# Wood boiler power outage protection



## jimdavidson (Aug 23, 2017)

My wool boiler overheated last winter resulting in a costly mess.  I have just installed a small circulator (45 watts) on the hot water loop of the furnace to take the hot water to a dump zone of about 80 feet of copper fin tube located in the ceiling of my wood shed next to the furnace room in the event of another power outage.   I am hoping someone can give me some direction regarding a UPS system (uninterrupted power supply) to run that small circulator for about 5 hours or so ( I am just guessing that this is the amount of time needed)
I called a company that sells them and the fellow suggested a "sine inverter/charger" by Kisae for about $400 which would require a 12 volt deep cycle battery (100 amp hour) which would be about $180.  Not sure if these are appropriate suggestions - and it is getting much more expensive that I had hoped.  Would really appreciate any suggestions.  my phone is 207-323-5858 and I live in Brooks, Maine.
Thank you
Jim


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## Bad LP (Aug 23, 2017)

What wood boiler are you using? 

From all that I've read the powerless dump zone should be gravity fed. Hot water supply to the top and cold water return from the bottom. Obviously the arrangement needs to be higher than the wood boiler and the zone valve should be normally open with no power applied.

I'm building mine this weekend using 32 feet of 3/4 BB and will pitch it slightly to aid in circulation. In my case it's all for (hopefully) nothing as I have a standby generator system.

I agree this project is costing a bit more than I thought but I'm balls deep into now. When LP returns to stupid $$$ again I'll be happy.


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## jimdavidson (Aug 23, 2017)

I have a boiler from Europe I bought from some guy at the Bangor Home show about 10 years ago - It is an Atmos.  it is outside in a shed and pipes underground to a large tank in the house.   I have installed about 80 feet to fin tube higher than the boiler in an adjoining wood shed and contemplated doing gravity but a guy told be I should do the UPS system - now that I have the circulator in it maybe that was a mistake.  Not sure how much flow/heat dissipation the gravity method would create
and i agree about the $ now that fuel oil is so cheap


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## Bad LP (Aug 23, 2017)

I'm no help then. I have an indoor unit because I was not getting dressed to load a boiler outside being a bit north of you. 

Love driving route 7 down to Searsport.


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## maple1 (Aug 24, 2017)

Ideally the dump zone should be right above the boiler, so it can naturally convect when the power goes out. With a n/o zone valve in the loop that opens on power loss. The dump zone should also be able to dump, when the power is on but the boiler overheats for some reason (damper sticks?). That in turn means also tieing the n/o zone valve to an aquastat that would break-on-rise to open the valve, and maybe also start a circ pump (likely the boiler circ/loading unit) at the same time. And then for even more redundancy, you could also run that circ through a UPS.

I have all of that - my upstairs zones are plumbed to dump to. I found a 2200va UPS, used, on Kijiji - think I got lucky there. Practically new, and it will run my Grundfoss 15-58 equipped loading unit until the fire dies. Not sure for how long exactly, since I haven't had to run it for a full load, but I think it will do 3-4 hours. It's an older unit still with original batteries - and it is big and heavy. Like, 150 lbs with batteries. I don't keep it plugged in all the time, only when I am going out while burning - as it has a cooling fan inside that is on all the time the UPS is plugged in, rather annoying since it is mounted from my floor joists right under the TV room upstairs. If your unit is outside in a shed, maybe a couple deep cell batteries tied to an inverter/charger? Not recommended inside because of off-gassing while charging/cycling - might have to be careful of that in a shed too.

I think I would scrounge up as much finned radiation as I could fit into the space above your boiler in the shed and add that. Even with my dump zone arrangement, it is borderline on whether it can dump enough heat just by convection if I have a power outage in full burn - these things generate, and hold, a lot of heat in full burn. Although, mine doesn't slow down when the power goes out since it is natural draft with the draft door wide open all the time.

