. I live in London where the water is hardish so I guess that that could be a factor?

What are the likely components to be causing this and is there an easy way of testing them?

All thoughts welcome, thank you in advance.

 

[Softus]

Turn on CH. Open a hot tap - does the flow switch operate (red LED on PCB)? If not then flow switch or PCB problem. If it does operate, then do the burner flames get bigger? If not, it's likely to be a common Puma fault, being the modulation PCB. It could alternatively be the gas valve.

Best advice is to get in a CORGI registered heating engineer - they'll be well-equipped to diagnose quickly and replace the faulty part to get it working.

 

[tooltime79]

Thanks for your quick response!

I tried putting the CH on and turned on a tap - the red led did come on. I looked at the flame and it does seem to get bigger...looks like may have to get someone in to look at it! Thanks for your help

 

[Softus]

If the flow LED lights and the gas train appears all correct, then the fault is likely to be a sticking diverter valve.

 

[Agile]

The diverter valve operates differently on this boiler. Its clearly operating correctly otherwise the rads would get hot.

The gas burner pressure may be incorrect or the pump may not be operating during DHW or the heat exchanger be be scaled or blocked. You could check the heat input by measuring the gas consumed at the meter.

Its possible that the boiler is unable to heat the water being used. It will heat about 8 litres per minute to about 40° C. Check the flow rate!

Tony

 

[Softus]

The diverter valve operates differently on this boiler. Its clearly operating correctly otherwise the rads would get hot.

Quite so - I stand corrected.

 

[tooltime79]

Thanks for all the responses...it sounds like the heat exchanger might have got scaled up as it has been getting worse gradually and the CH seems to be working without too many problems. Think I am going to get someone in to have a look at it as it sounds like it could be one of many differant problems! Will let you know how I get on.

 

[ChrisR]

The mains water has just got colder, resulting in lower output of HW from combis. Test your flow, you should get about 8 litres per minute at showering temperature.

 

[nycolas21]

Thanks for all the responses...it sounds like the heat exchanger might have got scaled up as it has been getting worse gradually and the CH seems to be working without too many problems. Think I am going to get someone in to have a look at it as it sounds like it could be one of many differant problems! Will let you know how I get on.

Mate, could you please tell me what the part was that was giving you the problem?