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  1. #1
    Join Date
    Nov 2008
    Location
    Northern California, foothills.
    Posts
    212

    Antique BDP Heat Pump--new tstat issue.

    Package heat pump.
    BDP/Carrier
    Product 542BU0030000PBAE (actually, first 0 is a greek phi, I think.)
    Mod 542B030HP
    serial 22/77/V/20227

    I'm guessing it is a 1977, 35+ years old.

    It had an old mercury bulb tstat on it and new tenants simply
    wanted something modern and nice.

    They wanted me to install a Honeywell they bought.
    I did. Heating and cooling were fine.
    However, when I turned the thing to OFF, the contactor
    for the compressor & outdoor fan stayed on.

    I tried a good Honeywell off my van. Same behavior.
    Called Honeywell. They thought my contactor was merely stuck.

    It wasn't. I didn't spend much time on it before it started raining on
    me, but it appears the W terminal on the unit was energized. Y wasn't.
    And that seemed to energize the the contactor, judging from its removal
    de-energizing the contactor.

    I don't remember seeing an O or B on the unit's terminal strip, so I'm
    thinking W was the correct place for the reversing valve wire.

    Of course, I don't have the wiring diagram. In hindsight, I should have
    taken the wiring diagram to the dry and perused it there. But the rain
    was gaining energy!

    So if anybody has a wiring diagram or can help, I would be extremely
    thankful.

    Thank you.

  2. #2
    Join Date
    Jul 2007
    Location
    Virginia
    Posts
    5,460
    Quote Originally Posted by georgelass View Post
    Package heat pump.
    BDP/Carrier Mod 542B030HP

    However, when I turned the thing to OFF, the contactor
    for the compressor & outdoor fan stayed on.

    It wasn't. I didn't spend much time on it before it started raining on
    me, but it appears the W terminal on the unit was energized. Y wasn't.
    And that seemed to energize the the contactor, judging from its removal
    de-energizing the contactor.

    So if anybody has a wiring diagram or can help, I would be extremely
    thankful.
    If you can get the mods to move this to the PRO forum, I'll post the wiring diagram.
    I won't post manuals or technical info in this "OPEN" forum.

    When the reversing valve (RR) is energized from "W", one of the two reversing valve relay contacts closes ("RR2" ), connecting "R" to "Y", to bring on the indoor fan.

    That relay contact could be stuck closed, powering the contractor?

    Sent you an email with the manual too.
    Last edited by rundawg; 02-19-2013 at 09:58 PM. Reason: added info
    Instead of learning the tricks of the trade, learn the trade.

  3. #3
    Join Date
    Nov 2008
    Location
    Northern California, foothills.
    Posts
    212
    Quote Originally Posted by rundawg View Post
    If you can get the mods to move this to the PRO forum, I'll post the wiring diagram.
    I won't post manuals or technical info in this "OPEN" forum.

    When the reversing valve (RR) is energized from "W", one of the two reversing valve relay contacts closes ("RR2" ), connecting "R" to "Y", to bring on the indoor fan.

    That relay contact could be stuck closed, powering the contractor?

    Sent you an email with the manual too.
    If W closes RR, then RR2 gets closed, connecting R to Y which closes the compressor/OFM
    contactor, regardless of whether the tsat energizes Y. That appears to be NORMAL
    operation for this unit. Or am I reading this wrong?

    I'm thinking that W should never be energized unless Y is also energized, that if I want
    to make this thing work with a thermostat that has W always energized unless in cooling,
    then I need to add a relay, power its coil with Y, and run W across the normally open
    contacts so that W is energized to unit only if both W and Y are energized from the
    tstat? I have never had to do such a thing before--modify a unit, but does that sound
    like it would work?

    Again, thank you, Rundawg.

  4. #4
    Join Date
    Jul 2007
    Location
    Virginia
    Posts
    5,460
    Quote Originally Posted by georgelass View Post
    If W closes RR, then RR2 gets closed, connecting R to Y which closes the compressor/OFM
    contactor, regardless of whether the tsat energizes Y. That appears to be NORMAL
    operation for this unit. Or am I reading this wrong? That is the way I read it.

    I'm thinking that W should never be energized unless Y is also energized, that if I want
    to make this thing work with a thermostat that has W always energized unless in cooling,
    then I need to add a relay, power its coil with Y, and run W across the normally open
    contacts so that W is energized to unit only if both W and Y are energized from the
    tstat? I have never had to do such a thing before--modify a unit, but does that sound
    like it would work?

    I'm thinking a heat pump thermostat that the reversing valve is energized in heating by hooking the "RR" relay up to the "B" terminal of the stat.
    .
    Instead of learning the tricks of the trade, learn the trade.

  5. #5
    Join Date
    Nov 2008
    Location
    Northern California, foothills.
    Posts
    212
    "I'm thinking a heat pump thermostat that the reversing valve is energized in heating by hooking the "RR" relay up to the "B" terminal of the stat."

    I'm pretty sure that IS the way it is with the two Honeywell thermostats that I installed.

    But after thinking about it some more, I don't think I need to add a relay.
    Instead, I think I can simply remove the RR2 connections, that enabling
    Y when W is applied should never be necessary, since the thermostat is
    always going to enable Y when it enables W.

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