Programmable thermostat coming for Harman PF100?

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accobra66

New Member
Oct 31, 2008
9
Marquette, MI
I just installed a PF100 Harman furnace. Does anybody know if anybody offers a programmable thermostat for this unit? I miss my regular thermostat that allows the house to automatically be at a certain temp at a certain time.
 
My dealer gave me the diagram for installing one. He suggested a Honeywell, but I went with a Lux instead.I have had it hooked up for about a month now and works great. Just like using one for a gas furnace. Keeps the wife happy, she likes it a bit colder at night.
 
The diagram to hook up a standard programmable thermostat is interesting but has one major disadvantage:
- during the 'daytime' setting the PF100 thermostat is running as normal - this is good
- during the 'night' temperature reduction the thermostat is basically just disabled and the programmable thermostat will switch the Harman thermostat on and off depending on what the programmable thermostat's setting is. This will not allow the PF100 to regulate its burn rate to just maintain the temperature. Instead it will frequently turn on and off.

In my opinion one of the major advantages of the PF100 is the feature to vary its output power (burn rate). This allows the PF100 - at least in my situation - to ignite only once a day and burn constantly at a rate proportional to the heat loss during the whole day.

I tried to get some information from Harman about their trip voltages and relationship of burnrate vs. thermostat voltage to create my own thermostat but couldn't get them to reply at all. So I am trying to re-engineer the thermostat interface. A simple way would be to have a second PF100 thermostat and have the programmable timer switch between them or use a little microcontroller to set the sensing voltage for the PF100 directly via a D/A converter. Shouldn't be too difficult but requires still a lot of time.
 
Does anyone know where i might find a proper programmable thermostat, one without many complaints or any problems, because i have bought too many, and they have all caused problems and I am getting very tired from it.
 
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