replacing room thermostat

[AndyPRK]

Well you could leave the thermostat connected up, to be sure that it never goes off. You will at least have a warm house. I guess you did this already?


As long as you keep the blue wire away for it you should not damage it.

Either of your pictures are fine. (Red & yellow to COM and NO)

 

[bernardgreen]

If the fuse blew then it is very likely that the contacts in the thermostat shorted Live to Neutral.

If the blue wire was in NC when the fuse blew then the Common to NC contact is likely to have taken the hit ( the short ). This pair of contacts is not ( normally ) used.

The contact between NO and Common may not have been damaged there is a chance the thermostat will still work. But the small explosion when the short circuit occurred may have damaged more than just the NC contact so be ready for the thermostat to fail soon.

 

[ericmark]

I look at the Horstmann DRT2 Programmable Digital Room Thermostat and the Timeguard TRT033 and although the latter does have a bed function and a frost setting the former nearly the same price has 4 pre-set temperatures for week day and separate pairs of temperature for Saturday and Sunday and connections are the same.

So if you have burnt it out maybe it would be better to get one with more functions while your at it.

It states Switch type: Single pole, single throw (SPST) so likely the short circuit will have burnt out the relay. As to opening and repairing well may be I would as a real Aunty Wainwright but I would then use it to control my beer temperature not main central heating I would use a new one for that.

 

[AndyPRK]

To dissect it correctly.

I found that the yellow gave me a constant live, the red was live when the thermostat switched on

I wired the yellow to the COM terminal, the red to the red to the NC and the blue to the NO,

So live to COM
Neutral to NO

This would have caused 230v across the contacts and welded them together, and hence the heating will no longer turn off.

If you know someone who is good at soldering, you could well replace the relay.

or if the relay in the unsealed type, so could open it and separate the contacts.

or if you purchased it from a DIY store, take it back and say it doesn't work!

 

[eveares]

The question is is normal in the state of calling for heat or in the state of not calling for heat???

Try wiring between COM and NC just to see if it works. Terminate the blue wire in a 5 amp connector block as others have said.

 

[JohnW2]

The question is is normal in the state of calling for heat or in the state of not calling for heat??? Try wiring between COM and NC just to see if it works.

If the problem were simply due to NO/NC confusion, wouldn't one expect the heating to turn off if one turned the thermostat up to a high temperature (higher than that in the room)?

Kind Regards, John

 

[eveares]

If the problem were simply due to NO/NC confusion, wouldn't one expect the heating to turn off...

If the heating does not turn off no matter the setting of the stat (i.e. turning it all the way up or all the way down) then your indeed correct.

Also the Timeguard TRT033 should only have 2 terminals or 3 if you include earth.

See here: http://www.tlc-direct.co.uk/Technical/DataSheets/Timeguard/TRT033.pdf

Something seems odd to me?


Blackdog1969; first check to see if the wires are damaged or in poor condition as the red and yellow wire might be shorting to each other causing the boiler to start up.

If you are sure it is not that then you might want to try the following tests. (leave the blue wire terminated in its own connector block during the following tests, and the earth wire connected to the back box)

1) With the thermostat removed and the power off, try joining the red and yellow wire in a terminal block. Now switch the power back on and hopefully the boiler WILL start.

2) Now turn the power off again and un-join the red and the yellow wire so they are in their own terminal blocks and are disconnected from each other. Now switch the power back on, the boiler should now NOT start.

If the test goes as suggested above, then its likely your thermostat is faulty and needs replacing or you have a incompatible model for your heating system.

 

[AndyPRK]

Read the thread!

He already did 2. Heating was off.

 

[eveares]

Read the thread!

He already did 2. Heating was off.

I was only reinforcing what others have said.

Either way, from my perspective it seems likely that the thermostat is faulty or has been damaged as others such as your self have also said.

What puzzles me is why his TRT033 has COM,NO and NC when the instructions for it suggest it only has L and SL?

 

[blackdog1969]

All the wires look like they are in good condition to me and I don't have any connector blocks at the moment to conduct the tests you suggest, I think that I would be a tad nervous about damaging my boiler as I am by no stretch of the imagination electrically trained. I just assumed when I bought the new thermostat that there was some kind of industry standard regarding the wiring (much like a plug). I have ordered some of the blocks and if I muster the courage to test it I will post results. Thanks to everyone who has taken the time to reply.

Blackdog1969; first check to see if the wires are damaged or in poor condition as the red and yellow wire might be shorting to each other causing the boiler to start up.

If you are sure it is not that then you might want to try the following tests. (leave the blue wire terminated in its own connector block during the following tests, and the earth wire connected to the back box

 

[JohnW2]

What puzzles me is why his TRT033 has COM,NO and NC when the instructions for it suggest it only has L and SL?

If you want to get even more puzzled, Fig 4 in the instructions lables the L and SL terminals as 'COM' and 'ON' respectively - and the spec. (section 5) describes the switching as "single pole, single throw" (which would imply that it did not have both NO and NC contacts accessible)!

Kind Regards, John

 

[AndyPRK]

although we have only seen the back plate.

 

[JohnW2]

although we have only seen the back plate.

True, but that has three terminals labelled 'COM', 'NO' and 'NC' which, as I said, does not correspond to the labelling (or number of terminals) indicated in either Fig 3 or Fig 4 of the instructions. I'm sure that would not be a problem for you or I, but it presumably would be confusing for many who purchased it.

Kind Regards, John

 

[blackdog1969]

Further worrying development...Now even when my programmer is set for the heating to be constantly off and I have the old Satchwell TLX2259 re fitted, when it starts calling for heat, the boiler now fires up the heating even though it should not as I have effectively turned it off using the programmer ...Have I damaged the programmer or the boiler as well?

Untitled

• blackdog1969
• 11 Jan 2015
• 1

 

[AndyPRK]

Sounds like it. Get a replacement one off eBay.

Search for drayton.