Curious heating/hot-water prob

[WaterTight]

Thoughts on this please:

System boiler, glowworm floor-standing, old.

Two two-port valves.

3 story property.

Drained down for rad change. Re-filled - got quite bit of air stuck in system.

Back-filled by connecting cold in to f+e to the vent. Back-filled a bit, went round and bled a bit, back-filled some more - until got water out of every rad.

Fired her up. Flow gets red-hot as far as (but not including) pump. After another 10-15 mins or so the pump itself gets hot and the pipework directly after luke-warm. Give it another 10 mins and another 6 inches of pipe work gets tepid - but this is the maximum.

There is power to the pump and it is spinning, pump is bled. Pump valves are open. Port valves open.

Thought maybe blockage so drained down again and refilled. This time giving pump the old on-off as it filled to swirly things around a bit. Lots of air going round the place. This time rads filled on their own and bled well without any back-filling. System full.

Turned her back on - exactly same problem.

 

[papahape]

can you stop the pump with a small screw driver inserted in the bleed port , some pumps can begin to fail overtime and if you have 3 floors your pump needs to be putting out on full power .

What setting do you have on the pump speed and if you change this does it change anything ??
btw I would imagine that the pump needs to be a 6metre head if you do have 3 floors

 

[Deaf Cat]

Hiya,

Interesting to know the solution, the only things I can think of are the things you've done,
rad valves open, bleed them all, 2x2ports open even manually, sounds like a horid system to re-fill air lock wise.

A while a go I use the garden hose on the drain off to try and push any air up and out of where it should not be....

Good Luck!
DC

 

[mikegas]

have you tried shutting all the radiators down apart from 1

 

[Billy Bob Bob]

if possible take the pump head out,have seen impellers blocked with crud,even fibreglass does sound like a pump issue

 

[erj]

sounds like air, try this one, take the boiler state out turn boiler on till it starts to boill! turn boiler off and see if that moves the air, you might have to try it a few times

 

[Bernie2]

Hmm!

Removing the stat is an old trick and relies on the hot water expanding and blowing the air out. It can go wrong of course and blow more than air out so make sure its got a free flowing vent.