Expansion tank refill bypass fix

I have an original boilermate (23 years old) in my house and have had british gas out several times over last 12 months to look at boilermate. We were getting the water trickling noise as described elsewhere on this site and after researching online thought that the expansion tank on top might not be refilling correctly. When I mentioned this to the last engineer he looked and said water level was ok but that it was not filling and the internal pipe which has a small external outlet at the bottom of the main unit was blocked solid.

He suggested and carried out a repair which involved bypassing the internal pipe with an external one, this seemed to solve the problem at hand. However since then the cupboard where the system is stored is very hot and this new external pipe and the top expansion tank are also very hot to the degree that all of the upstairs of the house is extremely warm. I know we are having a hot summer but our house seems much hotter than before and obviously we haven't got the heating on.

Is this a fault caused by the repair that has been done or is this normal?

I have e-mailed Gledhill and have had a response saying that the repair that has been done is quite common but that a 'London Loop' should have been put into the pipe work, it should have a 180 degree bend before it enters the cylinder. Does anyone know what this means and is it correct?

London loop.
Means the water can not go up but down first the up
180 degree loop U
Mike

Thanks Mike.

Having looked at this pipe again last night it would appear that this loop has been done but the pipe and the expansion (f & E) tank are still very hot, is this normal and correct or is something wrong?

Yes they do get hot.
Yours was low on water until it was sorted.
So that is why.
All working ok?
You can if the unit is in an airing cupboard and loft above.
Cut a hole in the ceiling and put a open / close vent in to release the heat in summer.
And then if you wish some vents in the airing cupboard door, wall etc.
Smart one chrome or brass finish or white.
Then vent into landing / house in the winter.
Mike