Suprima - advice needed

[noobdiyer]

Hi all,

Old suprima 70 boiler at home with a bit of a strange issue.

When I wake up in the morning, the boiler is off (solid red light). Wall thermostat shows it's calling for heat (little flame icon). Separate programmer is showing heating is "on". Thermostat is a wired type.

To remedy, I adjust the thermostat down, wait for the call to heat to stop, and then adjust back up. The boiler then fires up.

Just now to test, I turned the programmer to "off", and then manually turned it back to "on". The boiler fired up. So it looks like it responds to manual changes on the programmer, but not the automatic timed ones.

I don't mind replacing the PCB with the new 5111603 one, but want to make sure I'm addressing the problem. Sometimes it takes a few attempts to fire up, but I know it hasn't been serviced in a while so will get that done.

Are there any additional works/checks I should think of having done at the same time?

This has all started happening since we had a Fernox TF1 filter installed, along with 2 auto air vents recently. The boiler cover did come off as I think the engineer wanted to use a drain point, but decided not to as the one on the boiler was rusted up. I was watching everything and the cover went straight back on, so seems to be a coincidence...

Thanks!

 

[ianmcd]

link out your external controls first and see if that solves your problem, but if you still have the old PCB you will have to get it changed eventually

 

[nickso]

Er only if it's faulty

 

[Agile]

The new PCB should not be fitted by a DIYer as it involves work in the combustion chamber!

 

[noobdiyer]

Can anyone explain in slightly more simple terms what is meant by linking out external controls?

I'm thinking of replacing the old ACL LP722 with a new LP522 in any case (old one loses settings if we power off, and battery a pain in the @ss to replace). Would that have the same effect?

Wouldn't replace the PCB myself (though sorely tempted to) - just want to know if I should be looking at any other bits at the same time.

EDIT: Heating kicked in this morning, unlike previous mornings. Grrrr!!!

 

[ianmcd]

your boiler wiring control on the PCB will have a "loop" where one wire goes out to power any external controls and when they are in demand it will send the power back to tell the boiler to come on, linking out means removing the existing wires and put a short wire between the two terminals ruling out any external problems

 

[noobdiyer]

Hi all,

Just an update. After more testing, it looks like the problem is related to the motorised valve. It gets the signal, but either the synchron motor isn't working properly, or the physical valve is sticky.

My guess is that when the pipes are colder in the early morning, it doesn't make it all the way to the microswitch, but does when it's a bit warmer. Actually woke up very early, took the cover off the valve, and saw it struggling to reach the microswitch.

Going to swap the motor first, and then worst case replace the valve. Hope this helps some other poor soul!!

Thanks to all for the advice!