Replacing old room thermostat.

Discussion in 'Plumbers' Talk' started by Lazycarton, Oct 23, 2018.

  1. Lazycarton

    Lazycarton New Member

    The thermostat in our place is the original from when the house was built in 1988. It seems a bit reluctant to click in an out and has lost it's sensitivity. I am thinking of replacing it. There are many I could buy, does anyone have any suggestions as to which would be favourite?
     
  2. The Teach

    The Teach Screwfix Select

    if the existing is mains voltage with a neutral connection, for a basic room thermostat the honeywell T6360 works well.
     
    Deleted member 11267 likes this.
  3. Allsorts

    Allsorts Super Member

    Teach's suggestion is a good solid reliable model. It is analogue, of course, so were you thinking of the same or perhaps going digital?

    I would almost always recommend a Programmable type - these take over both the timings and the temps, so you can set it to control your house's temp automatically (eg: 20oC at 7am, down to 16oC at 9am, back up to 20oC at 5pm, up a little to 21oC at 8pm, then back down to 14oC at 11pm... that sort of thing, whatever you want. Then you just press a button at any time to override if it at any time).

    As for recommendations, the first thing is to see if your existing stat has 2 wires plus earth or just two - most likely the former. If 3+E, then you can fit a mains-powered room stat if you wish (no batteries to replace), but if only 2+E then it's batteries or add a further wire (usually not worth it).

    What else to consider? I guess the main thing is how easy it is to control - it should be intuitive (I have a Heatmiser 'cos I thought it was about the best at the time, but I need to instructions just to change the time...). Other features - how large and clear the display is. If you are going Prog Stat, then how many offs and ons it'll do each day, and can you do each day differently if you need this (most will do the 5 days and then the weekend differently.)

    I'm sure folk will recommend specific models if they are pleased with them.
     
  4. Lazycarton

    Lazycarton New Member

    Thanks for the replies. I will check to see what sort of connection I have (2+E or just 2)
     
  5. Allsorts

    Allsorts Super Member

    2+E or 3+E

    If you post a photo, we can advise further.

    Tbh, most new digital stats these days are battery-operated, so 2 wires is all you'll need for these.
     
  6. Lazycarton

    Lazycarton New Member

  7. Allsorts

    Allsorts Super Member

    I doubt you'll go wrong with that Honeywell Stat, although I have no personal experience of them. I still think you'd be nuts to not go 'Prog' Stat, tho'...

    Cool, you have 3+E, so could fit a mains-powered Stat if you wanted.

    To confirm which of these wires you'll need to transfer to the new stat (and which one to safely terminate behind the Stat), we'll need a photo - don't kill yourself - of the numbered terminals they are going to, along with the make and model number of that old 'Stat.
     
  8. Lazycarton

    Lazycarton New Member

    The thermostat is a Sunvic TLX2259. The Rd wire goes to No1, the Yel to No3 and the Bl to No4.

    Here are some pics :-

    [​IMG]

    [​IMG]
     
  9. Allsorts

    Allsorts Super Member

    According to this: https://www.edwardes.co.uk/uploads/...NS_TLX2222_2251_2251N_2259_2267_2356_2852.jpg (and the label on your stat) the red and yellow may have been swapped around incorrectly, in which case your stat probably didn't work very well - the wee heater inside would have been on all the time..

    Do you have a way of testing for 'live' other than using your finger? Cool. CAREFULLY test the RED - that should be 'live' all of the time, regardless of whether the room stat is turned up or down beyond its 'click'. The YELLOW should go 'live' ONLY when the stat is turned up beyond the 'click' and NOT be live when turned below the click.

    Good photos - but I cannot see the actual numbers on the terminals - any chance of catching it in the light so they show up?
     
  10. rogerk101

    rogerk101 Screwfix Select

    It's good to see that you're going for a programmable thermostat, but it's definitely worth going for one that is mains fed (especially since you already have the right wiring for it). That said, make sure you buy a mains fed one that has a battery backup, so that you don't have to reprogram it whenever you have a power failure.
     
  11. Lazycarton

    Lazycarton New Member

    Hi Allsorts, There are no markings for the wiring on the rear of the stat. The wiring diagram is shown on the plastic piece at the bottom of the front of the stat as shown in the 2nd pic posted at 10.16am. They are numbered 1,3 &4, there is no number 2?

    I have a multimeter which I use for making hifi amplifiers and other audio kit. The answers to your question are :-
    RED is Live all the time (249vac)
    YELLOW only goes live when the thermostat clicks clockwise.

    Incidentally voltage between LIVE and Earth shows 222vac, not sure what that means.

    In answer to rogerk101 I have just seen the reference to 2AA batteries, which I assume means that it is NOT mains powered. The entry says that it has mains power switching, so does that mean that the display is battery powered only? Is that bad?
     
  12. Allsorts

    Allsorts Super Member

    Hi LazyCarton (what made you come up with that?!)

    Ok, your current 'stat is wired incorrectly; the red and yellow are interchanged. This means that it never worked as sensitively as it should have - the wee accelerator heater inside it was always on, rather than coming on with 'demand'.

    That's not a prob. The only two wires you need to use for you new BATTERY-powered Stat is red and yellow. (If you choose a mains-powered stat, then you'll also need the Blue (neutral) in order to power the stat.

