An OWB dilemma.

[wheelinguy]

We decided to put an oil fired boiler in the house when we built it, oil was cheap.  Relatively efficient home 2700 sq ft home plus basement so we were heating about 3900 sq ft and doing hot water with 900 gallons a year.  Then oil started to go up in price, we looked into OWBs all told we spent about 10k on boiler and install.  Until last year when I became self employed we would always be able to "find" enough "free" wood to keep us going through the winter.  Since we have had the OWB I have added a work shop and now we heat over 5,000 sq ft with the OWB, the logs I bought cost about $1200.  This spring someone needed a bunch of trees dropped where they were going to build a house, all I had to do was cut the trees down and I can go back this spring and turn them into "free" firewood.  I couldn't imagine trying to heat all the space we have now with oil, $$$.  It sounds like you could use all those slabs to keep yourself pretty cozy in the house.  What about selling bundles of slab wood to OWB owners to help pay for your electric bill?

[r.man]

If the OWB is cheap enough the ROI becomes reasonable.

[Brokermike]

For me the math was easy. Just to keep our house at about 62 we burned 1500 gallons of kerosene (our tanks are outside) and 4 cord of wood in the woodstove located in our family room. That was with steam heat. It cost us about 20k to buy the boiler, convert our whole house from one pipe steam to hyronic (reusing the cast iron radiators), convert our oil furnace from steam to hyrdronic, and run all of the new PEX.

We will burn about 15 cord per year. Our house is at 71 degrees and very comfortable. We will also be able to heat our garage once I find a good deal on a modine.

Our breakeven, assuming our wood to be free, we cut it ourselves, is about 3 years

[gspren]

  The old cast iron radiators can often be found cheap on CL and they work great in garages. I have one radiator about 5" thick and 24" long in a 12' X 22' shed (man cave) and keep it at 60 degrees all winter, the radiator is also nice for drying/warming gloves with a towel rack about a foot above the radiator. Cheaper than a modine.

[Holmes]

 A couple ,few Cast iron radiators will make the garage warm.  Figure 50 btu's per square foot to get an idea how much heat you will need to heat the garage.

[thecfarm]

No idea how your garage will be used. Those radiators work good for a steady heat. But bring in a cold tractor to work on and it takes time to get things warmed up. A modine can really push some heat back into a garage to get a piece of equipment warm and the garage back up to temp too. But I know, money is a factor too.

[Thehardway]

Thanks for all the excellent honest and thoughtful replies.  I have cancelled the idea for this year.  I am contemplating building my own OWB for next year.  I can build it for cheap and still buy some solar panels and get the best of both worlds.  My goal is $0 electric bill.

Seems like most of you using OWB's are previous oil users.  What are electric rates in your area?  Is it too cold for heat pumps?

I know many of you live in much colder climates than I do.  It was 17F when I went to bed last night and 4F when I woke up at 6AM.  We set a new record low for our area.  Jan. has been unusually cold.  My little 12,000 Btu heat pump ran intermittently through the night and maintained 66F in the house with no problem though.  I was surprised.

I am in the position that I cannot use an indoor woodstove because my house is too well insulated and too airtight.  The stove would burn poorly without bringing in makeup air and even if it burned well, within 15 minutes the house would be too warm and I would have to shut it down.  Getting hot water from an indoor woodstove would be a pain as everything is concrete.

I've seen some OWB's made from discarded propane tanks.  I already have a large oil storage tank that would make a good water jacket.  I can weld so I think cutting a hole in the oil tank and inserting a 200# propane tank into it and then welding back up would make a nice firebox and water jacket combo.  I already have the Pex Pipe in place so no cost there and the outside insulted pipe/trench is already in place.  I live in the boonies so smoke or visible placement not an issue. Would be neat if I could figure out how to make a hybrid outdoor Rocket mass stove/water heater that would only have to do a short burn each day and use thermal mas to carry through.

Would be interested in seeing some other folks homebrew OWB's and would not mind if this thread got hijacked into low cost, DIY type OWB discussions.   This will be in my list of projects for next fall.  Do any of you with free wood burn the OWB year round for domestic hot water? Seems it would shorten the ROI some.

[jdonovan]

I am in the position that I cannot use an indoor woodstove because my house is too well insulated and too airtight. 

How about a thermostat controlled pellet stove?

some of the smaller ones can burn down to the 6K BTU level, and shouldn't run you out, and most can be setup for outside air.

