Using RV generator as backup for house?

[coolmom42]

My electricity is still on in Middle TN, no worries. But that may not always be the case in the future!

If I have a transfer switch properly installed, is there any reason I can't use the RV generator to power my house?

Water heater and range are gas. City water supply, no well pump. Gas furnace with (and this is the critical thing) an electric blower. 1 refrigerator, 1 small chest freezer. Lighting is mostly LED.


Google tells me that the furnace blower uses around 400 Watts. I'm going to check with the HVAC dude.


The only downside is having the generator running fairly close to the house, but I have multiple CO detectors, and probably would be able to leave it off most of the night.

Any input?

[enblethen]

Some states do not allow a lockout that takes two operations to prevent feed back. Those that want to use that style should check with their local electrical authority having jurisdiction.

[Dave_H_M]

999, what are your negatives on the lock out mechanism?

[rlw999]

mr_andyj wrote:

Easiest is to run some extension cords.
Safest is to run some extension cords.
Best is to have electrician install an cut-off switch

I think safest and best is to install a transfer switch. Otherwise you end up propping open a window/door (which can let generator exhaust in) to run extension cords to your furnace, 'fridge, and whatever else you want to keep running during a power outage. My brother-in-law tripped over his stairway extension cords in the dark, fortunately just sprained his wrist, but the last time you want to injure yourself is during a weather/power emergency.

If your power regularly goes out, then it's safer and much more convenient to have a transfer switch and a generator inlet outside. Definitely more expensive, but so is going to the doctor because you tripped over a cord in the dark.

[MEXICOWANDERER]

When I tested transformer polarity, I connected 120 vac to H1 H2 and H3 and measured voltage at X1 X2 and X3 to neutral or ground.

Let's open circuit your neighborhood distribution circuit beyond your transformer. 0 volts everywhere.

But then introduce 120 volts backwards from a generator to X1 to X2 or X3.

What do you think happens at H1 H2 or H3?

Perhaps 12,500 volts with enough wattage to instantly kill through bare hands.

Google HOT STICK.

Attachments on the end of a special fiberglass pole.

Working with gloved hands is ten or fifty times faster than doing connections and switch throwing with a hot stick.

A linesman is lifted in a bucket. His voltage detector screams.

Where is the back feed coming from?

Repair is halted.

Easter Egg hunt commences. A pain in a residential neighborhood.

Totally needless delay in service restoration.

--------------------------------------------------------------------------------------------------------

Your utility has an independent minimum size amperage rating for isolation relays or manual thrown isolation switches.

A licensed contractor has information to follow.

A NEMA 4 weatherproof box with bottom-side-only ingress and egress for conductors is best. Conductors may be required to be housed in EMT.

A 200 ampere rated TTDT 240 relay is not cheap.

This is an elaborately explained detail of why things are the way they are. Expenses for a correct installation can be "shocking".

[DrewE]

mr_andyj wrote:

Beware, it is possible to "backfeed" the house by running your generator into an outlet, but the DANGER is over-loading that wiring from that outlet to the panel and causing a fire. You can turn off all the circuit breakers except that outlet and the blower motor and maybe be OK, but what else is on that outlet's breaker?
I know what I am doing and would never backfeed an outlet just because of the risk of making a mistake.

That's not the primary danger in backfeeding through an outlet (which is generally illegal and, in any case, definitely should not be done). A bigger problem is backfeeding more than you intend, such as the whole power grid, which can be deadly to the linesmen who are working to restore power. Another bigger problem is the necessity of using an aptly-named suicide cord, which has a male plug at either end; should it come unplugged for whatever reason, you have live exposed prongs.

If you're going to power your house with a generator, do it properly with an approved interlock or transfer switch, appropriate inlet connections, and so forth--or run extension cords and don't interconnect to the building's electrical system at all.

[mr_andyj]

I live , as the wire flies, about a mile from the electric grid sub-station, and that might be why the power rarely if ever goes out at my house, so unless a tree falls in that one mile distance then power is always up...

Easiest is to run some extension cords.
Safest is to run some extension cords.
Best is to have electrician install an cut-off switch and a small panel box to power up just the things that you need (blower, fridge, a few lights), but that gets really expensive unless your brother in law is an electrician and willing to work for free.

