ALL radiators cold but imput pipes hot

[PJF220]

Hi, been looking at my dad's heating today. Boiler fires, pupm pumps, mid position valve works, water pumps to the radiators but only a couple get mildly warm. All rad valves are open. Been trying to bleed pipework, but cannot fond any more air. It's a bungalow so no issue of upstairs and down. The settings on the fads have not been touched and used to work fine. Any ideas?[/quote]

 

[craig51]

MMm.. boiler make maybe? what type of system ie closed/open etc

 

[PJF220]

The boiler is a pottetton netaheat e50 and its a vented system. Hot water is fine, just the rads.

 

[craig51]

How did you test the pump, it might be spinning but not pushing too well? On tip, is to remove the bleed cap on pump (but basin under it) and gently inset a screwdriver ir similar. A healthy pump should not stop and kick it back out at you.

Does the the pipe to hot water get hot when only heating it on?

Edit, is there a bypass somewhere on the sytem?

 

[PJF220]

We suspected a pump as it was noisey so fitted a new one.. there is a bypass valve fitted after the pump.

 

[craig51]

You can try closing the bypass to force the water around the heating circuit.
When you are closing it (clockwise to close) count the number of turns it takes to do this,with the heating on! Wait for a couple 5 mins while observing the boiler. After 10mins, reopen the bypass as per the turns you noted. Report back and importanty keep a track of how long the burner stays on.