Running Your Furnace or Water Heater without Electricity
Updated October 2021
Toronto and the Greater Toronto area were hit hard with an ice storm late in 2013. The weight of all the ice snapped branches and brought down trees which in turn took down the hydro to hundreds of thousands of homes. Some home owners were without hydro for several days and experienced plummeting temperatures. These same issues were experienced by Millions during the cold snap of 2020 throughout the USA, and especially Texas.
Tankless water heaters use very little electricity and can thus be safely run with a common battery backup designed for computers and electronics. This method is so effective Rinnai has outlined a few battery backup systems they trust in a technical bulletin. It would be fair to assume those same battery backups would be sufficient for other brands of tankless systems as well.
Battery Backup Bulletin
Rinnai has put out a technical bulletin providing 3 battery backup systems approved for use with their tankless water heaters. Check them out below.
These are the approved systems directly from Rinnai and are a bit pricey. Personally, we have a Navien combi-boiler and have managed to keep or system running for a few hours while the power was out on a small APC-BE650G1. The power came back on before the battery ran out so I can’t be certain how long it would have lasted.
We now run our system on a bigger more robust battery back up just in case. This is the system we use now APC BR1500MS2.
Running Your Water Heater With No Electricity
This completely depends on what type of water heater your home uses (conventional electric tank, gas fired tank, electric tankless, gas fired tankless) and each type has a unique soultion.
Electric water heater
Realistically, this type of water heater consumes a lot of electricity and will need a substantial amount of power. Even most homeowner style generators won’t produce enough power to run your electric water heater. There are a few systems available that are designed to adequately power your entire home when the power goes out. These large generators will be effective at powering your electric water heater as well.
A whole home generator will have a fully automated transfer switch so it instantly turns itself on when hydro goes out and shuts itself off once hydro is restored. It can power your homes electric water heater and everything else for that matter. These types of systems are the best, they are seamless and efficient. If you want the best all around system, by far the whole home generator is the way to go. They are also the most expensive option but they offer a entirely next level convenience factor. Check a few of these systems out below.
- Generac 7.5kw propane/natural gas
- Generac 22kw propane/natural gas
- Generac 10kw wifi propane/natural gas
Power vented conventional water heater
These systems need electricity to run the fan that pushes exhaust gases out of your home but the system uses natural gas or propane for the primary fuel. If your system has a normal outlet plug coming from the exhaust fan it is a candidate for a battery bank backup system similar to the one pictured. The benefit is that you get a surge protector built in, the larger the system you you purchase the longer your system will run. There are a lot of different sizes and prices, the picture is a link to a similar system we have used at our home in the past.
Tankless water heaters
Very much like a power vented system above a tankless needs electricity to run the fan that moves the exhaust gases out of your home produced during the combustion of propane or natural gas. Just like above its good to put your tankless on a surge protector and I would recommend buying the largest battery backup you can as a tankless can consume a bit more power than a power vented water heater.
Atmospheric Vented water heater – The venting is very restrictive and difficult to install but homes that have one of these hot water tanks will have no problems during a power outage, no electricity is needed for these systems. Propane and natural gas should still flow to these types of water heaters even when they electricity is down
How to get your Water Heater Running During a Power Outage
This is easy; visit Costco, Best Buy, or you can even purchase off Amazon here. Look for a battery backup system that is sold for computer or home electronic systems. At our house we purchased the largest system offered at Costco for $199. It simply plugs into the wall and charges itself with its built in smart meter and automatically kick on as soon as the power drops. We have since upgraded this system now, we purchased a bigger version off Amazon, it was $259 at time of purchase.
Depending on the size of the battery backup you purchase your water heater could run for several days during a power failure. Of course this depends on you either having municipal water or some type of backup power for your pump if you are on a well in the country.
When using a tankless it really should be standard practice to have your system hooked up to a battery backup, not only is it a great surge protector protecting your investment but also a sure fire way to eliminate any unexpected shutdowns during electrical storms, wind storms, ice storms, and all the other threats to our electrical grid.