Gravity Circuit Issue. Advice Appreciated

[Edgy]

Hello, I've just replaced an oil-fired range with a wood burning range. I have installed a gravity circuit in accordance with the maker's spec. I have water flowing very nicely around the circuit, however, it is returning through the cold water feed rather than the gravity return as the heated water is bypassing the sink radiator and water cylinder and venting direct into the f&e. I assume this is likely to be due to an air lock in the gravity return and wondered if there was any way to remedy without draining down and refilling.

 

[Toddyplumb]

You have got something wrong with your pipe layout or falls , any chance of a picture ?

 

[Edgy]

Thanks. A picture's virtually impossible as the pipes go through a three feet thick wall and then into the eaves.

I have the gravity riser going straight up 4 metres, a 45° bend to take it through the wall with another the other side. It then runs to the top of the sink radiator on a gentle upward curve and then on similarly to the hot water cylinder before rising about two metres to the f&e. The return side runs from the bottom of the sink radiator and the hot water cylinder below the level of the "hot" side with similar 45° connections either side of the wall.

The cold water feed is also higher than the cold water return.

Hot water is teeing into the sink radiator but not returning, likewise on the cylinder.

Any help gratefully received!

 

[ecowarm]

I think a sketch might help

 

[Toddyplumb]

Witout a sketch or picture difficult , but here goes .
You have teed to the heat sink and teed to the cylinder with the feed and expansion in effect at the end of the line and at the highest point. Gravity is working as it should and is heating your expansion tank !.
Take the feed and expansion back to the boiler , I am assuming you have 4 tappings, Top 2 gravity flow and expansion / vent. bottom 2 gravity return and feed.
When ever we install expansion tanks on pumped systems we always loop under the feeds to stop gravity circ

 

[Edgy]

Thanks. When following the installation instructions I did think the hot side would take the logical route so I should, in effect loop the feed side down before rising to the f&e after the cylinder tee to encourage water to take the correct direction.

 

[Toddyplumb]

Could really do with a sketch , if you cant get them back to boiler then on gravity and as long as there are no valves then just vent on the flow and feed on the return , and yes loop under the feed

 

[Edgy]

Many thanks for your advice, I now feel confident that I'll have the system running as it should.

 

[Plucky]

How do you mean loop under the feed?

Can you provide a sketch of what you mean? I have to install a system to a woodburner with pumped heating and gravity hot water and what you are saying is making me think I have things wrong in my head.

 

[justlead1]

Hi Water will not emerge from vent under normal working temp, providing the vent is taken high enough above expansion cistern and of course its a complete gravity system and no circulating pump is included anywhere.