Rayburn plumbing issue

[philallen]

I have got a solid fuel rayburn which has been plumbed in, according to the instructions, with a gravity fed system providing hot water to a cylinder and with a towel rail as a Heat Leak as per

problem that I have is that the cold water feed is ultimately getting hot, and is heating the water in the header/expansion tank. I would have expected the system to use the vent from the flow should it need to expand, and not use the cold water feed from the expansion tank.

Has anyone else had any issues with their rayburn plumbing, that can offer any advice?

Thanks F_Puuuu

[Andy Hall]

This is perfectly correct behaviour.

The feed pipe that you describe, is more completely described as the feed and expansion pipe. It is used to feed the cold water for initial filling and then to be the expansion path as the primary water heats up. This is a relatively gentle process, and if you look at the diagram that you posted, you will realise that the water level will slowly rise with expansion in the tank, and the level in the other pipe (the vent pipe) will also rise to be level with it, but not normally come out of the top of the pipe.

The vent pipe is used to allow escape of air during filling and as a safety device if Something Bad Happens and the water boils. Steam can then escape through it - won't be as gentle though.

During normal operation, there should not be any water coming from the vent pipe at all. If it does, oxygen is dissolved into the water and corrosion can occur. It shouldn't happen if the plumbing is correctly laid out.

Don't forget that corrosion inhibitor is really important.