Generator Powered Furnace

[jgruberman]

Hello, I am in Dallas experiencing heavy power outages and my family has been without power for 36 hours and therefore also heating. I have a 8000 w generator and a 100 ft 10 gauge extension cord. Is there any way that I can get this generator somehow wired to part of the Furnace so we don't have to have another night of sleeping in 40° housing?

Maybe I can wire it directly to the switch where the furnace toggles, or perhaps directly into the furnace circuit breaker in the breaker box. This is only temporary and would be undone after this whole crisis is over from concerned with my family and baby and senior pets not having enough heat.

The furnace is a S8B1B060M4 and the generator is this: 6250 Watt Portable Generator - https://www.briggsandstratton.com/na/en_us/product-catalog/generators/portable-generators/6250-watt-portable-generator.html

Any help would be drastically appreciated. I'm fairly knowledgeable about electrical and wires, just haven't done this specifically before and wanted to ask before I did something wrong.

 

[PEG]

Hi,the fact you are somewhat out of our area of regular work? restricts a definitive answer....but the main two points to consider,are firstly,you would need to guarantee separation between your main supply and your generator,for obvious safety reasons.
Secondly,you would need to ensure that any electrical safety features or functions,continue to provide any protection required,either by need,or regulation.

There are other things to consider,such as whether any electrical loads at the property,need to be interlocked out,to prevent overloading of any generator,not capable of supplying all the possible needs.

The nature of the characteristic of supply of some generators,may cause other issues with some electrical equipment.

On a separate ,but not unconnected matter,i would like to take a very rare opportunity to say"YEEEE-Har!" to a Texan,which from a Mancunian,not unfamiliar with the oil and equestrian business......feels almost compulsory ?

 

[jgruberman]

Hi,the fact you are somewhat out of our area of regular work? restricts a definitive answer....but the main two points to consider,are firstly,you would need to guarantee separation between your main supply and your generator,for obvious safety reasons.
Secondly,you would need to ensure that any electrical safety features or functions,continue to provide any protection required,either by need,or regulation.

There are other things to consider,such as whether any electrical loads at the property,need to be interlocked out,to prevent overloading of any generator,not capable of supplying all the possible needs.

The nature of the characteristic of supply of some generators,may cause other issues with some electrical equipment.

On a separate ,but not unconnected matter,i would like to take a very rare opportunity to say"YEEEE-Har!" to a Texan,which from a Mancunian,not unfamiliar with the oil and equestrian business......feels almost compulsory ?

So I could, in theory, run a line from the generator in to the circuit box for its own breaker to the main power, and while having the main power off and any other circuits that I don't want powered, I could use that generator circuit to power whatever I still have closed?

 

[brianmoooore]

Your generator is capable of powering dozens of furnaces of this type, so there's no problem there. What you must not do, however, is connect the generator to the house wiring in such a way that there is any possibility of the generator being connected to your incoming electricity supply. Simply turning off switches is not sufficient to prevent this, as there is always the possibility of someone turning it back on, and your local neighbourhood transformer is quite capable of working in reverse, stepping your 110 volts back up to whatever the distribution voltage is in the US. This could be fatal to anyone working on the line.
For a temporary connection, your best bet is to disconnect the power feed flex to the furnace at the wall, and connect a plug to it that can plug into your extension lead.
For a permanent generator connection in the UK, we are required to have an isolator switch disconnecting the incoming supply, then a changeover switch, serving as a second isolator, and connecting in the generator. This must switch all lives and neutrals, and we are also required to fit an effective method of earthing, apart from that provided by the energy provider.

 

[jgruberman]

Your generator is capable of powering dozens of furnaces of this type, so there's no problem there. What you must not do, however, is connect the generator to the house wiring in such a way that there is any possibility of the generator being connected to your incoming electricity supply. Simply turning off switches is not sufficient to prevent this, as there is always the possibility of someone turning it back on, and your local neighbourhood transformer is quite capable of working in reverse, stepping your 110 volts back up to whatever the distribution voltage is in the US. This could be fatal to anyone working on the line.
For a temporary connection, your best bet is to disconnect the power feed flex to the furnace at the wall, and connect a plug to it that can plug into your extension lead.
For a permanent generator connection in the UK, we are required to have an isolator switch disconnecting the incoming supply, then a changeover switch, serving as a second isolator, and connecting in the generator. This must switch all lives and neutrals, and we are also required to fit an effective method of earthing, apart from that provided by the energy provider.

Correct, I understand this and would turn off the main line in the breaker box (the 200a breaker). I then, in theory, could run a simple 3 prong extension cord from the generator to the switch box in the attic and run it directly to the 10/2 coming out of the furnace? If so, I read this may cause circuit board damages, is that a concern I should have?

 

[brianmoooore]

Turning off the 200A breaker is not sufficiently secure. It could be innocently turned back on by someone.
The 'damage' that could occur is not to your circuit board, but to a linesman some distance away, working on the distribution network.

 

[jgruberman]

Turning off the 200A breaker is not sufficiently secure. It could be innocently turned back on by someone.
The 'damage' that could occur is not to your circuit board, but to a linesman some distance away, working on the distribution network.

