Honeywell or Salus Thermostat

heffo500

Hi

I want to upgrade my thermostats in my house which are currently Sunvic TLM 2000 See link: http://www.sunvic.co.uk/products/electromechanical-room-themostats/tlm-2000-series/tlm-2000-control/

Currently I'm looking at three different replacements and would like to get your opinion as to which would be best.

Honeywell DT90E
http://www.honeywelluk.com/products/Temperature-Controls/Temperature-TPI-Control/DT90E/

Salus RT300
http://www.salus-tech.com/products/thermostat/digital-thermostat/_c1_30_digital-display-room-thermostat/

Timeguard TRT033
http://www.timeguard.com/products/climate/programastat/trt033-digital-room-thermostat-with-night-set-back

Any feedback would be greatly appreciated.

Many Thanks
heffo500

shane0007

Personally, I prefer the Horstmann range.
http://www.horstmann.co.uk/central-heating.php

The HRT4-B would be the equivalent of what you are reviewing.

heffo500

shane0007 wrote: »

Personally, I prefer the Horstmann range.
http://www.horstmann.co.uk/central-heating.php

The HRT4-B would be the equivalent of what you are reviewing.

Thanks for the reply shane, I'll see what my local plumbing wholesalers has in stock.

The old Honeywell stats were wired with only a live and switch wire and no neutral and I was told that is why the stats are poor to react, so will they battery powered ones by far more accurate as they dont need a neutral?

TPM

heffo500 wrote: »

Thanks for the reply shane, I'll see what my local plumbing wholesalers has in stock.

The old Honeywell stats were wired with only a live and switch wire and no neutral and I was told that is why the stats are poor to react, so will they battery powered ones by far more accurate as they dont need a neutral?

the fact that the stat was only wired with a live and switch wire has no impact on how the stat reacts.
once the stat switches it will instantly turn on/off the power to what it is controlling.
different stats will react differently, speed, switching differential etc.

shane0007

TPM wrote: »

the fact that the stat was only wired with a live and switch wire has no impact on how the stat reacts.
once the stat switches it will instantly turn on/off the power to what it is controlling.
different stats will react differently, speed, switching differential etc.

I'd have to disagree there.

TPM

shane0007 wrote: »

I'd have to disagree there.

well i would have to disagree with you disagreeing lol but I could be wrong

I would be interested to hear your take on it.

imo once the stat switches and closes its contacts it instantly powers up what it is controlling, basically like a light switch. a motorised valve wont open any quicker or slower once the stat contacts close regardless of a neutral being present or not at the stat.
different stats do respond dramatically differently and if you have a neutral available it may widen the options of which stats can be used but this will still not have affect how the controls respond once the contacts are closed

heffo500

TPM wrote: »

well i would have to disagree with you disagreeing lol but I could be wrong

I would be interested to hear your take on it.

imo once the stat switches and closes its contacts it instantly powers up what it is controlling, basically like a light switch. a motorised valve wont open any quicker or slower once the stat contacts close regardless of a neutral being present or not at the stat.
different stats do respond dramatically differently and if you have a neutral available it may widen the options of which stats can be used but this will still not have affect how the controls respond once the contacts are closed

Thanks for that the sunvic one that I have at minute require a neutral it's says on the wiring diagram I think it's because they aren't battery powered

shane0007

TPM wrote: »

well i would have to disagree with you disagreeing lol but I could be wrong

I would be interested to hear your take on it.

imo once the stat switches and closes its contacts it instantly powers up what it is controlling, basically like a light switch. a motorised valve wont open any quicker or slower once the stat contacts close regardless of a neutral being present or not at the stat.
different stats do respond dramatically differently and if you have a neutral available it may widen the options of which stats can be used but this will still not have affect how the controls respond once the contacts are closed

A stat without a neutral is just a switch, like a cylinder stat. A cylinder stat does not require a neutral as the only parameters affecting it is the heat of the water in the cylinder, so reacts accordingly.

A room thermostat is affected by air temperature but can fluctuate to false temporary temperatures such as when doors open & close.
Stats wired with neutrals activates an anticipator built into the stat. This is basically a tiny resistor that heats giving a very small constant temp within the stat so the stat is only affected by gradual air temps rather than sudden cooling by a door opening, etc.

Stats wired without this or that do not incorporate an anticipator have an average inaccuracy of approx 6C.

Stats with batteries use the battery to power its internal PCB which calculates the correct temperature, so stats wired with no neutral to the stat does not necessitate a re-wire, just a replacement with a live in live out battery operated stat.
Volt free boilers require these also if wired in series with a volt free timeclock as if there is a neutral, there will be 230V at the stat which would blow the boiler PCB.