Beware, it is possible to "backfeed" the house by running your generator into an outlet, but the DANGER is over-loading that wiring from that outlet to the panel and causing a fire. You can turn off all the circuit breakers except that outlet and the blower motor and maybe be OK, but what else is on that outlet's breaker?
I know what I am doing and would never backfeed an outlet just because of the risk of making a mistake.

If you are able to do home electric work yourself, has anyone run a completely separate and new electrical system? An outside way to plug to the generator, and a small panel and run wire to one or two places (the furnace and fridge) so you can unplug them from the house and plug them into the generator house outlets... This is easier than dragging out electric cords in the dark in a rainstorm or snowstorm...

My furnace is new, it is 120 and wired into an outlet box. It would be nothing to make that a 3-prong plug that plugs into that outlet instead, then I could plug the furnace (blower motor) into the generator much easier.
Gas is almost always on, I never iin my life have had gas not flow, but in TX they did as crews were digging and ruptured gas lines, so all of this blower set-up would be useless if that were to happen...

[coolmom42]

ktmrfs wrote:

time2roll wrote:
So the gas burns outdoors and is pumped in with the freon or a fluid? Sounds like a heat pump to me even if it uses heated air rather than the bitter cold outside air to move the heat.

I am sure the multi-speed blower and maybe multi-speed compressor make it very efficient.

One's I heard about have a plenum from the unit to the house to move hot/cold air for heating or cooling. Unlike an outside AC unit that has the freon lines going to the inside furnace and plenum.

think of it as a typical furnace mounted outside the house. Some are roof mounted.

So, no they are NOT a heat pump for heat, just a heat pump for the AC just like any AC unit is. Likely reason they need 240v is for the AC unit, so they run the furnace section off the 240V or may have an internal transformer for the furnace section.

This is exactly what it is. It's NOT a heat pump. I've lived in this house 25 year, and this is the 3rd one I've had. (2nd one was 5 yrs old and got fried by lightning last summer.)

They are very common in my small town, because 2 of the main subdivisions were built in the 1960s. Lots of growth in this area at the time, and budget houses were a great deal (and still are.) This is a very common style of house in this area. Crawl space, no basement, less than generous closet space, low slope attic, typical ranch style houses. So there is NOWHERE to put a traditional split system furnace/AC unit.

I sacrificed a chunk of the bathroom closet to the return air ducting. The houses were originally build either with electric wall heaters, or radiant ceiling heat, and large window air conditioner units.

[ktmrfs]

time2roll wrote:
So the gas burns outdoors and is pumped in with the freon or a fluid? Sounds like a heat pump to me even if it uses heated air rather than the bitter cold outside air to move the heat.

I am sure the multi-speed blower and maybe multi-speed compressor make it very efficient.

One's I heard about have a plenum from the unit to the house to move hot/cold air for heating or cooling. Unlike an outside AC unit that has the freon lines going to the inside furnace and plenum.

think of it as a typical furnace mounted outside the house. Some are roof mounted.

So, no they are NOT a heat pump for heat, just a heat pump for the AC just like any AC unit is. Likely reason they need 240v is for the AC unit, so they run the furnace section off the 240V or may have an internal transformer for the furnace section.

[wa8yxm]

Re Cable...TV/Internet
You can easily send power from the HEAD (the equivalent of a phone company Central office) to the line amps via the same cable that carries the signal. What I don't know however is how far you can send it.

IN FACT most RVers do precisely that. You talk about the OTA antenna Pre-Amp and refer to the wall plate with the switch as the Pre-Amp but guess what. That's not the pre-amp... The Pre-amp is up in the antenna head.
That is just the power supply.
So where is the power cables from the supply to the roof.. The coax carries power from the switch UP to the head and signal from the HEAD back to the switch

Cable companies can use the same technology but there is a limit to the length of the run or the number of amps that can get power that way run.

[time2roll]

So the gas burns outdoors and is pumped in with the freon or a fluid? Sounds like a heat pump to me even if it uses heated air rather than the bitter cold outside air to move the heat.

I am sure the multi-speed blower and maybe multi-speed compressor make it very efficient.

[Gdetrailer]

Dusty R wrote:
I haven't worked on a furnace for over 20 years.
I'd do a little more research. Start by checking and see if the breaker that powers the circuit that feeds is a 2 pole breaker.
Or a small transformer could be used feed the fan motor or furnace.

Wrong, Wrong, Wrong.

Did you not do any research?

OP SAYs they have a "GAS PACK" furnace/AC unit which sits OUTDOORS.

