Outdoor Wood Furnace Info
All-Purpose OWF Discussions => General Outdoor Furnace Discussion => Topic started by: kybaseball on January 23, 2013, 07:34:38 PM
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Just kinda curious about this. I checked my stove and it was on 175 so I went back in to check the vent to see what the temp is coming out. I checked it and it was 136. Just curious to see what others may be getting out the vent. Thanks
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temps out the vent may vary greatly..temps out the vent will change drastically depending on CFM you are moving..and to a smaller amount by what the temp of the air going over the heat exchanger is as heat transfer has a lot to do with the delta between the cold temp (the air being sent to the heat exchanger via the blower) and the water temps in the exchanger. although it may be intersting to see how these temps vary depending on type of furnace is in the home. i know my in home furnace is an "in ground water furnace" adn was designed to move lots of air at low temps...it never goes off low speed (not sure of cfm) but my ductwork is huge. (my duct where my exchange is measures 24 x 14) i may just measure my heat output and post it for you and see what the difference might be
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My stove settings are 170-180 and my vent temp is around 110 degrees. I have a 3-speed pump and run it on low
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My stove settings are at 170-180. When I sit my indoor thermometer on top of my vents, it usually reads about 95-96. I'll be honest, I don't know much about heating but I have been very happy with the purchase of my OWB last year.
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Temp outside 170-175
Vent temp 115-120
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vent temp115 setings 170 160
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My stove settings are 170-180 and my vent temp is around 110 degrees. I have a 3-speed pump and run it on low
I also have a 3 speed pump but it is ran on high. Should I change that to low? Or what would change if I did move the speed to low or medium?
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Leave on high, slowing the speed would increase delta T and we want that
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Man I am jealous ...love this forum hopefully me and scottm7 can hook up after some tax money gets rolling .The electric and propane is eating me up ....
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Man I am jealous ...love this forum hopefully me and scottm7 can hook up after some tax money gets rolling .The electric and propane is eating me up ....
Yea... This cold snap has people worrying about what the next bill is gonna look like. There is nothing better than being warm as toast and know that it's not costing you out the wazoo
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my blower fan on my "water furnace" is in low speed (950 cfm so says owners manual) and my water temp from the OWB is between 170 and 175 as i take this readiing at the register...105.3
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I have did alot of checking on this i have a 3 speed water pump running on low was 119 medium 121 high 127 now u can go and change your blower speed on your furnace most have low medium and high changing the air speed along with water speed can make a big difference in temp I aim on high now tomorrow i aim going to go to medium and then low and see what temp difference is.I will up date with results tomorrow night
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So... I take it is better to run the circulating pump at the highest setting vs. the low? I run mine on low currently.
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Hotter isn't always better, it just varies folks. This is part of why each job is a design within itself and one pump might cover you but not the next guy.
There is numerous variables, line size, how many restrictions there may be, pump size, heat exchanger type...
So there is no set answer, low may be fine, it just depends.
What we look for is a delta t around 20, that's the difference between supply side of coil vs return side, 180-160 is delta t of 20. You may be heating your home fine on low, but if your gpm is to low, your return temps could be way to cold.
Pump speed don't change efficiency really, your home requires the same # of btu, regardless of the heat source or pump size etc.... Higher pump speeds result in higher register temps, they also increase return temps,as the coil is at an average higher temp..
Sooooo.... With all that, set ups are just different, the only thing running a pump higher would hurt is probably just a bit more electric use by the pump, but if your system was designed to be run on low, it may be fine, most installers don't get to technical and a lot wouldn't know what delta t even is
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as scott says the only thing you need be concerned with really is the return water temps to your OWB. if your return water is lower than what your dealer tells you it should be you need to move water faster (or take less heat from it, and most of us don't want to do that)
if your return temps are high and your house is not heating good enough you need to take more heat from the water (bigger exchanger or faster blower or another heat source?)
if your house is heating and you are happy, and the return water temp is high enough then who cares about the temp at the vent
heat at the vents is controlled by many things (or a combination of things) heat of incoming water...GPM being delivered...size of exchanger...CFM of air being moved...
as for your "delta" there is nothing set in stone that is has to be 20 degrees, that is just an industry standard that is used as a target in most cases as it is also easy to work with when counting btu's. if your delta is 10 or 25 as long as yoru sytsem can maintain the proper return temps and can recover it should be fine
i know they say a delta that is more than 20 may increase fuel usage but we are burningn wood, i would try and tweak my sytem to get to that target i guess, but i wouldn't lose any sleep over it
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I'll also say in regards to another question low, medium, or high. We all dont have the same pumps or same systems, we have to remember that there are hundreds of pump choices and no two installs are the same.
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162 on heater
102 ish out of vent in house
3 speed pump on high
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checked all speeds of water pump and fan blower speed today for me seems high water speed high fan speed use to run it on medium and medium my results. now ever budys will be totally different u just have to try it and see but by me changing settings seemed to burn a little less wood temp at register went up and it took around seven minutes off how long the furnace ran. now that being said different wood could change burn time register heat like scott said is all different but what i think shows it is heating better is the time it took off running time i know weather wind and cold makes a difference. but its been close temps and changed that much i would think that is better friend has same set up he gets more out of his on medium and low fan. like scott said every single one will be totally different just have to mess with them and see what makes you smile. or like my brother in law said dont know what it is dont care thats all i know im warm and im not buying propane. have a good weekend all
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Just from what I have messed with I think when the pump is on low the water returns a lot cooler versus on high. More efficient on high because it keeps the whole tank a balanced heat due to more intense flow which produces better even mixing. On low the fan runs longer on furnace and therefore when returning to the stove it takes a lot longer to balance the stove water tank to a average temp.
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Just from what I have messed with I think when the pump is on low the water returns a lot cooler versus on high. More efficient on high because it keeps the whole tank a balanced heat due to more intense flow which produces better even mixing. On low the fan runs longer on furnace and therefore when returning to the stove it takes a lot longer to balance the stove water tank to a average temp.
It is possible yes for the higher return speed to increase circulation, so another benefit.
Most folks assume everything is fine simply because the house is warm. With proper care and boiler treatment these things could last a long long time
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I agree it needs to be looked at... If my 3 wrap don't melt snow your thermopex shouldn't either
My distributor for foam filled insulated pipe loves logstor, even though he carries both brands. I am tempted to try it next year, I've the test results for years but just never used it at my own home
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Scott I used the double tiled triple wrap and buried about 5ft deep since I am in high and dry ground but have rocky soil which is why I went with the 4 inch tile inside of a 5 inch tile for extra protection. I myself don't have a melt line but also know in the future I may replace it with logstor or thermopex just because. Im sure there is a difference but my stove is only 65ft from my house and the wife said NO on the better pex.
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I would also think on a high pump setting you would get more radiant heat off your exposed pex in the basement and also any sediment would get cleared out of your heat exchangers and endup in the bottom of the wood boiler to where you can drain out that nasty junk.
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So if you temp delta is too low and you wanted to slow down the flow on a single speed pump would you partially close the inlet or the outlet?
This is temp probes on the pex at the boiler wrapped with insulation, on this loop is a 20x20 HX and 135 feet of 3 wrap pex. I have swapped the probes and the readings are the same so it is not an off reading.
Bottom is out top is in.
(http://www.fourced.com/pics/OWB/delta.jpg)
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You measure your delta t with everything running, heat on and hot water
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You measure your delta t with everything running, heat on and hot water
I let the furnace run for 30 min and rechecked with it still running. 10* difference. I do not have hot water hooked up yet.