My house uses a heat pump + oil-burning furnace. It gives a pretty good combination of efficiency, and ability to handle really cold weather.
During the winter storm that just passed, a friend in the Midwest called that their house had no power and was rapidly cooling. The utility could provide no ETA to resolution. I walked them through (over the phone) safely enough backfeeding enough power from a gasoline generator (outside, with the extension cord run through a basement escape window) into their furnace circuit to bootstrap the furnace (and run the blower fan) to keep the house warm so that the pipes didn't freeze and burst. If the HVAC system had had a small battery and some way to generate power from the heat it was burning, the gasoline generator would've been unnecessary. Perhaps an integrated thermoelectric generator [2]? A standby generator isn't financially practical for most folks ($6k + install).
(EDIT: to the safety folks out there possibly concerned, the furnace breaker and main breaker were tripped, and the meter was pulled to prevent any chance of harm to electrical linemen from inadvertently energizing the utility line; take no chances with safety, do not attempt this at home)
[1] https://www.amerigas.com/about-propane/propane-tank-sizes
https://www.youtube.com/watch?v=1JNuovFpCpQ
* I don't like that they skipped putting a bushing or an NM clamp on the back of the box into the furnace, but otherwise the video looked sound when I watched it a couple weeks ago.
From what I've seen so far, unless your unit is super old, the 8.5A is almost certainly just a 'peak' startup current that's overstated as well. Your blower should say something like "1/3 HP" and from there it's straightforward conversion of 1HP = ~750W so a 1/3HP would be 250W. On a 120v service, that's 2 Amp. With maybe 15% efficiency loss, at peak speed, the blower motor wouldn't be drawing more than 2.5A. It could/will draw more than that to start, but literally just for a second or two.
https://d1049ui2fjityy.cloudfront.net/userfiles/inriver/docu...
That motor has a switch so it could be in 3 different settings -- As shipped, the blower motor speed is set to be faster for AC (more draw in the summer) to prevent the coils from icing over, and then it's shipped to be the slowest fan speed while in heating mode, but it is possible that your installer changed that. If indeed it is in the "slow" speed for heat, then 2.5A would be about right.
Something else to consider: electric pipe heat cable to keep pipes from freezing draws ~7 watts per foot, is quick to install, and easy to power if you've planned ahead.
Freezing pipes is one concern, though having heat for the humans is another pretty desirable thing, so if I could spend effort on something that would result in drained pipes and no heat or on something that would result in enough heat in the house to make that unnecessary, I'm going for option #2 every time.
That doesn’t sound like it should be up to code? I’d expect building codes to require a floor drain where your water tank is.
Unfortunately, this is not a universal feature in residential construction.
This usually adds up to several hundred watts.
In this scenario, high efficiency heat pump with a backup gas fireplace. Those typically don't require any electricity to run as they can ignite off AA battery or a push button. My PC battery backups barely last 30 minutes on a wifi router because of conversion loss. Furnace fans also account for up to 1/3 of energy usage of a unit. Cogneration would add $5-10k to a home build versus a 50 gallon propane tank with a single emergency gas fireplace unit.
Wood burning furnaces are a challenge because homeowners insurance providers don’t want to insure dwellings that use them (but will if certain conditions are met, such as it not being the primary hearing source, professionally installed, etc).
I'm always amazed at the ability of our questionable 1990s wood stove to happily heat the entire house. It's a great backup heat source on days when it gets proper cold out, which is thankfully rare here.
Depends on the fireplace. Direct-vent gas fireplaces take outside air for combustion and then exhaust it, with no inside air being used in the process. There are also direct-vent wood stoves that can do the same.
Wood stoves can get about 85% combustion efficiency, but that's not heat-delivered efficiency (often 10-20% lower):
* https://www.epa.gov/burnwise/energy-efficiency-and-your-wood...
The advantage of wood is you can burn it without any outside source of anything.
I have a SEER 18 heat pump for cooling which can reverse for heating in the winter but it also has a natural gas burner. Based on the installer's advice we set the system to use the heat pump if the outside air is 40F or above and switch to natural gas below 40F.
The problem was that when the power was out the electronics in the system could not communicate with the thermostat in the house. My Nest thermostat literally said there was no system connected. I wish there was some kind of UPS to power those electronics and the blower fan.
The 24VAC transformer for the control circuitry will be on one of the 120VAC legs, but it's likely the installer didn't specifically wire it to allow partial powering of just the transformer and electronics board.
That will take an HVAC person who knows who things work rather than just following colors on a wiring diagram. Probably easier and more supportable than trying to import and mod an out of region unit.