    RED is your permanent live.
    YELLOW is your switched live. This is the one that becomes live whenever your stat calls for heat. The yellow is the one that then tells your boiler to come on.

    Thing to do - choose your new 'stat. Then we'll tell you how to wire it up.

    Strongly recommend a Prog Stat, but only if you understand what it does and this is actually what you want. Ie - if you are more happy to simply turn the stat up and down as you need it, then that's fine.

    The difference betwixt mains and battery-powered is minimal. Battery types will last at least a year, often 2, before they need replacing, so not a big deal. When it comes to powering the displays, even mains ones usually turn their backlights off when not in use (they light up whenever you press a button).

    I did deliberately choose a mains one for myself as I didn't want to ever bother replacing batteries, and it certainly does that job well - it even holds the programmed info during a power cut. But it's not a biggie.
     
  13. Lazycarton

    Lazycarton New Member

    Hi Allsorts, thanks for your reply. I have found a Drayton programmable stat (see link) although I would ideally have wanted something a little more simple, but having said that I like idea of it adjusting the temp without my having to manually tweak it :-

    https://www.screwfix.com/p/drayton-digistat-3-room-thermostat/75750

    I may not be able to get to Screwfix tomorrow, but thanks very much for the offer of "then we will tell you how to wire it up"

    Yes...my username...a loooong story and not very exciting.

    Cheers.
     
  14. Allsorts

    Allsorts Super Member

    That looks like a very nice bit of kit, and most of the reviews are very positive. My only slight reservations would be to do with the system it's tied up to - if it's 'older' with an 'older' boiler, then it might not be as effective.

    It appears to have this 'algorithm' which saves energy by anticipating when the room is almost up to temp, and it then shuts the boiler off and on again in a few-minute stages until the temp is reached. Ie it doesn't want to over-shoot the room temp by waiting until the temp is reached before shutting off, but instead tries to toggle the boiler on and off so's it 'arrives' at the set temp easy-oasy.

    This does seem to mean that it turns the boiler on and off more often than more basic models; no idea if this is an issue for most folk.

    PLUMBERS? ANY THOUGHTS?

    What boiler do you have, make and model? And does your house get up to temp quite easily when needed, or does it take a while? (The ProgStat has options for 'slower' systems which would probably help this.)



    Anyhoo, on to more important issues - your username... :)
     
  15. Lazycarton

    Lazycarton New Member

    The boiler is a Potterton Kingfisher that was installed about 15 years ago when the kitchen was re-designed. Ii is not a Combi boiler. The house takes quite a long time to reach temp when the boiler has been off overnight.

    Now the more important issue....it is a play on words for someone in the music business, the reason behind the play on words would now be considered non PC.
     
  16. Allsorts

    Allsorts Super Member

    With a 'slow' system and an oldish boiler, I suspect you don't want this 'Stat's default algo to be turning the boiler on and off excessively. Instead you'd want it to simply remain on until the temp is reached, and then hold it there fairly steadily.

    I THINK this Stat has that feature; you can set it to handle different types of system, both 'slow' in traditional houses, and modern in very high-insulated houses.

    Might be an idea to search online for the instructions for this stat and give them a read.

    It does look like a very nice unit.


    Ok, am I going to have to search the dark web for 'cartons' or are you gonna spill? :)
     
  17. Lazycarton

    Lazycarton New Member

    Here is a PDF of the instructions, I can't see a "slow! mode but it says this :-
    What is Intelligent delayed start. The Intelligent Delayed Start is an energy saving feature which automatically reduces the warm up time for the heating system. As the weather becomes milder, Intelligent Start will delay the heating start times so that the fuel is not wasted bringing the room up to temperature earlier than necessary. Is this the same thing or similar?
     
  18. Lazycarton

    Lazycarton New Member

  19. Allsorts

    Allsorts Super Member

    That's different, but also clever.

    If you want it to give you, say, 20oC house temp at 7am, then you'd usually have to set it to come on at - ooh - 6.30 or even earlier. What this Stat does is to act on the temp you WANT the house to be warm at (eg 20oC at 7am) and it'll will then turn on your boiler at the best time to achieve this.

    So, in milder weather it might not turn on your boiler until 6.45 as it would have worked out that 15 minutes is all that it'll need to get your house to 20oC at 7am. However, in winter, it will have automatically worked out that it would need to turn on the boiler at, say, 6am for it to get to house temp at 7am. Basically, it records how long it takes to get the house up to temp, and adjusts this as the seasons change.

    I'll have a gander through the instructions for this other feature - suiting various systems.
     
  20. Allsorts

    Allsorts Super Member

    I can't find this option to adjust the unit to suit different systems, but one review says "I have an old oil boiler and single pipe system, so up against a few problems. Made sure I selected the "installer" options to select "oil" and "slow" system. Fitted in place of all thermostat and it works very well so far. For the price an excellent choice, though one option I think I would look for in future would be an illuminated screen, as no backlight on the system. However happy with the thermostat which now takes over from the old timer, which is left on permanent CH and only timed for the HW. Had to put an entry against reliability but of course not yet able fully say as time will tell. "

    Not sure how to access the 'installer options', but an email to Drayton (or more Googling) should provide the answer.
     

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