MS12A Modification to Thermostat

rlgdtime · March 15, 2011, 12:52:41 PM

Can this setup be used with a Honeywell Chronotherm IV Thermostat, connected to a 4 wire 24V system running an all electric A/C & Heat Pump? The Thermostat uses 3 AA batteries and is similar to this one http://customer.honeywell.com/techlit/pdf/69-0000s/69-1536.pdf, with the same wall plate, but manual switch for heat/cool/off and fan on/auto.

dave w · March 15, 2011, 03:47:09 PM

Probably. All the MS12A needs after the mod, is a contact closure from the thermostat. Do you know if the thermostat uses relays for the outputs to the heatpump/air handler? Relays will usually appear to be small metal or plastic cans on the PC board. If you can't tell, post a picture of the componet side of the pc board.

rlgdtime · March 15, 2011, 07:48:36 PM

Not sure about relays. Or which wires to hook up to moded MS12A. Also, do I need independent power source for MS12A, because thermostat uses 3 AA batteries (4.5V)? Or, I can always buy a thermostat that uses 2 batteries (3V). I have photos, but can't seem to load them. I have posted them here: http://img98.imageshack.us/g/img00037201103150236.jpg/. Thanks, in advance.

southtoms · April 30, 2011, 05:53:30 PM

Anyone know how to do this mod with a MS14A

dave w · May 01, 2011, 05:16:52 PM

The same way.

Circuitry is the same in that area.

southtoms · May 15, 2011, 10:52:48 PM

Can you tell me how to use the lux 9000 with a powerflash interface? Thanks.

Brian H · May 16, 2011, 06:39:44 AM

southtoms; Are you trying to add a Powerflash to an existing TX9000TS or TX9000A connected to an heating and cooling system or just use one to trigger a powerflash module by itself?

southtoms · May 16, 2011, 09:17:30 PM

I'm trying to get the lux 9000TS to activate the power flash. to send a signal to a RF124 to turn on the a/c in my motorhome.

Brian H · May 17, 2011, 06:19:01 AM

I would try. Setting the Powerflash to "B" Dry Contact
Connect the two terminals of the Powerflash to the TX9000TS {RC-RH} and Y terminals.
Using the Cool setting on the TX9000TS.
Remember the thermostat has a short cycle protector in it to prevent the AC from starting too soon after turning off. So it may take up to 5 minutes for it to kick on. Depending on where you set the parameter too.

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MS12A Modification to Thermostat