Most of these Euro boilers were designed to dump heat differently - with a coil inside that is plumbed to a fresh cold water supply that would open on overheat & dump water through it, to a drain. That's what mine has, but I didn't use it - I went the 'traditional' way for here. Bottom line - when it comes to overheat protection, redundancy is VERY important.


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## salecker (Aug 24, 2017)

With my storage it acts as the dump zone.
We have had a few power outages once right after i had filled the burn chamber.
The laws of thermodynamics keep the heat headed to storage,and without power the Econoburn acts like the demand for heat is over and the air to the boiler is shut off.


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## Fred61 (Aug 24, 2017)

I have several feet of fintube that I'll let go of for at a good price.


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## Bad LP (Aug 24, 2017)

Fred61 said:


> I have several feet of fintube that I'll let go of for at a good price.



Now you tell us after I just bought 32 feet of brand new 3/4. LOL. My original plan was to use what I had in the house while converting those areas to panels. Budget had other ideas... panels have to wait a little while.


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## Fred61 (Aug 25, 2017)

That's good ol Fred. Day late and a dollar short.


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## jimdavidson (Aug 25, 2017)

maple1 said:


> Ideally the dump zone should be right above the boiler, so it can naturally convect when the power goes out. With a n/o zone valve in the loop that opens on power loss. The dump zone should also be able to dump, when the power is on but the boiler overheats for some reason (damper sticks?). That in turn means also tieing the n/o zone valve to an aquastat that would break-on-rise to open the valve, and maybe also start a circ pump (likely the boiler circ/loading unit) at the same time. And then for even more redundancy, you could also run that circ through a UPS.
> 
> I have all of that - my upstairs zones are plumbed to dump to. I found a 2200va UPS, used, on Kijiji - think I got lucky there. Practically new, and it will run my Grundfoss 15-58 equipped loading unit until the fire dies. Not sure for how long exactly, since I haven't had to run it for a full load, but I think it will do 3-4 hours. It's an older unit still with original batteries - and it is big and heavy. Like, 150 lbs with batteries. I don't keep it plugged in all the time, only when I am going out while burning - as it has a cooling fan inside that is on all the time the UPS is plugged in, rather annoying since it is mounted from my floor joists right under the TV room upstairs. If your unit is outside in a shed, maybe a couple deep cell batteries tied to an inverter/charger? Not recommended inside because of off-gassing while charging/cycling - might have to be careful of that in a shed too.
> 
> ...




This is very helpful.  Lots of good ideas here.  Thank you very much


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## jimdavidson (Aug 25, 2017)

This is excellent.  Lots of good information here.  Thank you very much


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## maple1 (Aug 25, 2017)

One more add - for whatever circ would be pumping in a power outage, you might check out a newer ECM circ as they use much less power. Like a Gundfoss Alpha. That's what I have on my house zones - don't think it ever goes more than 20w. Would have to make sure it will flow what you need it to flow though. And you should also semi-regularly exercise whatever circ you have for that if it is a circ that would be used only for that. My loading unit circ stuck up summer before last - I had to free it up with a screwdriver when I started burning in the fall. Not an uncommon occurance and definitely not something you'd want to happen when you really need it to circ. That's where redundancy comes in.


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## jimdavidson (Aug 25, 2017)

Thank you - really appreciate it


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## Fred61 (Aug 25, 2017)

Jim
Pardon me but I get easily confused. Looking at the description of your set-up you stated that your cooling loop was in your woodshed next to your boiler room. Does that mean your woodshed is heated space?


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## jimdavidson (Aug 25, 2017)

Hi Fred

The wood shed is an unheated space adjacent to the boiler room.  Both are outdoors. The fin tubes are in the roof rafters above the wood and it is piped into the boiler room


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## Fred61 (Aug 25, 2017)

So the pipes are dry otherwise they would freeze, right?


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## jimdavidson (Aug 25, 2017)

Hi Fred

I have antifreeze in them and in the rest of the system


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## Fred61 (Aug 25, 2017)

Got it!


