Potterton 30HE DHW cut out problem

[pebrey]

Hi,

I have a problem with the above boiler. The hot waters keeps cutting out. Symtoms are as follows:

- Runs for 10 - 30 second. Temp led's get to 80 then the burner cuts out.
- Burner cuts back in after approx 5 seconds.
- Central heating is fine
- The problem occurs more frequently if the DHW thermostat is turned up.

The manual fault finding flow chart basically says to replace the DHW temp sensor first of all - have done this and its made no difference.

Next is the Gas Valve, followed by the PCB - both very expensive options. However, the gas valve seems to be operating (to me - but I am a DIY'er!) - the flame does increase / decrease in size when you adjust the thermostat. Would that indicate a PCB problem?

Other posts on here say it could be a blockage in the heat exchanger. I have an excellent flow rate through the hot water though? Also the water is softened, so I would be surprised if its scale? Is that something easy to check on this model?

Any suggestions of things to try before I call the cavalry in for the valve / PCB much appreciated!

 

[Kip]

Scale in the heat-exchanger boiling up by the sounds of things...Not able to shift the heat away from the boiler quick enough?

 

[Puddle]

remove and clean out plate heat exchanger

it will not be scale but rubbish from system

system may also require cleaning,which should have been done when boiler replaced

 

[pebrey]

OK. Will take a look at the heat exchanger on Monday (Missus banned me from tampering tomorrow on the basis that nowhere is open for spares. No fun!).

Is it something a simpleton like me could tackle? i.e. is it easy to get out and not involve any gas fittings?

Also, in terms of cleaning, what would you suggest? The chemist in me says white vinegar to clear any limescale, but if there is other sludge there I am not sure?

Thanks for the help so far!

Paul

 

[stevetheplumber]

OK. Will take a look at the heat exchanger on Monday (Missus banned me from tampering tomorrow on the basis that nowhere is open for spares. No fun!).

Is it something a simpleton like me could tackle? i.e. is it easy to get out and not involve any gas fittings?

Also, in terms of cleaning, what would you suggest? The chemist in me says white vinegar to clear any limescale, but if there is other sludge there I am not sure?

Thanks for the help so far!

Paul

its not the hot water side that will be blocked its the heating side easy to remove usually two screws youll see which is which as the heating one will be dirty flush with a hose shove in one hole then revervse shaking helps