Outdoor Wood Furnace Info
All-Purpose OWF Discussions => Electronics => Topic started by: nsflatlander on November 05, 2013, 08:38:46 AM
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I'm guessing that based on the non-responses to my other question, I'm not understanding and therefore asking dumb questions. Here's another one that I'm hoping might help me understand things and answer my entire line of questioning. What is the difference between 2H/2C conventional and 3H/2C heat pump? In the 3H situation, does one of the sources have to be a heat pump? Why? Can the 3H sources not simply be 3 different calls for heat source regardless of what they are? What am I missing here?
And for those wondering, no I haven't found a single person in my area that even understands what a multi-stage system is, and it's not for lack of trying. :bash: I'm still running the damn wood boiler by going into my basement and manually turning on the furnace fan. :bash:
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I know very little about heat pumps and I deal with wiring the wood boiler and blower very differently than those down south, each time I post about using aquastats and relays to control the blower, somebody always comments about backfeeding multiple thermostats, I'll give them a shot at it and if you wish to hear from me, let me know, a drawing of what you want to do would be helpful.
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Thanks slimjim. I'm from "up here" in Canada. I don't have a heat pump. Also, not sure if I could draw it because I don't know what wires or parts I need. But I can try to explain.
1 - there is a pump that circulates the water to the OWB (and domestic hot water sidearm). This runs 24/7. Temp is controlled by the Aquastat on the boiler. I don't want to change any of this.
2 - There is a second pump that circulates water through a plenum in a duct in the furnace. This is currently wired to run 24/7 until I get this figured out.
3 - there is my original oil furnace. There boxes on the front of the furnace that have a switch on each. Switching them manually, one turn on a low speed fan, the other a high speed fan. This was all there prior to the OWB install.
4 - I currently have one thermostat with two wires going to the furnace. From what I can tell, this only turns on the high speed fan, and oil.
What I would like is as follows:
1st Stage Heat: Furnace Fan Low, Plenum Pump On, Oil Off
2nd Stage Heat: Furnace Fan High, Plenum Pump On, Oil Off
3rd Stage Heat: Furnace Fan High, Plenum Pump On, Oil On
1st Stage Cool: Fan Low, Plenum Pump Off, Oil Off
2nd Stage Cool: Fan High, Plenum Pump Off, Oil Off
No I don't have A/C, but my basement gets really cool in the summer and I currently turn on the furnace fans manually to cool the house.
I think the kicker is that I only want one (two at most) Programmable 7 day Thermostat(s) to do it. I really just need to understand most of how to do this so that I can explain it to my electrician. Especially what thermostat will work, and how. No one around here has every done anything with multi-stage heating so when I tell them about a thermostat like TH8320WF, I get a blank stare.
Any suggestions, literature, websites, would be greatly appreciated.
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The thermostats are a simple make or break switch and to my knowledge with only 2 wires you can't make it a multiple stage system, sorry but I'm not really up on the multi stage thermostats, I can however set you up on how to kill the burner motor on wood boiler water temp and turn on the blower ( single speed ) from your thermostat and when the wood boiler water temp drops below setpoint your oil burner will run as normal, would that help?
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"with only 2 wires you can't make it a multiple stage system"
Sorry, I should have added, just because there are only 2 wires going to the thermostat now, it would be dead easy for me to run more.
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OK, the other guys from down south are far more used to the multiple function thermostats than I but my part will still work to kill and fire the oil burner
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It shouldn't be too hard to do what you want but it will require a few 24v relays and more wires to the thermostat.
Can both the low speed and high speed fan switches be on at the same time? If not, a little extra wiring will be needed.
Connect a relay across each of the switches for the fans. (common and NO terminal). May want to also use a relay to close the existing circuit to make sure nothing backfeeds in the thermostat. (just connect the furnace RH and W to the NO and common connections on the relay and the coil as explained below)
Then you would tie one side of each relay coil to the C connection in the furnace and the other side to the correct stage on the thermostat that you want it to control. You will need a wire between the RH in the furnace and the RH in the thermostat. It should already be there but if you replace the wire make sure that is put back. I would run a wire from the between the C connections also. It will be needed if you get a thermostat that doesn't use batteries and will make them not go dead if it is able to use them.
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Thanks RSI I've got to reread that when i'm not spent.
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If you find any mistakes, let me know. I had a long day too.
