Slow flowing CH

[DWPlumb]

Hi Guys

A customer called me out this week after having just turned on their CH, usual story rads not too hot. I've bled them and released a lot of air which did the trick, but not for long. The pump is working fine, The rads nearest the HW cylinder are constantly hot but as i follow them down the line the heat tails off considerably. The F & R pipes into the boiler (stove) and HW cylinder are nice and hot. I have removed offending rads cleaned them out and in a couple of cases changed the TRV's and valves where they have been crudded up. When I open the valves with no rad I get lovely hot water but when I replace them it is though there is no flow through them at all. Any ideas, power flush perhaps? There is no air that I can find in the system and as far as I am aware the valves have not been fiddled with from the previous year.

Cheers Dave

 

[gas sam]

yeah sounds like it needs a flush. water might flow hot with the rad off but pressure is forcing the water out. when the rad is connected only the circulation pump is pushing the water round. if the pipes are restricted the pump will be inefffective. before you go down this route be sure pump is good. balance rads. check flow and return temps. if they are over 25oc difference then its suggesting circulation problem. have rads ever worked. could be pipe sizing. All that said it sounds like the system is pretty mucky. just be sure as you can thats the problem before you start work.

sam

 

[DWPlumb]

That is my gut feeling too. Many thanks Dave