Programable stat which locks out W2

rerodOctober 2, 2011

I don't want my high efficiency gas furnace to run on second stage high fire until a predetermined outside temp has been reached. The White Rogers 95 series has the outdoor sensor which locks out W2 above a certain temp while in heat pump mode. But Im not sure if it locks out above a certain temp in 2nd stage conventional furnace mode.

Does anyone know if it would work with my carrier infinity furnace or recommend a stat which would?


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I am not sure about the WR stat but I do know that the Visionpro line from Honeywell has the capability. I have my strips locked out at any temp above 35 degrees which is essentially what you want to do. I would have chose a lower setting but if someone is not home for an extended period the margins are slim but the pipes could freeze.

    Bookmark   October 5, 2011 at 6:49PM
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I took a look at the installation instruction for my Carrier Infinity furnace (58MVC). It seems you could wire W2 to control the high stage of heat. You may need to change the dip switches on the furnace control. However I am not sure if the furnance will ever go into the low stage if W2 is energized.

I am curious as to why you want to do this. Are you doing this to save energy?

    Bookmark   October 5, 2011 at 10:36PM
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Thanks.. Yes you need to change the SW-2 set-up switch to on when using a two stage stat. I decided to order a old style mercury switch type two stage stat because Iv heard you'd be lucky getting 10 years from a programmable stat. More like 5 or less. My old T87 still works after 40 years so I decided to stick with a mechanical.

I just want my furnace to run on first stage and remain there during low load conditions. When using it with a single stage stat and SW2 off, it would kick into high heat after 16 minutes.. Then immediately over shoot and turn off. Kind of annoying. I could continue using the T87 and turn SW2 on which would lock out high heat but I would need to flip it back when it gets really cold out.

Here is a link that might be useful:

    Bookmark   October 6, 2011 at 7:42AM
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I have a 3-stage Infinity furnace and Infinity controller. The way it works is by default is starts in the low stage for at least 10 minutes and then move to medium or high depending on the indoor and outdoor conditions. If the setback is more than 5 degrees than it goes to the high stage immediately.

I don't see any overshoot. The controller is pretty good at staging up and down. I expect the controller to outlast my 10 year warranty. If not I am going to be upset.

    Bookmark   October 6, 2011 at 10:07AM
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Mine over shoots because of the single stage stat. My new, old school mercury stat should correct that.

This thread, and white rogers reviews on amazon convinced me to stay old school. Its just luck of the draw anymore I think.

Here is a link that might be useful: cap failure

    Bookmark   October 6, 2011 at 11:33AM
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shhhhh!!! don't tell my thermostat that it is supposed to die this year!!!

    Bookmark   October 6, 2011 at 3:50PM
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Vision Pro can't lock out high fire in gas mode. Not sure if the Infinity looks at outdoor temp or not. Don't think W-R can either. I have a toggle switch on mine (VP IAQ) to lock out high unless I want it and that's only if bitter cold. You can get a simple mechanical temperature control like commercial refrigeration uses to lock out W2 above a setpoint. That's how Williamson did it for 30 years in a similar manner. But their way only allowed high below the setpoint.

    Bookmark   October 11, 2011 at 8:39PM
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I ended up buying this for $60. Will see if I need that switch or not.

Here is a link that might be useful: HONEYWELL Y594D 1347

    Bookmark   October 11, 2011 at 11:56PM
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