I live in Montana, so no AC.  But could lose power either winter or summer (wind storms/fire/blizzards/whatever).  I have Natural Gas heat, water heater, refrigerator/freezer and an upright freezer.  Outages probably wouldn't be more than a week-10 days at most.  So, what watt generator to run the appliances, the water heater ignitor and the furnace ignitor and fan?

I'm pretty sure the ignitors and fan don't take much... and I can alternate between the refrigerator-freezer and the upright freezer in the summer.... freezer is in the garage so if power goes out in the winter I can probably go a few days without it running...not so much in the summer.

So, a couple of questions:  What wattage rating generator should I be looking at, and is a tri/dual fuel worth it?  And, is an inverter generator much of an advantage in the above scenario (I can store maybe 10 gallons of gas, or maybe a 30# propane bottle, and could have the NG line plumbed for a generator)...

I've looked up average wattage needs at startup for the above, and if everything started at the same time, I'm looking at 5500 watts or so... likelihood of this happening is a bit remote, and if I need the furnace, I wouldn't need the freezer very often and vice versa.

For me, a generator can be a significant investment, so I want something that'll do the job.  Something portable would also be useful for outdoor camping use as well.  Any and all advice is greatly appreciated

Thanks in advance!

Is the water heater electric or gas?    Do you have a well or municipal provided water?   If you have a well then do you know how large the motor for it is?   If not then the size of the breaker that powers it is a good place to start.   Do you have a sump pump or septic pump?

Gas water heater, municipal water, municipal sewer, no sump pump

Dad spent his career in industrial power sales, so I have a fair bit of background.
So some thoughts:

1) Whole house systems and portable units are different animals. Don't shortchange your primary objective by trying to rig up a portable unit to run a house.
2) Automatic or Manual Starter and Transfer switch? If unattended operations are needed, automatic.

A 7.5KW propane/6KW NG Generac with automatic transfer switch is $2k. Add in some more $$$ for the electrical as gas work. That is likely your top end out of pocket.

Is your stove electric, LP, or natural gas?  Do you plan on using it or do you have another method of cooking?  Do you use a microwave?  These will all draw a decent amount of power.

Need to look, at your specific loads.
Read the placards on the hvac motor, refrigerator, freezer etc.
Count the lights, TV, internet, septic pump, etc you want to run.
Add it all up, add some overhead for motor startups.

Your needs appear to be low. How many kWh do you use per month on your house electric bill? That will give us an idea what's reasonable to expect or if you have any unexpected loads.  

Looks like you have no need for 240v. If your stove is electric, get a propane camp stove and you still won’t need 240v. Based on your data provided, you should be able to easily run every essential appliance in your house on a 3500 watt generator and have plenty of power to spare for things like lights and such.

You can convert to natural gas but then you are at the mercy of the gas company. NG is usually very reliable but in the last deep freeze, we found out NG isn’t nearly as reliable as we thought. Just food for thought.

A HF Predator 3500 watt generator with a tri fuel kit and a quick connect for your house NG would probably be a perfect solution for you.

Remember, you don't have to run everything in your house at once.

I ran a Makita 5500 for 8 days straight after an ice storm. No problem. Not even a hiccup. Heat was on constantly, (oil fired furnace and hot water)

A 5500 will push a coffee pot, hair dryer, microwave, two refrigerator's, and an electric griddle all  combined with your other requirements, just not all at the same time.

Advice at this point will be all over the board but as others have said, it doesn't sound like you need much.   Buy too large of a generator and the  fuel costs will be excessive.   Buy too small and keeping things running will be a struggle.   A lot of use here have adopted a "dual generator" approach.   Whether or not you should will depend on your situation and only you can decide.    

I will start with telling you my background on generators and then some of the things that I say might make more sense.   I have formal training on maintaining electrical and mechanical devices from the Marine Corps.   On deployments we always took at least a couple of 3KW MEP-16B's for misc uses.   They were my responsibility.  

I got out of the Marine Corps in 1993 and built a new house in 2000.   The builder set the basement into the water table and we run our sump pump a lot.   The area has a lot of power outages so we bought a Honda engine driven Harbor Freight 8KW generator for power outages.   We ran it a lot.   It would run most of the house, including the sump pump, well pump, lights, furnace (gas), water heater (gas with power vent), microwave, TV's, and computers.   We would not run the electric stove or central air.   Well, we could get the A/C to start but it was hard on the generator and A/C so we didn't do it often.   The 8KW would use between ten and fifteen gallons of gas in 24 hours.   Managing the gas stores for the random and prolonged outages wasn't a pleasant experience either.  