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## jimdavidson (Sep 8, 2017)

I have installed an inverter/charger with a deep cycle battery in my wood furnace room- now I find out that this system outputs AC power even when the electricity is on.  I was wanting something that only had AC output when the power was off - as my 44 watt circulator dumps heat into a shed that is unheated and would waste heat when the power is on.  I thought that was what a UPS system does.  Evidently this has a UPS but power goes all the time. Is there a simple device I can plug into the output power source on inverter/charger that will prevent the power from going to the circulator when the power is on but allow the inverter charger to provide power when the power goes out - I have tied up a good deal of money in a system that does not do what I thought it did.  Painful lesson.


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## maple1 (Sep 8, 2017)

You could perhaps use an aquastat or temp controller that has a normally closed function, and also has a function that will close on temp rise ('make on rise') - then it could also stop power to your pump when boiler temps are low (pump doesn't need to run if it doesn't have to). But that is likely over complicating things. A simple relay should work? Wiring the pump to the load contacts that are open when the coil is powered (NC contacts) ? And just wire the coil to a power source that loses power when the power goes out.

EDIT: But, that won't help you if you want that pump to run in an overheat situation while the power is on. It would work if the ONLY time you want that pump to be running, is any and every time the power goes out.


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## Fred61 (Sep 8, 2017)

Jim,
When you purchased your inverter/charger you missed one small item. You needed a switching inverter. I had one hooked up before I had my back-up generator installed. In fact I still have it, You can get around your problem by installing a relay that will actuate when the power drops out. Just hook it up to a normally open relay and you're set to go.


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## jimdavidson (Sep 8, 2017)

Fred61 said:


> Jim,
> When you purchased your inverter/charger you missed one small item. You needed a switching inverter. I had one hooked up before I had my back-up generator installed. In fact I still have it, You can get around your problem by installing a relay that will actuate when the power drops out. Just hook it up to a normally open relay and you're set to go.


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## jimdavidson (Sep 8, 2017)

you guys are brilliant -- I am such a novice at this stuff.  You know more than the people at the place I bought the inverter/charger.  I will try to get these suggestions into my brain and get the parts.

thank you so much for all your suggestions.


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## Fred61 (Sep 8, 2017)

jimdavidson said:


> you guys are brilliant -- I am such a novice at this stuff.  You know more than the people at the place I bought the inverter/charger.  I will try to get these suggestions into my brain and get the parts.
> 
> thank you so much for all your suggestions.


Return it.  You spent too much money to get something that doesn't do the job. Of course that's the world we live in right now. They sell you an empty bag then you have to fill it at your expense. Primary example is your modern day pickup. You pay 35k for  them and before you can load it up you need to buy a bed liner. 

Sent from my SM-G900R4 using Tapatalk


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## Fred61 (Sep 8, 2017)

Just thought about this.  Is this a pure sine wave inverter? If not, it may not run your circ. If it does, you won't like the sound.  It definitely won't run the controller. 

Sent from my SM-G900R4 using Tapatalk


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## taylorfarms (Sep 28, 2017)

my solution was fairly cheap, 12V school bus circ. pump, battery maintainer, and group 31 batteries, relay to turn the 12V current on when the power drops out, the circ. is in series with my main load circ. to use my house as the dump zone, and it keeps the combine or whatever I rob batteries out of for the winter charged and going.

I had a ton of fin tube I was going to use, but did not want the clutter, and did not see a good way to keep the fin tubes from holding ash/crap that seems to slowly accumulate on every flat surface in the boiler shed.  plus I had everything laying around that I needed besides for the pump, and that was cheap enough at the local truck boneyard.

poor people have poor ways I guess


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## rkusek (Oct 3, 2017)

Overheat loop still needed for pump failures or plugged Y strainer.  I once had to clean strainer with a loaded boiler idling.  It was first startup after some mods and too much pipe dope.

I often wonder if the batter/inverter setup money would be better spent on one of the newer inverter generators
 that have electric start.


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## Bad LP (Oct 3, 2017)

rkusek said:


> Overheat loop still needed for pump failures or plugged Y strainer.  I once had to clean strainer with a loaded boiler idling.  It was first startup after some mods and too much pipe dope.
> 
> I often wonder if the batter/inverter setup money would be better spent on one of the newer inverter generators
> that have electric start.


