worcester heatslave 15/19 air in system

[manortim]

got a customer with a heatslave 15/19 oil combi.

issue is it keeps filling with air. it has if someone removes the water and tops up with air.

the pressure on the gauge doesn't drop or rise a great deal. the customer bleed the air from the rads and topped it up from .5 to 1.5bar.

i checked for any signs of air entering the system but was unable to do so. so i installed 2 autoair vents, drained the system that wasn't too dirty and then refilled plus 2x big bottles of inhibitor. bleed everything including water jacket and so on.

everything was fine and perfect for 4 days then he had to bleed the water jacket and a bit from 2 rads.

3 days later same again.

any thoughts?

BTW, presviously to me, it has had new hot water jacket, new expansion vessel (15psi cold) and new PRV.

 

[Terrywookfit]

What condition is the pump valve on suction side?

 

[wilhelm]

Are you sure youve bled from every bleed point on the boiler, Im sure heatslave has a few?
and if it doesnt im wrong.

 

[holty]

like terrywookfit says whats the pump valve like on the suction side, seen alot on the heatslave pump valves leaking reacently must be one of them bizzare things ,also have you bled the main heat exchanger. on the heatslaves theres about 4-5 bleed points