Hello - hope someone can help me with this query...
Bought an older house that came with a solid-fuel Rayburn as the heat source. The boiler only has two tappings, but there is a gravity DHW loop and a pumped CH loop.
When we first arrived, there was no injector tee on the system so when the CH pump was operating (it's on the return side of the boiler), it would drive the water backwards through the DHW loop and cool the cylinder. Having installed the injector tee, only the rads nearest the boiler on the 15mm CH loop will warm, and the 28mm DHW loop seems to receive the vast majority of the energy from the boiler and circulation from the pump.
There seems to be much more back-pressure from the CH circuit, making the pump 'choose' to circulate mainly through the DHW loop, and fail to drive the water all round the CH circuit.
FYI: the cold water feed tees off the return side of the cylinder coil, and the expansion tube tees off the feed side of the cylinder coil.
Is it possible to install a zone valve that isolates the DHW loop when the cylinder is warm enough? My worries are:
a) Can I install it without putting a valve or pump in the cold-water feed or expansion paths?
b) I've seen a diagram showing a valve between the feed side of the cylinder coil and the expansion tee. If that valve was closed, wouldn't the pump then drive the hot water into the expansion tank?
Any help gratefully received...
Bought an older house that came with a solid-fuel Rayburn as the heat source. The boiler only has two tappings, but there is a gravity DHW loop and a pumped CH loop.
When we first arrived, there was no injector tee on the system so when the CH pump was operating (it's on the return side of the boiler), it would drive the water backwards through the DHW loop and cool the cylinder. Having installed the injector tee, only the rads nearest the boiler on the 15mm CH loop will warm, and the 28mm DHW loop seems to receive the vast majority of the energy from the boiler and circulation from the pump.
There seems to be much more back-pressure from the CH circuit, making the pump 'choose' to circulate mainly through the DHW loop, and fail to drive the water all round the CH circuit.
FYI: the cold water feed tees off the return side of the cylinder coil, and the expansion tube tees off the feed side of the cylinder coil.
Is it possible to install a zone valve that isolates the DHW loop when the cylinder is warm enough? My worries are:
a) Can I install it without putting a valve or pump in the cold-water feed or expansion paths?
b) I've seen a diagram showing a valve between the feed side of the cylinder coil and the expansion tee. If that valve was closed, wouldn't the pump then drive the hot water into the expansion tank?
Any help gratefully received...