[Wick]

"Do any of you with free wood burn the OWB year round for domestic hot water? Seems it would shorten the ROI some."

I plan on doing that. That's part of my calc's.

[jdonovan]

"Do any of you with free wood burn the OWB year round for domestic hot water? Seems it would shorten the ROI some."

I have a heat pump water heater that dehumidifies my basement in the summer, that takes care of all my DHW needs.

[Thehardway]

If I had a way to turn my scrap wood into pellets, I might consider a pellet stove but if I have to buy pellets, then I am back to square 1.  Might as well pay for electricity or invest the money in Solar panels.  The solar panels will run a heat pump water heater, which would be more efficient than my standard electric DHWH but it most likely would not provide enough recovery to satisfy the demand. We all like long showers.  Most Heat pump water heaters still use electric resistance heat for fast recovery. 

[jdonovan]

The solar panels will run a heat pump water heater, which would be more efficient than my standard electric DHWH but it most likely would not provide enough recovery to satisfy the demand. We all like long showers.  Most Heat pump water heaters still use electric resistance heat for fast recovery.

I went with an add on heat pump made by Nyle its called the geyser. It wires in place of the bottom electric element. I've got the top element set down at 80f, so it never runs.  Then I paired it with a 105 gallon marathon water heater. Super insulated, and lot and lots of capacity to make up for the slower recovery of the HP style heaters.

The system took me a bit more labor to install, but the net cost was about the same as a 50 gal commercially available heat-pump water heater. The system I put together has 2x the storage, 2x the insulation, and the HP unit is about 50% more efficient than the ones built into the all-in-one.

We can satisfy 4 adults daily shower needs... as long as someone doesn't camp in the shower for 20 min.

I'm seeing about $50 a month in reduced electric bills in the winter, and almost $80 in summer due to the reduced running of the dehumidifier, and less A/C. My pay-back will be < 3 years.

[Wick]

The title of this thread hit the nail on the head for me.....dilemma. I pondered my decision a long time.
My replies were not to sway you one way or another, just give info. I believe you had 2 good solutions. Just have to go with your gut feeling. With any system you put in there will be some maintenance needs at some point. Just hope it's nothing extreme.
Now it sounds like you have another plan and wish you luck with it. You are fortunate if you have the time and skills to make it work. If you decide you can't there are some cheaper OWB's out there. They may not be as clean or efficient, but I was not as worried about the EPA as some people seem to be.

[Hilltop366]

I have a indoor HW boiler with in-floor heat, it works good, What I usually do is burn my wood at once and dump the heat in the floor, I have to keep a watch on the weather and adjust how much wood I burn and try not to get too much or too little heat in the floor so it works better when the temperature does not fluctuate a lot. When I first built I used my wood boiler for all my DHW, but after a few years of getting up really early and making a fire every day I added an electric water heater and put my electric bill up $50 - $60 per month.

If I was to do it over I would consider a large thermal  storage tank. I like the idea of burning the wood all up and storing the heat for later (more efficient and little to no smoke). I doubt I would have ever added a electric water heater with this system because I could add heat at any time of day or night for DHW when it is needed.

I think a system set up like this could work good with a few solar water heaters plumbed into the storage tank. With a system sized right you could be absent for days at a time and still have "free" heat and hot water.

[Thehardway]

jdonovan,

If you don't mind me asking, what was the cost for that Nyle Geyser unit.  Sounds like it might be the ticket for getting my electric bill down.  I could probably even connect one of those to my radiant floor system and set it low to heat the floors and de-humidify the house at the same time.  We don't mind the air being  cool (62-65F)  if the floors are toasty, its actually more comfortable for working around the house that way.

I think I may have been bitten by the OWB bug, (maybe my inner pyromaniac coming out) and still have to play around with building or finding a used one but the HP would be nice if I had to go out of town for the week and the wife had to tend things herself.

[MNBobcat]

I bought a used Central Boiler 6048.  I built a 12x24 building with metal walls and roof.  Poured a slab on one half and set my boiler on the slab.  The other half of the building is wood storage.  I have lights and an exhaust fan in the building.  I ran 250 feet or so of 1 1/4 thermopex.  I've got about $15k into the whole thing.

My first year of heating my home with propane was about $3,800 and that's when propane was $2.35 a gallon.  I figure about a 5 year payback.  With current propane prices which are higher the payback would have been even less.

