Do I have a problem?

reading this forum is enough to make you paranoid - not sure if I really have a problem with my boilermate 2 connected to a Suprima 30 or that I am expecting too much.

If the central heating is on the hot water production is pretty good - but if the heating hasnt been on - say overnight, the hot water runs out very quickly indeed.

So i started to investigate, can anyone confirm is the following are problems that need attention:

1 Boiler runs well when CH is on - but when HW only is required boiler runs for a minute or so - stops (green light flashing) then after a few mins runs again for a minute - the boiler goes round and round in a loop like this (I thought the boiler should fire until the temp was satisfied but the store is still calling for heat)
2 Boiler flow temp appears to be around 60 degrees C using an infra red thermometer - is this right?
3 The temp control on the boilermate sometimes does not "click" to indicate the current temp of the store across the whole range of the dial (could the store be so cold it wouldnt register?)
4 If appears that the boiler has not been wired to the neutral on the boilermate (I am guessing that this is icked up in the wiring centre?)

I have already:

Replaced the boiler pump (it was getting noisy)
Identified I need to replace the pump drive pcb (took out link and it just clicked - no pump running)
Confirmed the F&E tank is full and is also working to fill the main tank (drained down some water from a rad to confirm)


Thanks for any help you can give

Andy

Hi Andy,

1) The boiler short-cycling like this is typical beahviour for a Suprima with a failing thermistor or (new type) Siemens control board. Does yours have the latest Siemens board in it? It could also be failure of the boiler pump to run. Yes I'd expect the boiler to run continuously whilst the Boilermate is calling for heat unless it is an unusually large version of the Suprima.

2) No. Design flow temperature will temp control set to max is 82 degrees C. 60 degrees indicates either a boiler fault or virtually zero water flow rate through the boiler - pump again!

3) Yes this indicates the store is too cool if the green light is ON for the full range of travel.

4) There is no need for a 'wiring centre'. All wiring would normally be connected directy into the Boilermate. Has the system ever worked correctly? This could be an installation problem! But my money is on a boiler fault given you've replaced the pump already.

Cheers, Mike

Thanks Mike for the swift reply - the boiler does have the new type control panel I believe - with the single status light and the small square reset button - could this be the issue - I have read that these can have issues controlling the temperature?

Hi Andrew,

Yes a board fault seems very likely. Simple to diagnose - just fit another new board and see if the problem goes away ;-)

Not much help really I know as you'd have to buy another board in the hope that it fixes it. No prob for me though as I keep them in the van!


Cheers, Mike

Hi Mike,

Since we last spoke I have replaced the overheat sensor, thermistor and the pcb - but the problem still exists? The boiler short cycles unless there is a significant drop in the store temp then it will run well for a shot time - any advice?

Hi

I have the same problem.
I also changed the thermistor and overheat stat on the boiler with no change.

The green light on the boilermate 2 will not go out.

Can you recommend anything?

Cheers

I'm not an expert - so please take my advice accordingly

I put a temp gauge on the flow pipe form the boiler and it shows 60 deg C - i understand the boiler should fire at 80ish

This I believe is the reason the boilermate will not get up to top temperature

I understand from some searches online that the type 3 control board with the small square reset button does sometimes present a problem where the temp is not as it should be

I have recently taken out a contract with british gas and they came last week - today they will be replacing the thermistor and overheat stat (again) and also the main control board in the potterton boiler

I will let you know the results soon - hopefully all will be well - the engineer is committed to resolving the problem and will advise on next steps if todays actions dont fix it

We have made a temporary fix - I set the heating to come on in the morning after we have showered - this means nice hot showers as the boilermate isnt trying to satisfy both - its only a short term solution though

I hope this helps

Andy

If I turn everything off and on again the store reaches temp.

But if I run the hot tap. The store will demand heat but the boiler will not turn on for about 10mins and when it does it only fires for a short period of time and therefore not reaching the temp that the store is requesting.

I have had 3 engineers round now and no one can solve the problem.

BG engineer fitted new pcb today - no change - boiler flow temp still 60 deg C - anyone any ideas before I call them back?

Andy

I had this exact issue with my own Potterton Suprima 100. I had two different engineers who tried replacing (1) a thermistor, and then (2) the PCB (tried two of these, on different occasions). Neither of these fixed the problem. Replacing the PCB appeared to fix it, but the fault returned about a week later.

I finally managed to fix the issue by replacing all the wiring... So if you get a new PCB, make sure you also actually USE the new wiring harness at the same time. Don't just change over the PCB. The problem is likely to be caused by old/poorly connected wiring.

After I'd put in the new wiring harness (effectively replacing each wire in the system), the problem went away and has never returned.

I did this in Dec 2017, and the boiler is still functioning perfectly three years on...

So glad, as I'd spent ages trying to isolate the issue, and was just about to replace the boiler.