Such setups are easy to build if you want it and running a 100-200w blower doesn't require too many batteries either. However, if you need to run a compressor, the number of batteries required to power that for 6hours would start to get cost prohibitive.
https://www.amazon.com/s?k=2000w+pure+sine+wave+inverter+aut...
https://www.amazon.com/s?k=220v+automatic+transfer+switch+50...
https://www.amazon.com/s?k=100ah+lifepo4+battery
This guy has accumulated essentially everything you could want to know about such setups, at any voltage, any reasonable power range, in various applications: backup systems, full off-grid, mobile power.
https://www.youtube.com/@WillProwse
https://www.mobile-solarpower.com/
For a 240v load, there are inverters that output 220v or you can use one inverter to power each hot line, just buy the batteries at the same time from the same manufacturer and ensure they will stay balanced. In your case you could also use a cheaper manual transfer switch if you don't mind going into the closet to flip it when the power goes out.
An Honda EU2200i generator costs US$ 1400 (and less expensive generators can probably be found):
* https://powerequipment.honda.com/generators/models/eu2200i
You also need an external plug, a cable going from that plug to a sub-panel, and a line going from the sub-panel to the main panel with an interlock device for safety, if you wish to avoid running extension cords.
There are dual-fuel generators that can also use either gas/petrol or propane, and some tri-fuel generators that could also be connect to a natgas pipes (and conversion kits that can be added to propane-capable generators).
(FWIW, I believe there is an aftermarket propane conversion kit for the EU2200i. Converting a gasoline engine to run on propane is straightforward)
I also like that I don't have gasoline to deal with - I can stock up a 20lb propane tanks and generally forget about it. Rotating gas is a giant pain if you keep enough on-hand for an outage of any appreciable amount of time.
If you are at all handy this is probably a 30 minute job, it involves cutting a single hole for the propane tank connection and otherwise can be done with a screwdriver.
It's been reliable for me going on 4 years now - although I only really have run the generator for maybe 100 total hours since then.
I haven't looked for some time, but there are also other kits on the market. I those these guys due to reputation on forums, and how clean it is to install.
What I've found in traveling the whole country for a few years is that local power generation or storage always forces you to consider just how little power you actually need. You can pretty much never just power the whole house, or even a whole RV. Even 50amps is ALOT of power and trying to provide that from solar/generator/batteries is incredibly expensive.
So your real question is pretty much never going to be, "how do I power my whole house in an outage?" but rather, "What is absolutely essential to spend up to 3000w on?" and even then knowing that a generator putting out 3000w burns 20lbs of propane in about 4hrs and 3000w for 4hr on batteries would require 10 to 12 100ah lithium batteries at $350+ each.
I still agree with you that super efficient heat pumps are the future without fossil fuels but that probably also has to come with greatly improved insulation values in almost all homes regardless of region. Think double the current DOE recommendations. If you're running on electricity, you will feel the cost of every bit of heat you lose through the walls, roof, and windows. More insulation is a one time cost versus monthly, it always makes sense in the long run.
However, we'll need regulation to force home builders to invest in that instead of just adding unnecessary sqft that people never use but have to heat and cool anyway. For some reason people don't want to pay extra for a house that is well built and well insulated, they'd rather go with bigger is better even when it's already absurd, and builders have noticed this.
A heat pump would be a waste up here in Alaska esp given I don't need A/C. Just opening the windows and running some fans in the summer tends to do the trick for cooling.
The problem with 'natural' ventilation is you also get things humidity, pollen, dust, etc coming in as well.
One of the major advantages of mechanical ventilation (like HRV/ERVs, which cycle the air) is that things are tempered and filtered beforehand. Sometimes you also want to deal with individual variables: the temperature is fine, but the humidity is off.
Humidity isn't usually a big issue here most days. If anything, it can be a bit dry (but not as dry as running an A/C would make it). Though, I do have a portable dehumidifier I use when I need to :)
The house is mostly unoccupied (a second home). Operation in an outage has to be fully automatic - it needs an automatic transfer switch I guess. The typical indoor temperature is just 5.5C (42F) - this does not leave much margin for the house to cool down during an outage when outside is like -5C (or -10 or -20).
But it turn out that an oil pump and a water circulation pump do not draw THAT much power, so if I can run them off backup power (say, a new car battery plus an inverter), it should last for some time before ice has any chance to form.
Of course, now I’ve got a ton of data that I haven’t finished building my automation with. And, unfortunately, I’ve got an annoyingly bad Lennox iComfort for my heat pump thermostat and may have troubles building the automation anyway.