heating problem

[allybongo]

I have a combi boiler with tank in the airing cupboard.  The radiators are turned on but only the bedroom and bathroom rads get hot when combi is on continuous, while the lounge radiators are stone cold.

Any ideas on how to get the lower radiators to heat up.  They do not need bleeding as I've thought of that.

[Mortartube]

As obvious sounding as this is, are they turned on? One of those things it's possible to overlook. Otherwise the actual whole system may have an airlock or a sluggish, faulty pump may be to blame.

[dougielogan]

Go to the cold rediators and on the top corner left or right there will be a bleed valve, use a bleed key to open the valve and expel the air and the radiator will heat all the way to the top. You can get these keys at B&Q or I use the one that I use for an old clock.

[sddsddean]

Have they been off for a while and do you have thermostatic valves on them ?(They are the louvered things about the size of a plastic cup). If so, the valve could be stuck (at least one of my rads does this every year). At the bottom of the 'plastic cup' you have a number ring (to set it) and below that a knurled collar that screws the 'cup' to the pipework. Unscrew the collar and lift off the 'cup' assembly. You will see a little brass pin in the centre of the valve. Tap this very lightly with a hammer and you should see it pop up a bit. Re screw on the 'cup' assembly and hopefully it now works.

[gucciman]

if you've tried bleeding the radiators and the previous answer of unsticking the thermostatic valves (unlikely that all the ones downstairs would stick at the same time ) then it could be that your pump is on the way out ( they do not last forever ) the reason the upstairs radiators would be hotter than the downstairs is that heat rises.

[Tim B]

It's possible that your upstairs radiators are being fed by thermo-syphonic circulation if the boiler is lower than them and the pump is not working. (hot water rises)  At this time of year when the pump has not have been on for months it may easily jam. It is usually cured by a plumber giving it a good belt with a piece of wood ( not a hammer) or, if there is an access hole, by turning the impeller to get it started.  It can be prevented by using a proprietory addative to the primary system.