Battery backup for boiler

[Don1357]

Last year I came back from my winter family vacation to find out there was a power outage in the middle of a windstorm. By the time power came back pipes froze, broke, and water works ensued. It took a few $ks to fix that mess and that was only the plumbing with me doing the drywall.

Has anybody done a DIY battery backup that automatically kicks in when power goes down? There are many videos on building battery banks, mostly for solar charging, but in this case I would not mind having it charge from the grid. Looking at the wall mounted natural gas boiler it doesn't show an electric label with the amp draw, I imagine one of the first steps would be to calculate how much power it and the three water pumps in the system are drawing.

Basically a few days of backup power ought to be enough. This is Alaska; the power company bends over backwards to restore power as soon as humanly possible which in the middle of winter that can still be a few days. Between the house being good at holding heat and a few extra days of heat pumping this should help. The main requirement is that it kicks in automatically; if I'm here I don't even need it, I just burn wood.

 

[jlv03]

Does your boiler (and pumps) plug into a regular receptacle? If so, I think a decent sized UPS should at least buy you some time.

 

[danski0224]

Sumpro battery backup for AC sump pumps.

 

[mike93lx]

Does your boiler (and pumps) plug into a regular receptacle? If so, I think a decent sized UPS should at least buy you some time.

This. We need to know what the power requirements are to advise. Battery backups can be bought or built in any size that your wallet can handle. A couple hundred watts up to megawatts

 

[theoldwizard1]

Basically a few days of backup power ought to be enough.

You are correct, you need to calculate the load (amps) that can be drawn. Circulation pumps do not have a heavy starting load, but it is more than what will be on the plate. Your biggest problem will be not allowing them all to start at the same time !

LiFePO4 batteries are best, but they are expensive ! If you have the room and proper ventilation, 6V golf cart batteries are second best. Shop for an inverter/charger/automatic transfer switch. Plug the boiler and pumps into the inverter. Done !

 

[rlitman]

You're setting yourself up for failure by finding one potential cause of a heating failure without eliminating the numerous other possibilities.

My suggestion would be to first spend your money on a freeze alarm. Something that can alert you when you're away to the house going under a pre-determined set-point (and that is independent of utility power, or that at least sends an alert when utility power is out). Alarms are often designed to operate for prolonged periods without power on battery backup, and since they draw small amounts of low voltage DC, running an alarm for days is easy. My boiler itself only needs a 24VAC doorbell transformer to run, but it needs circulator pumps that require 120VAC, and the battery needed to keep that running for a few days would be 100x bigger than what the alarm needs.

Also, many flood alarm sensors double as freeze sensors.

 

[dogdog]

Probably going to be very/very/very expensive system. dependents on what type of heating system you have... OP's question almost no one can answer almost an open end question that answer with you need a system this biggg..... ?

If you have a natural gas steam system, electrical consumption will be less waste fuels... it burn gas and generate steam, the power usage is just controls consumption, if you have hydronics, pumps consumes most electricity, a furnace ? your fans... blowers controls, a hybrid of heatpump ? Electric heat ?

You'll first have to find out your load, there are plenty of solar systems /inverters for your needs, Lithium doesn't perform well in the cold climates.

Get an automatic whole house stand by generator for your climate and a big enough gas / gasoline to fuel it for the days you anticipate and keep up on the maintenance ?

 

[4x4Pete]

You have natural gas. Get a stationary standby generator. It will keep the heat on as well as the fridge, freezer, pumps and lighting and whatever else you want to use when the power is out.

 

[The Cobbler]

asking batteries to back up a pump & boiler for a few days is a huge task, you need a generator that will kick on on a power fail situation

 

[ipgenie]

If outages are days long, the genny is your best choice.

I use a decommissioned server UPS (120v 3000kva) with some large AGM batteries to keep my propane boiler running during outages.
My homes in floor heat draws about 300 watts when running (pumps, boiler, controls, etc.) and peaks at 900 watts for a few seconds when the ignitor lights. At idle it draws about 100 watts for a circ pump and controls.
I also have the fridge, router, PC and a few lights on the UPS (I have those circuits on a load panel/transfer switch) and with 8 100ah batteries it can run those emergency loads for probably 10-12 hours. 8 hours is the longest outage we've had since I built it. I picked the 120v UPS over a 240V one because if I need longer run times I can just fire up the Honda 2200 and plug the grid connection to the UPS into that and run it for several hours on a gallon of gas.

If your outages are short I bet you could get an old UPS in the 1400kva range for free, then hook up a few full size batteries instead of the little original ones and have something that would keep the boiler running for several hours and wouldn't break the bank. If you get long outages you'd need a lot of battery or an auto start genny.

 

[rlitman]

asking batteries to back up a pump & boiler for a few days is a huge task, you need a generator that will kick on on a power fail situation

You got me thinking. A decent sized battery is fine for a 12V emergency sump pump, so I started looking and it seems that 12V recirculation pumps are commonly used on solar hot water systems. If you could run that in parallel with your 120V circlator (wrapped in check valves), and if you have a 24VAC NG system, then they make 12VDC to 24VAC inverters (also from the solar world) for stuff like this. But if you've got oil heat, you'll need the 120VAC for the burner, so that would be an issue.

Now if you could figure out how to only run the system for a few hours a day, that could also extend battery life enough. It's a big controls project to be sure, but impossible.

 

[ipgenie]

The timer is an idea that could work.
With a UPS and bigger battery bank, you could connect that to a small RV transfer switch. Put grid power on the primary input and a programmable timer on the UPS input.
Then program the timer to be on for an hour and off for something like four hours. That should be enough run time to keep things warm enough to be out of the danger of freezing and would extend your battery run time by 5x.

Or just go with the genny. If this happens a lot the genny would be nice.

