thermostat with a small differential + anticipator?

[Mark07]

Hello,

I need some advice please. The central heating in our home oscillates the house temperature too much. It's specially uncomfortable at night, waking people up when the bedrooms become too hot.

I've just done some Googling and I learned about thermostats with smaller differentials (some even adjustable), and about anticipators. Excellent.

At Amazon I found a thermostat with adjustable differentials (down to 1C), and some others with anticipators. However, I couldn't find a thermostat with both.I guess it's probably due to lack of details in Amazon's tech descriptions?

Any suggestion please?

Cheers,

Mark

 

[Howsie]

Hi Mark, what do you have at the moment? Do you have TRV on the radiators in the rooms? If so, which ones? What's the property dimensions/type.

 

[ShaunCorbs]

and what room stat do you have at the moment

 

[Howsie]

and what room stat do you have at the moment

Good question.

 

[rpm]

and what room stat do you have at the moment

And where?

 

[Mark07]

Hi Howsi, ShaunCorbs, rpm,

Thank you for the replies,

We have a Honeywell thermostat, mechanic/analogue, looks oldish, I don't know the model name or number.
And Honeywell TRVs in all rooms, they look like this:
(I tried to post a link to a photo of a TVR that looks like ours but the Forum didn't allow it.)

The house is a smallish 3 bedrooms semi-detached (75m2). The thermostat is on the ground floor, in the hallway, by the stairs.

We have a toddler and his bedroom needs to be warmer than mine. I leave my TRV off, but even so my bedroom gets too hot for me. We leave the TRV in the hallway (near the thermostat) fully open, as the living room and the bathroom's upstairs. My son's (the toddler) TRV at 2, and his room's door closed.

 

[ShaunCorbs]

any chance you could pop the cover off to the stat there should be either 3 or 4 wires there

if theres just two theres your issue

 

[Howsie]

The TRV's (if working) should stop the overheating. I'd wager that they've seized. You can check easily, YouTube turned up this: https://www.youtube.com/watch?v=phFW-IIsH54

 

[Mark07]

any chance you could pop the cover off to the stat there should be either 3 or 4 wires there

if theres just two theres your issue

Hi ShaunCorbs,

I opened it, there are 3 wires, one is half green half yellow, another is blue, and a 3rd is brown.

 

[Mark07]

The TRV's (if working) should stop the overheating. I'd wager that they've seized. You can check easily, YouTube turned up this: https://www.youtube.com/watch?v=phFW-IIsH54

Thanks for the link Howsie, I'll check them tomorrow.

 

[ShaunCorbs]

Hi ShaunCorbs,

I opened it, there are 3 wires, one is half green half yellow, another is blue, and a 3rd is brown.

so 2 wires as green / yellow is an earth

the problem you have is no neutral which takes a new stat range from + or - 5dc to + or - 1dc

you have three options

replace with a battery digital one or get a heating eng/spark to run a new cable 3 core + earth and fit a new stat

or the third get a rf stat fitted

in the correct place eg 1.5m from floor and if a rad is there no trv to be fitted just normal lockshield

 

[drip-dry]

think howsie is right...trv,s faulty..

 

[Mark07]

Thank you v much ShaunCorbs,

I'll deal with it tomorrow. I guess a battery powered will be the easier and cheaper option, right? As I may be able to fit it myself?

And do these battery digital ones have a small differential? And anticipator? Don't anticipators require a 3rd wire, for the little "heater"?? Can a battery do that??

Cheers,

Mark

 

[Gasmk1]

No you need a 3rd wire for an anticipator,

 

[ShaunCorbs]

No you need a 3rd wire for an anticipator,

not if its battery

and yes and depends how diy you are and tools etc

 

[dancinplumba]

Should we be telling peeps how to do a sparkys job ? Could be 230v involved and possibly Boiler case removal

 

[ShaunCorbs]

Should we be telling peeps how to do a sparkys job ? Could be 230v involved and possibly Boiler case removal

no boiler case removal needed as you can tell which is which at stat

but down to op and if he has a multi meter

 

[ShaunCorbs]

Still giving sparkys job away

or heating eng

 

[dancinplumba]

Removed my post

 

[Mark07]

not if its battery

and yes and depends how diy you are and tools etc

But as I understood it, anticipators have a little heating element. Can a battery powers that? Wouldn't the (small) battery be drained in a few weeks, if not days?

 

[Mark07]

Should we be telling peeps how to do a sparkys job ? Could be 230v involved and possibly Boiler case removal

Don't worry dancinplumba, I would never risk doing a sparkys job. That is why I wrote that the battery version would be cheaper for me as I would be able to do it myself.

