Outdoor Wood Furnace Info
Outdoor Furnaces - Manufacturers WITH EPA-Certified Models => Polar Furnace => Topic started by: DaveB on April 06, 2017, 01:17:24 PM
-
Hi
I am building a home this spring and will be installing a Polar G2. I will have it going into the house for forced air and domestic hot water. I will also be putting a run into my detached garage with in floor heating.
I am having a hard time finding an installer in my area so I will be doing it myself. I'm not to concerned with putting the hot water side arm on or the water to air exchanger in the furnace. I will have my plumber and HVAC guys do that part when everything is being installed. The trouble I am having is determining what valves, manifolds, etc I will need to do it right the first time. I have the diagrams from the Polar web site but some of there lingo is still unclear to me at this point.
I believe the G2 has built in capabilities for two pumps right on the unit. I would assume I can run one to my garage and the other to the house. When I get inside is where the lack of information kicks in. I'm not sure how the system knows how to send heat to which unit/area. I see mixing valves, motorized mixing valves, circulators, thermostatic mixing valves, thermostatic radiator valves, diverting valves, diaphragm expansion tanks etc.
Want it right but don't want overkill.
I was hoping someone would have experience with this and be able to lend some guidance.
Thanks
Dave
-
PMs have been exchanged, feel free to call or EMail any time Dave.
-
It’s not that difficult really, if you don’t plan on burning year round just for DHW (domestic hot water) then it can be as simple as goto your water heater sidearm first, then from there to the furnace and back to the stove. For a little more flexibility or if you want the fan on your furnace to run all the time then you can either use a fan coil valve at the furnace, this simply bypasses the furnace heat exchanger with no call for heat and directs water thru it with a call for heat. A simpler way to do that is with a secondary loop using a small pump. You have one T in the line immediately after the water heater and a small pump, on a call for heat the pump is energized moving water thru the secondary loop to the heat exchanger and back to a T installed after the first T. Most prefer this method to using diverter valves as eventually the valve will decide to be troublesome.
I’m sure Slimjim will cover all this.
-
Hi Guys..
Thanks for getting back to me. I have been doing a lot of searching on how to do this. It seems a little easier now that you have explained a bit. I have attached a PDF of what I have and a few questions on each. Any help would be great. Like I mentioned, I am not total up with the lingo so thanks for your patience.
-
Okay first one is easy enough, you need the mixing valve or anti scald valve as with a sidearm the water temp in your water heater can actually get much hotter than it could if your using a flat plate heat exchanger, say 170+ degrees. The anti salad or mixing valve helps to ensure you never get hot water out of a tap any hotter than what you set the valve for regardless of how hot the water is in your water heater. I’ve never seen it suggested to cut the tube off in the water heater before though. I’ve also not seen it suggested to T your cold supply into basically the drain of the water heater.
Central Boiler really does have quite detailed schematics on their website.
You’ll only need an expansion tank if its a closed boiler, since I’m assuming like 90%+ of the outdoor boilers on the market Polar’s are an open system, you shouldn’t have any need for an expansion tank.
Lastly, if you go the route of using the valve at the furnace heat exchanger, then yes it will need 24 volt from some source to open it to direct water thru the HX (heat exchanger).
IF:
A: you don’t plan on running your fan on the furnace 24/7 or
B: you don’t plan on running year round for heating your household hot water
then you really have no need for a diverter valve at the furnace heat exchanger.
A more reliable way to do it is shown here using a secondary loop, look at the second picture to get a little better ideal about installing the t’s for a secondary loop:
http://outdoorwoodfurnaceinfo.com/forum/index.php?topic=8522.0
-
Your second PDF, I would skip the motorized valve altogether and go with a mixing valve that runs low enough for in floor radiant. I do take it your garage has in floor radiant in the cement?
Again, skip the motorized valve, they can and will be a nuisance eventually. I don’t show a picture of it, but I used a mixing valve for my sidewalk snow melt and skipped motorized valves altogether. Something like this should work fine: http://www.supplyhouse.com/Honeywell-Sparco-AM102-US-1LF-1-Sweat-Union-Mixing-Valve-Lead-Free
You might want a valve that is adjustable even lower, if your floor is too warm I find it leads to sweaty feet for starters. In my snow melt I actually used this one except in 1”: http://www.supplyhouse.com/Honeywell-Sparco-AM101-US-1LF-3-4-Sweat-Union-Mixing-Valve-LF
DO NOT ever run boiler temp water thru your concrete slab, you will be a very sad panda.
-
Marty is right on all of what he's saying, we used to have to cut some of the dip tubes if coming into the tank on the cold water side in order to get thermal siphoning but simply using the pressure relief valve opening solves that completely.
