I'm currently using ISY 99i Pro v2.7.7 with a Venstar T1900. I live in a 2000 sq ft 2 level loft (converted warehouse) in Ohio and have an electronic heat pump w/ emergency heat (2nd stage). The thermostat is on the lower level and averages with a remote sensor upstairs. I use the ISY to control multiple set points rather than the built in programing functionality of the thermostat.

 

Right now in "Winter mode" (I have 2 folders on the ISY) I am basically setting back the temp to about 66 when not home or sleeping and 70 when home and awake. The deadband setting on the thermostat is 3 degrees, so in order for the heat to kick on when not home, the temp would have to hit 63 or 67 when home.

 

I'm curious how others in a cool climate w/ heat pump have their ISY and Venstar thermostat programmed. Obviously, i'm trying to get it as efficient as possible.

 

Thanks!

I will try to give a short answer here.

 

I have over 150 interrelated temperature control programs so it will be difficult.

 

Some of this is not yet implemented... I am in the process as we speak.

 

1. I use large setbacks

 

2. I have the deadband before aux heat as an additional 2 degrees

 

3. I have the time before aux heat as 1 hour. (if I need it to heat up quick and expensive I can always manually engage emergency heat)

 

4. I have it setback at night and the hours before I wake up it warms the room up for me

 

5. I have I/O link modules used as "outdoor thermostats" whereas the t-stat's call for aux heat is interrupted if the outdoor temp is above a certain value related to the unit's COP and BTU rating at various outdoor temps. Somewhere in the 30s or 20s is a good start. The ISY will be using Weather Bug data for these descisions. I may be putting in multiple I/O links activated at different temps connected to different heat strips. IE if it is below 33, allow 5KW aux heat if called for, if below 23 allow 10kW aux heat if aux is called for. Emergency heat will bypass these I/O links.

 

6. see also: http://forum.universal-devices.com/view ... 2258#22258

 

Note: With heat pumps that use electric heat strips for aux heat, this is your biggest enemy. Actions that cause the heat pump to run much much longer, but without engaging these heat strips is always desirable compared any run time with the heat strips on.

Hi to both,

 

Please note that our next release 2.7.7/2 would allow for the thermostats to be in scenes as both responders and controllers.

 

With kind regards,

Michel