Help Rayburn Air lock

M

motorhomer

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I have a Rayburn connected to hot water cylinder indirect with radiators which turn on when at certain temperature. The system has been working for many years with no issues, but when I drain the system I get an air lock which sometime sorts itself out when the temperature gets to 90 deg.

I have drain the system yesterday to install a second radiator but this time the air lock will not budge. The radiators are turned on, I have tried running the rump continuously. At present the radiators do get hot but this also now blows into the header tank. I think the air lock is with in the cylinder coil and due to this the pump is back feeding the wrong way to the injector T.

Attached is a diagram, I was thinking would it be a good idea to put a gate valve 28mm where the pink star is on the diagram to close off when filling up. This should hopefully force the water through the cylinder coil and then open when full. Would this reduce the likely hood of an air
 

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Make sure your zone valve is closed and the pump off and slacken off the top connection on thecylinder. This will release any air. It may be a good idea to fit a bleed valve there anyway. Is the vent connection lower than the cylinder?
 
vent connection is inline with the top cylinder outlet. This is why I thought I would not need an air vent. I think the rayburn is filling up from the bottom and then up to vent outlet where it will lock air in the cylinder coil.
 
just done another drain and refill to see if it changes anything, Rayburn lit so waiting for water to heat up. May need to install more bleed valves in future and maybe fill pipe should go to bottom of the rayburn rather than the bottom of the cylinder coil
 
Are you sure it is piped as sketch.
The flow and return from boiler are reversed ie Blue should be flow Red return.
This should work on gravity circulation.
Depending on Boiler output. the radiator may be controlled via an overheat stat to prevent boiling.
The pump should be pumping towards the boiler, it would have been better fitted just before inj Tee on the return.
 
Yes I made a slight mistake on the drawing see new attached picture. Pump is pumping to wards Rayburn into T-injector into bottom of Rayburn. Been installed and working for about 15 years only issue is air lock when I drain it to do any maintenance.
rayburn2.png
 
As said Previously make sure M/v is closed and pump off when filling.
Personally I would not disturb the Primary flow connection on cyl.
Is the pipe rising from cyl to vent.
 
Just done drain and refill and got water temperature up, this time it cleared the air lock at about 80 deg and is running all ok. When filling I isolated the radiators then filled up and once filled took two buckets out of the drain connection bottom of Rayburn which allowed some air lock to move. Bit fiddley but its working ok now.
 
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