Coil blocked or pressure problem?

[SYS49152]

Let me start by saying I know very little about home heating or plumbing so please don't ask me about valves etc

I live in an average 2 storey, 4 bedroom detached house, 8 years old. My hot water tank is on the first floor in the hot press. Beside it, is a red (expansion?) cyclinder with a pressure gauge on top of it. The pressure normally reads 1 when cold and 1.5 or so when hot. My pump is located at the side of my house beside the oil burner and runs at the middle setting (2 I think). Now onto the problem.

The top feed pipe to the cylinder coil (flow?) gets hot as expected, i.e. when the heating comes on. The lower pipe (return?) gets warm VERY slowly. Almost like the coil has a blockage. BUT... if I turn off some radiators, the lower pipe heats up rapidly, indicating to me, that there is no blockage but maybe a lack of pressure?? I tried filling the system a bit more with cold water but this doesn't appear to help any. When I turn the radiators on, the temperature of the return pipe starts to drop off again slowly.

Any ideas? Your help is appreciated.

Untitled

• SYS49152
• 8 Mar 2009
• 1

 

[seco services]

what happens with just hw on not heating ?

 

[SYS49152]

I haven't tried that tbh? What would that prove, if you excuse my ignorance?

In my boiler cabinet, I have 2 mains plugs, one for the pump and one for the boiler. Do you mean switch off the pump and let the water feed itself around the system?

 

[gaspro1981]

my first thoughts would be that the tapstat is partialy stuck shut

 

[poolebybirth]

or the gate valve on the primaey return pipe is not open enough (try opening half way) - the htg can be stealing a lot of the heated water from the boiler

 

[SYS49152]

If by "tapstat" you mean the silver knob, the bypass pipe below it, is "cold" normally. I tried adjusting this knob and the pipe then get really hot. So it appears to work ok i.e. cold pipe normally, hot when adjusted down.