 

[Gasmk1]

they use a resistor to heat up, thats why it uses a neutral.

and that was my thoughts on a battery

 

[chris watkins]

But as I understood it, anticipators have a little heating element. Can a battery powers that? Wouldn't the (small) battery be drained in a few weeks, if not days?

The battery in the wired digital stat's power the electronic temperature sensing to 0.5 deg C accuracy it also operates the switching so you can use it to control different voltages (known as volt free switch).
There is no anticipator in these new one & the battery in my Honeywell one has lasted over two years (2X AA).

You need to take great care if you are doing the change your self, as others have said.
The cable marked green / yellow was often used by some (cowboys) as a Neutral this is dangerous as every cable must carry an earth even if the fitting it is connect to is double insulated & does not require one it is there to protect the cable.

Have you got a combi boiler of standard S or Y plan (hot water cylinder) ?

 

[Howsie]

Take a look at EvoHome, very clever stuff but a little of the dear side for some.

 

[Mark07]

Thanks for the info chris watkins,

I am not going to do it myself if it involves new wirings.

I wouldn't even be allowed, as we live in a rented house, I will have to talk to my landlord after this research, and get his permission for the upgrade. I'll see if he can pay for it too but I very much doubt it... But obviously I don't want to spend much on a rented house, considering that in Britain a private landlord can evict tenants at will with only 2 months notice!

We have a conventional boiler, with a water tank in the attic.

 

[Mark07]

Thanks Howsie,

Unfortunately we can't spend much, for the reasons I explained to chris watkins above.

 

[Mark07]

I had an idea, to reduce the "overshooting" of temperature in the house without the need to change the Thermostat: At the boiler's settings, reduce the water temperature for the heating system.

This way, when the house reaches the desired temperature, the radiators won't be as hot, and the overshooting will be less. The question is if this improvement will be significant.

Another advantage will be that all changes in temperature will be smoother, more gradual, also on the way up.

 

[chris watkins]

I think you may have stumbled on something there Mark07 so what you are saying is as the outside temperature increases you are going to turn down the boiler thermostat so the rads give out less heat ? Not only will that stop the temperature over shooting but it will improve the efficiency if your boiler is a condensing type because the returning water will be below 53deg C.

Now the problem is that you will have to stand next to the boiler & adjust the water temperature all the time as the weather & outside temperature changes all the time.
Your thermostat is inaccurate not only on the rise in temperature but also on the drop so you will still find your house getting cold before the stat calls the heating back on.

If you heat our domestic hot water via the boiler then the minimum setting on the boiler stat will need to be around 70 deg C when the water is being heated.

There is an automatic system that does just what you want & it saves you standing there adjusting the stat it is called a Weather Compensation control.

It might just be a lot easier & cheaper just to change the room state.

 

[Mark07]

Yep, we decided to buy a new thermostat, with a smaller differential, and easy to install = battery, so, no 3rd wire and no anticipator.

Now we just have to chose one, probably with a 0.5degree differential. Any suggestion, please?

 

[ShaunCorbs]

Yep, we decided to buy a new thermostat, with a smaller differential, and easy to install = battery, so, no 3rd wire and no anticipator.

Now we just have to chose one, probably with a 0.5degree differential. Any suggestion, please?

go for a branded one eg honeywell drayton etc

 

[chris watkins]

Honeywell DT90E Digital Room Thermostat + ECO | Thermostats | NoLinkingToThis

I have had mine for 3- 4 years working fine (touch wood)

 

[Mark07]

Thanks again chris watkins,

It looks good, and v good price too.

The screwfix page doesn't mention its differential. I went to Honeywell site, and they don't mention it in the main product page. Then I found and downloaded the specs, but again they don't list the differential... Strange. It's one of the main functions of a thermostat = how tightly/constant it keeps a house's temperature. A bit annoying.

I hope all these newer models have small differentials? Hopefully at most 1C? There are some on Amazon with just 0.5C, many with 1C. But I am not familiar with the brands there. Could be cheap imports.

The old one here in this house may be some 3C, or more, I guess, with the unavoidable overshooting it becomes even worse. I guess any improvement would be a... well, an improvement...

Anyway, thanks again for all the info,

Mark

 

[chris watkins]

The battery in the wired digital stat's power the electronic temperature sensing to 0.5 deg C accuracy it also operates the switching so you can use it to control different voltages (known as volt free switch).
There is no anticipator in these new one & the battery in my Honeywell one has lasted over two years (2X AA).

You need to take great care if you are doing the change your self, as others have said.
The cable marked green / yellow was often used by some (cowboys) as a Neutral this is dangerous as every cable must carry an earth even if the fitting it is connect to is double insulated & does not require one it is there to protect the cable.

Have you got a combi boiler of standard S or Y plan (hot water cylinder) ?

Diff no more than 1 deg C as far as I know.

 

[Mark07]

Thanks again,

All the best,

Mark