My rads are getting hot when just the hot water is on ???

[Mark Attridge]

Can anyone help with my problem?
I've just fitted new central heating with a new boiler in the garage and fitted a new control system with 3 port mid postion valve and pump in the airing cupboard. When just the hot water is on the rads start to heat up from the return side and the pipe that feeds the rads from the 3 port valve is only barely luke warm suggesting that the valve is not leaking.
Any ideas?

Thanks

mark

 

[scatmanjohn]

Try searching for reverse circulation.

Is it a brand new full system.

 

[Mark Attridge]

The system is 70% new.
I moved the airing cupboard and fitted a new boiler in a different location.
The pipe runs to the boiler are fairly long and the pump is in the airing cupboard. the returns from the cylinder and rads are joined under the airing cupboard and I'm wondering if I should have plumbed the return from the cylinder further down the line closer to the boiler?
How do you check for reverse circulation?

Thanks

Mark

 

[Rob]

i think you've answered all your questions youself.

 

[scatmanjohn]

The return from the cylinder should be the last connection into the system return before the boiler.

You have already said that the rads heat up from the return so you know that you have reverse circulation.

 

[Mark Attridge]

Thanks
I will have to sell a kidney to fund some more 22mm copper pipe and move the return further down the line.

Mark