After putting over 600 hours on the generator, my wife starting an in home business with clients, and my son needing in-home medical attention we bit the bullet and bought a 20KW propane Generac and a 1,000 gallon propane tank.   We have encountered people that show disdain for having and running such a large home generator.   But for our situation, we NEEDED to be able to continue life as normal through at least some of our outages.   The first six months that we owned the Generac we had four different power outages.   Most of them six or more hours long.   We love that thing.   We would come home and find the generator running and the kids making dinner.   We would ask the nurse if everything was ok and she would say "Yep.   There was a short power outage but it is back on now."   She had no idea the generator was running.   As great as the Generac is, it GULPS fuel.   Our 1,000 gallon propane tank will last between 14 and 21 days running that generator.   That is between $2,000 and $3,000 dollars in fuel, depending on price and availability.    It also cannot convert to gasoline.   It has worked out well for us and we don't regret the decision.  

To save on fuel costs we bought a couple of Honda EU series generators.   One is an EU2000I and the other is an EU2200I.   Both have Hutch Mountain propane conversion kits installed.   We can run them off the same 1,000 gallon propane tank.    But running the one EU2200I on propane that same 1,000 gallon tank should last 270 days.    Or we can run gasoline.   Those generators are really handy.   We use them a lot.   I have taken them to work and used them there.   They go camping.   They go to family driven construction projects.   It is often easier to drag out a Honda than it is to run an extension cord.   We have the parallel kit and both generators also have the pass through fuel caps so they can use a 5 gallon NATO can as an extended runtime fuel tank.  


We are often asked why we spent the extra money for the Honda's and didn't get something cheaper.   Well when we bought the first one, there wasn't the selection of the dual fuel options that there are today.   Not wanting to HAVE to maintain 30-50 gallons of gas on hand for outages dual fuel was important.   Also, I learned a long time ago to buy once and cry once.  

I should mention that since we bought the Generac our situation has changed.   The wife has moved her business out of the house and our son is no longer with us.  

So our strategy is that during short outages we let the Generac run.   For longer outages we run the Generac for 60-90 minutes in the AM while people get ready for the day.   Then we shut it down and run one of the Honda's to keep the fridges, freezers, sump pump, and furnace going.   Then at dinner time we switch the Generac for a couple of hours to make dinner and clean up.   After dinner we switch back to the Honda for the night.   This saves on a lot of fuel.    

Have you seen this?   https://www.ar15.com/forums/outdoors/Sandy-12-days-without-power-what-worked-what-didn-t-/17-661411/   It gets referenced around here a lot.    AR-Jedi does a good job of explaining the ins and outs of managing loads on a small generator.  I burn more fuel in 24 hours with the Generac than AR-Jedi burned in twelve days with his dual generator approach.  

In my opinion, you need to decide what you need to run and how much effort that you are willing to spend managing a power outage and go from there.    It sounds to me like _IF_ you are willing to keep switching things around then you could get by with a 2KW or 3KW generator.   But 4KW (or two 2KW inverter generators in parallel) would be a lot less hassle to manage.   And inverter generators are MUCH quieter and more fuel efficient than standard open frame generators.  

One last thing,  running on generator can wear on your nerves.   Between the noise, the hassle, the constant attention that needs to be given to what is running and what needs to run it just wears you down.   The longer the outage, the worse it can get.   I think that it is better than "no generator" but it might be worth considering how you and your family handle inconvenience when deciding if a couple of extra dollars on a better generator is worth it.

Let us know what you decide to do.

2Hut8's post is king.  Be sure to review his link to AR-Jedi's epic post.  OP, it looks like you don't have a huge electrical load to manage.  It shouldn't take too much to get you squared away.

Here's something to consider, I'm not saying it's the only approach, but a new way of thinking about things with the technology that is now available.

The smaller size (~2000 watt) inverter generators are quiet and very fuel efficient, and are light enough to be readily one-person portable.

Another characteristic of the newer inverter generators is that they can be paralleled - can run more than one at a time to add up the wattage.

So an approach that I think might be really handy is to have two of those generators. Can run both during the times you might need more power, but for the majority of the time you should be able to get by with just one... plus you can do maintenance, refueling etc as needed with an "offline" unit. And even if one breaks down you'd still have one running unit. If you wanted to be really cautious/prepared maybe have 3 of them.

I think that one of the biggest mistakes people make is buying a big generator…then they run a couple of LEDs and their tv while sucking down fuel.

I lived for months in Panama with only a single Honda eu2000 to power lights, fans, a freezer and water pumps. I would get up in the morning and plug the freezer in for an hour or so. Then we would go all day with the fans and tv on. It worked beautifully and ran a little over a gallon a day.

One thing about parallel inverters is that you can buy one generator one year and buy the second generator the next year.   Just don’t wait too long or you might not be able to get a compatible generator to pair to.   And then there is the whole “two is one and one is none” thing.   Redundancy has value as well.