# OWB wood saving tip - Saves A LOT of wood



## pdboilermaker (Dec 31, 2007)

I picked this up from an old guy that is on his second Taylor and have used it on my Woodmaster, I have noticed a very large drop in the amount of wood used without loosing any of the heating comfort for the house or the dhw.

Factory setting for water temp in the Woodmaster is 160-170 then hibrinate at 120.

I went in and changed my settings through the ETC box.  Now I run water temp from 140-170 and hibrinate at 120.  Letting the water temp reduce 20 additional degrees has made a big difference in the amount of wood that I am using, no scientific data but seems to have reduced my trips to the woodpile by about 40-50%


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## sdrobertson (Dec 31, 2007)

I've been doing this for several years now.  I have a CB 6048 and the factory setting is 185 degrees, but when the outside temp is averaging above 20 degrees I set the control down to 175 (which shuts off the air supply at 175 and opens it at 165).  I have a forced air system that I have on a programable thermostat that during the day, the house is at 76 degrees, but at night I set it back to 70 for sleeping comfort.  I do save alot of wood while it is set lower, but when it gets to be a really cold spell I can tell a big difference in the amount of time it takes to heat the house back up to the 76 degree mark.  I just watch the weather and adjust the boiler temp to respond to what the forcast is.  I once went all the way down to 160 degrees and was not satisified with the amount of time my blower on the furnance was running so I found that 175 is just about right for the setup I'm using.  Like you, I don't have a specific amount of wood saved, but I also have had to load the boiler with less wood for the same comfort in my home.


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## Eric Johnson (Dec 31, 2007)

Thanks for that, pd. I don't know why it wouldn't apply to any other boiler, indoor or outdoor. It would be nice to see a chart or other documentation of the relationship between system temps and efficiency.

My only concern would be low return water temps. Do you have a mixing valve or some other way of controlling the temp of the water returning to your boiler? I know that low-temp return water corrosion it's a big concern with gasifiers, but I think it's a concern, to some extent, with all boilers.


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## sdrobertson (Dec 31, 2007)

I'm not sure on low water return temp, as this boiler holds 393 gallons and I'm running a 3/4 inch line to the heat exchangers and back I don't know how much it mixes in before the water touches any of the metal in the firebox.  It would be an interesting thing to know though.


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## Eric Johnson (Dec 31, 2007)

I read somewhere that the lower you can run your water temp, the more efficient your system. At least I think I read that somewhere.

You can buy an outdoor thermostat that will make the temp adjustment for you, I believe, sd. I think my EKO controller can be set up to do that as well.

Seventy six degrees. Ain't life grand when you heat with wood?


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## TCaldwell (Dec 31, 2007)

eric,my garn manual has some correction factors for supply water temps and correlating correction factors, based on a industry standard of 215deg correction  factor of 1
                  210-.95
                  200-.86
                  190-.78
                  180-.69
                  170-.61
                  160-.53
                  150-.45
                  140-.38
                  130-.31
                  120-.25
                  110-.19
                  100-.13
 what this means is if a baseboard is rated at 1000btu/linft, contact manufacturer for output ratings, the table indicates that at 180deg the existing baseboard can deliver 69% of the rated btu's  or 690btu/lin ft. Also if a older system was sized twice as large as the actual heat loss, a common occurence, you could run the system on 150deg water. hope this helps.


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## velvetfoot (Dec 31, 2007)

I don't have a wood boiler, but I was able to buy an Argo Outdoor Reset Control unit that I could backfit onto an Argo oil boiler control unit.
It is not sophisticated like others I'm sure, but it does take note of the outdoor temperature and adjust the boiler temp accordingly.
I'm not sure of the numbers, but in milder weather the burner stops at something like 145F vs 175F.


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## Eric Johnson (Dec 31, 2007)

TCaldwell said:
			
		

> eric,my garn manual has some correction factors for supply water temps and correlating correction factors, based on a industry standard of 215deg correction  factor of 1
> 210-.95
> 200-.86
> 190-.78
> ...



That's really interesting, Tom. Thanks for posting and explaining that.

You don't say anything about relative efficiency, however. And it might be different for wood compared to fossil fuels, I guess. Is that something that can be devined for various water temps? 

Getting back to water temps--our first house had an old oil-converted coal boiler, which I tore out and replaced with a wood burner. There was a chart tacked up on the beam over the boiler from around 1910 that listed outdoor temps and the corresponding desired water temp to keep the house at a stable temp. As I started to use the wood boiler, I would compare the numbers on the chart to the actual numbers at any given time. Amazingly enough, they were pretty close. I guess that tells you that the old timers--the dead men--put some engineering into designing home heating systems. Apparently there was more uniformity across the installed base than you would think--at least enough so that you could publish a chart that actually worked for more than just one house.


