Help heating not working and snow outside!

[andymarkavery]

Hi

Our heating failed to work last night....

Symptoms:
- Boiler ok and heating the hot water
- Radiator pump pumping
- Valve at T joint in pipe is not doing its stuff....

There is a switch at the side of the valve which I can push up and feel like I'm driving some gears (dunno what's inside) and the radiators start to get warm.

So what is broken and how do I find out?

I figure it electrical fault as I can manually make it work. I don't really know how heating is wired up electrically though...
1) Obviously valve motor could be dead - is replacement a dry job?
2) What about wall thermostat? This feels old and doesn't give a positive click?
3) Something else?

How do I check without swapping things round? I'm not afraid of electrics and happy to buzz out mains if needed.

Hope someone can help

Andy

PS I've reduce the urgency by jamming a peg under the valve switch so it stays on...

 

[EliteHeat]

What does buzz out mains mean?

 

[andymarkavery]

I'm happy to go round with a multi meter to find out if 1) there is mains or another voltage 2) If wires are connected to each other 3) If there is a short where there shouldn't be.

I'm not really sure what voltage should be where....

If I put a meter across this switch I'm not sure what to expect so I don't know if its broken....

 

[Kev F]

your motorised valve has failed may just be the synchron motor which you can buy for around £10 - £30 pound, if it has a silver cover on you can change the motor if not you may have to change the whole head

 

[MANDATE]

Before spending anything, why not check out the room stat which you think is dodgy.
With CH switched on the room stat provides 240 volts to the valves 'white' wire. You can access this in the 10 terminal junction box (should not be difficult to find). Turning the room stat up and down should switch the power to valve on and off.

 

[andymarkavery]

Hi

Thanks for your help so far....

I can confirm that the thermostat on the wall is doing what it should.... I tested it direct and in the junction block... The result of the hot water and wall thermostat seem to go into the same place... is this normal? i.e. its 240 volts on the white cable unless both are off... Is it wired up wrong? Can anyone supply a simple diagram of the electrics on a home system I'm really baffled by this...

So after testing I'm starting to wonder what the point of this diverter is on my system... In the winter hot water and heating go on together in the summer I can pull the peg out so heating is off. The hot water has been fine today with peg in place and the radiators have been on and the whole system controlled by the two thermostats...

Having done all these tests it does indeed seem that the switch is faulty - Its a Honeywell 9020 Sundial Y Plan 3 pos diverter to quote the metal box.... Any idea where I can buy the motor from rather than forking out mega bucks for the entire unit? I assume not every synchron motor will fit?

Thanks again for the help

Andy

 

[MANDATE]

With the 'Y' plan you have 3 choices, 'HW' only, 'CH' only or 'HW with CH'
'HW with CH' means both sides are fed with water if both are in demand, but when 1 side becomes satisfied the valve moves so the non satisfied side gets all the water flow. So the valve will move accordingly.
In practice the valve will spend more time in the CH position because the radiators will lose heat much faster than the HW cylinder.
The valve is spring loaded so with no power going to it, it always returns to the HW position.
To get to CH only, It operates over two stages, first it goes to the mid point. It is driven there by the 'white' switched on by the room stat.
There is a 'grey' valve wire which can be made live by one of two actions.
When this 'grey' is live it takes over from the 'white' and drives the valve over the second stage. Whilst doing this it also triggers a micro switch which fires up the boiler.
If you select 'HW only' power from the programmer will go to the 'com' terminal of the cylinder stat, then from the 'not satisfied' terminal of stat to boiler.
When boiler is satisfied the power is diverted from boiler to the 'satisfied terminal of cyinder stat and this leads to the 'grey' mentioned above.
This 'grey' although live in this situation has no affect, because you have HW only and valve is not at the mid point.But it would have had effect if CH was also selected.
Of course if CH was on and HW was off then the 'grey' could not be made live through the cylinder stat. To overcome this problem, another wire is fed from the programmers HW OFF terminal to the 'grey' wire.
There should only be 1 other wire connected to the white wire if wired according to honeywell plan.
http://www.honeywelluk.com/lib/pdf/Wiring-Guide-Issue-14.pdf
You can get motors at Wickes and B&Q about £18.
When working on the electrics remember when HW and CH are both switched off, the 'grey' wire is still live so ensure power to boiler is off and fuse removed.

 

[Agile]

See if you have 240v AC across the syncron ® motor wires in the valve!

If so, then motor faulty! If not, look at controls.

Not everything in this world has to be as complicated as a solicitor pretends!

Tony



Snow in Dorset ?

Winterbourne Stickey