A have an old style central heating system (no combi boiler) and 2 days ago all my radiators stopped getting hot (except for 1 radiator which is warm (it is the radiator furthest away from boiler. The boiler is making a lot of noise like it is banging/bubbling. I am wondering whether there is enough water in the system. Hot water is fine. I have bled the radiators but not much air came out...
Any ideas greatly appreciated !!
Can you give any more details about the system, does it have motorised zoning valves, does it have an expansion tank and if so id it at least half full of water, what sort of timer control does the boiler have, do you what the make of the boiler is and how old the installation is ?
-- Reply to group please.
begin .......nothing!
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We need to know more about your system to give an informed opinion.
You almost certainly have a vented system, which will have a small fill & expansion tank in the attic. [Don't confuse this with a large header tank which feeds the HW cylinder - the F&E tank is much smaller].
The F&E tank should have about 3" of water in the bottom when the system is cold. If the ball valve has stuck, the water may have all leaked or evaporated and not been replaced. So make sure that the ball valve is ok. If stuck, unstick it, get some water in the tank and re-bleed everything.
If that's not the problem, it could be the pump. Without much system information, I'm going to stick my neck out and assume that you've got a gravity (convection) hot water and pumped central heating system. If I am right, and the pump packs up, the HW will be ok (because it doesn't use the pump) but the radiators won't get hot - apart from any which might get a bit of gravity circulation.
When the heating is supposed to be on, the pump should be rotating. There is a cap on the end which you can remove with little or no leakage, and you should see the shaft rotating. It it isn't rotating, it's either duff or it isn't being powered due to a fault in the programmer or room thermostat (if fitted) or in the wiring.
If this *isn't* the problem, come back with further details of your pipework layouts and of any zone or diverter valves fitted. [Have a look at
Hi, Boiler is a Flamingo model about 18 years old. I have put a new grundfos pump on the system about 6 months ago. I dont think it has motorised zoning valves. I will check level of water in the expansion tank tomorrow morning. The boiler has a 'bleed valve' on top of it, should I bleed the air from that?
if it has expansion tank in loft check there is water in the system first
If the shaft on the end of the pump under the cap isn't rotating then it could be stuck, and a twist with a screwdriver may well free it - unlikely to be so late in the winter season to discover this though ! definitely worth ticking off the list of potential problems though.
Nick
I would add the list of possibilities, that the pump has siezed. If it is not rotating, you may be able to fix it. Usually there is a slot in the end of the shaft that set square described. If you turn the system off, you should be able to manually rotate the pump with a screwdriver in the slot. If the pump has simply stalled on a lump of debris in the water then this may get you going.
Even if it is rotating, there's still the possibility that the (ceramic) shaft has sheared at the impeller
":::Jerry::::"
Yet another M$ using twerp who thinks inserting *begin* with their reply amusing. Can't remember you ever having anything useful to say, so join my plonk-ers list.
You have presumably already checked your water tank but most likely causes are stuck or failed circulating pump stuck or failed motorised valve
I have had a bit more of a look. My expansion tank does have water in it, and is filling up ok. When I switch the central heating on, the circulating pump does seem to kick in and with my hand on it, the pump seems to be running, but I did not check that the actual shaft is spinning
John wrote:
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