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Boiler power backup

Sumboodie

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These seem to be rated for "sump pump"

Any reason I couldn't use it for a boiler backup?

No one is around 8-10hrs a day, so would give a chance of the place not freezing before a gen set can be setup.

Of course could run days and days if the battery bank is large enough. I'd probably use a couple group 31s, can get them for about $100 each.



Boiler and pumps maybe use 500 watts, might be less even.


Have a natural gas auto on gen set, but it'll probably be a few years till I can get it installed, have a bunch of other things that need to get done before. (Dirt work... have to raise one area and lower another, probably 500-600 yards of gravel needs moved, redoing electrical, placing a connex, etc.
So in other words, this setup would be for now.
 
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wyliesdiesels

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These seem to be rated for "sump pump"

Any reason I couldn't use it for a boiler backup?

No one is around 8-10hrs a day, so would give a chance of the place not freezing.

Boiler and pumps maybe use 500 watts
that isnt a BBU, its an inverter. you would still need batteries to run that.

your boiler uses less than 5a according to the manual.

how many hours does the boiler run during those 8 to 10hrs?

if 4, you need more than 200ah worth of battery capacity. thats gonna cost you close to $400
 
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Sumboodie

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I'm surprised no feedback on this. Guess I'll be the one to test it.
 

dave*99

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theoldwizard1

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Any electric motor has a large "in rush" current. This will trip most inverters. Install a MicroAir EasyStart

Screenshot 2024-11-27 133939.png

Expensive, but then you can down grade the inverter to just handle the running watts. Shop around for a LiFePO4 battery and charger. Yes, it costs more but in the long run, it is worth it !

$433 280Ah LiFePO4 Cells Tested: Cheaper than lead acid!

If you just can't afford that much, buy 2 lead acid, golf cart batteries. They will last longer than a marine/RV battery !

Last, for anything where a battery is only going to get very intermittent use, connect the charger to an old fashion, mechanical lamp timer. Set it to run for a couple hours per day.
 
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Sumboodie

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Any electric motor has a large "in rush" current. This will trip most inverters. Install a MicroAir EasyStart

Screenshot 2024-11-27 133939.png

Expensive, but then you can down grade the inverter to just handle the running watts. Shop around for a LiFePO4 battery and charger. Yes, it costs more but in the long run, it is worth it !

$433 280Ah LiFePO4 Cells Tested: Cheaper than lead acid!

If you just can't afford that much, buy 2 lead acid, golf cart batteries. They will last longer than a marine/RV battery !

Last, for anything where a battery is only going to get very intermittent use, connect the charger to an old fashion, mechanical lamp timer. Set it to run for a couple hours per day.
It's just a small inducer fan and 2 pumps. Not much draw.

Based of info online, seems like maybe 500-700 watts on startup/ignition and maybe 300 after, and 150 when just the pumps are running.
So probably 300 "average".

Certainly nothing like a sump pump which the inverter is designed for.
Group 31 lead acid batteries are about $100 and rugged. 100 AH would mean it could run 3-4 hrs.

This is just an auto backup till someone could get a gen set on, though it's not common to have power out for more than 4-5 hours.

And super easy to find since most heavy equipment uses them.
4D or 8D would work well too, just heavy!
 
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Sumboodie

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Thanks.
Nothing came up while searching.
 

u3b3rg33k

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I'd advise caution when choosing your backup system. a LOT of UPSes fail "off" (instead of bypassed), making them less reliable than a wire.
 
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Sumboodie

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I'd advise caution when choosing your backup system. a LOT of UPSes fail "off" (instead of bypassed), making them less reliable than a wire.
Interesting.

I bought the 1500 watt model and ill get a group 31 battery or two for it.
 

ipgenie

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My propane boiler and pumps measure 900W during ignition and 300W continous. There isn't any spike on my Fluke meter when the little grundfoss pumps cycle on or off. I think that inverter and some deep cycle batteries would work just fine.