-
Thanks so much MLappin/SlimJim
Don't know why I am having a difficult time seeing this.. I don't understand what takes place and what is used when the thermostat calls for heat ?
I don't want to leave my furnace fan running 24/7 and I will not be using the OWB year round for DHW. I understand the mixing valve on the supply side of the hot water tank to mix cold water if the temperature gets to hot in the tank..
So, the boiler will constantly circulate through the hot water only to stop when the OWB is manually shut down ? Or are the pumps at the OWB controlled by the thermostat in the house ?
If you should never run boiler temp water thru the concrete slab, what cools it down, and how ? Another mixing valve on the return side that mixes the water that has already gone through the floor with water coming from the OWB ?
I have attached another drawing or what I think I understand for the house layout. Let me know what you think.
-
Thanks so much MLappin/SlimJim
Don't know why I am having a difficult time seeing this.. I don't understand what takes place and what is used when the thermostat calls for heat ?
Simplest way is to use what’s called an aqua stat on your hot line from the boiler, strap it on the pipe/tube and set it for lets say 140º, then you run the white wire from your thermostat to the common terminal on the aqua stat. Then another white wire from the NC terminal on the aqua stat to the W terminal in your furnace, from the NO terminal run a green wire to the fan terminal in your furnace. Water over 140℉ then the switch close and your white wire from the thermostat sends juice to the fan terminal in the furnace instead of the heat terminal, water under 140℉ then the white wire works as normal and the furnace runs just like you never installed an OWB (outdoor wood boiler).
So, the boiler will constantly circulate through the hot water only to stop when the OWB is manually shut down ? Or are the pumps at the OWB controlled by the thermostat in the house ?
It can be set up that the pumps only run on a call for heat, however with what little juice the newer pumps use this is somewhat pointless, some people leave their pumps run year round. On some boilers as well the pumps ar required to run 24/7 when it has a fire in it to help with mixing and circulation of the water.
If you should never run boiler temp water thru the concrete slab, what cools it down, and how ? Another mixing valve on the return side that mixes the water that has already gone through the floor with water coming from the OWB ?
Exactly, the hot from your boiler is hooked to the hot on the tempering valve, then the return from the floor is hooked to the cold, the pump is hooked to the outlet of the tempering valve. Of course the connections from the hot and cold are T’d in so as not to interfere with the flow from the boiler, basically this is a primary/secondary circuit.
-
Marty, you are awesome!
-
Marty, you are awesome!
I had a little time, bumped the owie toe and was turning an ice pack into a warm pack.
-
I saw that, it sure looked sore!
-
I saw that, it sure looked sore!
Better now not so much the bone but the nail is gone now so thats what sensitive. I did have it in a work boot yesterday morning when I processed the last half a dozen ash logs, hope to be planting that field in a few weeks if the weather ever straightens up.
-
Thanks for all the help MLappin/ SlimJim.
I think I finally have it.. The new G2 is ordered and I will let everyone know how it goes. Will share info and send pics too !
Probably be awhile though..have to start building the house right away, the OWB will have to wait until later in the summer.
Once again, thanks for the help. I may pop back with a question if I run into problems...
Dave
-
Once again, thanks for the help. I may pop back with a question if I run into problems...
Dave
Anytime, we can always snap pictures and post em as well, you know what they say about a picture.
-
Best of luck Dave, I think you will really like the stove, lots of makes sense stuff integrated into the build!
-
we used to have to cut some of the dip tubes if coming into the tank on the cold water side in order to get thermal siphoning but simply using the pressure relief valve opening solves that completely.
If I tap into the pressure relief valve what happens at the cold water valve on the hot water tank ? Would I tee into both ?
-
You leave it alone. Just go from drain to relief valve with the sidearm.
-
So I would cap off and not use the cold water in on the hot water tank ?
-
Cold water goes into the tank as normal. The sidearm is completely independent from the normal water connections.
-
If you want to heat the water before it goes into the tank then use a 20 or 30 plate heat exchanger instead. For that you would just put in series with the cold line and no need to tee into the other fittings.
-
I think what is confusing me is the diagrams from the Polar web site. They show the water from the sidearm going into the cold water supply for the hot water tank. But, they also show the dip tube being cut, which I understand we don't do anymore.
So, which would be better, the sidearm or the plate exchanger ?
See this diagram from the Polar web site:
-
Unless you have really hard water, I would use a plate but either should work.
If you have really low dhw use a sidearm might be better and if you have really high use a flat plate would be better. You do require higher boiler flow rate for a plate because it heats the water much faster than a sidearm.
-
Okay thanks..
