I've got a maple chase thermostat 9620, that was working on a ac heat pump. Have replaced the heat pump with a gas furnace straight cool unit. Will the Maple chase 9620 work?

The manual is here:

http://www.icca.invensys.com/manuals/robertshaw/110-732e.pdf

This t-stat work on a gas furnace, not really unless you want lousy comfort.

Before picking out a tstat for your gas furnace/AC you need to figure out how many stage of heat and cool are available.

Gas furnaces can have a low and high heat burner

AC units can have multiple stages too.

KISS, Thanks for the response and manual link. It is a single stage compressor, and I will not be hooking the heat up anytime soon here in Florida. Haven't used central heat here in Central Florida in TWO years. I can get the tstat to work in the cool mode, but can I use the Emergency heat connection and/or the Heat active reversing valve connection in the thermostat to activate the gas furnace in the heater mode? Is this normal, standard, or customary, or dangerous, hazardous and stupid? This would be done after I adapted the unit for propane, and properly vented the furnace. Thanks for your input.

Use B for W and Y2 for Y

Reasoning:

B(tstat) to W(furnace) will energise in heat and emg heat. Typically the gas furnace controles the fan and that's what you want.

Use Y2(tstat) for Y(furnace).
Problem is it's second stage cooling, but the Fan will be activated with Y2 which is what you want. Cooling would be delayed somewhat because it's stage 2.

Another dumb way of making it work would be a swich to select W(furnace) or Y)furnace) to Y1(tstat) . This swich would be located at the furnace and would select heat or cool.

What has to typically happen is when heat is called for the G(fan) termininal is not turned on. The furnace controls it usually. It turns it on when the plenum is hot enough and turns it off sometime after the call for heat is satisfied.

In cool mode Y and G are energized together.

The second way is better comfort wise.
In any event, it would confuse any HVAC tech unless some warning is placed by the furnace.

With a little relay logic, you could get it to work properly, but you'd be better off buying a correct stat.

KISS,
I get the reasoning for B for the heat cycle. But won't Y and G activate when the tstat senses a cooling demand, and engage the compressor and the fan? Why Y2 for Y? Thanks

There is only a Y1 on the stat and that activates for BOTH HEAT AND COOL, so you can't use it for Y.

You'd have to implement logic that says if Y1 on and O on then Y on else Y off.

KISS,
Much thanks for your knowledgeable answer. I'll try them tomorrow and post.

KISS,
Your best advice was use a different tstat. I ended up calling the tech help line, and they said "It will not work on a straight cool unit with gas heat." Even when I tried the ways we talked about, no workee. Evidently, there are circuits which the tstat needs to be used. (Y1)
So I had a rite temp, and it's working fine. I found it hard to believe that they would design a tstat which would ONLY work on heat pumps (reversing valve)

So... thanks much for your help and the education!

Using Y2 would take a LONG time for heat to kick in. Using Y1 and the switch requires the switch and the tstat to be in the same mode. Also the HP has a probably a 5 minute lockout. It can't turn on until it's been off for 5 minutes. You probably forgot about that.

There are HP and Conventional heat stats that can be configured either way but they typically have screens. You don't want all the extra buttons and lights on a HP case when operating as a conventional stat.

Your on your way.