Another OWB build "thoughts"

[David Wayne]

OK for a little background, I am not a rookie at fixing or building things. Nor am I a rookie at cutting wood, just havent been burning since we built a new home three years ago. So now I want to build a owb, will heat about 5300 sq. ft. total, house, garage, & shop plus domestic hot water. Some of what I like after research is grates with ash pan. Blower on back with air under the fire. Dry well, & Shaver's use of copper line inside water jacket for domestic hot water. And if possible the water pump in the basement with a spare plumbed & ready for a quick plug & play repair. I have just bought 2 fireboxes from a couple of buddies who started and lost interest, they are copies of Central Boiler. And I have 2 doors that are Empyre Delux. Now the questions. Is it possible to put grates in this type of firebox? And how much water should I shoot for? I have a 500 gal. propane tank that I could use as storage, some say insulate it and use it, the more water the better. And if I use it, do I cut back on boiler capacity? Your ideas-thoughts are welcome, so hit me-good & bad I can take it. Sorry I dont know the firebox sizes yet I hope to pick them up Wednesday. But I dont think they both will fit in the truck.

Thanks David

 

[Guswhit]

Good Luck! After running a central boiler for a few years I have decided to switch brands for the new house. I wish a could have swung a Garn, but I have chosen a Portage & Main and will be adding 1000 gallons of storage. I my opinion the central boiler just used way too much wood, perhaps if one was set up with mass storage as I am doing now it wouldn't be as bad, shouldn't compare apples to oranges though. I just didn't have the funds to invest in a separate building to house the Garn and the storage there(plus it costs at least 50% more to begin with). Anyway, I'm subscribed!

 

[cantoo]

I have an old Pacific Western. I wouldn't waste the time or expense building grates unless there is some benefit to it other than cleaning out ashes. I shovel mine out maybe 2 times per year and it is only a part loader bucket full. I burn year around. I have air blower in the door and my opinion is that most of the ash gets burnt so fine that it never adds up to much. The blower also blows lots of ash up and out the chimney at least I think it does.
Not sure about the extra storage thing, mine holds approx. 400 gallons of water and doesn't fire very often. If I had 1000 gallons of water I think my fire just might go out between firings. Summer and it only fires once every couple of days with decent wood so I burn softwood , newspaper fliers and cardboard so that it fires more often. It went out twice so far this summer when I out some decent wood in it.

 

[rancher2]

I drank the koolaid and bought the Garn. It has been ok. It will be starting its eight year shortly. I run it year around. I like the system of burning the wood and storing the heat. I have another 2000 gallon stainless steel tank sitting by the garn just need to finish hooking it up. If I were to do it over again I would weld a heating chamber up that would take long and big wood and have 3000 or 4000 gallon of storage. There is too much wood handing with the Garn. I burn 10 to 15 cords a year. I have to cut the wood too short and small to load the Garn. There is not reason to build grates. Just line the bottom of what your build with fire brick. That is all the Garn burns the wood on.

 

[AIM]

Well I have never bought into the storage tank idea but I think I'm alone in my thinking on this. To me, it may allow for fewer induced burnings but in exchange for longer duration induced burnings. (which to me, translates into equal wood consumption) Storage has nothing to do with unit efficiency. Again I am pretty sure I am alone in my thinking on this.
My biggest recommendation is a LARGE burn chamber. The more wood you can stuff in it, the fewer trips you have to make to the unit...

 

[NSMaple1]

Storage can help efficiency - it eliminates idling, or times when the boiler is sitting there with the fan off or damper closed.

But not sure how much it would help out an OWB - ideally the boiler would burn wide open until the fuel is gone & storage is charged. That would then mean the boiler would sit, not burning, until heat is needed again & storage is depleted. So would depend on how the OWB would handle the hot & cold cycles.

Also, a large burn chamber can mean a lot more time the boiler spends idling (& wasting fuel when it does). After just reading a CB manual for their new gasser, they recommend against it, and just load to try to match to heat demand.

 

[Guswhit]

There are lots of places to go research the water storage efficiency solutions. I would be happy to turn you on to a couple of places and then let you peruse the info at your leisure if you P.M. me, I'll send some links. I am not trying to persuade anyone either direction, just telling what I'm going to do. Truthfully, if you want to get right down to the cost of things, the best bang for you buck would probably be to have a 97% efficient furnace, spray foam the sidewalls, rim joist and an R-70 in the attic with no windows on the north and east sides of the house. Take the money that we are spending on ALL of the things that go with processing our personal use wood and I would bet that we would all save money. I just can't sit around so I'm stuck in this rut of cutting, splitting, stacking, burning and researching ways to get more useable heat out of my appliance, having no regard for the money I'm spending! Everyone needs a hobby.

 

[benp]

Storage can help efficiency - it eliminates idling, or times when the boiler is sitting there with the fan off or damper closed.

