UPS back-up

I've had the same question. That model APC generates a modified sine wave output when on battery. Some electronics are sensitive to the type of sine wave and prefer a true sine wave output such as that found in the APC Smart UPS systems.

Perhaps someone else on the forum can tell us which version works best for the Harman.

One of the models Harman recommends (BE750G) is a mod sine wave. It's up to you to trust in Harman's recommendation. I've had one for a couple weeks but haven't needed it yet. Actually, now that I have one, I'm sure I've seen the last of my power outages . ....of which I haven't had in a couple years anyway.

My venting is horizontal, so better safe than sorry.

I have the same one for my Mount Vernon AE. Has worked flawlessly in the few power issues I've experienced this year. (Not long term outages though)

scottvwgti said:

I have the same one for my Mount Vernon AE. Has worked flawlessly in the few power issues I've experienced this year. (Not long term outages though)

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Does your stove go into shut off mod, or continue to burn? If it continues on, how long does the UPS run it?

Jmart, while that's probably a great price, keep in mind, it's basically just for allowing your stove to shut down, not continue in burn mode on batt power. If fact, Harman has circuitry as of 2011(I think) that senses the presence of UPS power and goes into shutdown mode anyway.

It still may be nice to have the extra reserve power, but the 750 should be adequate to get the stove shut down smoke free.

THE ROOSTER said:

Does your stove go into shut off mod, or continue to burn? If it continues on, how long does the UPS run it?

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The computer on the Mount Vernon does not know if it is on back-up or not. It has only run for a few minutes back-up. I could not tell you how long it runs, however the display on the front has a battery life gauge. If it were to get low, just put the stove into shutdown before it dies. You wouldn't want smoke in the house.

P38X2 said:

One of the models Harman recommends (BE750G) is a mod sine wave. It's up to you to trust in Harman's recommendation. I've had one for a couple weeks but haven't needed it yet. Actually, now that I have one, I'm sure I've seen the last of my power outages . ....of which I haven't had in a couple years anyway.

My venting is horizontal, so better safe than sorry.

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The UPS the OP posted outputs a Stepped approximation to a sinewave just like the BE750G so if the power would go out the control board would pick up on it and go into shut down mode. Only real difference besides the Watts is the topology output is its line interactive vs standby. A Line interactive UPS will correct minor power fluctuations without going to battery vs. standby which goes right to the battery whenever a fluctuation is detected.

I dont think running that UPS would bother me unless there's another good reason why you shouldn't... .

scottvwgti said:

I have the same one for my Mount Vernon AE. Has worked flawlessly in the few power issues I've experienced this year. (Not long term outages though)

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For not much more than the price os a UPS you can install a backup battery on a MVAE. Any reason you have not gone that route? I, too, have an MVAE on a UPS, but for power filtering primarily (same circuit powers internet, security, etc).

Madcodger said:

For not much more than the price os a UPS you can install a backup battery on a MVAE.

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That's what I use. I use a battery maintainer to keep it charged.

The APC BE750G UPS will work fine. I have three of them on other equipment. The power goes out all the time here, and the problem with the MVAE is that if power fails for even a second it has to go through a shutdown / clean / light cycle. A battery backup precludes that, and the stove will run all day on a fully charged car battery. It won't light itself on battery power though.

The "stepped sine wave" as APC calls it is a laugh though, I've measured it, and it's more like a horrible approximation of a square wave. It doesn't matter though, at least not for a MVAE's power supply. A UPS a good idea for any sensitive electronics for its power filtering as you say - the Mt. Vernon's control board is muy $$$$$.

Ah - OK - now I understand. I think we have the same approach. UPS for filtering / surge protection plus "micro outages", and battery for backup in extended outages. One question on the battery, though, as mine has not been needed yet (house has generator): If the power goes out while the stove is running, would the battery keep it running, or would a re-light be required within minutes? And about how long until it goes into autoclean?

The reason I ask is that I have a APC 2200 SmartUPS that formerly backed up a server, mounted in the garage directly below the MVAE. That's the UPS that powers the MVAE and also the internet connection, security system (redundant to its own battery) and a control device for the house lighting (automated house) in a utility room adjacent to the garage. The battery on that UPS is going, so I'm thinking of modifying it to run on mutiple deep cycle batteries OR just replacing it with a sine wave inverter and multiple batteries. Then if power goes out I could allow the MVAE to go to its own battery backup by just "pulling the plug", avoiding ignitor use and greatly extending battery life on the UPS or inverter. I could then shut down the generator overnight and still keep the MVAE and critical systems running until I turned the generator back on the next day, a strategy that might help others here as well. Thoughts? Other input also welcome although we might need a new thread.

Madcodger said:

... If the power goes out while the stove is running, would the battery keep it running,

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Yes. With a battery connected to the 12 V input, the stove will ride through any momentary AC power interruption as if nothing occurred. Autoclean will be delayed as long as possible. The wall unit will display "maintenance burn" as the stove operates in a very low heat output mode. Eventually it will shut down and go into autoclean though, but it takes much more time before it does. I never timed it but I'll do that and let you know. Also, while on battery power, all the stove's heat outputs are reduced one increment - heat output, flame height, blower speed etc. are all reduced by one step. I surmise that is intended to conserve battery power.

The stove is primarily a 12 V unit and all its electronics are 12 V. Quadrafire really thought it through. Despite that fact, the stove's dealer was clueless about battery backup and originally told me what I proposed won't work. They advocated a UPS. You can find that discussion archived elsewhere in one of my posts from five years ago. A UPS is fine, but UPSs designed for computers and such simply aren't intended to run a pellet stove all day long.

Then if power goes out I could allow the MVAE to go to its own battery backup by just "pulling the plug", avoiding ignitor use and greatly extending battery life on the UPS or inverter. I could then shut down the generator overnight and still keep the MVAE and critical systems running until I turned the generator back on the next day, a strategy that might help others here as well.

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That's an excellent strategy, but rather than modifying the UPS to operate on multiple deep cycle batteries, you could just take those batteries (or just one of them) and connect it to the stove's 12 V input. That way you can shut down your generator overnight without having to do anything with the stove. It should run all night long on "maintenance burn" until you restore generator power in the morning, but if you need to perform a manual light, the procedure is idiot-proof. The wall unit tell you what to do. It loads the fire pot with an initial charge of pellets, then it tells you to open the door and light them. Assuming the initial charge continues to burn - another topic all to itself the stove resumes its usual operation.

Thank you for the great info! The multiple batteries on that big UPS are more to keep other things running overnight, such as the internet connection (high speed fiber optic, and if the battery on that modem goes down it can take a while to get the connection back). We both work from home so that's our income...

I plan to keep a separate AGM deep cycle battry on the MVAE so that I can float charge it (70 Amp hour) and then put it on my automotive charger (selectable 2/10/75 amp with deep cycle setting) when the gen is running to recharge it within the 12 hours or so I'll keep the gen going each day. We've had 4-5 day outages, but all in summer, oddly enough (big storms, lots of trees).

I knew about the MVAE backing things off one setting on battery, but back one from WHAT? I run in auto mode. Does it look at what I would have IF on manual and then back off from there? Always puzzled me a bit... Anyway, THANKS again!