No central heating, hot water fine

[deedee9]

Wonder if anyone can help :

I have a Potterton Puma 80 (Perm pilot). Essentially boiler seems to work fine on the operational and hot water circuit but radiators do not warm up. Had been fine and only occurred yesterday. Have read previous discussion (eg breezer) who had similer problems but I'm a bit confused.
Troubleshooting guide suggests the Thermostatc Divertor valve (Wax assembly Part) within the unit may not be working but I think there is a possibility (from breezer discussion) that the pump is useless. I have already undone the knob on the front of the pump and the impellor feels to be turning. Also it is getting 240V.

I also note that when running the hot water tap the first slug of water is indeed very hot and then cools down to control as normal.

General operation at moment is such that with central heating turned on, no radiators warm up but unit fires up occassionally (presumably to warm water in immediate circuit) then fires down. This would continue all day but no warm radiators.

I'm a little confused. is there any way I can check either item or just replace both ?

Many thanks (Please be gentle with me I'm not fully conversant with these things)

Thanks for any help offered, deedee9.

 

[ChrisR]

hmm well when the pump fails you do get a slug of HW, which stays hot.
Pumps which fil usually stop turning, too, so it sounds more likely the DV.
You could try disconnecting the pump to see if it makes any difference!

Trick with lazy DV is to heat up the front end where the waxstat is - might make your rads hot. Its usually the valve internals sticking rather than the waxstat itself.

 

[breezer]

If it is of any help, i would have put money on the wax valve thing being at fault, but as i mentioned it turned out to be the pump, (as also mentioned i saw it's impellar was broken when the bg man took it off)

would it not be easier to release pressure (thats what bg man did) put bucket on floor and open pump?, seeing as pump is held in by 4 allen screws, at least you will eliminate it, and it will only cost new pump seal. (i presume, i never watched new pump go on)

 

[deedee9]

Thanks guys. From breezer's experience I picked up a pump this morning. Will check it out this evening and advise. If that doesn't work then yes surely it's got to be the divertor valve assembly.

Thanks again, I'll let you know how I get on (hopefully tomorrow ...)

 

[deedee9]

Summary of findings / solution :

Pump - this was replaced but found NOT to be the problem. Had I known, operation of pump can be checked by undoing end cap and pulling bolt out slightly and then turning system on. Spindle should rotate. This says pump is working (unless of course its impellor is broken as per breezer issue).

Wax Capsule Assembly - replaced this and Central Heating System now works fine. Relatively simple to change over by closing isolation valves on heating system and draining water from boiler only. Guess internals were somehow broken but not sure how as it is difficult to see inside.

Prices were about £40 for pump and £70 for Divertor Valve (as no longer sell Wax Assembly part seperately).

Many Thanks for help and support given, deedee9