Central Heating Room Thermostat

I have an Intergas boiler controlled by a Honeywell CM927 room thermostat. Its been fine for a good number of years but, with the rise in gas prices, I decided to reprogram it; but the display has gone wrong - I can't see anything of use. It appears to be a well known problem. The CM927 is no longer available so I need a replacement, but what one?

I'm tempted by the Tado V3 starter, but know absolutely nothing about it. I think it uses a phone app for programming and comes with an appropriate receiver to replace the existing one, a photo of which is below. I've been unable to find an on-line user manual, all I have found is the usual vague gee-whiz advertising stuff.

Another possible replacement is the Adept T2R, but again no really useful information like the programming facilities.

Can anyone shed some useful light please? I'm open to suggestions.

Edited By Gary Wooding on 04/10/2022 10:50:59

Gary

Your picture appears to be the receiver connection to the boiler, not the thermostat.

A manual can be downloaded from:-

https://www.manualslib.com/manual/594061/Honeywell-Cm927.html

Gordon

I had the same problem a few years ago. The Honeywell helpline were great with suggesting a replaciment and reworking the wiring for it.

Thanks Gordon, but I did say that the photo was that of the existing receiver.

We have one of those in the conservatory and the display went blank.

They still appear new on eBay & Amazon (mine was from there) maybe others as well, but contact Honeywell first as Adam says.

Edited By V8Eng on 04/10/2022 13:53:30

When my Origonal Honeywell one went duf, i changed & bought a Nest.

The Nest is a remote thermostat connected to a USB supply & programmed by your phone on an app.

You must have home wifi though.

Bought from Screwfix.

Steve.

If you have the external weather sensor fitted to your boiler and set up properly - and I recommend that you should - then a Nest or Hive would be a bit of overkill in my opinion. You just need a simple timed thermostat. Personally, I'm not keen on wireless ones, but if you have a look here, you'll find a selction. I'd go with the Drayton or Siemens myself, but not sure what features you are looking for.

Links to https://www.heatingcontrolsonline.co.uk/wireless-programmable-thermostats.html?limit=100

No connection other than as a satisfied customer

Rob

As you have an Intergas boiler it would make sense to get a new control with OpenTherm capability.

I have a Remeha iSense controller, which has weather compensation and OpenTherm functions and together they give a very much 'set & forget' system that takes care of itself, regardless of the outside temperature.

A Nest also has OpenTherm, but uses local weather forcasts for its weather compensation which isn't quite as good as an outdoor temperature sensor, but nevertheless helps in keeping the boiler running at as low a temperature as possible.

Martin.

I've got an very simple controller. If the house feels cold I turn the heating on for half an hour, or an hour if it's really cold. The rooms we occupy have their own gas fires. SWMBO could not cope with radiator thermostats: just because the rads have gone cold because the room is hot enough she thinks there is a fault

You are an engineer. Find an old mechanical one and put it in a new box with a few LEDs. Put a DUMMY control knob on the front for the family to fiddle with and a screwdriver hole underneath for you to set the actual temperature.

Remember that fancy electronic ones will be declared obsolete in two years so unsupported and fail in 4 years so they can sell you another one.

I fitted a Tado recently to replace a wireless Honeywell device. As mentioned, it uses a phone app to control the settings. It was a little fiddly to wire up, but the installation guide that comes with the app is very good and the support from Tado was excellent, with very prompt responses. Now that it is fitted, it is simple to use and appears to be very effective.

James.

I always use the old mechanical type, if I am replacing for someone else in the village. Mine is 40 years old and still going strong. Once you have done the wiring, you can forget about it. Modern electronic / wireless ones don't seem to last and are expensive.

Andrew.

I installed a NEST thermostat 5 years ago, works great (still). Best thing I ever did, replacing the old mechanical thermostat.

Smartest looking one on the market.

Remember, the dinosaurs are not extinct, they just moved onto this forum.........

