Still reckon its reverse circulation !! that tee most likely although its difficult to be 100% without a look
you could try a flap type non return, as this is for low pressure might do it, but as you would need it vertical and the wrong way really might not work, could you fit it under the floor on a horizontal section ?
new connection in green that may be a better way but like 40 years says its hard without physically seeing the install
The GW Hide-Away as you should be aware has a much larger heat exchanger (less resistance than the new boiler)also the GW Hide Away would have a spreader dip tube in the return. Why not upgrade to an S plan which would be more efficient and save your mum some money.
Doing a Bit you could try a flap type non return, I may try that if moving the tee doesn't solve it, I could put it on the 'up' leg of the CH return (if you can picture what I mean) so I think it would work YNWA - unfortunately the picture you uploaded doesn't seem to want to work. Any chance you could try it again please? rome60 Why not upgrade to an S plan which would be more efficient and save your mum some money I mentioned that to her before I started, or even changing to a combi as it's only her and my old man there now. But she 'likes what she's got' And who am I to argue with my mother - she'd smack my legs! Thanks for all the replies fellas, I'll ket you know how I get on.
The spreader dip tube thats fits in GW Hide-Away boilers fits in the return conn,and directs the return water at a low angle to the front of the heat exchanger.This spreads the incoming water equally over the burner length.