Battery backup for Tankless

[Jen24]

Looking for battery backup for a Navien tankless. Any ideas other than Hugo? I have heard of a UPS type system but don't know anything about them. Saw a post that stated this:

A standard desktop UPS for your PC will probably work to keep it going long enough to finish your shower, but if you're looking to have hot water throughout a long outage, a deep cycle battery and a small inverter is probably what you'll need to move toward.

So I'm thinking this might be a better option for a long power outage. Anyone using this type of setup? If so could you give me details as far as set up and operation. Thanks

 

[Dana]

For a long power outage you'll want one of these:

To do a long term backup of any significant load with a battery system is just out-of-sight expensive from an up-front cost perspective, and has no financial or comfort rationale.

A computer UPS on a water heater might be "worth it" it if the prospect of the water suddenly going cold on you while in the shower is just too painful. But a long-term battery backup solution that sees only a miniscule duty cycle of use at first-world grid reliability makes no sense, even in hurricane country.

 

[Sponsor]

 

[Jadnashua]

It all depends on how long you expect power to be out and how big of a load the things you want to power is. A typical UPS is sized to allow you to have enough time to power down your PC before it just quits, potentially messing up the hard drive or other open files. You can buy bigger ones, and one might actually be a good idea with a small generator. Some of them don't actually switch from passing through the line voltage to making their own...they use the line voltage to power the batteries, and always make clean power on board. That can work well for sensitive devices. Those cost more than a simple one.

Tesla sells a whole home battery backup/storage system that could probably power the whole house for maybe a few days if you were conservative, but those aren't cheap.

Most small generators don't have very big gas tanks, so you'll have to stop it and refill periodically. Some of them don't make particularly 'clean' power, but will work with most things. Some of them can make some nasty spikes as it runs out of fuel, so it's best to do a disconnect, shut it off, then refuel, but you'd have to read the instructions to be sure. It may not work well if it runs out of fuel, restarting may be more difficult, but again, that depends on the unit itself.

There are whole house backup generators that can be configured to come on automatically and you can get them that use natural gas, so you don't have to deal with gasoline or diesel, but again, those are a bit more of an investment.

 

[Neal Banes]

Looking for battery backup for a Navien tankless. Any ideas other than Hugo? I have heard of a UPS type system but don't know anything about them. Saw a post that stated this:

A standard desktop UPS for your PC will probably work to keep it going long enough to finish your shower, but if you're looking to have hot water throughout a long outage, a deep cycle battery and a small inverter is probably what you'll need to move toward.

So I'm thinking this might be a better option for a long power outage. Anyone using this type of setup? If so could you give me details as far as set up and operation. Thanks

The problem with computer UPS is that the inverter will kill the battery even if you have a very light load. A gas tankless when not in use should use less than 50 watts to run the computers and sensors. My Noritz says it draws 172W when the pump is running and the exhaust fan. My 650VA UPS lasts about 30 minutes with that load. It isn't the load that kills it, it is the wasted power the inverter needs just to create the 50W for the main computer board to stay alive.

If we get up in the morning and the power is out, it is probably too late to grab a hot shower. The Hugo specs out at 500VA, but if it has a better inverter that doesn't kill the battery quickly with a 50w draw when the power goes out, it might be a better solution than the computer UPS.

A big deep cycle marine or truck battery with a very small 200w inverter might last longer but that is a little too, ah is it ok to say "home made" looking? I don't have a good PC term for it. Hugo does look ok.

We have ordered the Tesla whole house battery to go with our solar setup #RWTH