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[woodman]

powerstroke i have an 8 inch schedule 40 chimney, i have fabricated a 3 foot section of 8 inch with a 6 inch inside it, i plan on istalling this in my chimney next summer and pumping water from my stove around the chimney and back into the boiler. i am hoping to recover a lot of heat this way as when the furnace runs i know the stack gets quite hot. i am hoping ot increase my efficiency by at least 10 percent? if i put this right at the bottom of the chimney i dont think it will create too much of a problem with creosete. And this is R&D si uf ut fails i will jsut let teh water out and be doen with it..lol
 

I have been waiting to post this until I was confident in what I was seeing but, for what it is worth I got a really good deal on a aqua stack a couple of weeks ago. My furnace is a hawken with a force air draft. For 4.5 years I have watched the heat waves come out of the stack when the blower was on. I have a cap on my chimney and with a ir gun the inside of the cap would hit 500 degrees plus. So a couple of weeks ago I said to myself, "what the heck I will give it a try"(aquastack). My chimney cap now runs between 350-400 degrees at full burn and there is a NOTICABLE DECREASE in wood consumption. Now that temps have cooled down to more January like I think a 15% reduction would be conservative. I am very pleased to say the least. I was terribly sceptical and concered for creosolt but so far it seems to be no problem. I did have to adjust the air restricter plate to allow for a little more cfm's, as I was getting a little more smoke than I liked, but it now burns smoke free after start up.       

[willieG]

woodman what does that thing look like??

[woodman]

It is a very simple design. Basicly 2 long rectangles roughly 20" long linked at the bottom by a 2" port. There is a tab on either side that allows it to drop into the chimey from the top. Each side has a 1" female pipe thread port at the top. I plumbed it so the return water goes to the stack first then back to the owb. Note: it is designed for a 8" chimney.

[RSI]

powerstroke i have an 8 inch schedule 40 chimney, i have fabricated a 3 foot section of 8 inch with a 6 inch inside it, i plan on istalling this in my chimney next summer and pumping water from my stove around the chimney and back into the boiler. i am hoping to recover a lot of heat this way as when the furnace runs i know the stack gets quite hot. i am hoping ot increase my efficiency by at least 10 percent? if i put this right at the bottom of the chimney i dont think it will create too much of a problem with creosete. And this is R&D si uf ut fails i will jsut let teh water out and be doen with it..lol
 

Have you thought about making it a drain back design? Having it setup so when the boiler is running it pumps water up into it and then drains back out when it is idling. Doing that should keep from losing some heat off it while the boiler is idling. It would also allow turning it off to allow the chimney to run hotter to burn it out every now and then.

[jimr]

I called shaver direct and they gave me another number to call, and yes it was Ben. I have work very hard to make this work. We put alot of time in the floor making sure it was properly installed using 2" blue board, solar guard and plastic below that. My house is 7 years old and is 2400sqft the shop is 1200sqft.

As where I would direct the water diffrently... What if I used a water heater as a tank and a heat exchager to seperate the direct flow of water back to the stove. Whenthe floor is running I only lose 6-8* through the floor but when it sits idle and when it first comes on the water temp could be 40-50* colder than the stove.

i can't see where a bigger stove will cure this problem? dumping that amount of cold water back to the stove will drop your water temp big time and slow the recovery.

[willieG]

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i can't see where a bigger stove will cure this problem? dumping that amount of cold water back to the stove will drop your water temp big time and slow the recovery.
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in the radint floor  if 1/2 pex was used  there would be about (actually a little less) 1 gallon per 100 feet of pex. a 1200 squate foot shop would likley have about the equivelent of about 1200 feet of pipe that qould equal about 12 gallons of water i can't see where sending 12 gallons of cool water back to the boiler would cause your boiler not to be able to  recover quickly?

[willieG]

 Whenthe floor is running I only lose 6-8* through the floor but when it sits idle and when it first comes on the water temp could be 40-50* colder than the stove.
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the water temp coming out of the radiant floor should be 40 to 50 degrees cooler than your boiler when it is running..the temp of your water entering the floor loop should be less than110 degrees and likely your OWB is running 50 degrees above that

the 6 to 8 degree loss in your floor loop is perfect and i am guessing your house is losing about 20 degrees between in and out temps when the house is calling for heat...i really believe you are maxing out your stove in cold weather. lets go back to your underground pipe..does it melt the snow on the ground above it? what type of underground pipe do you have?

