# johnson furnace question



## cds11 (Dec 29, 2011)

hi everybody. nice forum you got here. looking foward to many years of enjoying it. i recently obtained an older johnson energy sys j-9900 wood furnace. its in pretty good shape for its age. does anyone here own one of these? i know im going to have several installation questions in the near future but for now im just trying to get it ready to install. does anyone have a wire diagram for the fans, switches, and thermostat on the back of it? i already hard wired the blowers and they both work and the smaller blower in the center which i think is called a draft blower it also works. when i got the furnace most of the wires were unhooked and it also has some sort of transformer screwed to the back of it that has a few wires coming from it. i have not seen another furnace with this on it. i will take a picture of it tomorrow and post it. only other questions i got right now are there are a few fire bricks that are cracked, should they be replaced or is it just cosmetic related? and last is the chimney connector on the back of the furnace is 7", would it hurt to reduce it to a 6" chimney? thanks for your help.


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## laynes69 (Dec 29, 2011)

The Johnson furnaces are close if not the same furnaces from usstove. If the unit has forced draft you should have a relay center, and a limit/control for the blowers. A thermostat is tied to the relay center which controls the forced draft. The forced draft is tied into the high of the limit/control so if the furnace gets too hot, the forced draft shuts down while the blowers continue to operate to cool the unit. The link below should get you what you need. It's from usstove and is for their forced draft kits, so it shows the complete wiring diagram. Do not bypass anything and make sure everything operates correctly before firing.

https://www.usstove.com/index.php?route=cms/article&path=6&article_id=11

Hope this helps, don't forget to follow duct clearances also.


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## cds11 (Dec 30, 2011)

thanks for the info. i downloaded the manual for the model 1537q as it looks like the one i got but mine does not have any kind of fan control center or relay center. mine does have the blower limit control. im going to try and post a pic of the rear of furnace.


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## cds11 (Dec 30, 2011)




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## laynes69 (Dec 30, 2011)

The baffle looks warped from the exhaust of the furnace. With all that paint missing it's been burned off, probably overfired. I would remove the side panels and inspect for cracking or warpage just to be on the safe side. Here is a link for the fan control, it's only 25.00 for the part. This way it's complete and done right.

http://www.drillspot.com/products/686095/honeywell_r8285a1048_fan_control_center

It's been around 7 years since I've wired the old furnace, it's gone now so there I can't help. At least you have a proper wiring diagram to follow.


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## cds11 (Dec 30, 2011)

ok. thank you so much for all your help. i really appreciate you finding and pasting links for me. will this fan control turn my air handler fan on and off?  also do i need to get an additional thermostat for the house that will tell the fan control what to do or can i use the digital that operates my air handler and heat pump?


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## laynes69 (Dec 30, 2011)

You need a backdraft damper to protect the coil in the airhandler. You don't want the heat backfeeding. Also you will need 2 manual 8" dampers for the 2 lines that can be shutoff in the summer to isolate the wood furnace. You do not wire the blower from the air handler into the furnace. A simple heat only thermostat is all you need for the forced draft. I'll give you a little tip, I wouldn't wire the forced draft into the wood furnace. They eat wood and don't make much difference with operation. I waisted 150.00 on ours and was very disappointed. How is your home setup, what's your square footage and how well is it insulated? There's a video on YouTube showing the installation of a furnace like that. It's real simple, just follow clearances.


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## cds11 (Dec 30, 2011)

the house is an older farm house that has been remodeled several times over the years. 2800 sq ft. insulated ok. the only reason i think i will need the help of the air handler blower is there are several registers that are the farthest from the air handler barely get any air. where do i find a backdraft damper for my air handler? do i need a backdraft damper for my air handler if i use the air handler blower?


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## laynes69 (Dec 30, 2011)

You will still need a backdraft damper for the air handler. Maybe the local hvac shop could build one for the ductwork. That's a bit of square footage for the furnace. You may want to keep the forced draft, but like I said it's a wood hog. If you stay warm though thats all that matters.


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## cds11 (Dec 31, 2011)

got another question, i have an attached  2 1/2 car garage and was thinking about buliding a furnace room in it. i would have to go through two walls to get to the air handler. here is the big question, there would be about 40 feet furnace to air handler. is that to far for the heat to have to travel?


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## laynes69 (Dec 31, 2011)

I would keep it in the basement. Those furnaces put off a great deal of radiant heat. Even though that would keep the garage warm, you wouldn't get much heat into the home with those 2-8" ducts at that length. Also most codes don't allow for an installation in a garage. If something would go wrong, insurance may drop you.


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## cds11 (Dec 31, 2011)

thats what i figured. it would be so nice to just walk out in the garage and load the furnace up though.


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## cds11 (Dec 31, 2011)

do you recommend the use of a barometric draft regulator? most of the furnace manuals show them as optional.


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## laynes69 (Dec 31, 2011)

How tall is your chimney? With the forced draft being used I would probably install one. You don't want a runaway fire.


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## cds11 (Dec 31, 2011)

chimney is 25 ft


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## laynes69 (Dec 31, 2011)

You could try without one for now, if you need one you could do it later.


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## cds11 (Jan 2, 2012)

boy im glad i took your advice and removed all the panels on the furnace! firebox looks great but i found a basketball size mouse nest in the bottom. can you imagine how bad that would have smelled? it smelled pretty bad after i got the top panel off,lol. if you can think of any other tips or tricks i should know please advise. thanks again, chris


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