Room stat,when does it call the boiler ?

[diydazzler]

Ok,so I have a Drayton RTS 1 room stat set at 21 degrees on the dial.

I can feel the temperature dropping but it has to be a good 3 or 4 degrees below that before the boiler kicks back in.
Is that normal ?
Or should it be coming in as soon as the temperature drops below 21' in which case the boiler would be coming on and off a lot more than it is.

Or is it just down to the stat not being particularly sensitive ?

 

[Burnerman]

Its just the hysteresis or sensitivity that the thermostat has - and they all do it to some degree.
John

 

[diydazzler]

'hysteresis'....I had to google that lol

Are there any particular models less hysterical

 

[D_Hailsham]

It could be that the stat is in a sheltered part of the room.

What is the difference between the click on and click off temperatures?

The hysteresis of an RTS1 is supposed to be less than 1 degree.

 

[diydazzler]

It's on the landing at the top of the stairs.There's a rad at the bottom of the stairs.There's no draughts.

There's 3 degrees or thereabouts between on and off

 

[45yearsagasman]

For not much money, why not go digital? Probably less than 1 degree from on to off. Hysteresis.......you learn something new everyday

 

[diydazzler]

For not much money, why not go digital? Probably less than 1 degree from on to off. Hysteresis.......you learn something new everyday

A digital display won't make any difference will it ?
Surely it's down to the electronics.....isn't the RTS 1 an electronic device ?

 

[namsag]

RTS1 are ****e stats, get a honeywell dt90 20 quidish

 

[mikely]

A digital display won't make any difference will it ?
Surely it's down to the electronics.....isn't the RTS 1 an electronic device ?

You’re right. However, the ‘digital’ DT90 does not exhibit hysteresis because it uses a different control method (self-learning ‘fuzzy logic’ time-proportional control algorithm). That may certainly help, although the position of the thermostat may also be a problem. Using the wireless version (DT92) would allow you to place the controller in the living area, but it is more expensive.

 

[foxhole]

Top landing is worst possible place to have stat, unless you spend most of your day sitting on the stairs.There is always an updraft on stairs, even if you can't detect it.

 

[diydazzler]

Thanks everyone