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Honeywell R8845u reliability vs transformer+fan relay

dynastyssdynastyss Posts: 14Member
Hello!

So I purchased a home that has a gas fireplace (only source of heat in the house) and for the first 10 months their setup had worked flawlessly. They were using a 750ma/24va sprinkler timer transformer to power the Nest which then went a Packard PR380 24vac fan relay. A few weeks ago the Nest would show that it is running, set to 68, but the house temperature dropped to 39 degrees. I drove up to look and the fireplace would kick on for a minute, then stop even though the Nest was still orange and allegedly heating. I replaced the transformer and it did nothing. I then replaced the relay and it worked again.
Obviously the spring or something in the relay had gone bad. That said, it is 200 miles away and I was anxious about it going bad again in an inconvenient time so I went about changing it. I bought a Honeywell R8845U1003 which seems to do everything all in one box, and I drove up and swapped it out. It works as expected but what I am really hoping is that it is more reliable. It seems this box is made for millivolt systems, but I am curious if anyone is using this and how long as it worked trouble free? Am I crazy to assume this should be more reliable?

Comments

  • Jamie HallJamie Hall Posts: 12,161Member
    Don't worry about the millivolt bit. That just means that the contacts have a low enough resistance (not all relays do) so it can be used on millivolt systems -- but it is not limited to them.
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • dynastyssdynastyss Posts: 14Member
    Thanks Jamie. How long can I expect the relays to last?
  • EBEBRATT-EdEBEBRATT-Ed Posts: 6,582Member
    As far as I am concerned Honeywell relays are as reliable as you can get.
  • dynastyssdynastyss Posts: 14Member
    That's good to hear! So presumably I can expect years of work out of these relays :)

    I wonder if the duration that they are "on" has any effect? Often the fireplace is on for 20+ hours a day.
  • Jamie HallJamie Hall Posts: 12,161Member
    Relays are rated in cycles, not on time. So the long on time is not a consideration. That said, the control board is sensitive to dirty electric power. If you are way out in the woods and the lights flicker and blink, a surge protector on that circuit -- at the very least -- would not be a bad idea.
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
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