Yes I understand what happens if current goes back up the line. My question was if I connect the generator directly to the furnace via the wire coming out of the furnace, can that cause damage to the Furnace?

 

[brianmoooore]

As long as the generator is the same voltage as the furnace, then no damage should be caused to it. I am assuming that any thermostats and pumps involved are wired from the furnace, and not from before where you connect to it.

 

[pc1966]

I would imagine your safest option is to wire the furnace to a plug / extension cable arrangement, start the generator and then plug the furnace in to power it. Some generators warn you not to start/stop them on load, so you really want some means to switch separately from that.

I'm guessing you know to take care against carbon monoxide poisoning? Make sure the generator is run in a very well-ventilated area.

 

[jgruberman]

As long as the generator is the same voltage as the furnace, then no damage should be caused to it. I am assuming that any thermostats and pumps involved are wired from the furnace.

That's a good question. I'm not sure how the thermostats are wired, as we are newer to this house. I think the furnace is a heat pump, model s8b1b060m3ps. I guess I assumed that if there was power to it, that it would automatically turn on... But I'm guessing it would still need to be triggered from the thermostat?

 

[pc1966]

That's a good question. I'm not sure how the thermostats are wired, as we are newer to this house. I think the furnace is a heat pump, model s8b1b060m3ps. I guess I assumed that if there was power to it, that it would automatically turn on... But I'm guessing it would still need to be triggered from the thermostat?

Have a look at your panel and see if any breakers are labelled for heating on anything that might match that.

 

[pc1966]

It is possible that the feed from your panel goes to more than just the furnace (e.g. heating control, water pumps, etc) but that is not going to be easy to find out under your current conditions.

If it looks as if only one breaker feeds the heating system, it might be best to disconnect that from the panel (having switched off the main supply first!) and then use your extension lead to power the disconnected wires feeding the heating system.

Keep the earth/ground wire in the panel, and just add your generator earth to the panel earth so you don't have some of the home on supply earth and the heating on you generator that might be "floating" as not having its own earth rod, etc.

 

[jgruberman]

Have a look at your panel and see if any breakers are labelled for heating on anything that might match that.

Yes, we have three AC breakers and three furnace breakers. There are three separate systems in this house. Of course I'm only focused on one, we're all pretty cold in here, no power for 48 hours now, 9 degrees outside. If I can get at least one system running, that'll help immensely

 

[pc1966]

Good luck!

 

[jgruberman]

It is possible that the feed from your panel goes to more than just the furnace (e.g. heating control, water pumps, etc) but that is not going to be easy to find out under your current conditions.

If it looks as if only one breaker feeds the heating system, it might be best to disconnect that from the panel (having switched off the main supply first!) and then use your extension lead to power the disconnected wires feeding the heating system.

Keep the earth/ground wire in the panel, and just add your generator earth to the panel earth so you don't have some of the home on supply earth and the heating on you generator that might be "floating" as not having its own earth rod, etc.

Got it. I will connect an extension cord into the breaker room, run the ground and common to the bars and connect the hot directly to the furnace breaker and see what happens.

Thank you for your help, I know it's not conventional to get direct help but like I said.. we've been without power for 48 hours and have a baby and now sick animals, I'm desperate to get my family warmed.

 

[pc1966]

It is not something I would normally suggest trying out, but I appreciate your circumstances and the very real risk of not having heat at all.

Just remember to check things carefully and isolate the incoming power before doing ANY work on the panel, etc, as it might come back on at any time.

Hopefully we will hear back with some good news later!

 

[jgruberman]

It is not something I would normally suggest trying out, but I appreciate your circumstances and the very real risk of not having heat at all.

Just remember to check things carefully and isolate the incoming power before doing ANY work on the panel, etc, as it might come back on at any time.

Hopefully we will hear back with some good news later!

I completely understand that and appreciate your effort. I am definitely aware of the real dangers of both sending current upstream and handling live current. I will let you know how it goes

 

[jgruberman]

I do have one final question about getting a circuit in the box once I have an Interlock device. Our circuit box is full but has close to a dozen breakers for lights/switches. Can I switch several of those out for tandem breakers to make room for a generator breaker?

 

[pc1966]

I do have one final question about getting a circuit in the box once I have an Interlock device. Our circuit box is full but has close to a dozen breakers for lights/switches. Can I switch several of those out for tandem breakers to make room for a generator breaker?

For a permanent arrangement?

Usually you would get an transfer switch to allow you to move the whole panel from utility power to a local generator, but you will need to shut down a lot of circuits as your generator is probably only 30A or so and not going to run lots of high current stuff.

Also you need to check if your generator provides a 120-0-120 supply so you can run both 240V stuff and 120V stuff safely (though I think in the USA 240V stuff is usually quite high power and might be too much for your generator).

 

[pc1966]

These sort of things:

Generator Transfer Switch Guide for [year] - All You Need to Know! - Generator-Review.com

After buying a generator to ride you through the next power outage, the second thing you buy should be a generator transfer switch. It gives you the hassle-free connection of …

www.generator-review.com

https://www.homedepot.com/b/Outdoors-Outdoor-Power-Equipment-Generators-Transfer-Switches/N-5yc1vZc7l9