Can I use a modern thermostat for an old fashioned furnace?

I live in an apartment that has an old fashioned gas furnace in the floor. It is controlled with one of those old thermostats that looks something like this: http://1.bp.blogspot.com/_SL6NrWGzdGI/Swjo8yJjQUI/AAAAAAAAAUk/PD1IaFerzeg/s1600/OldThermostatCropped.jpg

I don't really know anything about installing thermostats and I thought you guys might be able to help out. Ideally I want to install a Z-Wave thermostat so I can hook it into the rest of the HA system. Would it be possible to install a ZWave thermostat in place of the old one or is that crazy?

It appears you only have two wires (assuming yours is the same as this one). These two wire are likely "heat on" when closed and "heat off" when open.

New wiring will have wires for heat on, cool on, fan on, and power. Perhaps even more wires for low heat, low cool, low fan. The fanciest ones have gone to RS485 comm and talk with real data.

You may be able to just hook up those two wires to the "heat on" part of a new thermostat if it is a battery powered thermostat. It does not look like you will have any ability to control a fan separate, but if you have a radiator that would figure.

Looks to me like a 2 wire heat only setup. You should be fine. Are you thinking HA integrated or just a $20 Hunter?

It is possible (Is that for boiler / radiator style heat?) that the wires to that old thermostadt are 120V. I converted a setup like that once by adding a relay, allowing low voltage to a modern day thermostadt.

Monk

I have to do the same. I would like to convert my line voltage thermostats to accomodate HAI Omnistats. What type of relays did you use? How did you wire them? I was looking into getting this http://www.taco-hvac.com/uploads/FileLibrary/100-5.2.pdf

Dominic, do a search on baseboard heaters and actuators. I think you'll find what you need. I've not done it but I am thinking about it.

dominic said:

Monk

I have to do the same. I would like to convert my line voltage thermostats to accomodate HAI Omnistats. What type of relays did you use? How did you wire them? I was looking into getting this http://www.taco-hvac...ary/100-5.2.pdf

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Dominic - It was back in '00 I did that in an old house - was looking for the documents / receipts but cannot find them. Best I can remember the part was SIMPLE and reminds me of having been a relay or 2 mounted on a metal plate - which in turn mounted into a metal box on the boiler / furnace - super low tec - purchased from a hvac supply house..Good luck!

Sounds like Monk used what they call a fan control center. It's a 24VAC transformer and a relay on a plate that fits a metal electric box. The low voltage connections are outside the box with high voltage inside. They are not expensive and should be easy to find (although probably not at your local home center). They are used to switch blower motors and other such things. I use one for the pumps on my radiant heat system. When I goggled "fan control center" the first link was:

http://www.emersonclimate.com/Documents/White-Rodgers/catalog_06_pages/Cat_06_pg0104.pdf

As I remember I got mine at Grainger.

Well - I did some more digging - JimS description sounds like my generic remembrance - Looking at the link, I am thinking that was real close to what I used.

I found the crdit card statement but it is vague. In November of 2000 I spent $21.68 @ United Refrigeration, in Saint louis, Mo. The part (no number) was listed as "Furnace Controller" for a cost of $21.68. Gotta love Quicken!

Thanks guys! Ill let you know how it works out.