Central Heating Room Thermostat

My Nest was defeated by my wife, she is incapable of regulating her temperature it would seem so the Nest finished up with hundreds of learned points. I took it out of learn mode as it is impossible for any machine to learn what temperature my wife requires. Even with driver and passenger zones in the car she fiddles with the set point constantly.

Mike

As suggested by AdrianR, I'm going to try the repair route. Wish me luck.

Good luck!

When I moved to my current house, I found a system with a CH timer, mechanical TRVs on all radiators, and no central thermostat. It's a funny-shaped house but suited to zoned control - why heat bedrooms during the day? - but first step was a wireless thermostat in a central position (to avoid wiring problems). I ruled out a zone-valve based system partly because of the awkward shape of the house and plumbing access difficulties so went to wireless radiator valves with a central controller. I went Honeywell but there are a number of versions around these days including open-source options. It does give good control, local room override, app-based control if desired, and generally working well. Rad valve batteries need replacing every couple of years or so but overall I think the technology saves money, gives better control, and a more comfortable house then the alternative less-sophisticated systems. Sometimes, the bullet-proof dinosaur systems just won't do it!

That said, I'm very reluctant to update my boiler which is very old-school with cast-iron heat exchanger and no electronics inside...

I personally don't like having things relating to me being potentially visible on the internet, via Wi-Fi. Who knows who is snooping; logging when you are probably on holiday, because your heating has been turned down or off for two weeks?

Also, Apps and computer devices usually need navigating through menus and often have passwords - which need to be remembered. Not usually an impediment to those of us with an engineering mind, but can be very difficult for some users. An old-style electronic controller with on/off times is much easier (and far quicker) to understand and re-programme.

I am surprised that some houses don't appear to have a house thermostat, and occupiers have to switch the system on and off themselves according to temperature, (although they could still use a timer and the boiler thermostat to control it).

Good quality mechanical thermostatic radiator valves, (e.g. Drayton, Honeywell)*, seem to work fine, and I personally can't see the point in getting involved with wireless radiator valves, incorporating batteries and the inevitable App and Wi-Fi link up and programming. It takes only a few seconds to adjust a radiator with a mechanical thermostatic valve, with no menus or Apps to have to worry about. Having said that, those with teenagers at home, might find remote-control of bedroom radiators useful, to reign-in heat hungry occupants who don't pay the gas bill !

*As with anything, don't expect the cheapest valves to work as well as decent ones from a known brand.

.

Edited By John Doe 2 on 06/10/2022 10:41:38

JD": The room thermostat that failed is a Honeywell, and all the Drayton thermostatic radiator valves have failed over the years. Mechanical devices are not immune to failure - the ignition switch on my electric bike has failed after only 5 years.

Ignition switch on an electric bike? Is that the one which makes the li-ion batteries burst into flames?

We had a Honeywell wireless room stat which lasted about 8 years before giving up the ghost, it only used two sets of batteries in that time. We have a maintenance contract for the central heating system and when it broke they replaced it with a different make of room stat called Salus, it eats batteries about every six weeks, apparently a common problem according to comments on the internet, I can only presume it was supplied as a replacement because it was cheap, I would warn anyone to think twice about selecting that make if they are in the market for a replacement stat, it will cost a fortune in batteries. Dave W

I agree. We had a new boiler installed a couple of years back including a new wireless thermostat. The engineer asked if I wanted instruction to programme it. I said no, I’ll just turn the heating on when I need it and off when I don’t. Being wireless the thermostat can be positioned anywhere you like but we’ve left it in the hall as all the other rooms have TRV’s and you’re not supposed to have it in rooms with them.

I am amazed, Vic. Do you literally turn the heating on and off manually, without using the thermostat or a timer?

What about in the morning before you get up? That can't be what you meant.

The reason for not having a thermostat in the same space as a TRV is that if the TRV shuts off the radiator at a lower temperature than the room thermostat is set for, the boiler will keep running, to try to satisfy the thermostat, but with the TRV shut, all that will achieve is to keep the circulating water hot, thus wasting gas.

Likewise if the thermostat is in a space with no radiator, the whole house will have to warm up to trip the thermostat, unless it is set low.

Sorry to hear about Drayton TRVs. I have never had trouble. Have they gone downhill, to a lower quality?

By mechanical type do you all mean the ones with the mercury tilt switch?

;o)

Martin

Yes. We don’t get up at the same time every day and there’s no point in having the heating on when we’re still in bed. We just turn the thermostat up to a suitable level when we get up in the morning. If it gets a little too warm we turn it back down. Once the weather gets colder the temp set on the thermostat will turn it on and off more frequently than at present but the same principle applies. If they invent a thermostat/programmer that can anticipate when we’re going to get up and turn the heating on let me know.

