Potterton precision boiler problem

[colinmac]

Hi. I'm trying to resolve a problem with a 9 year old Potterton Precision boiler.

The problem is that it sometimes just doesn't start up when the controller calls for heat or hot water. There are no faults showing - the three diagnostic LEDs are dark - but there is power to the boiler. Generally, however, if I turn it off at the isolator then back on after a few seconds it will work fine, and will continue to work fine for some time - many hours or a day or two. But after being idle for a while the problem can kick in again, and another restart is needed.

The next step would be to get a refurb PCB, but is there anything I should try before that?

 

[terryplumb]

May not be the boiler ,but the control gear. What motorised valve/ s do you have ,is it a Y plan set up ?

 

[Mottie]

Generally, however, if I turn it off at the isolator then back on after a few seconds it will work fine, and will continue to work fine for some time - many hours or a day or two. But after being idle for a while the problem can kick in again, and another restart is needed.

Exactly the problem I had with a lazy motorised valve. Replacing the valve head cured it.

Odd problem with heating/boiler. One-off or something on the way out?

Odd problem, as above. Just got home from a weeks break. We have a sealed 'S' plan central heating system and unvented hot water. Vaillant ecotec boiler, Honeywell digital room stat, controller and motorised valves. When I went away I turned the hot water off at the controller and left the...

www.diynot.com

 

[colinmac]

Good info, thanks. The valve actuator is a Drayton MA1, and it's only a few years old. Can they be serviced, or is it best to just get a new one?

 

[Mottie]

Good info, thanks. The valve actuator is a Drayton MA1, and it's only a few years old. Can they be serviced, or is it best to just get a new one?

Have a look here:

 

[Madrab]

Sounds typically like the valve is at issue but would suggest it needs tested for correct live switching before looking to replace.

3 port valves are notorious for burning out after a few years and/or the microswitches become twitchy, it's down to the way they work. Cycling the power turns the switches off and on too, resetting them for a while.

Only real option is to replace, but before that happens though consider changing the system away from a Y plan to at least an S plan as you will almost certainly come across this same problem again.

 

[terryplumb]

As said ,testing should be carried out to confirm it is the MPV that's at fault before swapping parts .