I can buy 20 cords of wood for under $2,000.  So even if I bought all of my wood its still half the cost of propane.  Plus I now have a heated garage and pole building since installing the OWB.

[windy hill farm]

Well this is my 7th year heating with my Woodmaster 5500, we added my daughter's house 2 years ago and also heat both hot water systems. I replaced the blower on the front door this year and have used 2 seals on the front door. That's all I have done besides yearly maintenance. Now that said I have been hearing from a few people that their having leak's in there boilers after 5 years. This year has been very cold and windy more than usual, have gone through about 12 full cords so far. I will shut the boiler down the end of March and light my wood stove in the house for the rest of the burning season. My original cost was $9,200 installed for my house. Stove wood is still free as long as the back holds out. :D

[Tarm]

Thehardway
An outdoor wood burner would be massively over sized for your needs. You seem to have a $60.00 a month winter heat bill. Be thankful. That 1000 sq. ft. addition will suck up some heat though. So my suggestions to you would be to: 1. Install a small (Jotul 602 perhaps?) wood stove into you garage/workshop. Garages aren't as tight as houses so the air supply should not be a problem. Being in the garage/workshop it would keep the mess out of the house. That would also let you utilize some of your waste wood and satisfy your fire bug. 2. If your house is alined up right install a large solar domestic hot water system. A hot water system is much cheaper than PV solar panels and you stated that domestic hot water is your greatest energy need.
Hope this helps.

[Randy88]

With your electric cost, I'm not sure I"d personally mess with heating with wood if I were you, as for other options, maybe, that's up to you, but for heat pumps, I've heard quite a few horror stories about those in my area, know quite a few that just abandoned them completely and shut them down.   

For me it was sure dumb luck, I was renting a house that was a mansion, to say the least, I was told it took up to 4000 gallons a year to heat the old house, so we did the math, and my payback was something like seven years, so we bit the bullet and bought one, a couple months later, lp gas spiked to over3 bucks a gallon, so payback was less than one year, months in fact.   

Then we moved and the gas furnace in my current house was over 25 years old and needed to be replaced, so we just hooked up the owb and plumbed it all up, the house was fuel efficient and didn't really pay for where we had to put the owb at in the yard so we could get to it.   We also knew we wanted to convert a barn over to a shop, which we finally did this year, get it heated anyhow and insulated.    With the wood conversion we did for btu's of heat, not really accurate but we were trying to figure out how much actual lp gas we'd have had to buy, we came up with almost 6000 gallons to heat both the house, shop and an office area, this winter lp went up to five bucks a gallon for this winter.     

The downside is the handling of bulk quantities of wood, so we're investing in back and time savings features using mechanical means to process and handle firewood.    This winter alone we figured we saved about 20k verses lp gas heating, not to mention I'd have had to buy new furnace's for the house, another for the shop and third for the office.   

I'm now needing a much larger owb to use, we're thinking about building one if I can't find one to buy I like.    Not sure any of this is much good to you in your situation, but if I had that low of electric bill, I'd just keep doing what your doing now if it were me.    You need to also keep in mind which hasn't been mentioned, you need electricity to run the furnace, pumps and fans, from what your typed, just my thoughts here on this subject, but what you'd save on electricity heating your house, you'd spend on electricity to run the owb and everything associated with that, so from where I sit, I'm not sure your electric bill would go down at all, or enough to notice, especially if you went with a hot water system and had circulation pumps going all the time.   Not wanting to burst your bubble, just thought I'd mention something nobody else has.    I figure we use about 60 bucks a month on electricity to run my owb system and heating in the buildings, I know it far more than anyone else, but we also have six pumps and a blower going almost nonstop 24/7 due to my owb's being too small now, and this winter being so abnormally cold in my area.    Best of luck in your decision.     

[Thehardway]

You guys sure are all makin' me feel good about my house.  Randy, you said you figure about $60 a month in elec. to run the OWB.  Are you using water to air  heat exchanger and including the cost of the indoor blower or is the blower you mentioned just the one on the OWB?  I am all in floor radiant piping so the only blower I would need is  the stove blower.  Two 1/25hp circ pumps on timers would cover all my needs.   After what you all have said I'm leaning toward the woodstove in the shop/garage idea with a heat exchanger and a large hot water storage tank to use as preheat.  I'll have to take a look at that Jotul 602.  I'm also keepin my eye on craiglist for a used/cheap OWB.  Some people decide they are tired of tending and want them out of the yard.  Go figure.