Great if you are home to get it running.


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## rkusek (Oct 4, 2017)

I mean the ones that now have electric start.  Granted, I don't think they are turn key for this yet.  A small auto transfer type switch would be needed.  It would be a smaller version of the 3-5 grand whole home versions.


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## Fred61 (Oct 4, 2017)

In Vermont, Green Mountain Power is offering a Tesla Power Wall for $1500.00.


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## Bad LP (Oct 4, 2017)

rkusek said:


> I mean the ones that now have electric start.  Granted, I don't think they are turn key for this yet.  A small auto transfer type switch would be needed.  It would be a smaller version of the 3-5 grand whole home versions.



I have a 14KW generator now with auto transfer and was advised not to rely on it for protection. I took that advice and installed the NO zone valve and 32 feet of 3/4 baseboard directly above the boiler per the plans.


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## maple1 (Oct 4, 2017)

Redundancy

Redundancy

Redundancy


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## Bootstrap (Oct 12, 2017)

If it hasn't been suggested yet(I skipped to the end) think about a thermo syphon type of system. Old farm tractors used it before they decided to put water pumps on. Basically, you had the engine which created heat(obviously) and a connection at the top out the front of the head that led to the top of the radiator. At the bottom of the radiator, another connection which led to the bottom of the block. The heat in the block created a natural circulation. In that situation you had a fan, but I would think the coldness in winter would be enough. I would suggest a really large radiator such as one out of a HD pickup truck or larger.
A generator to keep things running would obviously be better.


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## Bob Rohr (Oct 12, 2017)

I have seen the fin tube installed with a bit of slope also, to aid thermosiphon.

Use a large diameter fin tube or two 3/4" in parallel to keep that pressure drop as low as possible to encourage thermosiphon.

The old gravity powered hydronic systems used large diameter piping to assure that flow movement.


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## Bad LP (Oct 13, 2017)

Bob Rohr said:


> I have seen the fin tube installed with a bit of slope also, to aid thermosiphon.
> 
> Use a large diameter fin tube or two 3/4" in parallel to keep that pressure drop as low as possible to encourage thermosiphon.
> 
> The old gravity powered hydronic systems used large diameter piping to assure that flow movement.




I thought of having a slope on mine feeding one end and returning at the other and was told not to bother I did however feed (and return) the dump zone in the middle of the run as well as add an air eliminator off a cross tee. I've tested it several times by shutting off the power to the boiler and it works very fast.


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## goosegunner (Oct 13, 2017)

I have 40' of fin tube all pitched properly with a normally open automag valve. It must be ok, John Siegenthaler used a photo of it in one of his presentations.


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## Marshy (Mar 4, 2018)

@goosegunner, that is a thing of beauty.  

I'm about to install my dump zone and have a questing for you guys. 

What side of the zone should the hot water enter, low side or high side of the zone? 

My thinking was the high side.  Anyone want to correct me? 
@Bob Rohr ?

@Bad LP, what was the thought behind not needing to pitch the dump zone?


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## goosegunner (Mar 4, 2018)

Mine enters on the high side or left and is pitch to the right.  The pipe on the wall below the dump zone is also pitched going back to the return.


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## Bad LP (Mar 5, 2018)

I was told not to bother in that the hot water coming out of the top of the boiler was going to push to the return side no matter what. I did put some slight pitch on the supply and return lines leading from the boiler verticals to the fin tube but it's a horizontal run under 2 feet away. Fin tube is dead level.

It's amazing how fast the hot water pushes out the cold water into the return.


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## Marshy (Mar 5, 2018)

Thanks, that's what I was thinking. The initial push from the density difference is the driving factor. I'll still add an inch or so of pitch over 7'. I realized thats about all the room I have anyways after I started to plumb it.

The automag valve looks restrictive to me, doesn't appear to open very far. Maybe I'll share a picture.


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