Venstar T5800 Installation Problem


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Old 02-03-14, 08:08 AM
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Venstar T5800 Installation Problem

I installed a Venstar T5800 replacing a roughly 5 year old Honeywell Touchscreen (don’t see a model number). The HVAC unit is an American Standard 15 heat pump/AC which is about two years old. The heating works but is not able to heat the house to warmer temperatures (say 70 when outside temps are low 30’s). I suspect that I have something wrong with the supplemental heat wiring although the Venstar shows auxiliary heat as being on (in the display) from time to time.

Old New
R-------- R (old had RC and R jumpered)
W O/B---- W1/O/B
Y-------- Y1
G-------- G
C-------- C

I had a tan? wire running to Aux on the Honeywell. It was jumpered to E. I thought I didn’t need this wire for this thermostat and have not connected it.
I have the dip switches set to HP for Heat Pump, O (for energize when cooling) and E for electric.

What am I doing wrong? Thanks for any help.
 
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Old 02-03-14, 08:16 PM
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Connect the tan wire to W2.
 
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Old 02-03-14, 08:43 PM
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Thanks for that. Does the gray wire go to a temp sensor in the unit?
 
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Old 02-03-14, 09:04 PM
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I see no mention of a grey wire in your posting.
The tan wire controls electric heat strips that serve as stage 2 heat.
 
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Old 02-03-14, 10:23 PM
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Sorry, I meant tan. It's working perfectly, thanks again for the help.
 
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Old 02-05-14, 05:05 PM
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I thought this was working but I must have been mistaken. It's 26 degrees and the unit can not get the house above 68. It's been running for at least an hour (probably much longer). Supplemental heat is NOT showing up on the display. I went in and manually activated "emergency" heat which is supposed to shut off the heat pump and use only the secondary source. No change in temp.

Ideas?
 
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Old 02-05-14, 05:28 PM
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http://www.venstar.com/Support/Manua...anual_Rev5.pdf

Page 35 mentions an Aux heat setting. What is the number of heat strips setting?

Set it for 2 heat / 1 cool and 1 stage of aux heat.
 
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Old 02-05-14, 08:05 PM
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Those are the settings I currently have. Thanks
 
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Old 02-05-14, 09:08 PM
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Do you have a digital "meat" thermometer?
Measuring the temperature rise between supply air and return air should help determine if the heat strips are energized.

Do you know what size heat strips you have? (5kw, 10kw, 15kw or 20kw)

1 hour isn't much time for a heat pump to raise the temperature of the house when it is 26 degrees outside.
 
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Old 02-05-14, 09:43 PM
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To clarify it was running for a minimum of an hour (likely much longer) at 68 degrees (not warming the house up to 68) - i.e., it could only maintain the 68 and couldn't get it higher after running for more than an hour. This behavior is clearly significantly different from before I installed a new tstat.

I can locate a thermometer but I believe the supplemental can't be working given it's inability to reach a 70 degree setting - never an issue before at even higher settings and colder weather.

I don't know the strip size. I think this is the HVAC manual but I'm not sure:
http://www.wolffbros.com/catalog/doc...15-4A6H5-E.pdf
 
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Old 02-05-14, 09:55 PM
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At this point you may have to open the air handler to check and see if the control section is being energized by the thermostat. Energizing the tan should activate a relay or sequencer for the heat strips.

A model on that air handler would be helpful.
I don't think your link is correct for your unit. In the unit listings there are only gas furnaces listed..... no electric coil type.
 

Last edited by PJmax; 02-05-14 at 10:13 PM.
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Old 02-06-14, 10:17 PM
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The air handler is a Trane GAM5 full #GAM5A0B30M21SAA.

I swapped the old thermostat back in. It's 20 degrees outside and it immediately went into Aux heat and warmed the house to 70 within a reasonable period. It has been several days since I have seen the Aux Heat indicator illuminate on the Venstar, it used to show as being on from time to time. Based on the run time shown in the Venstar app, I think it runs continuously during the day to keep the temp at 67/68.
 
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Old 02-10-14, 07:00 PM
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The problem was the 2nd stage deadband setting at 2 degrees. My heat pump was only capable of getting the house to 68 (no matter how long it ran) but because that was 2 degrees less than the tstat setting, the supplemental heat would not turn on.

Efficiency/equipment longevity question -- the scenario above has the heat pump running non stop for days or weeks at a time dependent upon weather conditions. I presume this is most efficient from an electricity standpoint (heat pump running continuously < strips being on for short periods of time). Additionally, I presume the eq. life is not adversely impacted. The eq. is designed to run continously and life is not materially impacted (possibly enhanced by the minimal cycling). Correct??
 
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Old 02-10-14, 07:06 PM
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With the cold we've been getting I'll bet it runs almost full time.

I find it strange that your heat pump will only heat to 68f. If it got warmer outside the unit should be able to produce over 68f air. I'm wondering if you may have a freon level issue.
 
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Old 02-10-14, 07:19 PM
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Temps have mostly been low 20's and teens -- at least while I've been monkeying with the tstat. Unit is about 2 to 3 years old but hasn't been checked since installation.

So I should leave deadband at 2 or more for best efficiency/life (it adjusts 0 to 6)?
 
 

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