You'll also need a charger. That is just an inverter and doesn't recharge the battery when the grid comes back online. Don't try to use a trickle charger, they don't put out enough juice to recharge the battery. You might be able to use one to maintain a battery once you've changed it with something else but I'd get a decent 3 or 4 stage charger like an Iota or similar. Saves a lot of money if you take good care of the battery.

Edit - it looks like it does charge the battery at 20A so you should be good to go. Charger is compatible with lithium batteries too so a future upgrade is painless.
 
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ipgenie

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Fluke 376 with inrush function. Technically there has to be some slight inrush current inherent to any motor, it's just so small on the Grundfos 1/25 HP pumps (according to Grundfos it's 0.75A on high speed) that it doesn't matter.

Maybe other pumps are different. I don't have any others to test, but I'd suspect that similar circulator pumps are about the same.

In any case, the linked inverter would work fine on my boiler system with two circulators, boiler and some low voltage control circuits. I ran mine on an old server UPS connected to some AGM batteries for a few years without a problem. I bet that inverter would work fine for the OP too.
 

djbmw

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Thats just the boiler though... where does the hot water go after, and how? Radiators? In floor radiant? Forced air furnace? What are the amp ratings of the water pumps in the system? How about the furnace fan motor?

You mentioned 500 watts total...which, on my 1500VA UPS tends to get me 25 to 35 min when pulling that type of load.. depending on the age of the lead acid batteries. Once you have an outtage the battery lifespan really takes a hit.
 
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Sumboodie

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Thats just the boiler though... where does the hot water go after, and how? Radiators? In floor radiant? Forced air furnace? What are the amp ratings of the water pumps in the system? How about the furnace fan motor?

You mentioned 500 watts total...which, on my 1500VA UPS tends to get me 25 to 35 min when pulling that type of load.. depending on the age of the lead acid batteries. Once you have an outtage the battery lifespan really takes a hit.
500 watts total
 

wyliesdiesels

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You mentioned 500 watts total...which, on my 1500VA UPS tends to get me 25 to 35 min when pulling that type of load.. depending on the age of the lead acid batteries. Once you have an outtage the battery lifespan really takes a hit.
this is totally dependent on the size of the battery in your UPS. I have an Eaton 5PX1500 w/ 1 EBM (extended battery module). The UPS has a 48v 7Ah battery string and the EBM has a 48v 18Ah battery string for a total of 25Ah. with a 210w load, i get about 2hrs 50mins run time

your UPS has about a 250Wh capacity and thus you only get about 30mins.
 
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Sumboodie

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fitter30

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"No one is around 8-10hrs a day, so would give a chance of the place not freezing before a gen set can be setup."
So for I've only seen a few hours at best. VRLA batteries still can give off gas that ups systems have. What happens if there's a ice storm or another weather event that lasts more than few hours. Going to sit in the dark. Any item that a generator or ups system is wired to has to be disconnected from the Circuit breaker panel as to not back feed into the grid.
 

PCustoms

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So for I've only seen a few hours at best. VRLA batteries still can give off gas that ups systems have. What happens if there's a ice storm or another weather event that lasts more than few hours. Going to sit in the dark. Any item that a generator or ups system is wired to has to be disconnected from the Circuit breaker panel as to not back feed into the grid.

WTF do you keep rambling about?

The guy wants a temporary backup to keep his boiler running until he gets home that night and plugs his generator in.
 

SlappyWhite

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It does not help the OP with his current boiler but if you have an old house the original hot water heat system may have been gravity fed. While the current system has a circulator pump, the system may run good enough with the pump powered down. Our old external to the boiler pump seized (motor) and apparently it was like that for many years. Some of the farthest rooms had poor heat on really cold days. Rooms above the boiler were fine. It was noted during some work and a new pump installed the system works way better since.

I have played around with the idea of some sort of UPS back-up power just for the boiler and not the pump. That should give the system a very long run time as the power is just running the gas valve.
 
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