air getting into system

[del15]

hi all. can someone please help me!!!!!!!!?????
have been to a house whose heating pump needed replacing.When got there sounded as if pump was hunting.Changed pump head 15/50. 2 days later had to go back,heating gurgling bled system called back again drained system refilled + inhibitor,called back added leak sealer.F&E tank full heating fill not blocked no sign of leak but still air getting in.Seems to be on hot water side not heating.Please any ideas welcome

 

[gas4you]

Any auto air vents that could be 'sucking in'. Are you 150% sure no blockage in fill pipe at T with heating system?

 

[del15]

hi dave
definately no auto air vents only manual.
feed pipe not blocked as drained down and refilled

 

[x-man]

If the air is getting in the system when hot water demand is made via boiler try turning down the pump speed as it sounds like air is being pulled down the open vent

 

[del15]

hi x-man.
tried pump on all settings no difference old system no probs before so not installation prob just started

 

[x-man]

so did you leave the pump on speed 1 and get called back day(s) later for this same problem

 

[del15]

yes. air in system on hot water side. gurgling and sound of running water. pump hunting. when put hot water & heating on have to bleed 3 rads but then same again next day

 

[Slugbabydotcom]

Fitting a de-aerator puts the vent and feed close together thus eliminating the probable cause of sucking in at the vent.

If you need to prove that it is sucking in at the vent then put a cap end on the vent for testing purposes only. Leave it for a few days and see how it goes. Dont panic ... the water can still expand up the feed pipe and allow for expansion. This feed pipe will be too small for you to leave it that way in case it does block in future; so don't be tempted.

If theres a leak on the negative side of the pump when the system is turned off then that could be the air source when it is running. So check pump inlet valve and rad valves

 

[x-man]

Just read your post. You say that the problem was not there before. Are you sure you have fitted the pump the right way round.

 

[ChrisR]

Check properly(!) that the feed pipe isn't partly blocked. Have had this where you change the pump and it pumps better and starts sounding airy. Clearing the feed pipe junction clears it. Often a drain cleaner up the pump valve will get there without cutting pipes. If it's an "H" it'll be a straight run.

 

[Soggy_weetabix]

Fitting a de-aerator puts the vent and feed close together thus eliminating the probable cause of sucking in at the vent.

If you need to prove that it is sucking in at the vent then put a cap end on the vent for testing purposes only. Leave it for a few days and see how it goes. Dont panic ... the water can still expand up the feed pipe and allow for expansion. This feed pipe will be too small for you to leave it that way in case it does block in future; so don't be tempted.

If theres a leak on the negative side of the pump when the system is turned off then that could be the air source when it is running. So check pump inlet valve and rad valves

Had customer on Wednesday did what you advised. ( I said baloon - I guess he had none)

On inspection, a tight fitting condom was over the O/V

He now has a system that not only wont allow the ingress of air, but will now be 99.9 percent sure it will not reproduce

David

 

[del15]

thanks to all you guys who have answered. Your advise is appreciated. Am going to look at heating fill for blockage and go from there. Any more thoughts welcome

 

[gas4you]

Fitting a de-aerator puts the vent and feed close together thus eliminating the probable cause of sucking in at the vent.

I would go with this at the same time and move pump close to it as M I's, possibly also change cold fill to 22mm. Something about cold fill should in theory hold 3% of system water or something