But not sure how much it would help out an OWB - ideally the boiler would burn wide open until the fuel is gone & storage is charged. That would then mean the boiler would sit, not burning, until heat is needed again & storage is depleted. So would depend on how the OWB would handle the hot & cold cycles.

Also, a large burn chamber can mean a lot more time the boiler spends idling (& wasting fuel when it does). After just reading a CB manual for their new gasser, they recommend against it, and just load to try to match to heat demand.

The new heat exchanger/water manifold that we built last year for the stove does just that.

The return line comes into it, is heated by the exchanger/smoke baffle, and then down into the main tank on the stove.

The water temp in the new manifold is about 30 degrees hotter than the stove tank when it shuts off.

The water keeps circulating through keeping the main tank up to temp as the water in the manifold cools down. Then stove turns on when the stove aquastat calls for it.

So, when the stove comes on, the upper water is already at the shut off temp of the stove.

Here's a pic of the unit on top of the stove. This was at the intial installation, it has since been insulated.



This was as it was almosted finished.
The closed parts are the water jackets and the open are the smoke chambers.



It works well enough that it eliminated the need to fill at 0200 in the sub zero temps. I can now go from 900pm to 0430/0500 and I am catching the stove just as it is turning on with a decent coal bed left.

Eta- On the top pic you can see the water line coming out of the hottest water jacket down into the stove.

The bottom pic shows the inlet for the return line from the whole system.

Our stove heats 10000 square feet.

 

[David Wayne]

Thanks Guswhit, I am interested in what you have. Just not sure how to send a PM.Not very computer savvy.

 

[rancher2]

There are lots of places to go research the water storage efficiency solutions. I would be happy to turn you on to a couple of places and then let you peruse the info at your leisure if you P.M. me, I'll send some links. I am not trying to persuade anyone either direction, just telling what I'm going to do. Truthfully, if you want to get right down to the cost of things, the best bang for you buck would probably be to have a 97% efficient furnace, spray foam the sidewalls, rim joist and an R-70 in the attic with no windows on the north and east sides of the house. Take the money that we are spending on ALL of the things that go with processing our personal use wood and I would bet that we would all save money. I just can't sit around so I'm stuck in this rut of cutting, splitting, stacking, burning and researching ways to get more useable heat out of my appliance, having no regard for the money I'm spending! Everyone needs a hobby.

There are lots of places to go research the water storage efficiency solutions. I would be happy to turn you on to a couple of places and then let you peruse the info at your leisure if you P.M. me, I'll send some links. I am not trying to persuade anyone either direction, just telling what I'm going to do. Truthfully, if you want to get right down to the cost of things, the best bang for you buck would probably be to have a 97% efficient furnace, spray foam the sidewalls, rim joist and an R-70 in the attic with no windows on the north and east sides of the house. Take the money that we are spending on ALL of the things that go with processing our personal use wood and I would bet that we would all save money. I just can't sit around so I'm stuck in this rut of cutting, splitting, stacking, burning and researching ways to get more useable heat out of my appliance, having no regard for the money I'm spending! Everyone needs a hobby.

I think you hit the nail on the head. When we remolded this three story farm house that is what we did. Spray foam every thing and put good windows in. We have a lot of windows. Like you I need a hobby so we cut wood and spent money to build toys to do that. Some day I may turn the propane back on. I have three 97% furances with coils in them the Garn heats and a 30 by 60 shop with floor heat.

 

[David Wayne]

We built this house three years ago.Has heat pump, high efficiency l.p.furnace and spray foam. Not hard to heat but I like the challenge of building a boiler and heating the other buildings. And I like getting out and cutting wood.​

 

[benp]

Damn....spray foam is the clincher. You're not playing around. Good job.

 

[David Wayne]

here is some pictures

 

[David Wayne]

Just an update, Steel is ordered for the water jacket. It will be 5'x5'x6' that should put me at +- 780 gallons. I talked with the local CB dealer, he is very willing to help with the details. And of course I will be buying most of my supplies, pumps, pex, blower..., from him.

 

[muddstopper]

I guess I have a different view of things, I dont own a OWB so maybe i dont know what I am talking about. as I see it, the whole purpose of running a OWB in the summer is to provide hot water. I do heat ,my hot water in the winter off my wood stove, but not in the summer. It just seems to me that a solar hot water heater would do the job much cheaper, cleaner and much more efficient than using wood to heat water. what am I missing?

 

[NSMaple1]

An ordinary electric tank type water heater makes even solar hard to justify.

Depending on how big you want it, you can buy & install one for around $300. Ours costs around $20/mo. to run, family of five, at $.18/kwh. I can heat my DHW with wood all summer, with one fire a week, but I didn't even bother this summer.

I checked out a solar DHW setup - around $5000 installed. I might have been able to do some or all of it myself for quite a bit less than that - but if it's only a $20/month saving and I'm heating it with wood anyway for half the year when heating the house that's a looonnnggg payback time.