Potterton Puma 80, CH slow and only lukewarm

[rolyatescort]

Hi Guys,

I have been posting and researching on here for some time now trying to get to the bottom of my central heating dilemna. I have also had paid professionals in to no avail.

I have the above mentioned combi running 8 rads (4 up & 4 down). HW system is excellent but CH is pitiful. When i inherited this system from the previous owner it was 1 year old (now 4). The house was always cold and there was always one downstairs rad that did not work.

I read up on BTU's etc and found that nearly all the rads were grossly underpowered for the rooms they were in. I worked out what each room required and then set about replacing where necessary, with double convector Henrads/Stelrads. I'll mention that at this point i checked the boiler specs in the owners manual to make sure it could cope with the extra work.


Now the boiler takes an absolute eon to get the rads hot (approx 3 hours for the whole house) and the front room rad will not work at all if all other rads are switched on.

I have balanced the system several times and had it balanced by a plumber, no difference. To balance i have followed the instructions off here, namely open the problem rad all the way up with all others closed, after it has warmed, gradually bring in the other rads opening their valves only as far as required to bring the heat through. However little or much the other rads are open the first one will still go cold.

I have repressurised the boiler with a bicycle pump to the correct pressure.

I have tried many times to bleed the pump, but it never actually bleeds. I can loosen the big black plastic nut as far as possible but nothing ever happens.

What am i missing? As said i have had a plumber out to this to no avail. What is the problem? I am at my wits end as is the missus who is now turning to ice...

Help...

P.s. apologies for the long post but i wanted to give as much detail as possible.

 

[andsam]

Sounds like the wax capsule in the diverter valve may be sticking. This should move depending on what is calling (heating or hot water) . A dripping tap in the property could also cause a similar problem .Try turning off your water supply either to the boiler or at your stop tap to see if your heating improves.

 

[rolyatescort]

thanks i'll gove that a try.

 

[rolyatescort]

Right, i have given that a try and it didn't appear to make a difference all that happened was i lost a lot of pressure and the rads stayed the same. I repressurised but it made no difference.

Any other ideas?

As original post am i doing something wrong when bleeding the pump?

 

[andsam]

I dont understand how did you manage to loose pressure from your system by turning the mains water off. Idont think you will need to bleed the pump as your hot water is working ok. I would still suggest either a dripping tap or sticking wax capsule.

 

[ChrisR]

Try heating the front end of the diverter valve, where the wax capsule is . Heatgun or blowlamp - your risk! It's diagnostic only - if it works, you still need the wax capsule!

 

[rolyatescort]

I'm not sure why or how i lost the pressure but i did. I turned off the HW outlet at the base of the boiler, was that correct?

If i was to try heating the diverter valve what result would i be looking for?

Where is the diverter valve?

Cheers

 

[rolyatescort]

Any more ideas?

 

[shaka]

divertvalve is problem same thing happend to me got one for £84 hrp works fine just make sure u buy extra washers as old ones fall apart.

 

[ivor7]

i had the same problem under the boiler on the flow and return pipes there is a pipe that goes between them with a gate valve on turn valve completely off and try heating to see if this is your problem it worked for me as it was sending water straight back to the boiler without much getting to the rads.