RADAIATORS HOT SOME NOT!!

[sticklebriks]

Hope someone can help!! My central heating is on the blink in such a way that none of the downstairs radiators are heating up and only 4 out of six upstairs are heating up.
It is an oil fired central heating system with the boiler in the utility room.
The boiler is working and there is sufficient oil in the tank.
Could it be the pump going inop and if so can you take it out without draining the system? Why are some radiators heating up upstairs ?Confused !You bet

 

[Softus]

The boiler is working and there is sufficient oil in the tank.
Could it be the pump going inop...

Yes. This is the most likely fault given the information you've posted.

...and if so can you take it out without draining the system?

In theory? Yes. Close the pump valves and remove the pump.

In practice? Most pump valves don't survive for the life of the pump and they fail to close off properly. If the flow is a dribble then it's possible to cope with trays, buckets, sponges and towels, but the pressure will be off you if you drain down.

Search the forum for pump changing - it's a common topic and the job has a small number of common pitfalls.

Why are some radiators heating up upstairs ?

Generally because hot water circulates as a result of convection, but only a small proportion of what the pump can achieve, so there's not enough flow to distribute enough heat energy to the downstairs rads.

 

[sticklebriks]

SOFTUS
Thanks for your help Bud.Much appreciated.I am a novice as far as central heating is concerned but can use a bit of logic when working out mechanical problems and the pump seemed the most likely problem!

I have just had a look at removing the pump and there are two isolating valves either side of the pump which makes life that wee bit simpler.
If I remove the pump what are the chances of getting it working again by flushing thru with fresh water or cleaning etc.etc. !?
Thanks again

 

[Softus]

I have just had a look at removing the pump and there are two isolating valves either side of the pump which makes life that wee bit simpler.

Er, be careful - don't assume that those valves will work; usually they don't entirely shut off.

If I remove the pump what are the chances of getting it working again by flushing thru with fresh water or cleaning etc.etc. !?

In my opinion? Absolutely zero.

Note that on some pumps you can remove the body - for example Grundfos bodies are retained by four Allen-headed bolts. You can replace this type with a new one without dismantling the pipework, but you still need the valves to work (or else you must drain down).

 

[sticklebriks]

Thanks Softus
I replaced the pump yesterday and the heating is now A1 again.Infact the radiators are all now alot hotter than they used to be.Happy days are here again!!!
Thanks for all your help and info.Really appreciated Bud.

All the best

 

[Softus]

You're welcome!

Just remember to set the pump speed to the minimum necessary for all radiators to get hot.