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O/T Furnace question

toolsteel

Titanium
Joined
Nov 9, 2012
Location
NW Wisconsin (BFE)
I live in a rural location (Wisconsin). I usually see more deer on my drive to work than I do cars.
I looked into getting a backup generator for my home but its pretty spendy for the equipment and install. I am ok to wire an outlet, a switch or a light. But by no means would i consider myself qualified to do the neccesary wiring for a backup generator. So i got thinking......my real concern would be heat during the winter in the event of a power outage. Our furnace is propane....500 gal tank in the yard. I saw a guy online (oh oh) who installed an outlet (single receptacle dedicated line) and instead of hardwiring the furnace he plugs it in. He claimed in case of an outage he can simply run an extension cord a short distance to a generator outside to run the blower motor on his furnace. Looked legit to me and seemed like a good back up plan.
My concern (maybe there are other concerns i am not thinking of)is the "quality" of the electricity coming from the generator ???? Is there a possibility that it would somehow screw up my furnace????
Not looking at this as some sort of off grid thing.....just an emergency plan if things went sideways with the electric service when its -30F.
Any of you done similar?
Thoughts?
 
Any decent generator will be fine. Generac, Honda, Kohler, etc. If you're gonna buy one from Horrible Fright....all bets are off.:D
 
When my house was built, the original owner installed a transfer switch between utility power and a plug hanging out of the switch. I have a late 90s Coleman brand 6500 watt generator. I've used it 5 times when we had power outages, on two occasions for nearly a week. I've had absolutely no issues with two different furnaces. I use a 12 gauge cord through the cat door and down the basement to run the furnace. I also run cords to the refrigerator, microwave, and some lights. And, to my wife's chagrin, the washer and dryer. I use blue painter's tape and plastic to seal up the gaps in the cat door to ensure no CO makes its way into the house, and run a battery powered CO monitor near the door.

I think the transfer switch is a useless complication, and a plug and receptacle would be fine. Just make sure you set the thermostat way low and make sure the furnace is not running when you switch the power.
 
Make sure to size the generator correctly. The ones I have seen (we looked a bit cuz hurricanes) will give you wattage and such, but unless you're way better electrically inclined than me, I couldn't teel you waht is what form those, but they may have something like "will run refrigerator and ac for 1-2-5 hours per gallon" or similar.
 
I had to replace my 1974 gas furnace last November. It had a very simple electrical system, just a transformer and a single phase fan motor, but I never needed to run it off my Honda generator. The new furnace and A/C is full of fancy computer-type electronics and has a Wi-Fi thermostat with touch screen. I would be hesitant to try a generator on it unless I did some research first.

Larry
 
I have the transfer switch setup, with certain key circuits moved to it. (well pump, furnace, kitchen outlets, fridge, microwave, some lights, etc.)

The transfer switch makes it easy and safe to go back and forth between Power lines and the genset. Mine happens to be a 3 pole switch, with neutral switching, so GFI outlets work properly.

There are certain things that will not be handled by a generator in this size (range/oven, clothes drier, etc), unless you choose to go with a large permanent install and whole-house setup.

You do have an annual task of changing out the generator fuel, if you go with gasoline, also need to keep the onboard battery charged up for the starter.
 
I have an old 6500 watt generator that I have used for power outages and such for years. It produces a steady 240 volts. I have been running my Lincoln Mig welder off of it for about 15 years. No problem. I would not hesitate to run any household appliance off of it - including the furnace or ac.
 
This part of the world we use many Gensets. Prime power and back ups.

For back up power in houses we typically use single phase (most houses are wired 3 phase)5-10kva petrol or diesel Genset. A change over switch is installed so when power is out we select the genset circuit and the changeover only powers the essential circuits of the house to insure the genset isn’t overloaded.

Just like what ps123 said.


