heating

[harrison_633]

Hi everybody

I have a potterton 80f boiler running hot water & heating. The system is fully pumped open vented. When i have the heating on i get air in the system. Ihave checked for leaks but cannot find any.A freind said it maybe coming through the vent pipe is this possible. IF so how do i fix it. all help most appreciated

 

[gasmick2]

it does sound like its sucking air down the vent a way you can test it is get a bottle of water fill it almost to the top go in the roof and put the end of the vent pipe on the header tank stay in the roof and get someone to turn on the pump if its sucking all the water will be pulled into the system that means the pump is prob up to high or the cold feed has been put in the wrong place and it could be even pumping over that will cause air and will also eat the system away eventually
it also depends where the pump is located because it will work on heads of water the higher the head the more the pump will work up to a max
try the bottle method and see what transpires from that test
it may need alterating and have an airjec seporater fitted that will give the correct combination of cold feed and vent and cannot pull air in or pump over

 

[harrison_633]

Thanks for your reply i will try the bottle and see what happens and get back to you

 

[harrison_633]

Hi i tried the bottle test.When the pump started it took some of the water then air bubbles came out and the water levell returned to normal.From this i assume its not sucking in air at this point. If i am correct can it be sucking in air somewhere without expelling water.The pump is located next to the hot tank.

 

[bengasman]

It won’t be drawing air in somewhere else. Read faqs,

 

[harrison_633]

You say it wont be sucking in air any where else, but could it be taking in air within the boiler ?

 

[bengasman]

You say it wont be sucking in air any where else, but could it be taking in air within the boiler ?

not even there

 

[Soggy_weetabix]

Can you install a non return vlv (the wrong way round) on the cold feed?

You must not fit it on the open vent!

An anti gravity vlv is best as there is less pressure to open it.

Dave