air locking fortic

[aircon30]

Hope someone might be able to help, i recently replaced a fortic primatic in my wifes grandparents cottage, the new fortic was about 100mm smaller due to the price, the primary is feed from a wood burning arga via 28mm flow and return with no temp control, the fortic is only for DHW aswell. installation went ok but about 4 days later the DHW seemed to air lock advised by a plumber i put a hose from cold water tap to the hot tap at the kitchen sink and pushed the air which i could hear going back into the fortic and venting into the cold water cistern, as soon as this done the hot water pressure is fine and is ok for a couple of days and then system air locks again,i'm going to fit a aav on the DHW outlet at the highest point, would this help? and what would cause the system to keep doing this, is it kettling and blowing the heating air lock into the DHW side of the cylinder as there is no temp control on the primary?, if you need more info on the system please ask, i'm a air con engineer but will give as much plumbing info as i possible can. Cheers

 

[compheat]

when you say air locking do you mean air in the flow and return pipe's or air in the hot water outlet

 

[kevplumb]

header is running dry at a wild guess

 

[aircon30]

The system seems to be air locking in the DHW supply not the flow and return, and the header/ cistern isn't running dry either.

Cheers Lee.

 

[buck51]

I would double check that, I think you will find Kev is right!!! AS far as im awhere there is no other way for air to enter DHW side,
Unless you have a blocked cold fill pipe but its doughtfull