dgbrown Posted November 12, 2012 Share Posted November 12, 2012 Looking for some help or ideas here guys. I just got around to relocating a C4 tstat from the second floor down to the equipment room and have a Aprilaire temp sensor in the same spot where the tstat was located.Givens:* I'm using the existing tstat wire from the second floor to the equipment room in the basement to connect the sensor to the C4 tstat. This sensor was connected to this same tstat when it was installed on the second floor using on the pigtail on the sensor and functioned fine.* I ran new 4 conductor 18awg from the valve relay box (Taco brand) on the furnace to the C4 tstat in the equipment room * The tstat is hooked up with a common red to Rh, white to W1, and blue to ts/C.* Red and white from the second floor sensor are to ts and ts/CSymptoms:* tstat powers up fine from common without a battery.* With sensor connected per above - and heat off - burner cycles on and provides heat to second floor when tstat powers up* With sensor NOT connected - and heat off - burner remains off when tstat powers up.Anyone have a clue whats going on here ? Some type of interference perhaps ? Link to comment Share on other sites More sharing options...
Cyknight Posted November 12, 2012 Share Posted November 12, 2012 Hmm, is the sensor SET to use the remote sensor? This has to be done for it to work properly - although I have not know it to behave the way you state when it isn't... Link to comment Share on other sites More sharing options...
dgbrown Posted November 12, 2012 Author Share Posted November 12, 2012 Yep. Set to use remote sensor. Same stat same sensor. Only the sensor uses the stat wire to connect to the stat now instead of just the pigtail from the sensor. Link to comment Share on other sites More sharing options...
Cyknight Posted November 13, 2012 Share Posted November 13, 2012 With the sensor connected, are your temp readings accurate, or is it off by much or jumping around a lot?It's possible the old wire to the tstat is messing with the overal resistance, or I've seen some furnaces give "bad power" causing fluctuations when using a remote sensor (the jumping temperatures are an indication of this).Only way that comes to mind right now to deal with the bad power scenario is to power the tstat seperately - but that requires rewiring the furnace to a relay, programming to trigger vs having the tstat work as a tstat etc. Link to comment Share on other sites More sharing options...
AK1 Posted November 13, 2012 Share Posted November 13, 2012 Check the fuel / heatpump switches on back of Tstat it is easy to accidentally move these. This occurred in my house when the Tstat fuel setting accidentally slid to "electrical" when it should have been "fuel" for my gas-fired boiler. Looking for some help or ideas here guys. I just got around to relocating a C4 tstat from the second floor down to the equipment room and have a Aprilaire temp sensor in the same spot where the tstat was located.Givens:* I'm using the existing tstat wire from the second floor to the equipment room in the basement to connect the sensor to the C4 tstat. This sensor was connected to this same tstat when it was installed on the second floor using on the pigtail on the sensor and functioned fine.* I ran new 4 conductor 18awg from the valve relay box (Taco brand) on the furnace to the C4 tstat in the equipment room * The tstat is hooked up with a common red to Rh, white to W1, and blue to ts/C.* Red and white from the second floor sensor are to ts and ts/CSymptoms:* tstat powers up fine from common without a battery.* With sensor connected per above - and heat off - burner cycles on and provides heat to second floor when tstat powers up* With sensor NOT connected - and heat off - burner remains off when tstat powers up.Anyone have a clue whats going on here ? Some type of interference perhaps ? Link to comment Share on other sites More sharing options...
dgbrown Posted November 13, 2012 Author Share Posted November 13, 2012 I have to say it's very odd. The same valve relay (6 way Taco) is running two other c4 stats without remote temp sensors without issue. Link to comment Share on other sites More sharing options...
Cyknight Posted November 13, 2012 Share Posted November 13, 2012 That just makes me think all the more it's power is "dirty" or inconsistent. This doesn't matter for powering the TStat or it's internal sensor, but has been know to aversly affect remote sensors because they are in the direct path of power (well in a way at least).Leaving the trigger rlay (w1) disconnected, hook it up - I fear you may see fluctuating temperatures on the t-stat Link to comment Share on other sites More sharing options...
dgbrown Posted November 13, 2012 Author Share Posted November 13, 2012 I'll check it and report back. Link to comment Share on other sites More sharing options...
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