Cold radiators - Baxi back boiler gravity fed system

[jtsplumbing]

What about hot water ? if you turn off pump and just run boiler for hot water do the pipes to the cylinder start to get hot ? sounding like you have a sticking pump.

 

[hands2bfree]

hot water has been very hot as i have had the heat high.
due to this it may take a while to find out the answer to that question.
once the pump has run for a minute or so that popping stops

 

[Anton]

If the pump is ok, one other thing to lookfor is an anti-gravity valve on the heating flow off the boiler. It's a brass valve which in length, including the nuts is approximately four inches long. These are designed to stop the first floor radiators heating up via gravity circulation when on hot water only, ie summertime (assuming we get one)
They can get blocked up with crud/sludge etc and stop the radiators from heating.

 

[jtsplumbing]

Its a bit strange upstairs hot down stairs cold keep thinking its the pump, but these are just shots in the dark water must be curculating or up staires would not get hot, is the gas burner on boiler getting a good flame when on for heating is it the gas burner that is popping or the pump?

 

[hands2bfree]

i have left the ch running and now the rads are all cold, they lost there heat.
the flame is good.

ok this is what happens:

pipe with pump in line has a drain off tap on it.
pipe of same diameter runs next to it.

on start up the impeller slaps because it seems to be running dry.
the pipe running parallel gets really hot during this time.

after a minute the slaps stop, which makes the pipe that runs parallel cool down and then both pipes are cold.

now and again the pipe running next to the pump gets warmer - i guess this is when water is passing through it rather than air

should i drain the system?
or should i shut off all but one TPV?

 

[hands2bfree]

bump mmm bump

 

[tipintim]

Sounds like you have got a blockage in the boiler/pipework. Try chemically cleaning the system. Put it in and run for a few days.
Is the pipe work on the ground floor burried in the concrete?
Can you post photos of the set up you have

 

[hands2bfree]

the pipe work is buried in concrete im afraid.

ill post some photos

ill try chemically cleaning

thanks for your help!!

 

[tipintim]

Went to a job recently where the pipework was burried. No way of draining muck out and struggled to flush because it was a one pipe system.
Customer then remembered there was a drain off in the garden for this purpose. Have a look around the out side of your buiding. His was hidden by a step!!

 

[hands2bfree]

the only other drain off i have is at the boiler, but ill look around

 

[hands2bfree]

srry i ahve one drain off on rad near front door and the additional one mentioned above by the boiler