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## atlarge54 (Jan 1, 2008)

What is the sequence of operations on some of these OWB's? What is the hibernate function?


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## pdboilermaker (Jan 1, 2008)

With a Woodmaster, they come set at 170, 160, and 120.  What this means is that the fan comes on when the water temp hits 160 then it runs until the water temp reaches 170, at that time the fan shuts off until the temp gets to 160 and so on and so on.  If the water temp drops to 120, the fan shuts off to preserve the coals until more fuel can be added.


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## atlarge54 (Jan 2, 2008)

Pdboilermaker what are you heating (sq ft and insul. level)? I assume you don't have baseboards since you can drop temp to 140. If you think dropping temp helped save wood what do you think would happen with blower disconnected? If you can afford a slower recovery why not try it? If my memory serves me right Woodmaster has a grate and supplies air from below the fire, which would be a plus, most Central Boilers don't even have blowers. If 140-170 works ok, why not 140-160 or less? My temp at the top of the sidearm runs 130-140. Tonight would not be a good time to tinker, gonna be a little chilly here in the midwest.


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## atlarge54 (Jan 2, 2008)

I don't have a true OWB mine is actually a OWB converted to a heat exchanger so it's tough for me to compare. With a fresh load of wood it'll smoke but once there's a bed of coals it burns clean. Keep in mind I'm not heating a McMansion. I've been burning a lot of green mulberry lately, I just fill up the back with green wood burn dry wood in the front and rake the green stuff forward the next day. I've got way too much wood cut and don't want to handle this wood again. My stove has had a fire burning non stop winter and summer about three years now. I'm glad to see people getting away from oil boilers to gassifiers. I tend to think peak oil production is already in the rear view mirror. Maybe if I move or build in the future I'll get a gassifier, and have to owe thanks to everyone here helping to perfect them.


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## atlarge54 (Jan 2, 2008)

There's a description on the " Ladomat 21 thermoregulator cost" thread.


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## Bartman (Jan 3, 2008)

You guys have me thinking about playing with my water temps, I've always thought that the temps I had set were relatively optimal. Here's how my system works, let me know if you have any suggestions on "tweaking" it. When in the "wood" mode, the wood boiler is in series with my oil boiler, supply is feeding the oil boiler return. Fire is started in boiler, modified stack switch sees initial heat from combustion, makes and starts draft blower. Draft blower runs until 165 degrees wood boiler temp, if there is no call for heat, fire burns low until 190 degrees, then kicks in "overheat" relay, overides all 4 zones to cool off boiler, (usually about 2-4min). By the time the overheat aquastat opens the boiler water temp has dropped to about 160, maybe less, draft blower starts again and the cycle repeats especially when there is no call for heat. Usually the house temp stays at about 70-72 degrees, normally my themostats are set to 67, and setback @ 62. Two of my zones are baseboard, two are radiant. My radiant is not tempered, both zones are run @ boiler temp and are set 2" in 4" concrete. It would be nice if I could lower the wood consumption a bit so I can get a whole night burn, at least until I get a gasifier.


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## ericjeeper (Jan 3, 2008)

Bartman said:
			
		

> You guys have me thinking about playing with my water temps, I've always thought that the temps I had set were relatively optimal. Here's how my system works, let me know if you have any suggestions on "tweaking" it. When in the "wood" mode, the wood boiler is in series with my oil boiler, supply is feeding the oil boiler return. Fire is started in boiler, modified stack switch sees initial heat from combustion, makes and starts draft blower. Draft blower runs until 165 degrees wood boiler temp, if there is no call for heat, fire burns low until 190 degrees, then kicks in "overheat" relay, overides all 4 zones to cool off boiler, (usually about 2-4min). By the time the overheat aquastat opens the boiler water temp has dropped to about 160, maybe less, draft blower starts again and the cycle repeats especially when there is no call for heat. Usually the house temp stays at about 70-72 degrees, normally my themostats are set to 67, and setback @ 62. Two of my zones are baseboard, two are radiant. My radiant is not tempered, both zones are run @ boiler temp and are set 2" in 4" concrete. It would be nice if I could lower the wood consumption a bit so I can get a whole night burn, at least until I get a gasifier.


 It sounds to me like you need to restrict all drafts.. sounds like the fire is running away at idle.. Any way to ensure when the damper is closed it is sealed off better?Or perhaps it is breathing through the draft blower. Maybe build a small aluminum box with a hanging flapper.. so that when the blower motor is off the door will swing shut/.When blower kicks on it will suck the swinging door in.. Might have to play with a bit of weight until you get it from free drafting.. It should not run away so easy..


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## Bartman (Jan 3, 2008)

Oh it's definitely leaking through the blower since it has an adjustable shutter for draft regulation. It seems to work pretty good cycling the way it does but maybe I should look into that. There are actually 2 places that air enters, 1 the shutter, and 2 the peep hole on the loading door, I've left that "peep" hole loose so it wouldn't bind when it heated up so I can check on the fire.


