Hi,
We have a single-pipe heating system. Several rads are new and have new valves (not TRV, just normal ones), all of which are completely open. All rads have bypasses under them.
Pipe leaving the boiler is very hot. Pipe returning to boiler is almost as hot. The feed pipe to every rad is very hot. The return pipe from each rad is cold. However the rads themselves are only warm-ish at the top, cold at the bottom. House doesn't get warm, even with heating full on.
I don't think it's a balancing issue: upstairs is as cold as downstairs.
What's going on, and what can I do to improve the situation?
Converting to a two-pipe system is unfortunately out of the question: oak and tiled floors which cannot be lifted.
My (inexpert!) diagnosis is that it does appear to be basically working, but the flow through the rads is poor. Being a single-pipe system it only has convection to move water through the rads, and this doesn't seem to be powerful enough to move much water. Most of the water is going through the bypasses, back to the boiler, almost as hot as it left.
I have one idea: in a few places I can get to the bypasses (two are above the floor and one is below a bit of floor I can lift). I could put isolator valves inline with the bypasses, which I could partially close to force the water through the rads instead. No idea how conventional this is - professional plumbers will probably be turning in their graves (if they're dead and still reading this) - although it does feel like it's probably work.
Advice much appreciated!
Thanks!
-Mark
We have a single-pipe heating system. Several rads are new and have new valves (not TRV, just normal ones), all of which are completely open. All rads have bypasses under them.
Pipe leaving the boiler is very hot. Pipe returning to boiler is almost as hot. The feed pipe to every rad is very hot. The return pipe from each rad is cold. However the rads themselves are only warm-ish at the top, cold at the bottom. House doesn't get warm, even with heating full on.
I don't think it's a balancing issue: upstairs is as cold as downstairs.
What's going on, and what can I do to improve the situation?
Converting to a two-pipe system is unfortunately out of the question: oak and tiled floors which cannot be lifted.
My (inexpert!) diagnosis is that it does appear to be basically working, but the flow through the rads is poor. Being a single-pipe system it only has convection to move water through the rads, and this doesn't seem to be powerful enough to move much water. Most of the water is going through the bypasses, back to the boiler, almost as hot as it left.
I have one idea: in a few places I can get to the bypasses (two are above the floor and one is below a bit of floor I can lift). I could put isolator valves inline with the bypasses, which I could partially close to force the water through the rads instead. No idea how conventional this is - professional plumbers will probably be turning in their graves (if they're dead and still reading this) - although it does feel like it's probably work.
Advice much appreciated!
Thanks!
-Mark