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i know this is not exactly what you want but what I do is run my furnace fan on low non stop 24/7
like you do in the summer to keep air moving in the house all the time. My pump feeding my water to air
is controlled by a separate 110v baseboard heater thermostat when there is a call for heat .
I find this to work very well and have never had more even heat thru the house and never has been more comfortable
without the variable rise and fall of forced air heat
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renoman, not what I'm looking for, would take forever to cool down after the desired heat is reached. However, you've given me an idea. I have a baseboard thermostat kicking around. I'm going to do this until I get this figured out. Thank you!!
RSI, thank you sooooo much for taking the time to write this out. I'm going to have a much closer look when I get home and have things in front of me. I've actually never tried running both fans at the same time (actually don't know if it is one variable speed fan or two separate). I'll try when I get home. I took the time to draw out the current wiring in the furnace. I'm only posting it if you are curious, I don't expect you to waste your time and fix my problem for free. I mostly just drew it out for my electrician.
Any suggestions on what thermostat I should get? Would ideally like one thermostat, 7 day program, wifi.
Thanks again to all who have read this. I'm so glad I found this forum, and hope that someday I'll know enough to start "paying back" to others with the things I've learned.
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Is the thermostat currently controlling the oil burner? If so, are you sure it is connected to the R and the G? Normally it would go to the R and the W.
I just noticed you want the pump to come on with the blower. All you need for that with the relays is to use double pole relays and power the pump through the 2nd contact.
You should be able to parallel them so when either in on the pump will run.
One thing you will want to watch out for using a programmable multi stage thermostat is if you set it to let the house cool down and then bring the heat back up, if it raises the temperature more than the difference between the stages it will kick the backup heat on too. That could burn a lot of oil if it was happening every day.
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So I went home and verified and now I'm totally lost. I still haven't changed anything on my original oil furnace, but the current wiring does have G and R connected at the furnace. To make matters even more confusing, G on the furnace goes to R on the Thermostat and R on the Furnace goes to W.
Furnace - Thermostat
G--------------R
R--------------W
Any ideas? Or should I call in the furnace pros at this point? And yes the furnace worked fine this way. Trying to Connect R-R and W-W and nothing worked. Furnace didn't wouldn't kick on.
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They are apparently using the fan center to run the oil burner.
If you are running more wires to the thermostat, I would swap the two so they aren't opposite like now. It is ok like that with the two wires only.
Did you check if both switches can be on at the same time? If so, just connecting relays to them will do what you want.
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Right, the two switches at the same time thing. I meant to ask about that. Partially I forgot to try it. What am I looking for in turning them both on. Just that the fan stays on high. What am I looking for to happen?
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I was just looking at your diagram. Where do the wires for the high speed fan switch go?
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Thanks RSI,
Here's an updated diagram. As for turning on both the low speed and high speed fan at the same time. As far as I can tell, if I turn on the low and then the high, it just switches from low to high.
I've decided that I could care less about cooling stages. As long as I can turn on the fan from the thermostat manually, that is all I need.
I've been working with someone that I know personally on this, and he sounds to be leaning towards using a 3H thermostat and a PLC control unit (not sure if I'm saying that right) in order to get the stages of heating that I desire. If I ever get this working, I'll post a thread on how we accomplished it.
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I still don't see the high speed fan switch on the diagram.
You shouldn't need any PLC controller, two relays with 24v coils should be all you need.
To just do single stage or even two stage you will need at least one relay. There isn't any low voltage wiring on the fan circuit currently. If you want the pump to come on with the blower, you will want to get a 2 pole relay so you can run the pump on the 2nd set of contacts.
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Sorry, I understand what you are asking now. The "switch" is on the box that has red blue and black wires coming out of it that says load fan, line fan, load limit. It's like a little button or post that pushes in.
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Ok, that is real simple then. You will need two relays. For the low speed, just connect the common to #1 and the NO connection to 3 on the box labeled shrack.
For high speed connect the common to a hot lead (#7 on the same box will work) and connect the NO to the A connection.
I think I mentioned if you want the pump to come on with it you will need to use 2 pole relays. Just run a hot lead to the common on the other pole (the same #7 may work if the wiring is big enough in that circuit) on both relays. Then on the NO connection on that side, tie together on both relays and run to the pump hot wire. Connect neutral direct for the pump.
If this is too confusing, I may be able to draw up something when I get some free time.