If I get a chance later tonight, I drew up various diagrams of wiring scenarios & I will post them.

TPM

its down to how the stat reacts before the contacts. having a neutral wire present at the stat location(or use battery powered stats) you can fit more advanced stats that can give you better control/options including the anticipator, time control. frost protection etc.
you can also have a stat wired with a neutral where the neutral sole function is to allow an indicator light show when the stat is calling for heat.

I am not going to get into a war of words, fundamentally having a neutral available can allow better temperature control.
IMO there generally isnt enough consideration and thought put into heating controls(stats, time clocks, controllers etc) in new installations and upgrades.

this thread has highlighted the fact that every stat isnt the same.

shane0007

TPM wrote: »

the fact that the stat was only wired with a live and switch wire has no impact on how the stat reacts.

I disagreed with this part of your statement. This is not true. No neutral means inaccuracy, therefore what you said here is incorrect. No war of words, just stating why it is incorrect.

Irish Steve

OOOhhh I love a good fur fight:D

perhaps a clarification will smooth things down.

Inaccuracy is a dangerous word to use with thermostats, in that it's not going into the issues closely enough;

The first inaccuracy can be where the thermostat doesn't respond at the temperature shown on the dial. That's totally unrelated to the presence or absence of a neutral wire, it's down to the design, and the way it operates, and how well it was calibrated when manufactured, and the age of the device.

The issue of a neutral, going back to older thermostats, is that when the circuit changes state, and switches either on or off, another change in the temperature will then be needed to change that state. On a thermostat WITH a neutral, there is some form of additional circuitry (at its simplest a small resistor under the bimetallic element, which heats the air in the immediate vicinity) which is designed to make the band over which the thermostat operates narrower.

In some assisted thermostats, there are also mechanical assists, such as a magnet, or similar, and one of the reasons for that is to ensure that with less movement and pressure from the bimetallic strip, the electrical contact made is a good solid contact, and not at risk of arcing because there is not a solid connection, and that sort of assist needs an additional assist device like the resistor to make the operating band narrow enough to be realistic.

So, in terms of accuracy, when new, both types are essentially "accurate", if correctly manufactured and calibrated.

Where there is "inaccuracy" is in the width of the operating band, a non assisted thermostat may well have a bandwidth of 6 or more degrees, so it switches the heat on at (say) 18, but doesn't cut out again until 24, and depending on the age and activity of the residents, 6 degrees of a change between on and off may well be noticeable.

An Assisted thermostat has a much narrower band of operation, so the residents won't see the same swings in temperature in the environment of the room, all other factors being equal.

Over time, both types of thermostat will deteriorate, and can then develop issues with accuracy due to wear, or changes in the physical properties of the bimetallic strip, or the strength of the magnets, among other things.

I've not even touched on inappropriate locations for a thermostat, which can mean that the air that affects the thermostat is not representative of the temperature in the area that it is supposed to be controlling, that's another issue that we could (and perhaps should) write a book about.

How's that .

shane0007

Sorry Steve, I just read your first word & the last, so I don't know what you mean by "ooohhh that".
All the rest was just a blur....

TPM

Ok I see where you are coming from, you are referring to a stat like honeywell t6360b in which case connection of a neutral allows the anticipator to function which provides better control.

but if you connect a neutral to a stat like robus rrf10 it only permits the indicator to light when the stat is calling for heat, it doesnt affect the control of the stat. the same could be said of some battery powered stats.

so I agree that in relation to some stats and applications the connection of a neutral can affect the control/reaction of the stat, but not as a general statement in relation to all stats

shane0007

Many stats do not have anticipators but they are generally found to operate fairly inaccurately.
Do you have a wiring diagram for that model?

Battery operated stats all have a PCB that calculates inaccuracies & therefore do not require anticipators.

shane0007

As promised....

shane0007

And...

heffo500

Thanks for the diagrams shane very helpful.
So I had upgraded my neighbours timeswitch for them but also installed a room thermostat for them yesterday, The only one I could get my hands on on saturday morning was the timeguard in my first post. So its working perfect one thing I don't like is that the blue backlight doesn't stay on like the timeswitch. I order two of the Honeywells myself but the only Horstmann ones I can across were DRT1 or DRT2 in B&Q in liffey valley and they seemed very cheap which put my off them. I'll post again when I put in the honeywell stats.

Thanks for all the replies lads.