[gas-on]

My stove is set at 140 *.

The snow when I have any this year stays right on top of the ground. I made my own lines. I wraped the lines in solor guard then pulled them thru black corragated pipe.

 I have temp guages on the incoming and out going lines. This way I can tell where I am losing heat. The house loop only loses 4-6* when it is nor calling for heat. When heat is on I lose 8-10*. The shop loop loses 6-8* when no heat is needed.

The floor is computer controlled and has a mixing valve that uses return water from the floor to control the ingoing water temp. It just seems when the floor turns on the massive drop in water temp causes the stove temp to drop to 80*. It then takes forever for the stove to catch up.

[willieG]

again i caution you taht your house and shed on  those very cold nights may be drawing over 140,000 btu per hour and i read here your stove is estimated at 150,000. i think (only my assumption) that your stove may deliver that amount of heat for an hour,maybe 2. remember an oil or gas furnace can deliver its set rating continuously as the fuel never runs out but wood on the other hand burns down and give of less btu's as it does. this means you will be delivering less (likely less than you need) aprt way through a fill. if you are taxing your stove to the max then you will require to fill more often to keep enough fire in teh box to deliver those high btu.

it is still my belief your stove is too small

another thing i dont see clearly is if your floor is properly installed how does the water in the lines cool 50 degrees between cycles of the floor loop?

if you are introducing water into the floor at 100 degrees and you say it is leaving the floor 50 degrees cooler by the next time your floor loop cycles then your insulation under  the slab sends of a red flag to me as that would be ground tempature?

[willieG]

you also say yor shop loses 6 to 8 degrees when the floor loop is not running. i take it you have a by pass and the water from the house to the stove is circulating always? if that is the case and you are losing 6 to 8 degrees in this loop it may be nothing or it may be something, that depends on where this heat is going and how fast your water is traveling.  again  what about the floor loops temp. if your room is 70 at about chest hight (likley where your thermostat is) and by the time this area cools down 3 or 4 degrees (likley where your thermostat would call for heat again) you say your floor loop has cooled to 50 .if your floor loop water is 100 then you say it cools to 50..that is cooling rather quickly don't you think? if your room cools 4 or 5 degrees between when the thermostat shuts off and turns on and your floor has cooled 50 degrees don't you think that is a little extreme

if your floor loop cools off to a temp less than your room between calls for heat i would guess your floor is not insulated properly  and your floor is actually drawing heat from your room?


 

[gas-on]

I have two pumps running. One for the house and the other for the shop and yes I have a bipass loop installed for the shop.

The thermostat is set at 60* that controls the floor. I have a temostat on the other side of the room It always reads 65*. I work in the shop during the winter mostly on weekends. The floor only turns on every couple of hours. I have never checked on how often it turns on and off.

I thought that if the water did not return to the stove that it would keep the stove temp higher and not have such sudden drops. Would some kind of heat exchanger help or would it not be worth even trying?

[willieG]

how hot is the water going into your floor loop

[gas-on]

The water from the stove is 140* it enters the shop at 138-136* it then can bi pass and return to the stove or when the floor pump turns on it goes in the floor at 100* after the mixing valve does it thing.

[willieG]

just for a try i would up the stove to 155 or so on and 165 or 170 off and then turn the floor heat in temp down to 90

i am not sure this will help but hey, you can try this for free

it is my belief that if you feed hotter water to the floor loop on delivery and turn down the floor loop it will do two things
1 use more of the return water to cool the loop and use less of the hot water being delivered
2 it will cause the floor loop to run longer to reach the desired temp so the floor will not cool down as often and dump that colder water  back to the boiler

if you notice that this makes an improvement you might try lowering the floor loop temp a little more (i have heard of guys running at 85 in a shop) but you must keep the delivered btu rate above what your building is losing in order to heat it.

as i said this is just something you can try with no cost and may help .......good luck

[jimr]

gas-on,,,,what modifications have you done to your shaver?