I have read
(http://www.gasman.fsbusiness.co.uk/f...ed_systems.htm) that on a
fully pumped open vented system the cylinder return must be the last
conection before the boiler. Why is this? I have this system but the
cylinder return is 3 radiators with trv's into the heating return side.
Is this going to work or should I extend the return back to the boiler?
(which will mean taking the floors up again). Or is there an easier way
around it?

Thanks for any help


Harry

On Thu, 09 Feb 2006 01:25:42 -0800, harry wrote:

I have read
(http://www.gasman.fsbusiness.co.uk/f...ed_systems.htm) that on a
fully pumped open vented system the cylinder return must be the last
conection before the boiler. Why is this? I have this system but the
cylinder return is 3 radiators with trv's into the heating return side.
Is this going to work or should I extend the return back to the boiler?
(which will mean taking the floors up again). Or is there an easier way
around it?

Thanks for any help


There is a possibility that if some of the radiators return before the
cylinder return _and_ some after the cylinder a problem will occur.
When doing HW only then some of the return water will flow backwards
through the 'upstream' rads to point where all the radiators have a
common connection on the flow side. Then through the remaining rads to
join the 'downstream' return connection. This will cause the house to heat
when not required. A confirmation that this is happening is that some
radiators will get warm starting from the side that's normally cooler.



--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html

Thanks Ed
Is there an easier way round this?
Whats stoppping an upstream flow if the cylinder return is first by the
boiler?

On Sun, 12 Feb 2006 02:45:31 -0800, harry wrote:

Thanks Ed
Is there an easier way round this?
Whats stoppping an upstream flow if the cylinder return is first by the
boiler?

Nothing. Either the cylinder should return after the radiators or the
radiators returns should join together before joining with the cylinder
return.

If the return pipework is not easy to modify then zoning the two sets of
the radiators (if that's a reasonable idea) would also fix the problem.

--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html