room stat operates even when programmer is off

[alexfrs]

Hi all,

I've just moved into a new build and have had a few problems with the room stats not working. They have been replaced and now operate but there is still a fault somewhere. I have given up hope with the plumber and would like to fix this problem myself.

There are two zones, upstairs has radiators with wireless honeywell room stats and downstairs has under floor water heating using a wired honeywell stat in the lounge and a danfloss wired stat in the kitchen. All the stats operate regardless of what the programmer is doing, even if off the stats still work. The plumber had a hard time wiring the lounge honeywell stat because I think it was for 3 wires and the lounge had 5.

Either way, he got it working eventually but its not right due to the programmer not doing anything. What do I check, seems like the programmers outputting a constant live and never switching? Any advice appreciated as I dont want the plumber out again, he blew a thermostat and the programmer trying to install them incorrectly!

Programmer is a danfloss TS715 si, it will set up correctly etc and appear to work but physically doesnt shut off the stats.

Cheers

 

[stem]

When you say that the thermostats are working when the programmer is off, I assume you mean that the heating is still coming on when the programmer is switched to off.

The Danfoss programmer has a red light on it to show when the heating is on, when you turn the programmer off (or it goes off because of the time settings) you should hear a click and the red light should be extinguished. Does this happen?

If it does, and you are competent to do so, using a multimeter, then check to see if the switched live (terminal 4 on the programmer) is operating correctly. You should remove and isolate the wires connected to this terminal whilst doing this test. You should see 230v on this terminal when the programmer is on, and 0v when it is off.

Assuming this is all OK, it would suggest that the thermostats are receiving a live supply from somewhere other than terminal 4 on the programmer which suggests to me incorrect wiring, however, without a drawing showing all of the existing wires and where they go, it is unlikely anyone will be able to diagnose the fault remotely.

 

[doitall]

Can't see how it can ever work properly with a single channel time clock.

You need to throw it back to the developer/builder

 

[stem]

Can't see how it can ever work properly with a single channel time clock.

The single channel would be used to turn all of the heating on or off at preset times. The thermostats allow a different temperature in the various zones.

Extra channels can be useful perhaps to some so that they can have the upstairs heating on at different times to downstairs, but it's not essential.

 

[alexfrs]

Thanks for your replies.

Yes, the heating comes on if I turn the room stat up, whether the programmer is on or off. The programmer doesnt activate the stat, if I turn the stat up manually the red light will come on (on the stat iteslf) and the floor begins to heat. The same upstairs, if the programmers off, I can turn the room stat on and the rads heat up.

I will check if the red light on the programmer comes on when it should, i cant remember off hand.

I believe the programmer did "click" originally and operate correctly before the plumber blew the stat and programmer. I think his wiring of the lounge stat has caused a permanent live. This was when he upgraded from the danfoss lounge stat to the digital honeywell with extra wires.

I am competent with electrics, just never been involved with central heating before. I'll see what term 4 is doing and let you know. Would it help if I tested the wires at the stat when the programmer is on and off, would this offer an idea to the cause, as its the only place that was interfered with by the plumber?

Do it all, The single channel time clock would work because all the room stats are controlled by it (or should have been!), therefore allowing all of the heating to be on or off at certain times, just independent temps for upstairs, lounge and kitchen or am I missing the point somewhere?

I do appreciate your replies as I really don't want the builders plumber out again, it took 6 weeks to order the stat and two weeks to install it. Winter will be almost over by the time he manages to rectify a problem like this, If its a case of him miss-wiring the lounge stat in the first place then I'm sure if let you know what wire is doing what then I can get to the bottom of it, i hope.

 

[doitall]

Sounds to me like the timer should control the underfloor separately as it should, and the stats control the zones.

 

[alexfrs]

I'm sure when I moved in the builder said downstairs floors and upstairs radiators are all time controlled by the programmer. I don't mind it working that way, I want to know that everything is off during the day and on for when we get in from work but as it is, everything has to be set to 0 degrees in the morning and then turn them all up when we get home and its beginning to do my head in because if the programmer did function correctly it would all be done for me.

 

[alexfrs]

the red led on the programmer illuminates when it reaches the on time.
everything functions correctly on the programmer, except turning the stats on or off

 

[doitall]

You haven't got a programmer.

The underfloor should be on almost continuously at a low temperature, on it's own circuit.

 

[stem]

I believe that the Danfoss TS715 programmer (or timeswitch if you prefer) uses a relay for switching so that it can be used to switch 24vdc or 230v. It is possible that if someone has introduced a short circuit at some point (which would probably also have blown a fuse) that the programmer contacts have welded together to be permanently connected, the light would probably not be affected. Testing the output from terminal 4 will tell you.

 

[alexfrs]

When I first moved in the programmer would control all of the thermostats, upstairs and downstairs, except the lounge one which had to be replaced.

This was when the replacement one and the programmer blew, also, the under floor heating manifold fuse blew at the same time. The thermostat (a different type that had to be rewired), programmer and fuse were all replaced and the system appeared to work correctly, last month.

Now that autumn has arrived I wondered why the room stats were turning on at the right temp but when the programmer should have kept them off, I reset the programmer and realised that it didnt make any difference what the programmer was programmed to do, all of the stats (including upstairs) would turn on and off independently. So I can only assume that however he has rewired the new lounge stat, has caused some sort of permanent live in the stat which is why the programmer cant over ride the room stats? would wiring one stat cause all the others to also have a live feed and be able to power up regardless of the programmers signal?

 

[doitall]

The SPDT in the TS 715 si is volts free.

What is the boiler make/model.

 

[stem]

The SPDT in the TS 715 si is volts free.

What is the boiler make/model.

Indeed, that's the idea of a relay, the contacts are potential free, so you can connect them to whatever volatge you like (within limits of course )

 

[stem]

So I can only assume that however he has rewired the new lounge stat, has caused some sort of permanent live in the stat which is why the programmer cant over ride the room stats?

The timeswitch doesn't overide the thermostats. If it's wired properly, it provides the live supply to them, then they distribute it to their individual circuits they are controlling. The timeswicth goes off & the power to the thermostats is removed. You are right about the permanent live, but I still think it's highly likely someone has created a short circuit so that the relay contacts are welded together inside giving the permanent live.

 

[doitall]

Would think it was dependent on the 3 stats.

Whatever you can't run underfloor heating with an on/off timer linked to the radiators, it will never work properly.