Outdoor Wood Furnace Info

Outdoor Furnaces - Manufacturers with NON EPA-Certified Models Only => Aqua-Therm => Topic started by: VTsmoke on June 20, 2010, 07:22:05 PM

Title: low water volume and effect on operation
Post by: VTsmoke on June 20, 2010, 07:22:05 PM
I am looking to upgrade to a new outdoor wood boiler.  I looking at the Aqua-Therm.  I like the closed system and eco-one design.  I am concerned, however, about the small volume of water in the water jacket.  many other boiler companies put 300gal. plus in their larger boilers, Aqua puts only 76.  I am concerned about overheating.  Are people putting in auxillary tanks.  I know many gasification units, like Tarm, almost require an external water tank to be efficient. 

Any input from users would be great.
Title: Re: low water volume and effect on operation
Post by: juddspaintballs on June 21, 2010, 01:51:45 PM
If you want that furnace, I'd guess you probably want to add storage too.  The benefit to adding storage as opposed to having it built in, is that you can get it cheaper most of the time. 
Title: Re: low water volume and effect on operation
Post by: rosewood on July 19, 2010, 07:23:52 PM
 i think you will need to add storage . the more the better, don't be fooled by dealers saying no its not needed.less capacity means lots more cycling of the stove, if you buy the stove i would look in to adding 500- 1000 gals of storage .if you add up the costs of tanks ,extra pumps ,insulation ,storage building,etc  your not to far from a garn.
Title: Re: low water volume and effect on operation
Post by: yoderheating on August 10, 2010, 05:32:25 AM
I was talking to a dealer the other day, he said that he runs a secondary pumping system to keep the furnace temps from falling to much. He said if you pump water direct from the boiler the return water is too cold causing the boiler temps to drop to fast and cause problems with condensation.
Title: Re: low water volume and effect on operation
Post by: willieG on August 23, 2010, 02:41:16 PM
I have never yet seen an aqua-therm over heat only way its going to is if you load the whole stove up with wood and it gets to 50 above during the day !!! you have to regulate the wood you put in !!!all stoves will over heat if you fill them up when day time temps get to 40 or higher during the day. you need to regulate what wood is being put in

not all stoves overheat if it gets to 50 in the daytime. All stoves that leak air into the stove may

many folks turn down the thermostat for the summer to say 140 or 150, this allows the air feed (blower) to shut down at this temp and gives the stove a much higher "shut down of the fire" range. Lets say your stove shuts down at 140 but we all know the fire still rages for a few minutes as the air in teh stove is used up, this early shutdowm temp allows for the stove temmp to rise as the air is used  up but the air should be used up before boil over temps are reached

if your stove can not accomplish this...you have a bad air leaking stove

Lets not forget, many folks run their stove year round!
Title: Re: low water volume and effect on operation
Post by: yoderheating on August 26, 2010, 07:23:31 AM
 I agree with WillieG, a properly built and maintained furnace shouldn't over heat even in the summer. Normally the HeatMaster furnaces I sell do very well until the outside temps hit around 100 in the summer.  Only then do my customers have to load the stove a little at a time.
Title: Re: low water volume and effect on operation
Post by: MattyNH on September 12, 2010, 02:48:13 PM
 I own a aqua-therm 275..This winter will be my 4th yr heating 1800sq ft house..Theres no need for external holding tanks.. etc  Less water is  heated quicker..Your oil furnace in your basement dont hold hundreds of gallons of water. As far as overheating my buddy has the exact same furnace..He runs his all year long..Never a problem of overheating in summer months...Only time the unit will overheat is if the door isnt shut all the way or the fan flapper isnt seated right..Other than that you can fill it all the way and dont have to touch it for a couple of days...Depends what type of wood is being burned too..
 