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## Bartman (Jan 3, 2008)

Here's a pic of the blower, I thought I had it on the last post.


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## pdboilermaker (Jan 3, 2008)

Boilermaker, oops, I mean Hoosier (forgot you werent blessed

I am heating a 2 story with about 3200 square feet.  Walls are r19 and the roof is r38.  I need a fast recovery to cover showers in the a.m.  There are 6 of us to get up and ready for work / school everyday (2 adults / 4 kids).  Plus that oldest boy that is 16 takes a whirlpool tub every night for about 30 minutes, dont know why though he cant be dirty, I wonder what he does in there every night?


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## atlarge54 (Jan 3, 2008)

Pdboiler how is your system plumbed? Sidearms are pretty bulletproof but not the greatest on recovery rate. Heating water shouldn't be a huge load on a boiler most water heaters are about 40K BTU. I assume you have a front load washer, top loaders are huge energy and water hogs. Does the water temp on your water heater get up to 170 deg. ?  I'm also assuming  a mixing valve at exit of water heater. You might still be able to lower boiler temp. and increase hot water recovery with a pumped loop through tank. Baseboard, radiant or forced air house heat? Did you install any of your system? Are you a school of engineering graduate from PU? Don't forget "If it ain't broke don't fix it". Another factor is wood supply, do you buy or cut? Do you ever get the kids and wife to help?


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## Eric Johnson (Jan 3, 2008)

You can put a circulator on the sidearm and speed up the heat transfer. Or, get a small flat plate hx and/or a bigger water heater/tank.


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## pdboilermaker (Jan 3, 2008)

atlarge54 said:
			
		

> Pdboiler how is your system plumbed? Sidearms are pretty bulletproof but not the greatest on recovery rate. Heating water shouldn't be a huge load on a boiler most water heaters are about 40K BTU. I assume you have a front load washer, top loaders are huge energy and water hogs. Does the water temp on your water heater get up to 170 deg. ?  I'm also assuming  a mixing valve at exit of water heater. You might still be able to lower boiler temp. and increase hot water recovery with a pumped loop through tank. Baseboard, radiant or forced air house heat? Did you install any of your system? Are you a school of engineering graduate from PU? Don't forget "If it ain't broke don't fix it". Another factor is wood supply, do you buy or cut? Do you ever get the kids and wife to help?



Ok Hoosier  many questions, let me address each one, sorry to use quote but I needed to read so I can answer 

Pdboiler how is your system plumbed? Sidearms are pretty bulletproof but not the greatest on recovery rate. - Since I have a ttankless hotwater heater (put in 1 year prior to the boiler), I have a plate type water to water heat exchanger.  The idea was that I would run it into the exchanger from the pump and heat the water to around 110 degrees then let the tankless heater polish it up to 125.  In reality, what I get is water at 135 from the heat exchanger and the mixing valve wide open.  The tankless never comes on in the fall/winter/spring while I have my Woodmaster going.  But what can happen when I drop the Woodmaster to 140 degrees is this.  In the morning, both the upstairs and downstairs furnaces are heating the house up from 60 to 70 degrees.  The thermostates come on at 445 a.m. then I take a shower at 5am, my wife at 6am, the 4 kids from 615 until 645 am then the thermostats knock the house temp back to 60 degrees because we are all at work/school.  So if it is really cold outside and both furnaces fire, and 6 showers when the boiler is down to 140 degrees it can over run it.  A lot of energy used in a short span of time.  Other then when this "Perfect Storm" hits, all is well.

I have a Whirlpool Duet front loader washing machine and dryer

I have 2 forced air furnaces, one for upstairs and one for downstairs.

I helped to install the system.

I cut my own wood, my neighbor is a tree trimmer so he brings me more than I can use that is already branched.  Most pieces are 8-16 feet long, straight and anywhere from 6" to 18" diameter, he dumps it in my barnlot.

The kids help alot we told the wife she didnt have too or she wood, er would.  In fact the boys also cut and split exrat wood to sell for their "jobs".  Each boy typically makes about $1500.00 year in spending money.  I do cut the wood but they split, stack, and deliver it.  The boys are 9, 12, 15, and 16.


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## Eric Johnson (Jan 3, 2008)

I would think that adding another water heater or tank would be the cheapest and most effective approach. That way you'd face the morning with twice as much hot water.

I cut wood for my dad when I was a teenager, and have been doing it ever since. Loved it then; love it (even more) now. The girls always liked the sixpack abs from all that splitting.


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## atlarge54 (Jan 3, 2008)

Sounds like a well thought out system. You are probably ready for the " leave it alone" phase. Good Luck.


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