Room Stat problems

andya121 · 31 Jul 2006

Can anyone please help!!!

I have a Honeywell Plan Y system - V4073A Mid Pos Valve, T6060B Room Stat and L641A Boiler Stat with Potterton EP2002 Controller and Glowworm Mk II Boiler.

The room stat isnt controlling the boiler, mis position valve or pump?

The switched live on the room stat (supplied by controller) looks ok, as does the operation of the room stat (i.e switching power correctly). Whoever originally installed the system has used various types of cable / junction boxes and I cant work out how it is wired.

Where does the output of the room stat then go? (I had some building work done in the locale of the room stat recently and suspect the wiring may have been damaged)

I'm an Electronic Engineer and so will be able to sort it if I have an idea of the wiring schematic.

Many thanks for any help you can offer.

Cheers,

Andy

scatmanjohn · 31 Jul 2006

Wiring diagram here

http://content.honeywell.com/uk/homes/systems.htm

Good Luck

andya121 · 31 Jul 2006

Cheers, thanks for your speedy help

The schematic shows a junction box/wiring centre, is there a usual place for this to be located? I seem to have loads of junction boxes under my floorboards!

scatmanjohn · 31 Jul 2006

andya121 said:
Cheers, thanks for your speedy help

The schematic shows a junction box/wiring centre, is there a usual place for this to be located? I seem to have loads of junction boxes under my floorboards!

Could be anywhere.

From the fault you are describing i would be looking at the mid pos valve actuator.

Find the white wire from the actuator and check for 240V with the clock on CH only and the room stat calling.

If there is 240V but the actuator is not moving (take off the cover and have a look) you will need a new synchron motor.

andya121 · 1 Aug 2006

Thanks, I'll give that a proper looking into later...

andya121 · 1 Aug 2006

You were spot on with your diagnosis

Next questions, do i need to replace the complete valve or can I replace the internal motor?

If I need to replace the complete valve is this a do-able diy job for a non-plumber (i.e. me)?

Cheers,

Andy

scatmanjohn · 1 Aug 2006

Just change the motor.

//www.diynot.com/shop/SYNCHRON_MOTOR/6208

An easy job for a man with your skills.

andya121 · 1 Aug 2006

Job done, on order

Screwfix no longer appear to stock them so I got one from Keeptheheaton.com

Thanks a lot for your help

andya121 · 7 Aug 2006

Well I've fitted the motor and that appears to be doing it's job (i.e moving the valve when the room stat is on and off) but it's still not switching the boiler and pump on? Presumably that's done by the valve microswitches?

I'm highly suspicous of the operation of one of the two microswitches in the valve, it sticks, can you buy spare switches / pcb's anywhere?

Thanks for any advice you can offer

Andy

scatmanjohn · 7 Aug 2006

Ooops.

You can buy one of these:

But only if yours has got the little lump on the cover (see above picture)

If it has no lump then its a drain down job.

http://www.onlineplumbingsupplies.co.uk/acatalog/Motorised_Valves.html

You should get 240v on the orange wire once the valve has motored open.
If not its a new actuator i'm afraid.

diynot

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Room Stat problems

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