This is not a standard gas furnace that sits in your basement that you are thinking of.

It is also NOT A HEAT PUMP although they use a similar style box and ductwork.

A gas pack system is a all in one Gas furnace with Central A/C all in one box that lives totally out side.

Since the built in A/C would need to have 240V, it stands to reason the the BLOWER MOTOR WILL ALSO BE 240V!

Some posts up I posted a photo of what they look like AND a link to the installation manual.. There is no mention of a blower motor on the one I posted using 120V even for the smallest unit they build..

These units are typically used for industrial types of applications and are designed for 208/240V, will not function with 120V. Many times you will find these types in use in small retail shops sitting at the side of the building or even on the roof..

These all in ones may not be popular in homes in all areas but obviously the OP HAS one of these..

So, YES the OP NEEDS a gen that provides not only 120V BUT ALSO 240V if they wish to run their gas furnace from a gen.

Besides, OP just said that their HVAC person (HEATING AND A/C person) has stated they need 240V.. While I am sure there are some HVAC folks not as bright as a light bulb, I suspect that the OPs is knowledgeable enough to figure out the difference between 120 and 240 is all about..

[Dusty_R]

I haven't worked on a furnace for over 20 years.
I'd do a little more research. Start by checking and see if the breaker that powers the circuit that feeds is a 2 pole breaker.
Or a small transformer could be used feed the fan motor or furnace.

[coolmom42]

Well it's a NO-GO.

I had an extended conversation with my HVAC dude. My heat blower requires a 220V input. He said that the variable speed blowers are almost all like that.
So not going to happen with the RV generator.

My goal is to be able to at a minimum, have heat in the house when electricity goes out. That need can be met with a gas fireplace or heater of some type.

Ideally, I would love to be able to power the entire house. That means a whole house generator, supplied off natural gas (which I have.) My natural gas does not freeze up, unlike in TX.

So time to get some quotes and info on the options.

[Gdetrailer]

opnspaces wrote:

coolmom42 wrote:

time2roll wrote:
3000 watts should run that house fine. Electrician will probably put the critical items on a 120v sub panel in addition to installing a switch and a power inlet to connect power.

My generator is 4000 watts. It would be nice to be able to run the whole house, including TV & internet. Not essential, but nice.

Just wanted to touch on this because I had the same thoughts about how cool it would be to keep the internet up. The problem is unless you are tethering the internet through cellular, once the power goes out the internet goes out too. Yes I can get my cable modem back up and running on the generator. But after the signal leaves my modem it is dropped by some unknown system down the line because it has no power either. So in reality once the power goes out the internet goes with it.

Cable Internet uses the same cable as their TV services and in order to have enough signal to arrive at your home they must use booster amps along the cable run every so many miles.

Those booster amps are mounted on the poles the cable is hung on and they must get power from the electric company.. If you lose power in the wrong place between the cable co plant to your home, your Internet like the cable TV will go down..

My local Cable Co has backup batteries in their pole mounted amps, but that only is good for about 2 hrs.

Was one of the issues that I knew was going to happen when DW needed faster speed than the phone co DSL service we had.. Last week ram into the cable co's battery backup limitation after we had a power outage for 3 hrs and the Internet went down after 2 hrs..

Phone co DSL is powered directly from the switching stations' battery and gen backups so as long as the phone lines were not damaged the Internet stayed up indefinitely..

Another reason I am not jumping on the streaming bandwagon and staying with my Dish, the cord cutting streamers will be disappointed and have nothing to watch when their high speed cable Internet quits due to power outage :B

[ktmrfs]

opnspaces wrote:

coolmom42 wrote:

time2roll wrote:
3000 watts should run that house fine. Electrician will probably put the critical items on a 120v sub panel in addition to installing a switch and a power inlet to connect power.

My generator is 4000 watts. It would be nice to be able to run the whole house, including TV & internet. Not essential, but nice.

Just wanted to touch on this because I had the same thoughts about how cool it would be to keep the internet up. The problem is unless you are tethering the internet through cellular, once the power goes out the internet goes out too. Yes I can get my cable modem back up and running on the generator. But after the signal leaves my modem it is dropped by some unknown system down the line because it has no power either. So in reality once the power goes out the internet goes with it.

in our house if power goes out doesn't mean I loose internet if I power back up the fiber box in the garage and the modem in the living room. Once those are on I have internet. (assuming the intenet/cable hub hasn't gone down.)