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[onezero1010101]

Hello all, I have been looking thru this wonderful site, trying to find help on my particular situation.  I am in the process of installing an OWB, its a Legend brand.  Has a temp controlled fan blower on the stove box set to 180deg, and I'm planning on wiring the pump up to run thru the winter non stop.  I have the heat exchanger I am working on installing just above my furnace / ac coils.  The furnace is about 3 years old, all electric heat with ac.  I currently have a cheap programmable thermostat from Lowes running the original furnace.  From what I understand, I can have a 2nd thermostat set to say 70deg, at which point would kick just the fan on my electric furnace on and blow the heat from the water exchanger, then have my current thermostat set to say 65, and if temp drops to that, then the backup electric heat would kick on as well?  So to do that, can I tap into the wires on the back of my existing thermostat, or do I need to run new wires back to the furnace, and then how do I know which wires to connect to the 2nd thermostat, just for the fan?  I have read there are two stage thermostats that could combine this into 1 unit, is it worth the money to buy one?  I have bought a cheap analog thermostat to get this up and running for now, may change it out later, but just need heat for now.  Thanks

Side note, a local heat / air guy said he usually puts a relay in to control the water pump as well, but it wont hurt to have it just on a breaker and control it manually will it? 

[hondaracer2oo4]

A recent post just talked about this. I believe that you HVAC guy is telling you that he would put a relay in so that when your thermostat calls for heat it will turn on both the blower in the house AND turn on the pump outside on the boiler. Most of us don't thermostatically control our pump, we just run it 24/7. A few advantages to this are that when your house calls for heat you will immediately have hot water instead of having to wait for the pump to exchange out the water that has cooled down in the pipes, another advantage is that you never have a threat of a line freezing if it stays dormant for a while. You will waste some energy though since the water will cool down in the loop when it is flowing and return cooler temperature water back to the boiler when there is no call for heat in the house.

Now the way I set up my FHA in my house is this. I left my thermostat to control just the oil furnace and set it at 55 incase the boiler goes out. Then I ran a second thermostat just to turn on the blower in the FHA when the house calls. In order to do this you are going to need a 24 volt transformer and relay. Some people discussed using the 24 volt transformer that the furnace already has for this(the thermostat runs on 24 volts). Then you need to switch the blower on and off with a relay that the thermostat will control with the 24 volt circuit. The way I did this was I bought this http://www.lowes.com/pd_314869-74493-RA89A1074_0__?productId=3355572&Ntt=honeywell&pl=1&currentURL=%3FNtt%3Dhoneywell%26page%3D3&facetInfo=
That has a 24 volt transformer in it which I ran to my thermostat to power it. Then I ran the power through the Single Pole Single Throw switch inside the unit to power up the blower in the FHA system.

[onezero1010101]

Thats what I was thinking as well on the pump, just run it thru the winter and shut it off manually.  It has a 500gal tank on the boiler, which I will also be using for hot water in the house as well, so what little electric the pump will use, and extra wood shouldn't be much of an issue.

But regarding the fan control, with my current furnace and thermostat, I have the option to turn the fan on only with the thermostat, what is the purpose of the extra relay and transformer?  Could I not use the same wires on the existing thermostat to connect a 2nd thermostat to, but only connect it to the fan control wires?  I am sorry, I understand the concept, but have never done much with the furnace / thermostat except replace the old analog with the new programmable. 

[hondaracer2oo4]

Your thermostat has a connection for a second thermostat which would control the fan only circuit? I have never seen that before, I have seen a switch on the thermostat which is a 'fan only' switch. That is so that you can just turn on the fan and circulate air through your house, possibly if you had a humidifier on your system and wanted to just humidify your air but not run the ac or heat.

[onezero1010101]

Yes, fan only.  After some digging, I found this post http://outdoorwoodfurnaceinfo.com/forum/index.php?topic=2146.0 , would the reply on that post work?

Run 2 jumpers from current thermostat, from R on current, to R on new, and from Green to W on new?  Would that accomplish what I need, without having to add relay or transformer?

Just install a separate cheap digital stat right beside the one you have now.  Takes about 20 minutes, just run a jumper wire from the r post on the one you have now to the new ones r, and from the green post on the old one to the w post on the new one and you've got it.....   

[jerkash]

I have a Legend and I tied another thermostat to the one I had just to turn the fan on in the existing furnace.  It works great and my pump runs 24/7. No relay needed. I love my Legend!!

[onezero1010101]

I have a Legend and I tied another thermostat to the one I had just to turn the fan on in the existing furnace.  It works great and my pump runs 24/7. No relay needed. I love my Legend!!

jerkash: did you wire the 2nd thermostat in the way i described from another topic?  that is all I am trying to do, but I know nothing at all about thermostats and the wiring.  I almost have my piping finished up and will be ready to fire the stove soon. 

[jerkash]

That's exactly what I did.  Not sure what kind of wall you have your thermostat mounted on, but mine was sheetrock so I installed my new thermostat above my old one.  This way I was able to run the wires from one thermostat to the other behind the sheetrock and didn't have to worry about a trying to go thru a stud keeping my wires hidden.

[onezero1010101]

Thanks so much!  Yea I hadn't thought so much on mounting yet, I'm going to try to wire it up hanging out of the wall tonight see if I can get the fan blower to kick on before I mount it.  Good idea going above it though, I will have to see where the stud is in relation to my current one.  Do you have your pump running 24/7 on your Legend?  I really don't have much of an option as I only ran electric out to the stove, which will power the porchlight, pump and blower fan on the door which is attached to the tank thermostat.

[jerkash]

Yes I run my pump 24/7 and from what the pro's on this site say, everybody should.  A few more tips for you - Put wood in stove twice a day and only put in it what you think it will burn until you load it again.  You will get the feel of how much wood to put in at different outside temps.  If you burn dry wood you will see very little smoke.  I cut my wood 2 - 3 years ahead of time.  (I have plenty and also have somewhere to store it under a shelter)

You will need to keep your main thermostat on heat to make the new one work.  Just set the temp down low.

Good luck and if you have more questions, just ask.  I got lots of help from people on this board and they are glad to help!