Outdoor Wood Furnace Info
All-Purpose OWF Discussions => General Outdoor Furnace Discussion => Topic started by: peeworm on September 07, 2013, 01:42:32 PM
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I was wondering about how many gpm i should try to get from my system
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Depends on a lot of different factors, with no info on anything your doing, it's impossible to say
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ok when you install a boiler how many gallon per minute do you shoot all i want is a round about number
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It depends, am I going to forced air through a plate, am I going to multiple forced air, am I going through a header system, what are the btu requirements of the home or job were asking it to do...
You'll have to give us a full detail of your system, because it could vary depending on what your doing with it.
There all not installed the same way and each job is unique, so it's not something I can just say 5gpm will be fine, it could be, but it could also be the early death of your boiler if 5gpm isn't enough to carry the heat demands your job places on the unit
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im running a grundfos alpha pump about 75' to a 30 plate heat exchanger for hot water and then about 2' to a 20"x20" water to air heat exchanger and back to the boiler there are no 90's in the line. oh and the heat exchangers are about 8' below the boiler.
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The grundfos alpha will have to be ran on high to do that job, hopefully you do have 1" lines for that
The alpha although a good pump, senses changes in head pressure to ramp up and slow down, your systems head pressure won't change, so therefore the pump will slow down and won't be effective
So to use that pump, you can, but you can't run it on auto, run it on high, which is still only 40 watts and you'll be fine!
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im running a grundfos alpha pump about 75' to a 30 plate heat exchanger for hot water and then about 2' to a 20"x20" water to air heat exchanger and back to the boiler there are no 90's in the line. oh and the heat exchangers are about 8' below the boiler.
your head loss will not be high so shooting for the recomended flow rates would be acceptable 8 gpm for 1 inch pex and 12 gpm for 1 1.4 pex
you can as scott said get by with less if yoru heat load is not high. the faster you move your water the less heat you will take from it and the higher your return temps will be to your boiler (good thing) i believe scott also mentioned this
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Yep, it's "possible" that the pump could work on auto and his home be warm, but there could be destruction on the boiler end of the loop due to cold return temperatures
But with what he's described, if its ran on high he will be fine, warm, and the boiler will be happy too
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I just filled the boiler and fired the pump up and i getting 5 to 6 gpm on high just wondering if that might be enough to heat a drafty old house with updated windows and new insulation.
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I just filled the boiler and fired the pump up and i getting 5 to 6 gpm on high just wondering if that might be enough to heat a drafty old house with updated windows and new insulation.
I think so, def couldn't go much lower but I think it will suffice. Just be sure to run boiler around 170-180 and it will help
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This is one of the few times that I will disagree with Scott and it may be totally because of product, we want our boilers to be run as hot as possible without steaming off, usually mine are run between 185 and 195, with a large heat load like greenhouses or dry kiln's I will run our chip boiler as high as 208, it is far better to run them hot and pay attention to the Delta T, there should be no more than a 20 degree temp difference from the supply to the return on any boiler. Install temp guages on the supply and return at your manifold and monitor it, adjust pump size or speed accordinly. the temp guages can also alert the homeowner if there is a problem with a pump or a heat exchanger getting plugged up. This is one of the big differences of an installation that costs 18,000 and one that costs 15,000. Cheaper is not always the best way to go.
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Slim, I don't see how you were disagreeing with me at all????
Most of the folks on these forums try to run there boilers 145-160, as per many manufacturers recommendations, I was hoping and that saying 180 would encourage him to run it higher than most users of that brand of stove and such.
The reason being was all about the delta t, his pump is big enough according to any chart I have, but if he runs at to low or a temp it could be an issue regardless
Not sure where you disagree?
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I am planning 180 or 190 degrees on thee boiler. i also installed the check valve i the pump how much do you all think that will hurt the gpm.
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The check valve won't make a huge difference but I would take it out. It really isn't needed on an OWB system and I have seen them cause pumps to get airlocked.
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I guess that was perhaps not worded properly, sorry Scott, I hear people at the shows all the time speaking about running their boilers at 160 and below to try and save wood, in my opinion this is not a good idea as it promotes condensation within the boiler, I would far sooner see much higher water temps, this helps control condensation and creosote which we all know leads to premature corrosion inside the boiler. My friend Dave that sold the other brand boiler at Acton fair says that his factory aquastat will only go as high as 180, honestly I can't understand why a manufacturer would want to keep the temp so low. the aquastat is a love control and I know that the parameters can be adjusted, do you know if this would void any warranties as he will be doing the Rochester NH. show with me as well and we feel that we would like to turn it up.
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Thanks for the replys and help guys. I also wonder if maybe a bell and gossit nrf 22 might get a little more gpm. I have 3 new pumps I ordered the boiler with the small pump setup then ordered the b&g as a back up and I also wanted to try the grundfos as the primary.
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I guess that was perhaps not worded properly, sorry Scott, I hear people at the shows all the time speaking about running their boilers at 160 and below to try and save wood, in my opinion this is not a good idea as it promotes condensation within the boiler, I would far sooner see much higher water temps, this helps control condensation and creosote which we all know leads to premature corrosion inside the boiler. My friend Dave that sold the other brand boiler at Acton fair says that his factory aquastat will only go as high as 180, honestly I can't understand why a manufacturer would want to keep the temp so low. the aquastat is a love control and I know that the parameters can be adjusted, do you know if this would void any warranties as he will be doing the Rochester NH. show with me as well and we feel that we would like to turn it up.
It shouldn't void the warranty I don't think
Hell have to get past the pass code though
Empyre corrects delta issues with there optimizer system
If they were just sized properly to start with though it wouldn't matter
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It s not cold here yet but i have 190 degree water dumping into water heater and when I run the hot water and check my thermostat on the return it is showing about 160 so I am dropping about 30 degrees thru my w to w exchanger.
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How r u checking it? R u using the temp at the stove and checking it after the exchanger with something else
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if your readings are correct, i would guess your gpm delivery from the OWB is too low. the reason i am unsure. if yoru plate exchanger is at least a 20 plate, flow reduction is almost nil. \\your water to air exchanger should not restirct things too much either i wouldnt think,unless it is partially plugged or way to small. i really tink you need to find your flow rate and go from there. i think someone suggested another pump in series?
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I have thermostats on the line before the w to w and after the w to air that I bought from pex supply that fit the gator bite t's. By the way im using the read out on the aquastat at the boiler. All componets of system are new the w to w ex is 30 plate with 1 1/4 inlet and outlet and the w to a is a new 20 By 20 with fan from andersons outdoor wood furnace center.
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If readings are accurate the delta is to high already with just water being heated
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Did you say you are using a Grundfos Alpha? If so, what GPM is it displaying?
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It is showing 5 gpm
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I would just keep an eye on it for a while and see how low it drops when the supply temp is lower.
The NRF22 will give you less flow than the Alpha. You would need an NRF25 to get a little more.
Since you already have the NRF22, if it can be done fairly easy on your system, I would add it inline with the other pump. It should give you another couple gpm. It could be setup to come on when needed so only the Alpha runs 24/7 if you want to keep the power usage down.