Thermostat issue

[stender]

Hi All,
I have a main thermostat on my wall in my main hallway and a second one in my conservatory working 1 radiator in there. All of a sudden the second one has stopped working. I bought a second hand same model off eBay as its no longer made and that was said to be working ok.
However after replacing it it still doesn't work.
I have no idea what else to check. I believe the wires goto my airing cupboard upstairs as there is a joint box on the wall which is where a bilermate was until I had a combo boiler fitted and that was removed.
Any ideas if theres anything else I can check? fuses anywhere etc... I have to assume the new thermostat works so don't want to buy another. I'm also concerned buying a newer model in case the wring is different. On this one there is a blue on 4. white on 3 and brown on 1.
Current thermostat is a Horseman HRT2

working main is a drayton digistat

Thanks in advance.

 

[stender]

If I do need to replace the thermostat can anyone suggest a suitable replacement which would use the same wiring?

 

[simond]

You bought one off eBay? Would you want a heating contractor to fit stuff in your own house from eBay?

A new Horstmann dial stat is only £10 plus VAT (HRT3).

 

[stender]

The HRT2 is discontinued hence why I had to buy secondhand. I could replace wiring like for like and paint wouldn't be affected. HRT3 didn't look same size or wiring.
I can get an HRT3 but how do i confirm both thermostats are knackered? No wiring has been touched in the house so shouldn't of been affected. I have a multimeter but no idea how to use it.

 

[Echo the husky]

Photos of the airing cupboard and joint box would be useful, this should be a very easy fix, but it depends how your setup is configured.

 

[stender]

Thanks Freddo. Apologies for poor quality pics!

So there used to be a boiler mate in here which was removed when i had a combi fitted so I assume the switch on left was for emersion and have never touched it. The box is to the right of it. I see one cable coming in which isn't connected to anything. Then have a cable which goes downstairs to I assume main thermostat or boiler???Thats the one you see going into the top of the joint box, 3 cables and the blue not connected anywhere.
You then have what I assume is 1 cable coming from wall behind the box which is connected to the bottom of the joint box. This has yellow, earth, blue and red connected.
Now again I am assuming the blue on the cable going downstairs connected to top of joint box which isn't connected to anything has never been connected? It hasn't been touched although the cable may of been knocked? The screw is open at top and doesn't look to of broken off.

 

[Echo the husky]

There doesn't seem to be much there, where are the valve(s) for the 2 heating zones? I want to see the valve wiring. What programmer do you have?

 

[stender]

Sorry no idea what you mean. I have a drayton digistat in hallway for whole house then this broken horstman in conservatory for 1 rad in there.
as i said nothing has been changed just the conservatory one stopped working

 

[Echo the husky]

Programmer= heating timer.
Drayton Digistat covers both programmable and non programmable thermostats, what model Draton Digistat do you have? When it was working, did this one need to be on for the conservatory to work?

The 2 thermostats are likely to control 2 motorised heating valves, one for the house, one for the conservatory. I expect the valve for the conservatory has died, so it doesn't open when the thermostat is turned up. It is also possible that it is set up completely differently. Without knowing where these parts are and what parts you have it is not possible to advise further. They could be hidden in the loft or under the floor, they could be right by the boiler.
What model of boiler do you have?

If you can't locate or identify the parts you will need to call in a heating engineer.

 

[stender]

The drayton is a digistat2. The boiler is a vaillant ecotec plus. We have never had the second one on when the primary wasn't so not sure if they work independently.

I found a valve under kitchen sink. That goes to a mains joint box.
Black power lead off valve and White power lead going to thermostat and mains cable. Looks to be one of these
http://www.screwfix.com/p/drayton-ma1-679-3-3-port-motorised-valve/81844


Thermo - White goes to valve brown
Thermo - Brown goes to red mains
Thermo - blue goes to black mains.

Valve - brown goes to thermo white
Valve - Blue goes to black mains.
Valve - earth to mains earth

it's a 2 way valve. I pushed the lever over and could then feel hot pipe either side. Rad is now getting hot in conservatory. Any ideas if this means the actuator needs replacing?

 

[Echo the husky]

The drayton is a digistat2.

This appears to have a built in timeclock.

what do the motorised valves look like?

This.

However the thermostat in conservatory physically stopped working i.e. the orange light it has no longer comes on. Would that be the case if the valve was broken?or would the light still come on but the heating wouldn't?

The light would still come on if the valve was faulty. As the indicator doesn't light, it looks light the problem is before the thermostat. Is there 240V between the blue and brown wires at the thermostat? If not you will need to check that any timer that feeds this is switched on (it might be the drayton one). There may also be one near or fitted as an option into the boiler.

If you still have no power to the blue and brown wires, you will need to find where the thermostat is wired back to, which is probably a junction box near the valve it controls.

 

[stender]

It's a drayton 2 way valve http://www.screwfix.com/p/drayton-za5-679-2-2-port-motorised-valve/32455

Tomorrow when I can turn power off I'll switch back to my original thermostat as I know the light worked on that. If the light comes on then it is the valve.

pushing the lever over on the valve I now have heating. What's the implication of doing that? does it just mean heating will be permanently on when main boiler is?
Do you know what I need to replace? would it just be a new actuator? that looks to be £43 at screw fix whereas a whole valve is £55. new motor £15. Although I don't fancy the hassle of doing the whole thing. Plumbing makes me nervous!
I see it could be the motor or could be the gears? Concern is if it's the gears can I replace the whole actuator without water coming out?

 

[Echo the husky]

Tomorrow when I can turn power off I'll switch back to my original thermostat as I know the light worked on that.

To save swapping the thermostats you need only to test for power at the valve, see last part of this post.

If the light comes on then it is the valve.

Not necessarily. You need to carry out some simple voltage tests first before replacing parts.

pushing the lever over on the valve I now have heating. What's the implication of doing that? does it just mean heating will be permanently on when main boiler is?

The manual lever on the valve opens it for draining or filling when there is no power. The radiator in the conservatory will now be on when the other radiators are on.

Do you know what I need to replace? would it just be a new actuator? that looks to be £43 at screw fix whereas a whole valve is £55. Although I don't fancy the hassle of doing the whole thing. Plumbing makes me nervous!

You can easily test with a multimeter set to measure AC volts. Follow the flex from the Drayton valve back to where it is wired in. With the conservatory thermostat turned up, there should be 240V AC at the blue and brown wires going to the valve. Carry out this test before doing anything else.

If there is 240V you will need to replace just the actuator, no need to change the brass bit.

If there is not 240V you will need to check the thermostat and its wiring.

If you do not feel confident you can safely measure mains voltages, you will need to call in an engineer to test for you.

 

[stender]

I have a multi meter but not really used it. So I set it to AC Volts. Where am I placing the prong? when you say follow the flex from the drayton valve. do you mean the black power one which goes to joint box with mains and thermostat? and put the prong in the blue and brown wiring block?
Thats the bit that scares me. was always told not to stick metal in electric sockets

 

[Echo the husky]

Sorry i missed your previous posts when i was typing my last one!