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2-Stage Thermostat Slow to Heat

Posted by Heatcrazy (My Page) on
Wed, Apr 2, 14 at 16:25

We just had a new Trane XV80 2-stage variable speed furnace installed. My issue is that it never goes into the 2nd stage. This morning it took 55 minutes to heat up our house 3 degrees, from 64 to 67 degrees. It still had another 3 degrees to go. I would think that it would know if it was taking too long to kick into the 2nd stage to speed things up. I hardly think it should take almost 2 hours to heat up a house by 6 or 7 degrees. Thermostat is a Trane XL802, which is a 3-stage heating thermostat, and it seems to be wired correctly. Ideally I would just want it to use the 2nd stage when it takes a long time to heat, or be able to manually set it to temporarily use the 2nd stage. Any advice? Thanks so much. And btw, we live in Northern California and it was maybe 48 degrees outside.


Follow-Up Postings:

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RE: 2-Stage Thermostat Slow to Heat

I would expect the furnace to go into the second stage after 5 minutes if the set point is more than 3 degrees below the room temperature. It sounds like the thermostat has not been set up correctly.

System type selection (0170) should be set to 9 which is 2 heat and 1 cool selection. The default is 1 which is 1 heat/1 cool. I suspect the installer did not set this correctly.


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RE: 2-Stage Thermostat Slow to Heat

Mike - thanks for that, but the mystery continues. The thermostat doesn't show a code 170. In fact, it's missing a bunch of codes shown in the manual, even though I verified it's the correct model. It's missing codes 170 to 310, 340 to 380, 530 and 580 to 660. I should add that we don't have a cooling unit, remote sensor or humidifier. There are only 5 wires connected to the thermostat - W2, R, W1, G, Blue. The W2 wire is physically orange. I'm wondering if there's a bad connection on one of the W wires so it's not sensing a 2-stage connection? I had verified, as best I could, the connections on the furnace. Thanks so much for your help, this is driving me a bit crazy.


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RE: 2-Stage Thermostat Slow to Heat

IIRC, on my thermostat, in "Homeowner" mode I can only access select settings. In "Technician" mode, I can access ALL settings.


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RE: 2-Stage Thermostat Slow to Heat

Do you have the installation manual? If not the link is below.

As Saltidawg pointed out, you have to go into the installer set up menu (see page 11) in order to see all the settings.

I doubt it is a bad connection on the W2 wire. This is not a communicating thermostat so there is no feedback from the furnace to the thermostat. It is possible the wires were connected incorrectly at the furnace, or the control board is not set up properly.

Have you talked to the HVAC contractor about the problem? If yes, what was the response?

Here is a link that might be useful: Trane XL802 Installation manual


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RE: 2-Stage Thermostat Slow to Heat

Wow, thanks so much. That was it - I was not in the Installer mode. It took a different combination of buttons to get into the right mode. Setting 170 was indeed set on #1 rather than #9 for 2-stage, so I changed it and now it works great. I also got to turn off that irritating adaptive recovery thing. Thanks so much for your help - much appreciated.


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RE: 2-Stage Thermostat Slow to Heat

I don't like the adaptive recovery setting either.

I am glad I was able to help. I find it annoying when a contractor can't spend the few minutes it takes to install a thermostat properly. I hope there are no other mistakes with the installation.

Good luck.


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RE: 2-Stage Thermostat Slow to Heat

Could you (anyone) expand on your feelings toward adaptive (intelligent) recovery?

Since the OP has solved his problem, I'd like change the direction of this thread a little. Hope you all don't mind.

I have a Rheem modulating furnace. The stat (411) went bonkers and was replaced with a 412. Since then, we have not been able to get the same level of comfort that we enjoyed previously.

As one possible solution, the contractor disabled my intelligent recovery. His reasoning was that since I had 3 program periods within a 2 hour period, it was screwing things up. Wasn't so with the old stat. Since the change, discomfort hasn't improved any.

Your thoughts, please.

V


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RE: 2-Stage Thermostat Slow to Heat

My Infinity controller has smart recovery. What the way it works is 90 minutes before the scheduled end of a set back period, the thermostat is supposed start the system so the room will be at the new programmed temperature.

I turned this feature off because all it does is reduce the amount of the set back period. Temperature set backs are an effective way to reduce energy costs. I think I am a little smarter than the thermostat, so I plan the set back transitions so I balance energy savings and comfort.