 

[Don1357]

To clarify, as stated this would be for when I'm gone during Christmas vacation. If I'm here i don't need it, I just burn wood for as long as it takes. An alarm would not be all that useful as I would probably not even be in the same continent, is not like I could just drop by to address it.

Last year's wind storm lasted several days and so did the outage, many trees came down. If the natural gas boiler and its three water pumps would had been running for even a few extra hours everything would have been fine.

 

[danski0224]

Sumpro battery backup is made to run 120v sump pumps. It'll also run a fridge. It has an outlet.

Pretty sure that it's a pass through design, so wire the boiler to it, and it will automatically back up the system when the power fails.

Capacity can be extended with more batteries.

It's an engineered solution.

Pricey, but it works.

 

[nh_yota]

How about a propane Monitor/Rinnai heater that only kicks on below a certain temp if the central heat fails?

 

[mike93lx]

Lots of self contained systems now from jackery, ecoflo, anker and others. And many can charge directly from a solar panel

 

[fitter30]

Lp generator and 250 to 500 gallon tank. Lp doesn't go bad like gasoline. Or lp stove

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And a lp generator 6500 to 7500 watt for fridge ,lights, electric hot water, pump and whatever. Can't run everything together but can heat the water turn it off take a shower turn pump on. Cook on ur cook stove . Microwave.

 

[jlv03]

Sumpro battery backup is made to run 120v sump pumps. It'll also run a fridge. It has an outlet.

Pretty sure that it's a pass through design, so wire the boiler to it, and it will automatically back up the system when the power fails.

Capacity can be extended with more batteries.

It's an engineered solution.

Pricey, but it works.

Pricey is right, almost $2k!

 

[danski0224]

Probably less than what it cost to fix the damage from freezing last time.

 

[Noltz]

If you're not around to fix it a standby generator is your solution. Definitely not cheap but they are internet connected and do self tests regularly. You'll get alerts if there's a no-start issue so you can call a repairman back home and tell them where the key is. I've done what ipgenie did and bought some retired commercial 24V UPS's. They're protecting my network (PCs, security, router) and while mine are just new internal batteries for critical systems like yours I'd wire it for external batteries. Do a load calculation or directly measure it if you have an amp-clamp and see if your price point vs. standby power reserves makes sense for you.

 

[Don1357]

I found something that could be cost effective. So there is this:

https://www.amazon.com/gp/product/B0B3S4CXX7/?tag=atomicindus08-20

Which is a sump pump backup system. The beauty of it is that this is just the controller, you still need an external battery. My guess is that it would be a matter of sizing my power needs and from there just attach a bank of batteries that is large enough? At $549 for this controller unit the total cost with batteries should still be quite reasonable.

 

[rlitman]

I found something that could be cost effective. So there is this:

https://www.amazon.com/gp/product/B0B3S4CXX7/?tag=atomicindus08-20

Which is a sump pump backup system. The beauty of it is that this is just the controller, you still need an external battery. My guess is that it would be a matter of sizing my power needs and from there just attach a bank of batteries that is large enough? At $549 for this controller unit the total cost with batteries should still be quite reasonable.

That's a good idea. You'd still need a sizable battery bank though, and that's going to be more expensive than the controller.

You could actually rig that up with a timer pretty easily. Something like a pool pump timer between the controller and the boiler that's set to turn the boiler on for two 4 hour periods per day. Then have a 120V coil contactor that gets coil power from utility that shorts the output of the timer, so the boiler gets power all the time when utility is up.

 

[Don1357]

That's the next step, to calculate how much battery would be needed for say 24 hours of operation. That would not even be a continuous 24 hours as the boiler turns on and off as needed. Considering how diligent our power company is about restoring power this would provide a quite ample safety net.

 

[fitter30]

It's not only the boiler running theres pumps and controls. With a lp stove can use a gold contact relay n.c. In series with the built-in thermostat when power in killed relay drops out contact closes stove turns on. Power restored stove turns off boiler comes back on. With another thermostat and 2 nd gold contact relay n. o. wired the parallel across the other relays contact if the boiler doesn't turn on temperature drops relay makes stove turns back on. Main thermostat set at 60° 2nd thermostat set at 50°.

 

[nh_yota]

Just remember the more complex the system the more points of failure it has. Keep it simple.

 

[Sumboodie]

Generator and have a neighbor or friend fire it up?

I was glad I was home during that storm, was all I could do with the stove going to keep the house and garage warm. Had no power for 5 or 6 days.

 

[HoosierBuddy]

Years ago I bought a thermostatically controlled ventless natural gas space heater for use when my floor heat can't keep up or during power outages.

The thermostat/remote control runs off AAA batteries that last for about a year. The power for the gas valve on the heater runs off a 9V battery that lasts about a year. It has a live pilot that runs all the time.

It's 29,000 BTU's I think.

Just another option for you to consider.

It backs you up not only against power loss, but anything that knocks your boiler out of operation. I just have the thermostat for that set a couple of degrees lower than my house t-stat. It's not going to hold you at 68 degrees inside, but it would provide significant protection against freezing.

 

[Noltz]

Years ago I bought a thermostatically controlled ventless natural gas space heater for use when my floor heat can't keep up or during power outages.
(snipped)

You have a link or a name for this? Might be a good idea for me too.

 

[HoosierBuddy]

You have a link or a name for this? Might be a good idea for me too.

I bought mine 15 years ago and they don't make it anymore.

Here's one that works pretty much the same way, although mine is just a tower heater and this is a nice "stove" type model.

Bluegrass Living Vent Free Natural Gas Stove - 25,000 BTU, Remote Control, Black Finish - Model# BQSN25R

Shop online for ventless gas heaters, ventless fireplaces, infrared heaters, gas log sets, blue flame heaters at wholesale prices.

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