Plenty of hot water but no heating?

[Ninty]

Hello All,

I must admit, I know very little about central heating, though I've just finished an electronics course in college, and would really like to get into plumbing at a later point,

Anyway, i've got a problem with the central heating at my mum's house. When you select "heating constant" or "heating timed" on the programmer (Switchmaster SM805) the heating just does not kick in. In fact, nothing actually seems to happen at all.

However, when you select "water timed" or "water constant", the everything kicks into action, the pump starts turning and the water heats up.

I asked a friend of mine about the lack of heating, and he immediately suggested that it was the pump, though as I said, when the water is on, the pump seems to be turning fine, and I can change the speed of the flow using the switch on the side, and the pump seems to react to this.

While clicking around the internet, other people seem to suggest that the problem may lie with the "diverter valve" or "change over valve". If this is the case, how would I go about testing these?

The image below shows the pump and what I think are the "diverter valve" or "change over valves".

My instinct was that it must be the programmer, though it doesn't work on either "heating constant" or "heating timed" and they are both separate buttons.

I've also fiddled with the thermostat, though that didn't make any difference.

If you need any more information, please let me know.

I look forward to hearing from everyone,

Nathan
Swansea

 

[tamz]

It needs a motorised valve for the heating side. You can't get a head for the ones fitted so you will have to change the full valve.

BUT

Since you are into a bit electronics, if you have a bit patience you can remove the head and take the cover off it.
Buy a synchron motor (thats what you ask for, costs under a tenner) and change it and put it back together. You may have to cut the wires (the orange ones) inside the head and join them with a bit connector block. Turn the power off before you start playing with it.
Go on, impress yer mum

 

[steadyon]

Two things worth trying before spending money:

1. You say you have fiddled with the thermostat. I assume you mean the central heating room thermostat. Turn it up to maximum, and turn any thermostatic radiator valves to their hottest setting. Then try the programmer on heating, constant.

2. If the motorised valves have a manual lever on them, latch both in the on position (they should move against spring resistance. At the end of their travel you should be able to move the lever slightly sideways to latch it). Try again with controls as in 1) above.