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Discuss Honeywell Wireless issues in the Central Heating Forum area at

  1. smk82

    smk82 New Member


    We had a new boiler system installed last year, including a new programmer and wireless thermostat. These are a Honeywell wireless enabled programmer (ST9420C) & Wireless room thermostat (DT92E) as far as I know (The stat is correct, I think that's the correct programmer).

    The stat intermittently (but regularly) looses its RF connection to the relay box and requires resetting. In the last year, its dropped 15 times (including 3x yesterday alone - doesn't seem like much, but obviously heating wasn't required for most of this year!)

    The programmer is installed next to our pressured hot water cylinder in the airing cupboard upstairs along with the relay box for the wireless stat. The relay box for the thermostat is positioned at least 30cm away from anything metal; so shouldn't be experiencing any interference.

    The stat is downstairs in the hallway, probably about 5-6m away total, so has to transmit through 1-2 walls/1 ceiling. According to HW specs, it should connect through 3-4 walls and 30m range. However despite trying to move the stat in all different rooms of the house, unable to get a "strong" signal apart from literally right outside the door of the airing cupboard.

    Based on the evidence, does this seem like a faulty stat?
  2. doitmyself

    doitmyself Well-Known Member

    Which make/type batteries are installed in the dt92e stat?
  3. smk82

    smk82 New Member

    Duracell AA I think from memory.
  4. doitmyself

    doitmyself Well-Known Member

    Sounds good; at least they are not rechargeable. Have you tried new batteries?
  5. smk82

    smk82 New Member

    First thing I tried. Tried moving the thermostat to different rooms as well, only place able to get a strong signal was literally right outside the door to the airing cupboard. Its been causing issues on/off for the past year.
  6. JCplumb

    JCplumb Plumber

    Have you got any other devices that may be using the same frequency which may be interfering with the signal from the stat?
    Telephones, wireless alarms, wireless microphones, wireless keyboards/mice/headphones etc. The list goes on.
    Turn them off or move them out of the way and see if your problem gets better.
  7. smk82

    smk82 New Member

    hmm, that's a thought. Whilst I have wireless keyboard/mice I doubt they would be the culprits. I didn't think of the alarm however . I just checked and our alarm utilises 868Mhz, the same (apparently) as the thermostat.. Thing is the stat is mentioned to only use "burst" transmissions as is the alarm, so I would have thought that they wouldn't flood the bandwidth and interfere with each other?
  8. doitmyself

    doitmyself Well-Known Member

    So the ST9420C is located inside the airing cupboard? Was the programmer for the previous system in the same place? If not why didn't you use the original location - or didn't you have a programmer?

    Is there much metal in the cupboard which could block the signal - e.g HW cylinder? You could try moving the programmer outside the airing cupboard - my BDR91 wireless relay is outside the a/c and I've never had any problems with signal strength.
    • Like Like x 1
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