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Thread: Is there ANY reason to favour a HR91 over an HR92 other than price?

  1. #11
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    wouldnt the batteries last longer because there is no screen to drive? Also on the topic of the screen the HR92 has too many delicate parts that make up the screen.

  2. #12
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    Quote Originally Posted by paulockenden View Post
    Simon, when you talk about build quality remember that the early devices we had were prototypes. For all we know the outer bodies might even have been 3D printed (proper 3D printing mind, not those noddy kits you see for a couple of hundred quid).

    I suspect that the main production run will be more polished.
    Fair point, but I'm not about to buy a retail one to satisfy my curiosity when I've already established that they don't play nice with my valve bodies. (Or at least the prototype didn't) I also already have HR92's on all my radiators now, except for one radiator that has been removed a year ago and not replaced - but when I replace that radiator I'll just get one more HR92, it wouldn't make sense to put something different there for the sake of a tenner.

    As I said in my previous post I'm sure they work fine for many people and many applications, but I wanted to make sure people were aware that a number of significant features of the HR92 are missing like the stroke setting that some may rely on for their valve bodies to work properly, and that was certainly the case for my valves.

    They're not just an HR92 with the screen removed, they're a completely different design with different strengths (mainly quietness and cost IMO) and weaknesses.

    I try to be as impartial as possible especially when giving an opinion about something - if I like something I will say so and praise it but I'm not afraid to say I don't like something or point out any shortcomings I perceive with it either.
    Last edited by DBMandrake; 12th January 2018 at 10:21 AM.

  3. #13
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    Quote Originally Posted by bruce_miranda View Post
    wouldnt the batteries last longer because there is no screen to drive? Also on the topic of the screen the HR92 has too many delicate parts that make up the screen.
    The screen will use next to no power - it's a standard backlit LCD screen which spends 99.99% of its time not backlit.

    LCD watches last so long on tiny button cells (years) precisely because LCD screens use such little power. You can keep a static image on a segment LCD screen like this with basically zero power consumption because it is just an electrostatic charge that maintains a symbol in the on or off state.

    From a power saving perspective you don't even need the main CPU to be running to maintain a static display on an LCD, nor do you need the LCD controller/multiplexer to be active. You can simply have an extremely low power latch driving the LCD display to hold the last decoded display when the device goes into its sleep mode, so keeping the display showing a static image is basically "for free".

    My bet is the entire device, cpu, radio receiver etc powers down during the sleep period with the only things remaining active being a hardware timer on the SoC to wake everything up at the right time for the next broadcast from the controller, the LCD display latch to keep a static image on the screen, and the IO controller for the button and knob. (Since using those also wakes it up) Power drain in this state is probably in the tens of microamps range.

    You've actually got me interested to measure how much current it draws in different states especially idle, so I might have a play with that this weekend.

    So the removal of the screen on the HR91 will have no real effect on overall power drain. It could be less, similar or more than an HR92 based entirely on other factors like the motor, which surely must be the single biggest contributor as it will be drawing hundreds of milliamps to push that pin down...

    I agree about the HR92 screen being fragile though - our toddler has broken the screen on the one in the living room which is now hanging on by only one of its pivot pins... Sigh. I had already repaired the pivot pins on the screen from a previous furniture related knock some time ago (which had also pulled the ribbon cable right out of the insides, so a full disassembly was required to fix it that time) which broke it despite the angle brace being fitted, but there isn't enough left of the pin to repair this time. So one advantage of the HR91 is that it has no fold out screen to break off!
    Last edited by DBMandrake; 12th January 2018 at 10:25 AM.

  4. #14
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    I saw on one site a tamper-proof case for the HR92, which I suppose is aimed at this sort of case. Bit ugly though.

  5. #15
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    Quote Originally Posted by MrBoy View Post
    I saw on one site a tamper-proof case for the HR92, which I suppose is aimed at this sort of case. Bit ugly though.
    Expensive, quite ugly, and in this case I can't use it as the HR92 is too close to the skirting on the wall as it is right on the edge of a bay window alcove so there is less than 10mm of clearance between the HR92 and the skirting without the big chunky tamper-proof case over it.

    Besides, if I protected that one he'd just break one of the others.

  6. #16
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    Quote Originally Posted by MrBoy View Post
    On EHS it's 40 difference on a pack of 4. However if you buy a 16 pack of HR92 and 4x4 packs of HR91 the unit price is the same at 50. I've not seen anywhere really tout the 91, maybe they just haven't taken off.
    They've put the prices up of the HR924UK multipack then, i'm sure they were only usually 215 for a pack of 4. So in which case, yes if you are buying off the theevohomeshop then there is 45 difference which is quite a bit. But seeming you can pick up a pack of HR924uks for around 200 elsewhere then you aren't really saving much.

  7. #17
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    If I was someone looking again for a new smart heating system for a house with 19 radiators, the difference in cost between the HR92 and a Wiser TRV (39.99 from Screwfix) would give me a lot to think about.

  8. #18
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    There was a range wide price increase from Honeywell a short while ago.

    Need to look into Wiser a bit more, but I wasn't overly impressed with what I saw last time I checked (which i admit wasn't very in depth).
    Kind Regards - Dan Robinson (Jennings Heating Ltd)

  9. #19
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    I have so far never needed to buy a HR92 because my HR80s from a Hometronic and CM Zone installation are still going strong. But I do remember thinking that the pivoting screen design of the HR92 was just asking to trouble. The HR80 has so few moving parts by comparison but I miss being able to see what the current temperature in the room is.

  10. #20
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    Quote Originally Posted by HenGus View Post
    If I was someone looking again for a new smart heating system for a house with 19 radiators, the difference in cost between the HR92 and a Wiser TRV (39.99 from Screwfix) would give me a lot to think about.
    not seen that one, is it like for like with their own controller box, RF Comms, etc?

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