potterton puma 80 - no hot water

[Gasguru]

Your looking at the wrong part.

The flow limiter (restrictor) is a seperate plastic device to limit the water flowrate. I think it's located in the end of part 91 (92)...the isolating valve. Just cut out the center.

 

[ChrisR]

You've removed 64 completely?

If you loosen 64 where it goes to 98 and disconnect it at 84, you should be able to get lots of CW out of there.

The waxstat in 108 reduces flow until the water's warm. You can take it out.
Can't remember exactly how you'd do it but you need to check flow out of 108.
It may be a faulty waxstat, or it may be a really blocked heat exchanger. Is your water very hard? No one's suggested that so perhaps I missed something. ??

 

[Gavinth]

Your looking at the wrong part.

The flow limiter (restrictor) is a seperate plastic device to limit the water flowrate. I think it's located in the end of part 91 (92)...the isolating valve. Just cut out the center.

Okay, I see what you mean. The manual says the valve has an automatic limiting device and strainer inside which could well be partly blocked. Too late for me to do now but will let you know outcome tomorrow evening.

 

[Gavinth]

You've removed 64 completely?

If you loosen 64 where it goes to 98 and disconnect it at 84, you should be able to get lots of CW out of there.

The waxstat in 108 reduces flow until the water's warm. You can take it out.
Can't remember exactly how you'd do it but you need to check flow out of 108.
It may be a faulty waxstat, or it may be a really blocked heat exchanger. Is your water very hard? No one's suggested that so perhaps I missed something. ??

Thanks. No I didn't remove it completely, just plenty enough for a spray of water. I think it's a water flow problem. This only happened after a recent CH draindown. 2/3 weeks ago HWS was no problem and the CH is working fine. I'll see what happend tomorrow when I check the flow limiter/strainer as suggested by gasguru. Thanks again guys.

 

[Gavinth]

Thanks everyone. It was the restrictor/strainer in the cold water mains valve. When I took it out it was 'caked' with scale. Hot water (and heating) is now perfect. Is there anything I can do to prevent this scale build up as I am obviously in an area prone to this? I'm wondering what it is doing to the heat exchanger etc.

 

[Gasguru]

Just cut out the centre of the flow limiter/restrictor.

Not sure what are of London you're in but the water (despite feeling hard) has little adverse effect on Puma heat exchangers so don't worry about it.

 

[baxpoti]

I dont read the manuals but would set the switch to about 1.5 mm and NOT 5.5 mm.

5.5mm is the correct setting, measured from the brass to the end of the thread.