Wireless Thermostat for Traditional Heating System

[jerrysimon]

I have a back boiled with hot water tank etc and the wired thermostat is on the first floor. These are the thermostat and controller at the moment

With cover off

Controller

As per my other posts I am getting a power flush plus some new radiators fitted.

All the up stairs radiators have Honeywell TRVs on them but even with these set low the thermostat is probably in the wrong place as it would only turn off the heating when the hot air reaches it from down stairs.

BG offered me one of the wifi/internet controllers for £199 but I reckon I don't need to have that and simple wifi one would do the trick and be cheaper.

So as I understand to connect this I would :

1. Fit the base/transmitter station to replace the existing fixed thermostat. I am happy wiring the new base unit but would like to know that this will be compatible with the existing power and thermostat wiring there at the moment ?
2. Turn my CH to constant
3. Continue to use my existing controller to set HW times on and off
4. The wireless thermostat could then be used anywhere in the house to control CH i.e. temp and settings for times on an off ?

In terms of units which would you recommend I am drawn to this one

http://www.ebay.co.uk/itm/HONEYWELL...arden_Hearing_Cooling_Air&hash=item20d51e9cc5

Would like one that will enable programming for 7 days i.e. be able to change it for weekends. Any others that you guys recommend ?

Finally I expect to change my system in a few years when it finally gives up, so will I be able to use this unit on a new combi ?

Regards

Jerry

 

[D_Hailsham]

So as I understand to connect this I would :

Fit the base/transmitter station to replace the existing fixed thermostat. I am happy wiring the new base unit but would like to know that this will be compatible with the existing power and thermostat wiring there at the moment ?

I think you mean the receiver. You need to check that there are three wires to the existing thermostat, on terminals 1, 3 and 4.

2. Turn my CH to constant

That's OK if you are confident no-one will fiddle with the CH setting! It would be safer to move the wire from the CH ON terminal to the L terminal, then anyone can fiddle with the CH settings and it won't do a thing.

Continue to use my existing controller to set HW times on and off

Correct.

The wireless thermostat could then be used anywhere in the house to control CH i.e. temp and settings for times on an off.

But you will need to set the TRV in the room with the wireless stat to max, otherwise the TRV may shut the rad off before it reaches the temperature set on the stat. The stat will then keep the boiler going for ever trying to get the room up to the required temperature.

The Honeywell CMT927 (aka CM927) will do exactly what you want and will be suitable for any new boiler. The receiver wiring will almost certainly need changing - but that's down to the installer.

 

[jerrysimon]

Thanks.

I pretty much only leave the bath room radiator on all the time but the rest of the bedrooms are left at frost protect so only the radiators down stairs get used. None of the radiators down stairs have TVRs.

I am happy wiring the the receiver myself.

I guess I need to take the wired thermostat off to see what wires are running to it.

Jerry

 

[jerrysimon]

Ok I opened it up and took the unit off the wall. Four wires coming out. Red, Blue & Yellow and a bare wire earthing the back plate.

So Red (live) pin 3, Blue (Neutral) pin 4 and Yellow ? pin 1.

Also a couple of thinner white wires but they all run internally.

So when connecting the receiver (sorry I meant that not the battery transmitter) with the Red and Blue wires for Live and Neutral to power it won't I need another two wires i.e. yellow plus another to connect to it for the thermostat as well ?

PS Looking on the installation manual for the CMT927 unit we have

NLL ABC pins.

So for my system I would connect Blue to the N pin and Red to one of the two L pin and Yellow to the A pin ?


Regards

Jerry

 

[jerrysimon]

Ah I think I found it as shown in the instructions section 4 Burner (Direct Control)

So, Yellow to B and then add a jumper from one of the L's to A

Are these the best units or would others recommend a different one ?

This has week/weekend program is quite a bit cheaper!

http://www.ebay.co.uk/itm/Salus-5-2...arden_Hearing_Cooling_Air&hash=item2c6d6f4134

Regards

Jerry

 

[jerrysimon]

Anyone got any other recommendations or is the CMT927 the best of breed ?

It does seem that all of these units suffer with failed receivers after about three years or so


Jerry

 

[D_Hailsham]

Ah I think I found it as shown in the instructions section 4 Burner (Direct Control)

So, Yellow to B and then add a jumper from one of the L's to A

That's correct. The other end of the red wire will be connected, probably via a wiring centre (junction box), to the CH ON terminal of the Potterton programmer. As I said earlier, it would be better if this was connected to a permanent live.

Are these the best units or would others recommend a different one ?

This has week/weekend program is quite a bit cheaper!

http://www.ebay.co.uk/itm/Salus-5-2...aring_Cooling_Air&hash=item2c6d6f4134[/QUOTE]
There are more problems reported on this forum with Salus products than the Honeywell; so draw your own conclusions. I have had a CM927 for about six years and never had any problem - apart from installing new batteries every three years.

PS Never heard of CM927 with failed receivers.

 

[jerrysimon]

Thanks for the reply D_Hailsham.

Most the problems with failed receivers seems to be the Drayton units with loads of "fixes" for them being sold on ebay.

I am tempted to try one of the Salus RT500RF units.

http://www.ebay.co.uk/itm/Salus-5-2...arden_Hearing_Cooling_Air&hash=item2c6d6f4134

Watching the video on the listing it seems that these need the loop wire across live and common but it also says that the yellow wire (normally open) switch live ?

Regards

Jerry

 

[DP]

Jerry, have not read the interchange between you and DH so excuse me if I am doubling up on info he has posted.

I take it you are not able to run ch by itself ie when you select ch, hot water also goes active. If that were the case, I would replace the brown programmer with a 0 voltage timer/ programmer to control hot water and fit a programmable room thermostat in a room that is naturally cold (and remove the trv head off the valve)

System then would be under programmed time and temperature control 24/7 that would give you frost protection when you are asleep/ not at home, background temperature when you are active, and bit better temperature when idle/ watching tv.

If HW does not go active when ch fired up, programmer can stay but wiring within for ch altered to allow progstat to take over the programmer and thermostat functions instead of hat you have at present.

Incidently, why the call to have power flush carried out and what is the time scale to do this. This task is often pushed without though, sometimes not needed and at other times carried out badly. If all your radiators are heating correctly, I fail to see the need for it

 

[jerrysimon]

The existing controller unit allows independent control of both HW and CH. So the HW will be left as is and the CH moved to constant/wired so it is on all the time.

I am pretty sure in the next couple of years I will need a new boiler so the powerflush and magna clean will set me up for that with BG. Its unlikely as well they will let me remain on contract if I don't.

The existing system is sludged up. Currenctly a magnet hangs off the pipe work in a lot of areas so I think it needs doing ? I guess I could drain it myself ?

I also need a radiator replacing and another new one put in the lounge so I don't have to keep using the gas fire to supplement heat.

This should split the cost between now and then.

Regards

Jerry

 

[DP]

Magnetic particles that attract the magnet will not be removed y power flushing, only by chemical cleansing. You appear to be on the ball with your thinking.

 

[Chris333]

I have a Siemens RDH10RF and it is fantastic!

Mine is the same set-up as yours - HW is left as it is on a timer at the boiler and the CH is on all the time but controlled by the Siemens RDH10RF.

An electrican fitted mine.

 

[jerrysimon]

Thanks guys.

Jerry