central heating not working

If the voltage going into the pump is 240v ac then it should be running. If not it ought to be getting quite warm.... Often they seize up when not used in the summer and can be freed up by removing the large round screw cover (with a coin) and rotating the end of the shaft with a screwdriver. Do this with ch power off. There may be some water leakage when you remove the cover, its nothing to worry about but don't let it fall on anything that matters as it will stain. If the pump has burnt out, possible if it has been powered on whilst jammed, they they are fairly easy to replace as they have isolating valves either side. Get new one of equal or higher head rating (4/5m) from B&Q or similar. Obviously you need big spanner/wrench for pump connections.

Probably the pump. Could be the zone valve, although they might not have bothered to fit one. Even if they have, the controls should have been wired so that the pump only fires when the valve is detected to be open, but they might not have bothered to wire properly.

Christian.

But also check:

• the programmer - should be set to Heating On
• the room stat - should be set to a high enough temperature
• radiator valves - some fool may have turned them all off for the summer!

It's unlikely that there's no water in the system - otherwise the hot water wouldn't work. But check the small header/expansion tank anyway, and check that it's ball-valve works properly. [It should only have a couple of inches of water in the bottom when the system is cold - but the outlet in the bottom of the tank *must* be covered - otherwise air will be drawn into the system].

HTH, Roger

OK - I'll see if it's getting hot or not and that will tell me if it's burnt out or jammed ( I think ).

There's no room stat and there's no heat in the pipes leaving the boiler for the CH so I doubt the radiator valves so I think I'm OK there. Programer is OK - I checked it gets voltage at the pump and I presume that voltage is only there when the CH is on - I could check that to make sure it does turn it off just out of curiosity.

I've had a look at

There's a picture of the outside here, I think this link will work -

Thanks for everyones replies.

Peter

Yep. You appear to have gravity circulation. I would recommend upgrading this. The simplest method would be to add a 2 port valve, pump and cylinder thermostat. This will stop the water getting too hot, save energy and reduce boiler cycling. In the longer term, the systems can be combined when you replace the boiler with a single circuit controlled by the 2 zone valves. You then only need one pump.

You also say there is no room stat. Add one ASAP (and a zone valve if it has none) and make sure other rooms have TRVs too. You are wasting gas like it grows on trees.

Christian.

Peter Smithson wrote in news: snipped-for-privacy@news.cis.dfn.de:

I am no expert, but in my recent studies I came across this

If it is, then you need, like everybody has said, to look at the pump.

HTH

mike r

They share the *same* water - which gets heated by the boiler, and either flows by gravity through the indirect coil in the hot water cylinder - or by pump action through the radiators.

Pipes only get got (except for a small amount of conduction) when hot water flows through them. If there is no flow round the radiator circuit, the pipes in that circuit (the pair on the heating side of the boiler) won't get hot. You have to determine *why* there is no flow. As I said earlier, it is probably a duff pump - but it just *could* be that all the radiators are turned off - because this would effectively kill that circuit.

Roger

I think I've just got it going! I took that screw out and although I could not move anything in there - there was just a blank plate with a very slight indentation on it. So I tried to move it but no luck. I put it back together, turned it on - nothing. So I put the speed marker up to 3 from 2 and it's making a very slight noise and the boiler has kicked in! Just checked - the radiators are warming up. So thanks for the advice everyone - this is a nice news group.

Certainly seems like I need to invest in a new system a bit later although all the radiators have those thermostats on so it's not that wastefull a system. I think the annual bill is about £100 for gas (got an electric cooker).

Cheers

Peter

Slightly puzzled - I thought the OP said that all radiators had TRVs. If so, why do you need a room thermostat? In fact, which room do you put it in?

If I understand correctly, a room thermostat turn the CH off once a specific room has reached a certain temperature. At this point any other room which is below optimum temperature cannot heat up.

This leads me to deduce that the room thermostat should be in the room to heat up last and cool down first, so that all the other rooms are able to come up to temperature and then shut down the radiators via TRVs to keep at optimum temperature.

If this is correct then the remote wiring required to install a thermostat just to regulate one room seems pointless - just give this room a TRV as well.

Or am I missing something?

Cheers Dave R

To stop the boiler cycling through the bypass loop once the all the TRVs have shutdown because the house is warm. This cycling is using energy just to keep the boiler warm not the house. OK it will heat the house but it is heat which isn't required.

One without a TRV on the radiator. The hall is generally accepted to be a good place but there are almost religious debates about this from time to time. Otherwise your understanding of the implications of the room stat on system with TRVs is correct

Yes! The boiler and pump will continue to run unnecessarily unless switched off by a stat.

Unless, of course, you go for a Rolls Royce solution - and put a zone valve controlled by a room stat on each radiator feed - and connect all the zone valves' voltage-free contacts in parallel to control the boiler and pump. That way, you can conrol the temperature of each room independendly (like with a TRV) BUT also have the system automatically shut down when all demands are satisfied. [If you used a programmable stat in each room, you could even have different rooms heated at different times if this would be useful for your particular lifestyle].

Roger