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Thermostat Settings

Posted by glockman45 (My Page) on
Sat, Mar 8, 14 at 1:04

The Trane installers have just finished installing 1/2 of a 2 system install. I have an XV95 furnace and an XL15i heat pump, along with Trane 803 stats (I plan on getting the IAQ later on) and I have a few questions about the thermostat settings. I am posting those settings with differences from the Trane "recommendations", but I am not sure the differences are detrimental. I wanted some input before I changed them or inquired about them.
170 Heat and cool selection: currently set to 12
220 Cycles per hour 1st stage compressor set to 6: Trane recommends 3
230 Cycles per hour 2nd stage compressor set to 6: Trane recommends 3 but I have a single stage HP
530 Adaptive Intelligence Recover is set to off (don't know if I need this anyway)

Also, auto changeover is set to "off" and I have read mixed reviews as to whether this should be used or not (mainly system damage if the A/C turns on when ambient temperature is below 55). Any opinions here?

Should I use the "dehumidify" feature? I understand it isn't dehumidify on demand like the IAQ, but is it worthwhile in the meantime?

Thanks in advance

Follow-Up Postings:

RE: Thermostat Settings

The cycles per hour setting is usually set to 3. Setting it to 6 could allow the system to short cycle. I suggest starting at 3 and see if the temperature is kept within one degree of the setting. If not then try 4.

I don't care for the adaptive intelligence recovery. I have mine turned off in my Infinity thermostat. I would also keep the auto change over feature off. It is another feature which wastes energy in my opinion.

I would turn the cool to dehumidify feature on and adjust the humidity setting as needed. The temperature may go as low as 3 degrees below the set point to achieve the humidity. If that happens raise the humidity level a few percent and try again. In time you may find yourself raising the temperature which means you are saving some energy. I think this is a great feature and it would be a shame if you didn't make use of it.

RE: Thermostat Settings

Thanks for the reply Mike. That was kind of the way I was leaning.

I am still confused about setting 230- the CPH of a two stage compressor and setting 170. I would have thought setting 170 should be 9 instead of 12; my HP is single stage. 9 is for 2heat/1cool. Do you have an opinion? It seems this would affect setting 230 as well, but maybe not


RE: Thermostat Settings

You might be right about the 170 setting. It seems logical to use the 2heat/1cool setting with a single stage heat pump. Ask the contractor and have him explain the reasoning.

I think if you set the 170 setting to 9 (2heat/1cool) then the 230 setting will no longer be available since there is no second stage.

RE: Thermostat Settings

Thanks again Mike. I will leave everything alone until they finish Monday in case there is a reason they did this (I can't think of one but I'm not the installer either).

I appreciate the information on the dehumidify feature as well.

RE: Thermostat Settings

Ok guys, full disclosure. I know to an extent you guys monitor other sites (here HVAC-Talk), and I know I am cross posting. The reason is I am afraid some of my questions now will cross their NO DIY guidelines. I have absolutely no intention of DIY, but I understand where they are coming from. So, here is where I stand (from my posts there):

This is what I want, but I don't know how it should be set up (other than the setting above, it may be). I have the HP locked out until 40 (wouldn't mind to lock it out a little higher, but 40 is ok). Anything below 40 is the gas furnace. Also, during the night I set the thermostat back to 65-67 depending on the outside weather. When I get up and raise the thermostat setting, it says Aux Heat on, but I think it's the HP kicking on (temp was below 40)EDIT: I DONT KNOW WHAT'S KICKING ON, BUT IT ISN'T THE HP AND I DON'T THINK ITS THE FURNACE BECAUSE THE AIR IS COOL AND THE TEMPERATURE ISN'T MAINTAINED. Regardless, I would prefer that to be gas-- if the thermostat needs to catch up quickly it should use the gas furnace. If I switch to emergency heat, the gas furnace kicks on and heats quickly.

I haven't programmed a schedule yet. The installer comes back tomorrow and may change the settings anyway.

Also, if I were to change the setting of 170 to #7 does there need to be a change in any wiring?

For that matter, is a wiring change necessary for anything I am wanting to do?

I just noticed in the installer settings (200) that my auxiliary heat source is set to 0 (electric). I'm not sure what electric heat I have as backup, but I am thinking this should be set to 1 (fossil fuel)--and in doing so will pretty much give me what I outlined above.

So, I think I should set 170 to 7, change CPH to 3, and Aux heat to fossil fuel (gas). Assuming this is the case, then setting 210 (external fossil fuel kit) should be changed from the default of 1 (external fossil fuel kit controlling pump backup heat) to 0 (the 803 is controlling backup fossil fuel).

Is this correct?

And finally, I did look at the wiring of the thermostat (again, no changes nor have I looked at the furnace or HP), and have attached a pic of the back of the thermostat. Looks different than the Trane 803 because that's the back plate of the old Honeywell 8321 they replaced. I have the back of the 803 with the Honeywell 8321 faceplate.

ANY input ANYONE has is appreciated. They are coming back tomorrow to finish, and I want to have THEM do this correctly.


This post was edited by glockman45 on Sun, Mar 9, 14 at 13:31

RE: Thermostat Settings

Here is the picture from 803 which is supposed to run the units for our upstairs. Again, they are an XV95 and an XL15i, only smaller sized.

RE: Thermostat Settings

I have never owned a hybrid dual fuel system, so I am giving you advice based on what makes sense to me. You should review all of this with the contractor and get answers to all of your good questions. You would not be the first homeowner which has an improperly set up thermostat. Don't assume the contractor has it right. I think this thermostat can do what you want which is very reasonable.

The back up should be set to fossil fuel. When set to fossil fuel either the gas furnace or the heat pump should operate. Electric heat strips can energize as needed to augment the heat pump because they supply a small amount of heat. The heat pump and gas furnace cannot operate together because you will have over heating condition and the furnace will (hopefully) shut down.

I am not sure if 40 degrees is the optimal balance point for energy and comfort savings. You can experiment over time. A setting of 35 degrees may be better. Did you ever post your electric and gas rates? In my area it is always cheaper to operate a high efficiency gas furnace than a heat pump.

It looks like you have all the wires you need. Let's see what the contractor says on Monday.

RE: Thermostat Settings

Any ideas on what my electric backup may be set to? And how do heatstrips work/do all heatpumps have them?

They thermostat wouldn't be trying to use them as auxiliary heat would it?

RE: Thermostat Settings

You should not need auxiliary electric heat strips since you have a back up furnace.

Heat strips are used in an all electric installation. They are used to augment the heat pump when the heat pump can't deliver enough heat to keep the house at the desired setting. They also energize during a defrost cycle so you don't get a blast of cold air. You may have heat strips for this reason. Ask the contractor about it.

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