Radiators no longer heating up after cold weather

Question

I have a Worcestor Danesmoor boiler that lives in a stone outhouse and heats the water and radiators in my house.

The heating is set to come on at certain times of day, but during some recent cold weather it stopped coming on. I tried pressing the manual reset button a few times, but assume there was something frozen in the system somewhere as it would just turn off again. Once the weather warmed up to above zero, the boiler started coming on again as usual.

However, since this happened, three radiators in different parts of my house have stopped heating up. The rest of the radiators in the house are working fine. I know the radiators were all working properly before the cold weather as I had recently bled them all and checked. One of the radiators that doesn't work will sometimes come on if I leave the heating on long enough, but then starts to cool again. All of the radiators have thermostat valves.

I noticed that the boiler pressure had dropped a bit, so increased it back to the recommended level, but this made no difference.

I can't find a plumber to come out for at least a week, and was wondering if there was some quick solution I could try to get the radiators working again?

Any advice much appreciated.

Answer 1

I assume that this heating system is hot water and not steam since you said that you bled the rads. That said, when the boiler is working and most of the rads are hot, try bleeding the ones that are cold. If water comes out of the bleed valve then there is enough pressure in the system. If not raise the pressure. At that point, the problem is probably water flow. You could have bad thermostatic valves, frozen or plugged lines, a bad circulating pump or something else. Try this and let us know the results.

Answer 2

Here is a great Boiler Troubleshooting Tool that walks you through several issues, depending on your boiler model. Also, a link to a video regarding cold radiators.