# Wood furnace/power outage



## treesrgreat (Jan 31, 2011)

We have been using a wood furnace for 2 years. Never give it much thought until a truck accident last week caused us to loose electricity for over 4 hours with no warning. My wife was home and managed to close the air down to the wood furnace and remove the top of the furnace per manufacturer instructions. She said the top and sides of the furnace, and the 8" ducts from the top of the furnace was dangerously hot before she got things apart. The air that was rising thru the ducts was extremely hot as well, which i would think would be a definate fire hazard if someone is not home here and power is lost. We have been gone for hours to go shopping, church, work and other things and never give it much thought until this event. 
Does anyone have a battery back up system on their wood furnace blower for such a circumstance? I know generators set ups designed to kick on automatically for power lose. i also know battery back up systems for sump pumps also. 
Thanks.


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## gloud (Jan 31, 2011)

If it is 110V you can get a computer UPS. Size it to the load of the fan.


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## dancan (Jan 31, 2011)

gloud said:


> If it is 110V you can get a computer UPS. Size it to the load of the fan.


 
That's a good , simple , easily findable and installable solution that is easy to test periodically .


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## atlarge54 (Jan 31, 2011)

I doubt a computer UPS will solve your problem, not enough arse to run a blower. 

You need to know what your furnace takes for start and run amps.

A load of wood in a furnace or boiler with a power outage is NOT any fun BTDT. I use a Tripplite inverter/charger with a couple large batteries (in the summer they're on the boat). The inverter is 750 Watt which might not be big enough for your furnace, I'm only running a couple pumps which is a pretty light load. If the power goes out it automatically switches to battery power and recharges the batteries when the power comes back on.


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## treesrgreat (Jan 31, 2011)

*more info on wood furnace fan*

I didn't know when I did the post what the motor rating was on the wood furnace blower. 
The motor that runs the blower is:
-115v
-1/10 hp
-Permanent split capacitor motor
-Full load amps 2.05
-Freqeuncy 60 hz
Thought I would include the specs. I found on the motor.
The back up system must run the fan for a minimum of 4 hours I feel.
Just wondering does anybody else have something in case of power failure?
The computer battery backup is a good idea, but will it run the fan for time needed? I'm sure they make larger units where larger draw of power is needed.


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## atlarge54 (Jan 31, 2011)

That's really a light electrical load. A single 125amp/hr battery should run your blower for 6+ hrs with a cushion. I get the biggest batteries they have at Walmart for about $85 each. Somebody had Tripplite inverter/charger units on ebay for just over $200 on ebay a few months ago.


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## Labman (Jan 31, 2011)

Your blower is only about 250 VA. Easy to find an UPS that will handle that, but not for long. You would need to add some deep cycle batteries.


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## kstill361 (Feb 1, 2011)

I installed a safety heat dump this year. The door is held shut with a 212F fusible link. We havent experienced a power failure yet but I unplugged the blower just to test it out, it didnt take long for the door to pop open either.


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## dave_dj1 (Feb 1, 2011)

kstill361 said:


> I installed a safety heat dump this year. The door is held shut with a 212F fusible link. We havent experienced a power failure yet but I unplugged the blower just to test it out, it didnt take long for the door to pop open either.


 
That's a realy good idea! Where did you get such a thing?


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## CrappieKeith (Feb 1, 2011)

That looks like a heat dump we build.

OP...if you have all metal ducting and the proper clearences as per code you should not have to worry about gravity heat outside the fact that your warranty may be voided.

Sure you can have 500-600 degrees rising out of your plenum and for the 1st 6 feet or so but then the temps will drop. Keep in mind 135 degree water from your hot water heater seems really hot & will burn you almost but that temp will not start a fire or hurt metal ducting.

Good to see you following the manual.....


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## mooseracing (Feb 1, 2011)

atlarge54 said:


> I doubt a computer UPS will solve your problem, not enough arse to run a blower.




Depends what you size out, like someone stated. There are plenty out there that will run that blower.

It might be cheaper to look into a few AGM batteries and converter though.


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## timbrjackrussel (Feb 1, 2011)

Furnace power backup system 
I had a similar experience with my Surefire wood furnace last March, ice storm and loss of power. All this happened at 2 AM just after I loaded it full of White Oak, and was getting ready to leave the house at 4AM. I scrambled to get the generator going. But what would of happened if I was't at home? I made up a automatic power transfer switch good for 30 Amps. at 120 V.A.C.. It is safe that it can't connect the load (the furnace) to the power grid and the standby source at the same time. I use six 8C6V floor scrubber deep discharge batteries in a series parallel connection to power a 1000 watt inverter at 12 volts to produce 120v.a.c. to run the furnace. It is just like a LARGE computer back up supply. The batteries should run it about 36 Hours!! I have a telephone dialer that calls my cell if the power to my house goes off. When I get home if the power is still off, I pull the starter cord on the generator, load in some more wood and head out to help my neighbors.


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## kstill361 (Feb 2, 2011)

dave_dj1 said:


> That's a realy good idea! Where did you get such a thing?



Yes, CrappieKeith is right , I did ordered it from his company. 
I got it here, ,Safety heat dump and its a good idea to order a few extra fuses till you get ur fan limit switch set , it takes some adjustment to get it right. I think I turned mine down to 175 on the upper limit

My 12" round supply line actually drops downhill close to 12" before it ties into the gas furnace main trunkline.My 12" supply also has a heavy gauge backflow damper that closes when the blower stops, so for me gravity heat will not work this way. This is a new stove I purchased in the middle of the last heating season and have seen what a power failures will do to the firebox. This safety heat dump is there for my piece of mind for preventing damage to the firebox in case Im not home to help manage to cool it down.. 

Now my power was just out for 12 hr and came on about 10 min ago, since I was home, I went ahead and took the cabinet apart and made it a stove and removed 3 supply lines from the registers upstairs and let gravity to the work that way. it was windy and 18F and it still kept us at 71F


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## 100 Watt (Feb 2, 2011)

Yep, our power was out last night for 3 hours. Of course it waits until I have a roaring fire going. I pulled the 8" supply off the top of my add-on and let it gravity feed the basement. I also have a damper installed so the heat was trapped until I took the supply apart. I put my flue temp guage on the supply before I disconnected it. +300°. Glad I was home.

The generator was out in the barn, and I figured as soon as I got it set up the power would come back on. I'm definately going to look into an automatic back up of some sort. 

I hope that stinking ground hog stays in his hole today!!:fingers-crossed:


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