Hi,
I've got a problem in my house. Yesterday we decided to turn central heating on. On ground floor all radiators are OK, but first floor ones remain cold. I am going to try to check if there any air stuck in them. But if not, what else can I do? If it is important; we have a boiler in the kitchen downstairs and water tank is on the first floor.
Many thanks.
Assuming you've got a vented (not sealed) system, you will have 2 tanks in the attic - a large cold water header tank for the hot water system, and a small fill & exansion (F&E) tank for the heating system's primary circulation circuit.
Chances are that the ball valve has stuck on the F&E tank - and that it has failed to open in order to make up the water level to compensate for evaporation an/or slow leakage. So check that first, and make sure that the outlet pipe at the bottom of the tank is covered by 2 or 3 inches (it doesn't need a lot) of water, and that water flows when you press the ball down.
Then bleed the upstairs radiators. If that doesn't work, you may still have some air trapped in the pipes. You can often free this by turning off all the rads, and turning on just one problem rad at a time - so that the full pump output is directed through it.
I was just about to post a similar question - my downstairs rads are cold, the upstairs only warm. This seems to be causing my boiler to trip out with it's overheat protection. It's a Keston 130 and seems sensitive to this, it's also been blowing water out throught the vent valve.
Do you mean that it's a non-vented (pressurised) system - and that it's discharging water through it's safety pressure-release valve?
If so, you've almost certainly got a problem with the expansion vessel. With the water system at zero pressure, check the gas pressure in the expansion vessel using a car-type pressure gauge. If water comes out of the Schrader valve, the diaphragm is shot, and you need a new expansion vessel. If water
*doesn't* come out, but the pressure is low, pump some air in with a car tyre pump, until the pressure is about 0.7 bar (10 PSI). Then connect the filling loop (it *isn't* connected all the time, is it?!) to pressurise the wet system to 1 Bar (cold). Hopefully, when the system heats up, the pressure will remain under 2 Bar - with no further loss of water, and all the rads will work. They may need bleeding again - after which you may need to top up the pressure again with the filling loop.
yes it's pressurised but i'm not sure which valve is releasing. There is a pipe that runs to the outside of the house which can be used to manually dump water from the system (and i suspect is the safety pressure release you're talking about).
There is also, on the pipe above the boiler, a little pot shaped thing (a bit bigger than a 35mm film canister) with a red plastic knob on top that can be screwed down. the last time we had an engineer in (to reroute some pipes) he unscrewed this, which must have been closed since we moved in) and said it should be open. i understood this was to let air out of the system - it's this valve that's been blowing a bit of water.
OK, I may have misunderstood.
AIUI, the valve you describe should only be open for a while after initial fill until all the air is purged, and then kept closed.
What pressure is the pressure guage showing when the system is (a) cold and (b) hot? The filling loop *is* disconnected, isn't it?
Does your system have inhibitor in it? Do you get air collecting in the radiators?
That's an auto air vent. See the Sealed CH system FAQ below for full details. Especially the section about never filling up.
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