Print

[juddspaintballs]

Ok, no one I've asked so far has been able to figure this out yet. 

I have a Bryant heat pump and air handler.  The air handler is variable speed.  I want to keep that system in place and functioning normally if the temperature drops lower than my OWB setting.  For the purpose of this explanation, let's assume I want to run the OWB to heat my house to 72 degrees and my heat pump to kick on if the temp in the house drops down to 68 degrees. 

I want the air handler to come on whenever the OWB calls for heat and I also want to open a zone valve for the coil in the plenum to let the hot water flow through the coil.  My circulator will run 24/7 since I'm also heating my domestic water and running a cast iron radiator off of my OWB via a supply/return manifold system.  How do I do it?  The heat pump has electric coils for emergency heat and I want to keep those in place as well, just in case the fire burns out and it's so cold out that the heat pump needs to defrost while running. 

I was planning on two thermostats most likely.  My current thermostat is a Honeywell Vision Pro 8000 (without cooling via humidity controls) and I have a simple digital Honeywell heat/cool thermostat as my secondary one. 

[poncho64]

I have a Geothermal unit and have set up very similar.  The only difference is your zone valve.  I circulate through my furnace exchanger all the time but have the ability to bypass the exchanger during warm weather.   I was able to accomplish what you desire on your heat pump on my geothermal by connecting the red wire R (+24V) from my geo unit thermostat to the red(R) on my single stage Honewell.  Connect the W(heat) terminal on the single stage Honeywell to the G(Fan) terminal on heat pump thermostat.  I can keep my Geothermal as backup and I set it to come on 4 degrees below my boiler setting.   I do not have a zone valve but would say you could use the (G) fan output of your single stage thermostat to open your zone valve.  You could manually turn the fan to the on positon on the single stage thermostat to open the zone valve during heating times.  I'm not a HVAC person but the above setup worked well for me.  I found the wiring diagrham on the Central Boiler web site.

[yoderheating]

Powering the G terminal on a variable speed fan will not bring the fan up to full speed. I always use an aquastat instead of an additional thermostat when I install into a variable speed heat pump. Also, on some units you need to put a relay between the old and new thermostats powering the G terminal, on some units hooking it up direct will cause the outside heat pump unit to kick on.

[Scott7m]

I called yoderheating the other day with this same issue.......    he was a big help

what i ended up doing was flippin the thermostat to emergency heat setting, and removing the white wires where they actually hooked to each side of the heat strips, and taped them up

the fan did come one and run at full speed, which is normall the problem i have on a variable speed blower.  On a regular speed sometimes I'll just put the white thermostat wire in with the green wires and it will kick the fan on without the heat strips.  on a variable speed fan, this works but the blower runs realy slow.    by unhooking them bigger wires of the coils themselves it still runs at full speed

[juddspaintballs]

I got it wired up like so (and working beautifully):

One thermostat controls everything.  Regular heat pump system with electric coils as aux/backup heat. 

I tapped into the Y1 (yellow) wire that controls the compressor to the outside unit.  I have an aquastat strapped to my supply manifold that senses water temperature.  When the water temp is 120 degrees or better, the aquastat breaks the Y1 wire so it is not complete (and therefore, the compressor will not come on).  When the thermostat calls for heat, the air handler kicks on and and a zone valve to my coil in the plenum also opens via a relay.  If the thermostat needs more than 4 degrees of heat, the AUX heat kicks on.  If water temps in the supply manifold are below 120 degrees, then the aquastat completes the Y1 wire and allows the heat pump to function as normal and the zone valve closes so my heat pump doesn't heat the water in my OWB.