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I have an older oil fired boiler that I have used on a generator many times over the years with no problems. One thing I did run into however is that if you lose power to the house, your thermostat will probably not work. I have three sources of heat (wood, heat pump, and oil furnace). The heat pump and oil furnace share the same electronic thermostat (my oil furnace is my emergency heat rather then heat strips). I can't run the heat pump on my generator so when I lose power I have no way of calling for heat on the oil furnace. I fixed that by getting a cheap mercury and bi-metal type thermostat and wired it to the oil furnace in parallel with the electronic thermostat for the heat pump. When I lose power I use that to control the oil furnace. When the power comes back on I just crank the old style thermostat all the way down and it is out of the picture.
 
Anytime you connect your own power supply to the existing power system you MUST make sure there is no way your power system can connect to the outside distribution system. You should have a transfer switch, U/L listed or otherwise approved for this. The reason is obvious. If you plug your power system into the house wiring and do not disconnect from the outside world, then you are energizing the outside lines. Anyone touching the "dead" power lines will be shocked and possibly killed. Remember those transformers that reduced the high voltage to a house voltage? They also work backward to take your 120 volts and boost the line voltages back to the 4000+ volts.

Secondly, for your own safety, connecting cables should not have any exposed terminals that you would need to connect to a house receptacle.

If decide to proceed, these are steps you should take.

1. throw the main breaker to "OFF" to disconnect the house from the outside.
2. connect your cables from the generator to the furnace receptacle.
3. start the generator.
4. let the generator stablize before turning the switch on to the furnace.

Always run the generator outside the house, not in garage. The fumes are poisonous and can kill. Carbon Monoxide.

Tom
 
and instead of hardwiring the furnace he plugs it in.

That's what my Dad does. Harbor Freight 4000 watt generator out in the barn.
He has a permanent extension cord running from there into the basement.

Runs the pellet stove and hot water heater(propane). Another extension cord up
through a hole in the floor to the living room for TV and computer. One up the
stairs for the refrigerator and their bedroom.

For how often power goes out, he can't justify doing the fancy wired in thing,
problem is when the power goes out, its usually out for quite a while, last month
or earlier this month he was out for 3 days, and the POS HF generator kept him
going.

He didn't even have to pay for the generator. I had it kicking around. I was back
east visiting one October, maybe 8 years ago when they had that pre-halloween storm,
22 inches of wet snow with leaves still on the trees. I put off leaving for 5 days,
no power the whole time.

All we had was a 400 watt invertor that plugged into a
cigarette lighter. Running the car half the day so you can watch football is not
the most fuel efficient way of doing things. It would run the hot water heater
so we could shower, it was almost like camping. Pot Belly stove in the kitchen
for cooking and heat. Beer outside in the snow.

Next trip out, I brought him that generator.
 
That's what my Dad does. Harbor Freight 4000 watt generator out in the barn.
He has a permanent extension cord running from there into the basement.

Runs the pellet stove and hot water heater(propane). Another extension cord up
through a hole in the floor to the living room for TV and computer. One up the
stairs for the refrigerator and their bedroom.

For how often power goes out, he can't justify doing the fancy wired in thing,
problem is when the power goes out, its usually out for quite a while, last month
or earlier this month he was out for 3 days
, and the POS HF generator kept him
going.

He didn't even have to pay for the generator. I had it kicking around. I was back
east visiting one October, maybe 8 years ago when they had that pre-halloween storm,
22 inches of wet snow with leaves still on the trees. I put off leaving for 5 days,
no power the whole time.

All we had was a 400 watt invertor that plugged into a
cigarette lighter. Running the car half the day so you can watch football is not
the most fuel efficient way of doing things. It would run the hot water heater
so we could shower, it was almost like camping. Pot Belly stove in the kitchen
for cooking and heat. Beer outside in the snow.

Next trip out, I brought him that generator.

