OWB users, what RU using for tstats?

[Madspeed]

I don't have all the specifics on my system off the top of my head, but I currently have an LP gas furnace/heat pump system in the house and will be adding an OWB in the very near future. What tstats are recommended for this type of setup? I'll be hiring a pro to do the hookup as I'm not all that familiar with that end of it, but would like to shop around and get a good tstat beforehand.
Would a 2 stage t stat already be "maxxed" out with my current setup being as it is controlling the LP furnace and heat pump?

Thought or recomendations are greatly appreciated!!

 

[Butch(OH)]

I don't think there is any way to run two systems with one 'stat and have it automaticaly switch systems for back up? May be something with a microprocessor out there in hi-buck land? There are dual thermostats made to run two or more parallel systems (so I am told). All the house thermostat does in a typical OWB installation is control the fan. Assuming that is true in your case the following might be of use to your installation.

I went with the dead simple and dead cheap way but my OWB and heat exchanger are fully capable of heating the entire house, if your is not then that is a different animal. Switching of my systems at my place would only happen when the OWB runs out of wood or system operational failures. My other furnace is a ten year old Amana Hi-ef natural gas forced air with whole house A-C. It does have the micro-controller type of control unit. Here is what I did and how mine works. The original thermostat is a simple digital unit. On that 'stat there is a "fan on" feature. "fan on" will usually be the hi fan speed if you have a multi speed fan. All I did was break one of the control wires from the fan on circuit and wire in another digital thermostat in series with those two wires. Two feet of wire and a $12 'stat is all that I needed. When the OWB is up and going I set the fan on switch to run and the second thermostat then controls the heat in the house by turningthe fan on and off as needed. The original thermostat is set a few degrees below so the gas furnace will act as a back up to my OWB heat. The only "wrong" thing my system will do is if the OWB runs low the fan doesnt know it and will run continuously when the 'sat is calling for heat. The original furnace burner cycles as the back up 'stat calls for heat but the fan would run all the time. This can easily be fixed by adding a temp probe and switch into the boiler loop. No boiler temp? then fan on is cut out. All this sounds a whole lot more complicated than it is. I could show it to you and you would understand in a minute. I have been told that other furnace control systems wont work like mine so do some checking. But I have also been assured that my A-C wouldn't work right with mine wired as it is but it too works just as it should

 

[Madspeed]

very interesting! So, your 2nd t stat only acts as a switch for the fan basically. When the second t stat is OFF, system relies on the first t stat and then utilizes the furnace for heat?

 

[fletcher0780]

I don't have all the specifics on my system off the top of my head, but I currently have an LP gas furnace/heat pump system in the house and will be adding an OWB in the very near future. What tstats are recommended for this type of setup? I'll be hiring a pro to do the hookup as I'm not all that familiar with that end of it, but would like to shop around and get a good tstat beforehand.
Would a 2 stage t stat already be "maxxed" out with my current setup being as it is controlling the LP furnace and heat pump?

Thought or recomendations are greatly appreciated!!

not sure if this is exactly what your looking for, but I have an aquastat on my OWB that when above 165* turns off my oil boiler via a zone relay. if the temp falls below 165* (fire going out) at the OWB my oil boiler reactivates to handle the house heating load.

The circ pump on the OWB side of the heat exchanger runs constantly to help protect from freezing in the event of the fire going out. the circ pump on the oil boiler side of the heat exchanger side only runs when the house calls for heat/ hot water.

 

[Butch(OH)]

very interesting! So, your 2nd t stat only acts as a switch for the fan basically. When the second t stat is OFF, system relies on the first t stat and then utilizes the furnace for heat?

Yes, almost. Both thermostats are on "heat" The gas furnace 'stat is set a few degrees below the OWB 'stat. If the house temp falls below the OWB 'stat the fan comes on, and we heat with the OWB. If it falls below the original 'stat setting the furnace comes on just like nothing else was heating the house, all automatic, dont have to touch a thing all winter except to change room temps. If it got something stupid cold and the BTUs delivered by the heat exchanger couldnt keep the house warm the burner would kick on and help out. So far we have not seen a temp cold enough to cause that. You may know this but in most cases the OWB takes care of itself and keeps the heated water loop between X and X temps. (Sure as I say "All" then somebody will show me one that requires controls.) Also in most cases the ciculator pumps run all the time 24-7 thus no controls are needed, you turn them on in Sept, and off in May. There are exceptions on the pumps. The standard system as Hardy would like to see it operated starts and stops the pumps every time you call for heat. No more amps than a pump pulls I would rather not have the added complication of controlling them. Mine combined pull exactly one amp or about one 100watt bulb.

 

[mtfallsmikey]

I'm using a separate 'stat that will control the furnace blower and secondary circ. pump via a separate relay. a heat pump 'stat could be used, the second stage could start an oil/gas furnace, boiler, or the simplest is to have a line voltage relay run the fan.