# PSG Caddy Wiring Help



## upstatematt (Oct 19, 2015)

Hello!  I'm formerly Matt701 (I couldn't login for some reason) and owned a hotblast 1557 for probably 8 years and over the summer found a PSG Caddy add-on for a steal at $200 but the only problem was it didn't come with the 24V damper motor or thermostat, so i just bought that.  Furnace is all installed, looks and works great manually controlling the damper, but I'm struggling with the wiring, even using the manual and have some electrical knowledge.  I hooked the limit switch the same way as the hotblast, using the 24V circuit on the existing furnace, so when the box heats up, it turns the propane furnace blower on.  Now I received a 24V thermostat as well as the damper motor in the mail and need to wire it up.  No matter where i measure, I can't get 24 volts from the transformer/relay box and I can't figure out how to get the relay to close the circuit.  I need to simply get the thermostat to control the damper motor by hooking the transformer/relay, damper motor and thermostat.  I really appreciate any help you might have!


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## brenndatomu (Oct 19, 2015)

Welcome back Matt!
First things first...$200!? You suck!  
So when you power up the transformer you get no output?


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## upstatematt (Oct 19, 2015)

brenndatomu said:


> Welcome back Matt!
> First things first...$200!? You suck!
> So when you power up the transformer you get no output?



Actually I had a bad voltmeter.  I have 24 volts now out of the "O" and "C".  When I hook the damper motor across these points,  the wheel will slowly move and when disconnected slowly move back to start.  Now having 24 volts, i can just run one side through the thermostat to make it work, but is there any way to use the limit to cut the power to the damper motor to kill the fire if I get an overheat?  It has a relay in it and I can see it, but I don't know how to trigger it. 

I can't get over the deal I got on it.  It was listed on Craigslist as "wood furnace" and I tried to zoom in but couldnt tell if it was a caddy until i drove 2 hours to see it.  I bought it assuming it was a wreck, but ended up not needing to replace anything, not even the original firebricks.  I'm ok with the $160 i had to pay for the damper motor   I can't believe the heat it puts out using very little wood, I love it!  Also, i had trouble trying to find someone to make a plenum for me and ended up getting one custom made in Nebraska from a guy on Ebay for $60 shipped.


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## brenndatomu (Oct 19, 2015)

upstatematt said:


> is there any way to use the limit to cut the power to the damper motor to kill the fire if I get an overheat? It has a relay in it and I can see it, but I don't know how to trigger it.


Not sure what you have for  a limit switch but there should be a set of NC contacts that open up on overtemp, run damper motor power through that...


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## Wisneaky (Oct 20, 2015)

upstatematt said:


> Actually I had a bad voltmeter.  I have 24 volts now out of the "O" and "C".  When I hook the damper motor across these points,  the wheel will slowly move and when disconnected slowly move back to start.  Now having 24 volts, i can just run one side through the thermostat to make it work, but is there any way to use the limit to cut the power to the damper motor to kill the fire if I get an overheat?  It has a relay in it and I can see it, but I don't know how to trigger it.
> 
> I can't get over the deal I got on it.  It was listed on Craigslist as "wood furnace" and I tried to zoom in but couldnt tell if it was a caddy until i drove 2 hours to see it.  I bought it assuming it was a wreck, but ended up not needing to replace anything, not even the original firebricks.  I'm ok with the $160 i had to pay for the damper motor   I can't believe the heat it puts out using very little wood, I love it!  Also, i had trouble trying to find someone to make a plenum for me and ended up getting one custom made in Nebraska from a guy on Ebay for $60 shipped.


I agree you really suck. What was the other guy thinking that you bought it from, why on earth would he sell it so cheap?


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## sloeffle (Oct 20, 2015)

PSG has the manual with the half a$$ wiring schematic on their web site.  Somehow you are suppose to use that to wire your furnace up with. 

I just went downstairs and looked at my wiring coming out of my 24V coil. It looks like I have a two wire thermostat wire ( not the wire coming from the thermostat itself ) going from the damper to the 24V coil and then the two red wires tied together from that and the actual thermostat wire. The two white wires are hooked up to the 24V coil.



upstatematt said:


> I can't believe the heat it puts out using very little wood, I love it!