If you think 3 days is long, don't ever come to hurricane country! :D Irma had us out for a week +. The crappy thing, it was almost just us. Neighbors across the street never lost it, neighbors a few doors down were fine in a day or two. Not us. :(
 
I would recommend a propane or NG engine. No fuel to go stale. Keep a can of starting fluid nearby. With all the computers onboard at least have a surge suppressor outlet for the fridge. Not all generators produce pure clean sine waves.
Maybe use a line reactor on the fridge circuit. They are cheap on the bay for used 3 phase units. For single phase just ignore the extra terminals.
Would an old computer APC line conditioner work without the batteries?
Bil lD
 
I run my generator out in the shop where it is safe and backfeed through the breaker that feeds the shop. The first thing I do is pull the meter face to disconnect house from transformer. I asked the power folks if it was okay to do this and they said they would much rather have the meter face pulled then someone getting killed on the primary side with a generator on the secondary. Another handy thing to do is to mark your breakers with red dots or something so you can turn off all the breakers except for the ones that feed your essentials (refrigerator/freezer, furnace etc.). Trying to figure out which breakers to turn on is no fun in the dark after the power goes off.
 
If you think 3 days is long, don't ever come to hurricane country! :D Irma had us out for a week +. The crappy thing, it was almost just us. Neighbors across the street never lost it, neighbors a few doors down were fine in a day or two. Not us. :(

The joys of a master planned community. All utilities are underground. Power was back on the 3rd day. Water never went out. Internet was back as soon as the power was back.
 
The joys of a master planned community. All utilities are underground. Power was back on the 3rd day. Water never went out. Internet was back as soon as the power was back.

Obviously you are wealthier than me!! :eek: :D

We bought an older remodeled house (still 175 large!!). I think Duke is planning on moving all their utility lines underground, but I get the "luxury" of paying for it I am sure...
 
The biggest thing that I am aware of when using a generator is to be the CO2 exhaust. But you already know that.

Electrically, the biggest no-no is having it back feed into the power lines. That creates a danger to the power company's line men and also to anyone who may come in contact with a live wire on the ground which often happens in storm situations. Using the individual plugs with extension cords on the items you want to run should be OK. No danger of back feeding there. But do avoid any jury-rigged wiring into the existing house wiring. The best way, probably the only way to tie into the existing house wiring would be a proper change-over switch that is properly installed.
 
I recently set up an anti-backfeed system for my brothers server rack battery unit. He has a generator he runs out of his garage, and about 20 minutes of battery power to get it switched. I basically added a second power input line into the rack, and tied both lines through a double pole, double throw relay. The main power in energizes the relay, and then goes through the normally open contacts to the distribution center and battery unit. The generator input goes to the normally closed set of contacts so when the power goes out, it's automatically tied in. All he has to do is run an extension cord through the window and start the generator. When the power comes back on, the relay switches back to the mains. Nice and simple, and cheap. The relay provides its own mechanical interlock in the form of the contacts.
 
The summer after the Y2K panic passed, I bought a new Generac. 7500 watts continuous / 13500 surge. Paid an electrician to put in a simple manual transfer switch and run heavy wire to the doorway nearest the outside operating location. It doesn't get used often, but it sure is nice to wheel it outside, plug it in and make power.

The only issue was a tripped breaker on one leg of the split phase when the wife tried drying cloths and baking at the same time. NOW, she understands anything but not everything. No fancy inverter clean power, but never done any harm to anything including computer and TV.
 
Any decent generator will be fine. Generac, Honda, Kohler, etc. If you're gonna buy one from Horrible Fright....all bets are off.:D

A tale of woe about Generac. Twenty years ago, we had a serious flood. Spent 6-7K on a Generac on a slab, mostly to insure a working sump pump. Six or seven years later, I accidentally discover that the sump pump circuit wasn't wired in! But it hardly mattered because the unit kept having faulty oil pumps (or cavitation plates, for all I know). Free for the taking--one yellow and black boat anchor.
 








 
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