I seem to remember in one of our old houses we had week day and weekend settings on a programmer that sort of worked but once you retire you’re not ruled by the clock any more, well we aren’t anyway. I know some silly bugger that still gets up at 06:45 every day and he retired years ago. Each to their own.

That's exactly what we do, we don't get up at the same time every day, and with decent insulation the hose doesn't get freezing cold overnight, if it gets cold give it a blast for 30 minutes or an hour. We also put on jumpers in winter, I always found the office I worked in too hot, shirtsleeves in winter is nonsense

I have a Drayton Digistat +3 RF programmer/thermostat which has a very annoying algorithm which runs the boiler for short periods of time as it approaches the set point temperature. The algorithm can only be set for fast or slow responding heating systems as far as I can see in the manual and neither cures the boiler cycling issue which is very wasteful.

CS

I come from a time when there was ice on the inside of the bedroom windows in the mornings, so I quite agree with putting on a jumper indoors rather than running a tropical household.

Our house thermostat is currently set to 13° C and that is perfectly adequate for us. But the boiler also heats the hot water, so it sometimes needs to come on before we have our showers etc. and it is nice if the bathroom is not also icy cold when one is in one's birthday suit ! In the summer there is no need for the boiler to run in the morning though - the house thermostat takes care of that automatically.

Regarding a boiler anticipating when you get up; as part of my house renovation work, I am going to add a switch by our bed to turn our boiler on remotely, if required, without having to get up and walk all the way downstairs !

The non-electronic radiator valves, (TRVs) I was talking about are fitted to the radiators themselves, and are mechanical but still automatic - operated by wax capsules I think? - like the so-called "thermostats" in car engines. You set a required temperature and the valve will automatically regulate to maintain that, as far as it can. Saves a lot of money because the house thermostat cannot "see" all the individual room temperatures, so can overheat a non-regulated bathroom, for example, and waste gas.

One thing that can happen to heating systems is that there is not sufficient inhibitor fluid circulating, so internal corrosion occurs and radiator valves etc. can get blocked up or be prevented from moving.

In the last two houses I have owned, I have seen this and completely flushed the systems out and added inhibitor. I also fitted cyclone type filters for the circulating central heating water. These 'filters' actually have a cyclone and a very strong magnet. The cyclone spins out any debris, and the magnet collects the iron and steel particles - preventing them from blocking valves. Every 6 months or so, you can isolate the unit and clean out the collected debris.

The last house I did this in, the (combination) boiler was not working very well, and I discovered that its internal valves were full of these corrosion debris particles, which were blocking valves open or closed, and preventing correct operation.

Inhibitor and a cyclone filter costs way less than the cost of having to have a new boiler fitted.

.

Edited By John Doe 2 on 07/10/2022 10:16:13

John

I also came from a time when there was ice on the inside of the bedroom windows when you woke up, very few houses had central heating in those days. Since we have had a woodburner fitted in the lounge, when the woodburner is in use it generates so much heat that we leave the lounge door open and heat percolates through the house, on really cold days the gas central heating thermostat kicks in and warms all the rooms. I think my wife would like to go back in time to the old days because she won’t have the rad in the bedroom switched on and always we have to sleep with a bedroom window open regardless of what temperature it is outside, I just go along with it I gave up trying to resist many years ago. Dave W

.My house is fitted with a Drayton Digistat 1 room stat which is hard wired into the system but which I think is no longer currently available. I gather that there was a later model Digistat RF which presumably worked on a radio signal basis. Perhaps someone could explain what is meant by the term 'mechanical' used in this context and how the two systems worked.

Interestingly, most of the thermostats I have replaced for other people have been all singing and dancing high tech wireless gizmos. On asking what functions were actually used. The answers was "adjusting the temperature" So all that expensive high tech was totally wasted on them.

Andrew.

Wireless thermostats can be moved around which can be an issue. Our church has a Hive system and we found the wireless thermostat had been put in a cupboard in the vestry so it didn't get fiddled with. This and the church hall are sensible buildings for a remote control system as they may need turning on and off without the operator being present in person. Domestic remote control systems only encourage people to set the heating to come on before they get home and heat an empty house.
However I wish I had a remote for the only heat in this house - the small inset log burner in front of me as I have to get up out of the armchair to adjust the air flow. sigh.

BTW if you want to provide a remote off switch for TRVs you can put a small resistor on them and use it to deceive them as to the room temp. Sure it uses a Watt or two but that is less than the heat wasted from the radiator.