Potterton Puma 80e - Hot Water Switching Off Boiler

[pmd]

I have a Potterton Puma 80e:

The system works fine save for the fact that when the hot water is running the boiler will switch off and fire back on again periodically of it's own accord. It also does not appear to be able to handle the mixing of cold water to hot through the bath/shower taps as this causes the same thing to happen. - This results in hot/cold showers which is not much fun!

Please could someone advise as to the possible root cause(s)? Thanks

 

[bengasman]

How long since the boiler was taken apart and cleaned thoroughly?

 

[powell30]

Dirty/blocked/scaled plate heat ex........get it cleaned or replaced.

Oh and the problem with your shower is nothing to do with the boiler...see my comments above or you have a low pressure shower mixer fitted

 

[kevplumb]

puma dont have a plate h/ex

 

[baxpoti]

Dirty/blocked/scaled plate heat ex........get it cleaned or replaced.

Could be the usual hot water flow switch maybe diverter problem (or both)
possibly blocked cold inlet (poor flow) or ............... Rgi things e.g. gas valve settings

 

[pmd]

boiler was last serviced/cleaned about 10 months ago...

I'll go the RGI route...thanks anyway...

 

[Baxmax]

A.P.S Tube blocked/splt....

 

[Agile]

I suspect you kind of know what the problem is already.

My guess is that you have a low flow rate and the boiler gets too hot even on its minimum setting and the burner just cycles on/off.

If you have a hot water temperature control knob on the boiler and you have left it at maximum then turn it down half way.

Two possible solutions, clean/poke the shower spray holes to increase the flow rate or turn on a hot tap at the same time to use more hot water.

This may also result from an incorrect gas setting on the boiler but that needs an engineer!

Tony

 

[pmd]

re flow rate - not at all...shower head is clear of scale etc. Hot water temp on boiler is also turned down to minimum and makes no difference. One thing I have noticed is that the temp of the hot water (even on the lowest setting on the knob) is much hotter than when this wasn't occurring...turning on another tap reduced the pressure to much in the shower...

FYI - it has been like this for about a month or so but it's only now got on my nerves enough to do something about it!

 

[Agile]

In that case I would revert to the gas setting as the likely problem.

Just in case you could measure the two temperature sensors with the boiler cold. They should be about 13k.

Has anyone been fiddling with the gas setting like "doing a service" a month ago?

Tony

 

[pmd]

Yes - the boiler was repaired about 2 months ago (1 month was an approx) because it would fire up and then make a loud noise and cut out - i noticed the problem with the hot water not long adfter that but decided to wait and see if it persisted - which it did!!

Thanks very much for the advice, will feed all my info back to my RGI when they visit so they have the full picture...thanks

 

[Agile]

As long as he is not abusive then I am happy to give him any advice if he called me.

Tony