Vision Pro - Duel Fuel --- Setup

[wango]

Need a little help here with my Vision-Pro setup? I have a 95 fue two stage variable speed furnace with a heat pump. The Vision Pro is the 3 heat 2 cool version and the outside temp probe has been installed. I had read on another thread that the VP will not work correctly with the equipment configuration I have. My HVAC guy is not familiar with the VP and I am concerned he may not set up the system right.


I'd like to set the day time temp in the winter to 68 and would like to set it back to 62 at night. Is it possible to have the furnace set to handle the morning recovery or is VP going make that choice based on the balance point and what the outside temperature probe is reading?

[BaldLoonie]

The VP will decide based on outdoor temp. If above setpoint, pump runs. If below, gas runs. Make sure you do whatever to your 2 stage furnace to use the timer as VP will not control 2 stages of backup.

[wango]

so the setup should be based on 2 heat 1 cool. And on the unit the Automatic Heat Staging Jumper must be set - this will set the first stage heat for either 5 or 10 minutes before it switches to the 2nd stage. From your experience would you choose 5 or 10 minutes before switching over to the second stage? I guess the other question would be is the unit just as efficient in first stage and second stage?


Is there a thermostat brand that would adjust the 2nd stage heat?

[BaldLoonie]

let the 1st stage run long as possible. If 5 & 10 are your choices, definitely go 10. OR if you are inventive, you can put a toggle switch or outdoor thermostat between that jumper to keep it off high in mild weather!

From what I can see, the White-Rodgers 1F95-391 will stage the backup too. Mucho more dinaro than the VP though.

[wyounger]

Hmm... hold on a second before you worry. Do you have a two stage heat pump, or just a regular one? Since it's 10 SEER, it sounds like it would be a single stage.

If it's a single stage heat pump with a two stage furnace, I think the VP can handle that. It just doesn't have provisions for handling a fourth heating stage.

Aside from the White-Rodgers, the Carrier Thermidistat can also control a two stage heatpump in a dual fuel configuration with a two stage furnace (4H/2C).

[BaldLoonie]

The TH8320 will handle a 2 stage pump but only single stage backup. It has Y1 and Y2 but only AUX for backup heat. Otherwise the one I won would be on my wall!

[BobbyBJr]

One thing you could do is use the stat in heat pump setup for 2 heat/1 cool and a outdoor stat. Connect Y1 from the tstat to the common on the outdoor stat. Connect Y on the heatpump to the close on temp rise contact terminal. Put the close on temp drop contact termimal back to W1 on the furnance. Wire the AUX on the stat to W2 on the furnace. When the outdoor temp is above the balance point, you get heatpump. When the outdoor temp drops below the balance point, the outdoor stat switches Y1 over to energize 1st stage furnace. If the indoor temp continues to drop, the AUX brings on 2nd stage furnace. On most brands, if the AUX calls above balance point and enegizes W2, it does nothing until W1 is energized. You'd have to wire the emergency heat to bypass the outdoor stat and bring on the furnace. I have added a Em heat relay to do that, but it is not needed most of the time. I know this defeats the purpose of the duel fuel feature in the stat, but if you want to use the two stage feature, it will work.

Bobby

[wango]

Thanks for all the good info - I think i will see how the Automatic Heat Staging Jumper setting works before i go with a differant thermostat.