Edited By Howi on 05/10/2022 10:58:42

It is possible to get replacement LCDs for CM927, google "CM927 replacement screen"

I've installed three Tado units for friends and family. All are working very well. Can't remember why I opted to use Tado over the other options such as Nest etc. Installation is straightforward but recommend you download the professional installer notes.

The thermostat can directly replace a wired old style unit. If you want to use it 'wireless' you need to install the Extension Unit at the boiler (again straightforward to do). Either route there is a dongle to hang off the WiFi router that acts as the comms hub.

Using the Extension Unit means you can move the thermostat from room to room to reflect where you need the heat to be focussed. You can also add WiFi connected radstats to the network for localised control.

Profile programming is from a Smartphone or from a Desktop. The profile is stored on the Tado cloud which will immediately horrify the anti 'anything to do with the cloud even though my banking is' fraternity. If your internet connection goes down you can still control the thermostat in non profile mode.

The smartphone control allows you turn up the CH and water as you exit Arrivals making homecoming a much more pleasant experience. The app provides various stats on usage and consumption. If you want it, it also uses geofencing to turn the temperature up or down depending on whether it detects your phone is at home or not.

Dinosaurs? Well, as the old mechanical type are much much cheaper and considerably more reliable, what is there not to like?

Unless you are the type that must have the latest tech gizmos.

Andrew.

The media would have us believe that we are heading into a serious situation over winter with fuel shortages. They also, probably correctly, imply that the more senior members of society will suffer the most from an inability to heat their homes.

I would guess a significant number of these homes will have the traditional single mechanical thermostat located in a draughty entrance passage or similar. This is not an area of the house that they will choose to hunker down in as temperatures drop.

I can see that a wireless device close to hand controlling their immediate surroundings and not wastefully heating the rest of the house would have its attraction in these circumstances. As to whether a blob of mercury in a glass bulb is more reliable than the latest tech gizmo I am not privy to the facts to be able to objectively comment.

Does the electronic model have a facility to warn you before it shuts down when the days buget for heating has been spent ? Or does it just run up the bill and let you worry how to pay it ? Noel.

I despise the new electronic thermostats, and electronic devices in general.

The problem is no two operate the same. You can't repair them either.

In my older car, it has some simple buttons for heat and air.

My new car has a computer screen, and you have to have a PHD in physics to navigate through the multitude of levels, even to do something simple like reset the clock.

The electronics in microwave ovens do seem to work well.

People don't seem to know how anything works anymore; they only know how to use apps.

My central air/heat system has an electronic control module, and when it goes out, it is about $300 to replace.

My daughter's central air/heat has a gas valve with thermocouple, and there are no electronics to go out.

A thermocouple is about $25.00, and they last for many years.

I am seeing a worldwide shortage of chips/electronics in general now, and so does anyone know how to go back to mechanical relays? I do, but few others do.

And I don't like to be a slave to a smart phone and its apps.

When I retire, I am going to be phone and app free.

For similar reasons, I don't have DRO on my shop equipment.

I aways know that when I got out in my shop, those hand knobs will always work, and never break.

I do use digital vernier calipers.  The batteries don't last very long, but I can't really live without digital calipers in the shop.  Electronics do have their uses, but they seem to overload everything with electronics, more as a marketing thing.

My daughter's new car has apps that the car company tries to get you to subscribe to monthy, so you can use all the features of your car.  This is basically blackmail, in my opinion, but his is the trend, and there is a term for it, which I forget.  Soon there will be an app to use the loo.

Edited By PatJ on 05/10/2022 16:11:59

All the ones I have been exposed to (friends think that computer programmers can program time clocks etc). The problem is "life style". Do we always come in, go out in the same pattern, weekdays, weekends, holidays etc. Did it feel cold today, did we have guests that wanted more hot water than usual.

Its a minefield to program. Thank goodness we have a log stove, chuck another log on if its cold!