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Doer of Many Things!!!
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Discussion Starter · #1 ·
I'm not a heating and air guy by trade but this was pretty simple swap out. I took an old Lennox thermostat out for my grandmother and put this Honeywell CT87K model in that she got from Lowes.

I've mounted it, leveled it and made the two wire connections (red and white) and it operates the furnace fine. She has a Ruud High Efficiency Oil/Forced Air system. However I'm having to turn the thermostat up to about 76 to get it to kick on and warm up to the targeted 68 mark she's looking for. I've set the switches on the back for high efficiency air per the manual. I've tried setting them back to normal forced air settings with no luck as well. Am I missing something or do I have a faulty thermostat?

Any input is appreciated. I'm a floor and paint guy so this isn't really my department but I never had an issue like this with the old T87 model that still had a mercury switch.

Thanks.
 

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Steve
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317 Posts
Does the new Tstat read 68 as the current room temp? The unit will only turn on if it is really cooler then it thinks it is. I have changed a lot of old units out in which the old mechanical thermometer was way off.
 

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Handle It!
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Doer of Many Things!!!
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Discussion Starter · #5 ·
Yeah, yeah, I know. Convince grandma of that! Regardless, this Thermostat should work in this application. The fact that it doesn't is irritating me. I'll swap it our for another one and if it still doesn't work right, something is goofy here. Maybe it just isn't compatible with her heat system, regardless of what it says.
 

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Registered
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You might want to jumper the r& w wires. This will energize the heat circuit manually. If the system fires up right away, yo know it's a t-stat issue. If not, then you will sayve yourself a trip.

The stat that Malco posted is a nice one for the older folks who don't like "technology"
 

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Doer of Many Things!!!
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Discussion Starter · #8 ·
Took the CT87K back to Lowes where they threw it in a bin with about a dozen other Honeywell thermostats marked "defective".

Went to Hajoca (local plumbing supply store) and got a T87, which is evidently the exact same thing minus the wall plate that can be mounted behind it. It was $10 cheaper and worked perfectly. Lowes must get the seconds.
 
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