My furnace has three stages which I feel is enough to cover all the comfort needs. The modulating furnace on the other hand is a little over kill. It has variable blowers and gas valves. I seems it gets quite complex how the thermostat is going to control it for comfort. Perhaps the control algorithm in the old thermostat was better at comfort management than the one in the new one.


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RE: 2-Stage Thermostat Slow to Heat

My Honeywell thermostats also have an adaptive recovery feature and I also don't care for it.

The difference is whether you want the setback setting change time to be when the new temp is reached, or when the heater (A/C) starts working. I just have heat, but because it starts blowing at something more than 30 degrees warmer than the room temperature, it "feels" warmer and the chill is broken long before the set temperature is reached. In fact, at wake up, having the heater come on too soon before wakeup makes the bedroom a bit too warm.

I guess you could outthink the feature by setting the recovery time to sometime AFTER wakeup or return home, for example, but that's too complicated. I'm happy for it to start working just 15 or 30 minutes early.


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RE: 2-Stage Thermostat Slow to Heat

Mike wrote:

"My Infinity controller has smart recovery. What the way it works is 90 minutes before the scheduled end of a set back period, the thermostat is supposed start the system so the room will be at the new programmed temperature."

No offense Mike, but coming on arbitrarily 90 minutes prior doesn't sound very 'smart'. The way that mine works is that it will turn on allowing 5 minutes for each degree of recovery. The modulating thermostat knows the current temp and how many degrees it needs to make up, and adjusts the firing rate accordingly, starting out at a high(er) rate. I timed the process with the new stat and it took 20 minutes and 25 seconds to recover 4 degrees. After this, the furnace will continue to run at the lowest possible rate to maintain set point until the house and its contents reach equilibrium.

"I turned this feature off because all it does is reduce the amount of the set back period. Temperature set backs are an effective way to reduce energy costs. I think I am a little smarter than the thermostat, so I plan the set back transitions so I balance energy savings and comfort."

"My furnace has three stages which I feel is enough to cover all the comfort needs. The modulating furnace on the other hand is a little over kill. It has variable blowers and gas valves. I seems it gets quite complex how the thermostat is going to control it for comfort. Perhaps the control algorithm in the old thermostat was better at comfort management than the one in the new one."

I tend to agree that this unit has a software glitch. The furnace seems to run less and wait longer to start the next cycle, so even with setting the set point higher, we're still uncomfortable. Can't stand temperature swings.

V

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RE: 2-Stage Thermostat Slow to Heat

I am not offended since I didn't design the thermostat. :)

I am going by what is described in the installation manual. It supposed to learn how long it takes to recover in 90 minutes. I assume this is the "smart" part of the algorithm.There is an outside temperature sensor but I am skeptical how much the outside temperature is taken into account as part of the recovery.

It is a shame that a modulating furnace can't keep you comfortable. Maybe you should go back to the old thermostat model.


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RE: 2-Stage Thermostat Slow to Heat

With mine, it might start out at 90 minutes, but it adjusts the time based on its success at reaching the desired temperature at the desired time. If it is late, it increases the time the next day. If it is early, it decreases the time.

Also, since I have a heatpump, it does not activate auxiliary heat even if the setback is more than 2*. If I turned off the Recovery mode, it would turn on auxiliary heat immediately if the setback was more than 2* (which it is).

I can't speak to multi-stage gas but I would like to think that it would start in a low stage and stay there as long as the temperature increases in 5 minutes or so.


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RE: 2-Stage Thermostat Slow to Heat

Thanks for posting that link to the thermostat, it looks enough like my Honeywell to give me the installer codes I need to reprogram the daylight savings default dates...petty but annoying.

I used to work as an Alarm tech, so am familiar with Honeywell products...their programming is all in sections and my user guide had a lot of gaps in the numbers. I assumed the missing programming sections were where all the fun stuff was.


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RE: 2-Stage Thermostat Slow to Heat

Veesubotee:

"I have a Rheem modulating furnace. The stat (411) went bonkers and was replaced with a 412. Since then, we have not been able to get the same level of comfort that we enjoyed previously."

There was an issue with the modulating function of the 412 thermostat. Don't know if this was ever fixed:

http://hvac-talk.com/vbb/showthread.php?439932-Rheem-thermostat-412-Touchscreen


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