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  1. #1

    2-stage heat relay issue - Help

    My house is using 2-stage heating. 1st stage is Radiant Heat (oil furnace). 2nd stage is Forced Hot Air (Unico system). I have 2 thermostats controlling the house (1 for upstairs, 1 for downstairs). My upstairs 1 is set for 2nd stage to come on 20 minutes after 1st. It seems that even after the room reaches temperature and the thermostat stops calling, the relay in my machine room doesn't turn off (which makes it continue to run). If I disconnect the relay wire for my 1st stage so I only use 2nd stage, it works fine (relay shuts off). What's also weird is that it seems if I set my 2nd stage to turn on in 5 minutes (instead of 15 or 20) it also works fine and shuts off. My HVAC guy tried a new thermostat and same problem exists. Also tried changing relay, with no luck. He is now telling me that he want to install 2 thermostats, 1 for radiant and 1 for Unico (which I don't want). Other people have suggested that it may be an issue with the wiring (pinched wire etc.). Help!

  2. #2
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,119
    Probably a control wiring issue, not punched wire.

    All the 2 stage radiant with forced air as second stage that I have in. Use the temp to determine if second stage should come on or not. makes for a more comfortable room/house.
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    How many times must one fix something before it is fixed?

  3. #3
    You think its a wiring issue? I just can't fiigure out why it worked fine when I had it set to come on 5 minutes after 1st stage, but crapped out when I bumped it up to 15. Even more bizarre, if I go into the machine room and re-connect the wire to the relay, it immediately goes back on, but if I wait a day or 2 and re-connect, it won't go on until the thermostat really needs it.
    Looking for answers. Anything I can try test to confirm what it really is?

  4. #4
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,119
    Too difficult to try and fix it over the internet. A good tech can figure it out fairly quickly on site.
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  5. #5
    Join Date
    Jul 2004
    Location
    Massachusetts
    Posts
    6,837
    That control strategy is whacked, IMO. Here's why. It's 30-degrees outdoors, how long does the radiant system need to run to heat the room? Now it's 55F outdoors, how long now? That's why timing isn't a good parameter to use for turning on supplemental heat. Therefore, I would recommend a true 2-stage thermostat be used. This will likely require an isolation relay to keep the transformers from conversing with each other but otherwise, the radiant should be able to heat the room under some set of outdoor conditions and below those conditions, you'd need supplemental heat. To think you need supplemental every time the radiant doesn't turn off within 10, 15 or 20 minutes is to defeat the most attractive of the radiant assets, its ability to deliver constant heat without turning off.
    If YOU want change, YOU have to first change.

    If you are waiting for the 'other guy' to change first, just remember, you're the 'other guy's' other guy. To continue to expect real change when you keep acting the same way as always, is folly. Won't happen. Real change will only happen when a majority of the people change the way they vote!

  6. #6
    I have the thermostat set to 68. It is climatouch. The setting is 'if stage 1 runs xx minutes turn stage 2 on. I can set the minutes from 1 to 59. It also kicks in stage 2 if the temp drops too quickly to help keep up. The HVAC guy is telling me that he wants to put in a 2nd thermostat too separate the stages, but I would have to manually turn it on and I don't want 2 thermostats in my room.I just want it to work! Suggestions?

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