Gravity Hot Water

[cornishgas]

Help, I have a problem getting gravity circulation going through an indirect cylinder. Rayburn LPG, pumped central heating with check valve on CH flow and pump on return, f&e feed taps into top of return at cylinder, expansion into top of flow at cylinder. Have tried to kettle system, back fill through drain-off and lots of other things. System is 20 years old, cylinder replaced 4 years ago with standard indirect model (not dedicated gravity coil) and has been working fine all that time. I'm getting heat to heat leak rad and all CH also heat at flow tapping on cylinder. Return remains at room temperature! Am tearing my hair out (whats left of it!!) Does anyone have any ideas? Thanks

 

[ianmcd]

seems you have tried most things , bit of a long shot as the air lock is in the gravity water and not the pumped heating but you could try reversing the pump it sometimes works good luck ian

 

[Dan Robinson]

Blocked tee where the feed enters the system.

Other than that you need a gravity coil. The fact that it worked at all is more by luck than judgement.

 

[cornishgas]

Thanks Ian & Dan, I'll have to put some sort of bypass past the check valve to enable the pump to be reversed but I'll give it a try after checking for a blockage on the tee. I was thinking it might be a new cylinder with gravity coil but its going to be a difficult sell. I drained down to put a new valve on the heat leak, filled up and it doesn't work, she thinks its me! Wish I'd used me bungs in the F&E now!!