Daily Pump Air Bleed!

[Bob Deverill]

Why do I get so much air in my central heating system? This is evidenced by the pump making whining and churning noises when the water is hot. Bleeding the pump immediately quietens it down for few hours(so pump not faulty) but this has become a daily chore.
We have not been long at this address and have inherited this rather dated but otherwise perfectly OK system. The Grundfoss pump is mounted about 1 metre from the boiler along a horizontal run of pipe (pump shaft correctly horizontal)across the garage ceiling, before turning up through the first floor to the airing cupboard, where there is the usual air trap and bleed point - a small amount of air is also bled off here daily. I had wondered if I was collecting steam and not air in the pump is this possible? also is its horizontal mounting making things worse (Grundfoss do say you can mount horizontally but prefer vertically)
Any help greatly appreciated.

 

[kevplumb]

fit an auto air vent
better still stop the vent dragging it in
also check the feed/vent config

 

[chivers]

I have a similar problem - I'm having to bleed my radiators every couple of days, plus they're a bit noisy due to the air moving around I presume. It started last year when I had to fit a new pump.

For some reason I have to have the pump on maximum power otherwise my water tank doesn't get hot, but at this power setting I hear water coming out of the vent and falling into the header tank every time the pump switches off.

I was very interested in these suggestions:

better still stop the vent dragging it in
also check the feed/vent config

How can I stop the air vent dragging the air in?
Also what should I be checking for in the feed/vent config?

Cheers!

 

[kevplumb]

raise the level of the vent expansion pipe if its pumping over

cold feed and vent pipe should be close together and both on the same side of the pump the incoming side

 

[chivers]

Cool, thanks. That all checks out and my vent can't go any higher.

I think that the pipe run to the hot water tank may be partially blocked, which is maybe why I need the high pump pressure (although I have no idea how it could have got that way.)

Do you think that power flushing ever helps, or do you think it is a waste of hard-earned cash?

 

[kevplumb]

try a chemichal cleanser in the system

http://www.gewater.com/applications/sentinel/ferroquest.jsp

 

[Bob Deverill]

Hi Kevplumb. Thanks for reply. I'm not an engineer so how can you prove if the vent is dragging air into the system and how would you prevent this happening? My vent pipe is pretty standard I guess and runs from the airing cupboard to the loft.

 

[kevplumb]

hold a glass of water under the vent
start the pump and see if it sucks it in

 

[PEDANTICVINDICTIVEMAN]

Central heating sucks, sooner we burn more fossil fuels and cause more global warming the better, then the uk will be warmer all year round and we wont need CH or the russkies bloody gas pipeline the terrorists are going to blow up every week.