On Jul 27, 9:53*pm, Onetap wrote:


What's the problem, is there another boiler or a pump in the same
heating system?

The problem is that the woodburner back boiler feeds and returns have
been simply plumbed into the main central S plan heating arrangement
with plain T joints - at some considerable distance from the oil
boiler. The result is of course that the oil boiler ends up heating
the water in the back boiler (along with long runs of 28mm pipework)
as well as the rest of the house . I discovered this problem when
balancing the radiators after replacing several of them using one of
those clever infrared temperature thingys. The input temp at the
radiators was 5 degree C or more less than it should be.

I solved the problem initially using simple ball valves on the
woodburner flows and returns and remembering to open them when I lit
the woodburner - highly unsatisfactory (and potentially dangerous). I
had a heating engineer round about fitting a Dursley Neutraliser. He
seemed to know his stuff but couldn't really work out a way to sort it
without considerable expense.

The point is that we never need to use the oil boiler and woodburner
together. Also the woodburner is rated at a much lower output than
the oil boiler, and procuring and lugging into the room all the wood
needed to keep the woodburner going at full tilt simply does not
really fit in with our lifestyle. It isn't really necessary anyway -
it is a big house, but having the oil boiler running for up to 4 hours
in the morning, with perhaps the occasional topup during the day, is
adequate to keep it reasonably warm. The woodburner is in the room we
sit in at night, and a fairly small fire is enough for our needs.

The only fail-safe answer I can come up with is using 4 "normally
open" motorised valves, wired so they close when the boiler comes on,
but these cost a minimum of £65 each for 28mm valves as far as I can
see. So I was toying with the idea of just fitting two on the central
heating side of the woodburner pipework and somehow working out if I
could make do with non-return valves on the HW side - if such things
existed - hence my question.

At least I know they do exist now, I just haven't quite yet got my
head round where I should fit them and whether they would help.

Keith