Honeywell DT92E Wireless "thermostat"

[Chris Morgan]

I live with my grandmother who had a new boiler installed, some years ago, on the government scheme. We were "lucky" enough to have one of these stats installed in the hallway (which I think is a silly place), and I have found it quite erratic at times. It is usually OK when the weather is not too changeable , but every so often have bizarre variations in temperature over past three years. Most of the time, it is set to 20 or 20.5 C, depending on weather., resulting in a room temperature between 21 and 22 which is pleasant and bearable, and most importantly, my nan is not cold. Have had incidents of excessive heat, resulting from windows left open upstairs or front door not shut properly (last year, put new draft seal on east facing front door , as stat was being skewed by "Beast from the East"). But recently, this has been randomly occurring, and I have checked carefully for things influencing the thermostat, upstairs windows etc. I have finally dropped the thermostat down to 19, resulting in a reasonably consistent 21 C (ish) throughout the house . But you can bet your bottom dollar, in a day or two, the stat will spontaneously decide that 19 means 19 and the house will be cold, AND my nan will insist I am trying to freeze her to death. I aim to keep the main "living" areas of the house at 21 C as per Age UK's recommendations, but room temperature keeps exceeding 22.5C which is unbearable. I constantly have to manage the temperature to keep my nan warm, and myself sane! If my nan was managing the temperature, there would be no thermostat, and the boiler would run flat out 24/7. I hope I don't sound like I am being too controlling, but myself and the rest of the family need to care for her and the climate needs to be tolerable!

Are these digital thermostats a POS? It seems that whatever temperature you set is basically "ip dip dog ****". Would we benefit from "downgrading" to an old fashioned analogue stat? I've tried going into engineers menu and changing "cycles per hour" to no avail. My nan does not need any fancy pants systems like Hive , or Nest... Just need a consistent temperature!

 

[oz-plumber]

Firstly, replace the batteries and see if that improves it.

Secondly, if you have been playing around with the internal parameter settings, you may have changed the thermostat setting points.
If the thermostat is reading the wrong temperature you can adjust it through the parameter setting to read the correct temperature.

You may have done this inadvertently.

 

[garygvl]

if you think the hallway is a silly place its wireless you can move it and experiment with different locations

 

[Riley]

Should be in the coldest part of the house and nowhere near a rad with a TRV on it

 

[Murdoch]

The hallway is the best place for a room stat IMHO .....

 

[Welder]

I live with my grandmother who had a new boiler installed, some years ago, on the government scheme. blah blah blah

Firstly, with older people especially, I used to often relocate the stat to where they sat. Older people feel draughts and very slight temp variations as they skin thins very dramatically and they lose the layer of insulation fat under it.

Most older people though suffer with draughts more than simple temp because they often sit by windows so get a natural draught across their feet. Due to age circulation is much poorer in their legs so they feel it more. Move 'em out of the draught or put a blanket round.

The other point here is that this stat is quite complex in its simplicity! It may well be that you have altered its many options to the detriment of its ability to control. Lastly, its what Honeywell call self learning. That's nonsense. What it does is look at the last 'period' and predict what it's going to be like. The weather never plays ball, so when a severe and sudden change occurs then the stat is well and truly caught out.

 

[Riley]

Isn’t this a bog standard on off stat or am I getting my Honeywell’s mixed up

 

[Welder]

Isn’t this a bog standard on off stat or am I getting my Honeywell’s mixed up

No. Its adaptive. Its TPI which is a cheap (!) version of PID.

 

[gmartine]

I had a similar problem with my elderly ma's wireless stat but as suggested try it somewhere else, the hall might not actually be the best location where the temp can fluctuate for all sorts of reasons.

 

[Chris Morgan]

Firstly, replace the batteries and see if that improves it.

Secondly, if you have been playing around with the internal parameter settings, you may have changed the thermostat setting points.
If the thermostat is reading the wrong temperature you can adjust it through the parameter setting to read the correct temperature.

You may have done this inadvertently.

Hi. Thanks for your reply. Yesterday was the first time I have ever changed settings on the installation menu, in my fruitless attempts to rationalize the stat.

 

[Chris Morgan]

The hallway is the best place for a room stat IMHO ...

Until someone leaves the door ope

I had a similar problem with my elderly ma's wireless stat but as suggested try it somewhere else, the hall might not actually be the best location where the temp can fluctuate for all sorts of reasons.

This my main reasoning that the stat shouldn't be in the hall. The front door has been left open before, resulting in everywhere except the closed off hallway turning into a sauna. If it's the middle of the day, I've had to shut it off completely for an hour, then gradually increase the temperature to normal to avoid excessively heating the rest of the house again. I have thought about moving it before, but potential locations are limited.

I do wonder though if some of these digital stats are too clever for their own good. The only advanced setting I changed was the cycles per hour down to 3 from the default 6. Reasoning in my mind that perhaps with reduced cycling, the temperature would have more time to stabilise before the stat calls for heat again. Does this make sense to anyone?

 

[Chuck]

The only advanced setting I changed was the cycles per hour down to 3 from the default 6. Reasoning in my mind that...

Put it back to 6 cycles unless you have an oil boiler.

Follow Yorkshire Dave's good advice and see how things go. Make sure that the TRV in the room with the thermostat is left fully open. Also, there shouldn't be any supplementary heat sources, e.g. electric fires, in the room with the system thermostat. If the rest of the house is too hot/cold with the sitting-room at 21°C then the system may benefit from some adjustment to the way it's balanced.