 
Title: Re: low water volume and effect on operation
Post by: Larson88 on September 13, 2010, 06:51:36 AM
my uncle has a aquatherm and he burns way more wood than he should. Im not bashing aquatherm but out of lets say 20 owb manufacturers there is only 1 that says you dont need much water. I would say aquatherm is out numbered.
Title: Re: low water volume and effect on operation
Post by: MattyNH on September 13, 2010, 08:08:25 AM
Whats way to much wood..I burn about 9 cord.. Hydronic wise less water is more efficient. My bro-in law bought the new pellet owb from Central..Only holds 90 gallons of water
Title: Re: low water volume and effect on operation
Post by: Larson88 on September 13, 2010, 01:45:41 PM
he burns about 20 cord. i just built an owb and it holds over 200 gal of water... lately it has been in the fourtys at night and 60 during the day and  if i fill it full it will last over 3 days with green wood.
Title: Re: low water volume and effect on operation
Post by: MattyNH on September 13, 2010, 03:25:01 PM
wow 20 cord..I havent fired my furnace up yet..Mine will be fired up next month..Thats pretty cool homemade owb
Title: Re: low water volume and effect on operation
Post by: vpd66 on September 29, 2010, 08:27:41 AM
I have a 145 and heat a 1200sf house and a 1200sf shop. I use about 5-6 full cords a year (Wisconsin winter). There are pluses and minuses about low water volume. I can have my whole system up to temp in less then 45 minutes with the right wood. I've always been able to get 10-12 hours burn times with my setup. I've already come home to 120 degree water temp and still had a warm home and it only took 20 minutes to get it up to 185 degrees. I have the most problems in warmer weather like now trying to keep the stove going. It idles to long and the fire goes out.
Title: Re: low water volume and effect on operation
Post by: MattyNH on September 29, 2010, 01:13:28 PM
What I found is that in the warmer weather I cant put straight pine in..For some reason pine doesnt keep the hot coles like hardwood does..I run mine till the middle of May..My buddy runs his all summer..He mixes the wood..
Title: Re: low water volume and effect on operation
Post by: willieG on September 29, 2010, 02:05:58 PM
here is my thought on low water volume vs high. Low water volume in a regular fired boiler (gas and oil) is ok when you need to heat the water the heat is instant. however when you want to heat with wood you have to take into consideration of the start and stop time of your fire and think of all the smoke (that is unburnt gas) that you get at these times. it is my belief (and i have no proof just my thoughts) that more water gives a longer burn cycle so you save on the wasted gas from these start and stop times the trick i guess is to insulate your tank good so you also dont lose the stored heat to a place where it is wasted. ??
Title: Re: low water volume and effect on operation
Post by: MattyNH on September 29, 2010, 02:28:06 PM
 Mine smokes the most is when you first fill it... Probably like any other brand of owb..Once any moisture in the wood is evaporated..Pretty much run like a wood stove, hardly know its there..I got a fan to get the fire fired up quickly..Natural draft ones are gonna smoke way more..Gonna take sometime to get that fire going..Either way they all have a bad rep.. for smoking..Looks like the new epa ones dont smoke like the older ones..
Title: Re: low water volume and effect on operation
Post by: Hydronix on March 15, 2012, 11:43:49 PM
If you want to know more about storage or buffer tanks goto Lochinvar site and read the spec and sizing info on their buffer tanks. Also another good place is Caleffi and their video on them, think of storage tank as a giant hydraulic separator. You can kill many birds with 1 device. Air -dirt- hydraulic separator all in a buffer tank. The amount of volume in relation to the volume of your in-house piping and heat loss are factors on how long the boiler will go between cycles. 76 gallons is actually a fair amount to alot for an average house of 1800-2000 sqft. By adding more storage if calculated correctly, which many do not, you can have 12 - 48 hours between burn times. More is not always better, if you read some threads , you'll find some have a hard time or never can maintain their 1000gal or more storage tanks at or above 160*. Not good if your system was meant for 180*.  How you pipe your boiler is just as critical to making good use of the water you have. Every boiler( except mod/cons) that I am aware of requires return temp protection in the way of a boiler bypass or mixing valve bypass. We always use a boiler bypass ( just a ball valve or balancing valve adjusted for DT 20* like most I&O manuals suggest) unless the boiler volume is a much higher percentage of the overall system volume and it takes too long for return temp to climb above 120-130* condensate temps.

http://www.lochinvar.com/_linefiles/BT-03.pdf (http://www.lochinvar.com/_linefiles/BT-03.pdf)

http://www.caleffi.us/en_US/caleffi/Details/Magazines/pdf/idronics_10_us.pdf (http://www.caleffi.us/en_US/caleffi/Details/Magazines/pdf/idronics_10_us.pdf)