Need Help Finding Replacement Thermostat

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Need Help Finding Replacement Thermostat

Postby mateck810 » Tue Dec 25, 2012 10:16 am

Hello.
I have a Lennox G61 with a Surelight 49M5901 board. The furnace is a two stage heat with variable speed blower. The Lennox 81M2701 thermostat that is not working (display messed up and won't turn furnace off ever). I need a replacement, but it seems that all the thermostats I look at do not have the "D" contact that the 81M2701 has, which I think controls the variable speed blower. I'm not sure how important that all is. I do have A/C with this unit, but no hudmidifier or dehumidifier. I would love one of those cool looking color wifi thermostats, or even the ordinary looking Honeywell wifi one sold at Home Depot, but when I look at the installation instructions for them, they do not have a "D" contact. Even the fancy new Lennox Wi-Fi thermostat says it will only work with a couple of their furnaces, mine not being one of them.

Can someone suggest a thermostat for me? I thought this would be simple! Merry Christmas to everyone.

Matt
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- Need Help Finding Replacement Thermostat

Postby Freon » Tue Dec 25, 2012 3:34 pm

Look at the Robertshaw 9801i2 Programmable.
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- Need Help Finding Replacement Thermostat

Postby mateck810 » Wed Dec 26, 2012 7:59 am

Thanks for the suggestion. I see where it has the "D" terminal. I also have found that the IAQ Honeywell Prestege series has a contact that you can program to be "humidifier", which I guess is what the H is for, and apparantly what is needed for the variable speed blower communication. It's a lot more money then the Robertshaw, but looks like it has some cool "geek" factors that might entertain me! Thanks.
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- Need Help Finding Replacement Thermostat

Postby Freon » Thu Dec 27, 2012 12:11 pm

Remember to always turn off all power to the furnace while geeking around. As you know, ICs are very susceptible to minute static (sparks).
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