We only use our Caddy for some of our heating needs and only burn around 1.5 - 2 cords a year. I can usually go a whole day on 8 - 10 pieces of decent size ash splits.


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## upstatematt (Oct 20, 2015)

Wisneaky said:


> I agree you really suck. What was the other guy thinking that you bought it from, why on earth would he sell it so cheap?



He was a really nice guy.  It was advertised for $400 originally and when i got there he informed me immediately it was missing a part.  He told me his mom had it installed in her house years ago from a dealer and she passed and he was just moving in and he wanted to burn coal, so he was getting rid of it but didn't really know much about it.  He went on the internet and showed me the part I needed which was listed at $190 and he offered to take 200 off his asking price, so I couldn't say no!  I still wasn't exactly sure it was a caddy since it said Annexe Caddy on the front of it (I was trying to google it from my phone), didn't have an EPA sign anywhere, but then i figured it must be a Canadian version of the unit.  I'm thinking I can sell my hotblast 1557m for what i put into this


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## upstatematt (Oct 20, 2015)

brenndatomu said:


> Not sure what you have for  a limit switch but there should be a set of NC contacts that open up on overtemp, run damper motor power through that...



I'm using the limit switch it came with, a 3 wire which includes the connection you are mentioning, 24 volts out unless the limit is reached and the circuit opens.  I'm running that using 24V from the propane furnace which loops back to the propane furnace to kick the fan on and off when it reaches temp.  Can I power the damper with same 24V from the main furnace and not even use the PSG transformer/relay?  I would run power to the damper motor from the limit switch (through the thermostat) and then hook the second wire of the damper motor back to the 24V Common wire on the propane furnace circuit board, correct?  I just wanted to clarify so I don't blow the 24V circuit on the main furnace and my new furnace becomes that much more expensive.  I really appreciate your help.


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## brenndatomu (Oct 20, 2015)

So do you have it wired up like this right now? And it is working?


Do they all have the interlock even if there is no fossil fuel burner option on it?
Maybe it would be easier to use the wiring diagram of the Tundra furnace, just not use the interlock if it has it...


I would say if you want to use the transformer of the gas furnace that it can be done, I'd hafta ponder on it a bit. It'd probably be easier to just use the separate transformers though.
As far as kicking the gas furnace blower on...easy enough, just wire the coil side of a 120v relay to the Caddy blower wires, use the NO contacts to activate the gas furnace blower...


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## upstatematt (Oct 20, 2015)

I was ab


brenndatomu said:


> So do you have it wired up like this right now? And it is working?
> View attachment 164594
> 
> Do they all have the interlock even if there is no fossil fuel burner option on it?
> ...


l was able to get it working tonight with the new digital thermostat.  
R1 on the propane furnace board leads 24 volts to the limit switch in the plenum, when it calls for heat, it sends 24V to the "G" on the propane furnace to the fan relay.  I can adjust which speed the fan runs by changing the jumper, right now its on low, but I might move to medium low if my duct temps get too hot.  I took the advice above from you (thanks so much) and ran the limit wire to the damper motor.  I hooked my digital thermostat between the other damper motor wire and the 24V common on the propane furnace board.  It's working perfectly and I don't need the extra relay/transformer at all. I hope my explanation makes sense of how it's hooked up.  I really appreciate the help!


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## laynes69 (Oct 20, 2015)

upstatematt said:


> I was ab
> 
> l was able to get it working tonight with the new digital thermostat.
> R1 on the propane furnace board leads 24 volts to the limit switch in the plenum, when it calls for heat, it sends 24V to the "G" on the propane furnace to the fan relay.  I can adjust which speed the fan runs by changing the jumper, right now its on low, but I might move to medium low if my duct temps get too hot.  I took the advice above from you (thanks so much) and ran the limit wire to the damper motor.  I hooked my digital thermostat between the other damper motor wire and the 24V common on the propane furnace board.  It's working perfectly and I don't need the extra relay/transformer at all. I hope my explanation makes sense of how it's hooked up.  I really appreciate the help!



When I had our old furnace in series, I took this approach. I'm sure there's a reason for the interlock, but we didn't use it. The best part was if the central furnace would happen to run, it would stop the blower long enough then fire back up. The only thing was making sure for any reason the central furnace would fire. If it would error out, the blower would disable. That's one hell of a deal!


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