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  1. #1

    Thermostat Issues

    I've been a lurker here for a long time. I get a kick out of the wall of shame. I've owned seven houses, and each one had HVAC / electrical plumbing issues
    that could have made the wall.

    What I'm asking for today is some advice on thermostats. I have a 1960's ranch house here in San Jose that has some nice energy efficiency features like a living room vaulted ceiling with no insulation. Hey everybody knows that by the 70's nuke plants will make electricity too cheap to meter.

    When I had a new 80% eff. Trane furnace and 4 ton SEER 12 system installed 6 years ago they gave me a crummy White Rodgers thermostat.
    I went and replaced it with a Honeywell Chronotherm IV Plus. I guess some of you guys would consider that DIY. This may not endear me to you but I have a master's degree in electronics and can wire a stat. When I want the refrigerant checked I'll call one of you guys.

    Anyhow the thermostat is on an interior wall right next to the main return duct. In both summer and winter when returning the thermostat from setback (or setup?) I have a couple of hours for which the thermostat reads a couple degrees lower in summer, and higher in winter than what a thermometer in the same location reads. I believe this is because the stat
    is somehow reading the temperature of the wall. ( An idea first patented in
    1939 Patent 2158435 )

    I don't want to go to a zoned system ( my ducts are already pathetically
    small that I had replaced 6 years ago, but I figure I'm moving 350 CFM per ton, which is not good, but not terrible )

    What I want to know is there a good residential thermostat (system )
    with multiple sensors. Or failing that, just a digital thermostat where I
    can tweak or turn off the wall measurement feature?

    You probably will be offended that I have a 4 ton system in a 1700 ft^2
    house. But that's what the contractor put in when I bought the house and
    was starting a new job and not paying attention. And it can drop the temp.
    here on a 105 degree day. Fortunately humidity removal is not a big issue here.

    Over the last twenty years I have paid contractors for 3 new central Air systems, one heat pump and two gas furnaces. (In seven different homes)
    While I haven't funded the HVAC industry like I have Realtors, you folks haven't done too badly on me.

    Anybody know a good thermostat? Aprilaire?

  2. #2

    Hidden Agenda

    I do have a hidden agenda here.
    I'm desperately trying to stop myself from starting a thermostat design and build operation. The last time I did that sort of thing was to create infrared remote control devices for my model trains. If I start a big side project now here in silicon valley, I'll probably get laid off immeadiately.

    So please what are the commercially available thermostats with multi/
    sensors and or no wall sensing?

  3. #3
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,765
    If you want commercial stats, you can use one.

    But why not just get a residetial one that can have remotes.
    Like a Honeywell IAQ.
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  4. #4
    Multiple sensors in different rooms which the Honeywell IAQ could do
    would be a good idea, since I have some significant variation.

    However what I think is really undesireable about my current Chronotherm is its wall temperature measurement feature. Its possible I'd be happy with a thermostat that just did a better job of measuring the air temperature. I don't know whether the wall temperature thing is just a Honeywell thing, or not. And maybe the newer Honeywell's don't have it. Does anybody know?

  5. #5
    Join Date
    Nov 2007
    Location
    Tucson AZ
    Posts
    166

    KISS

    You may be trying to over engineer this problem.

    How about a first pass at a solution by just making sure that there is no airflow from the wall cavity through the hole used by the thermostat wires, and also maybe add a wood plate to mount the thermostat on and restrict its ability to measure the wall temperature?
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  6. #6
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    67,765
    Any thermostat mounted to a wall, or other object that has mass. Is effected by the temp of the mass it is attached to.
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    How many times must one fix something before it is fixed?

  7. #7
    Multiple sensors in different rooms which the Honeywell IAQ could do
    would be a good idea, since I have some significant variation.

    However what I think is really undesireable about my current Chronotherm is its wall temperature measurement feature. Its possible I'd be happy with a thermostat that just did a better job of measuring the air temperature. I don't know whether the wall temperature thing is just a Honeywell thing, or not. And maybe the newer Honeywell's don't have it. Does anybody know?

  8. #8
    Join Date
    Jan 2008
    Posts
    85
    Why don't you contact Honeywell customer support with a pre-sales question?
    The stat can't be moved?

  9. #9
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,765
    The Honeywell wireless doesn't. You can set it on your coffee table if you want.
    Then take it to your bedroom at night to control the temp based on your bedrooms temps.
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  10. #10
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,296
    Quote Originally Posted by bobRitchie View Post
    I do have a hidden agenda here.
    I'm desperately trying to stop myself from starting a thermostat design and build operation. The last time I did that sort of thing was to create infrared remote control devices for my model trains. If I start a big side project now here in silicon valley, I'll probably get laid off immeadiately.

    So please what are the commercially available thermostats with multi/
    sensors and or no wall sensing?
    If you want to go geeky with your comfort, go geeky on your house. Vaulted ceilings with no insulation? Do you live in an Eichler or Like-ler (post and beam roof with no attic)? If not, and you have an attic, get some insulation up there. It's just asking for trouble to carry a 1960's house into an era of perpetually unstable energy prices. If your house is an Eichler or the like, I'd be looking into redoing the roof with insulation applied to the exterior of the roof deck. There are companies in the Bay Area that specialize in working with Eichler houses.

    As for your Chronotherm, biggest problem with any thermostat is the holes made in the wall for the t-stat wires to pass through are seldom sealed. Any air movement in the wall cavity behind the stat will affect the t-stat's reading if the hole is unsealed. I also like the idea of the wood panel behind the stat, as shown in a previous post.

  11. #11
    Thanks for the comments.

    A couple of years ago I caulked the hole where the wires
    go through.

    I still think my problem my be due to the fact that according to
    the manual this chronotherm delibrately is designed to sense
    the temperature of the wall. The wall on which the stat is on is
    the chase for the return duct and opens to both the attic and
    crawlspace. While I've stuffed insulation around the duct at both
    ends, its not like a normal interior wall. Believe it or not in this
    house because of walls of glass, fireplaces bvents in walls, the only
    normal interior walls to put the stat on would be the kitchen, bedrooms,
    or the living room with the uninsulated ceiling.

    As for my house, yes the living room is Eichler like. Fortunately the
    rest of the house has attic, to which I've add R30 insulation. But in
    the living room I have planks that are stained and visible from below that
    the roof sits on. I like the look from below. I suppose the best thing to
    do would be to use spray foam insulation and put drywall underneath.
    But I'm told that would be against code in Calif. right now, since attics
    of any sort need ventilation. And it would not be a visual improvement.

  12. #12
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,765
    Your stat is old. And may just be ready for replacement.

    Most people would be very irratated if their stats reacted to air temp only.
    It would cause short cycling.

    Try the wireless.
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  13. #13
    Gee I've lived somewhere long enough for something I bought
    for the house to get old?

    Actually its done pretty much the same thing for years. But I had
    other more pressing issues in the house and yard.

    The wireless may be the way to go. I guess I'm old enough to remember
    the garage door openers in the early 70's that would activate from stray
    signals etc. I just kinda associate wireless = flacky = unreliable.

    And I would be given a hell of a hard time if I changed the system from
    2 degrees off thermostat setting, to going crazy.

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