As I mentioned, I am very new to this. Still trying to figure out what my flow rate and such will be.
Looking around Polar site to find flow rates for the G2 but can't seem to find anything.
-
The G2 flow rate is within its own primary loop, what you will need to be concerned with Dave is the flow throughout your heat loop, the primary loop on the boiler guarantees enough flow that condensation, hot or cold spots do not happen within the boiler, the golden rule is that for each gallon of water flow with a desired temp differential of 20 degrees you will be able to extract 10,000 BTUs, with the Polar boiler we are not at all concerned about you return temps to the boiler but if you don't have enough flow throughout your loop inside then the last heat load on the loop may very well suffer from low water temps.
-
If you want to heat the water before it goes into the tank then use a 20 or 30 plate heat exchanger instead. For that you would just put in series with the cold line and no need to tee into the other fittings.
Since I have 2 girls in the house with me I have found this is the best way to go. My water heater kicks in if for whatever reason there isn't enough water used to keep it warm. The more the hot water is used the less the water heater has to run. Sounds odd I know. I ditched my sidearm because it wouldnt keep up with our hot water demands and went to a 30 plate.
-
I can understand needing more but why not at that point use both?
-
I can understand needing more but why not at that point use both?
Thats what I did on mine when I redid all the plumbing in the basement, mainly out of curiosity. With all the gauges I installed I can see exactly how hard each pulls. Sidearms pull a lot easier, but can’t supply the volume, flat plates can supply an endless volume of hot water but pull harder than the HX in your furnace. This is of course dependent on your cold water entering the flat plat, one nice thing about a well, it doesn’t get super cold in the winter unlike somebody who is hooked to town water thats supplied by a tower.
-
Thanks everyone
Maybe the plate is the best to use..it just goes in the cold water supply for the hot water tank...
Won't be using a lot of hot water, Except when my kids and their families come for visits.
So, when calculating the loop size in the house, I include the distance from the boiler to the house and back as well as all the piping inside right ? And for the garage loop, from the furnace to the garage then to the manifold and all the pipe going in the floor ?
-
Does this look like I am on the right track...or not ?
Assume 80' from boiler to house and 20' inside.
Target drop in temputature = 30 degrees Farinhiet
GPM = BTU / Delta T / 500
GPM = 160000 / 30 / 500
GPM = 10.67
1” PEX Velocity of 4.22 ftps @ 11 gpm
1” House loop head = 100' x 2 = 200
Loss per 100' = 2.41
Ft of 1” = 200'
Add 10% for fittings and valves = 2.41 x 2 + 10% = 5.3 psi pipe loss
5.3 x 2.31 = 12.24 ft head
Pump Requirements = 10.67 GPM @ 12.24 Head Ft
-
That looks good!
-
I can understand needing more but why not at that point use both?
Good question, I don't have an answer for that slim. I could still do that.
-
If you want to heat the water before it goes into the tank then use a 20 or 30 plate heat exchanger instead. For that you would just put in series with the cold line and no need to tee into the other fittings.
Since I have 2 girls in the house with me I have found this is the best way to go. My water heater kicks in if for whatever reason there isn't enough water used to keep it warm. The more the hot water is used the less the water heater has to run. Sounds odd I know. I ditched my sidearm because it wouldnt keep up with our hot water demands and went to a 30 plate.
Try turning your water heater temp down or turn it off. I doubt you will run out of hot water. The sensor is low enough that the water at the bottom of the tank can get cold enough to kick on the heater but the top is still plenty hot.
-
Does this look like I am on the right track...or not ?
Assume 80' from boiler to house and 20' inside.
Target drop in temputature = 30 degrees Farinhiet
GPM = BTU / Delta T / 500
GPM = 160000 / 30 / 500
GPM = 10.67
1” PEX Velocity of 4.22 ftps @ 11 gpm
1” House loop head = 100' x 2 = 200
Loss per 100' = 2.41
Ft of 1” = 200'
Add 10% for fittings and valves = 2.41 x 2 + 10% = 5.3 psi pipe loss
5.3 x 2.31 = 12.24 ft head
Pump Requirements = 10.67 GPM @ 12.24 Head Ft
What are you going to have for heat exchangers? depending on what you use, it could add a lot of head loss.
-
Thanks..
These numbers are just estimates at this point, like I said I don't even have it installed yet. Just want to make sure that I am on the right track so that once I get the unit in position and know the exact distances I can figure out what I need for pumps, pipe, etc. I read somewhere that the target for heat loss is from 20 to 40 degrees. That's why I chose 30. Should I be aiming closer to 20 ? Just concerned about water going to in floor heat in garage could be to hot ? I don't know.. Could I have two different sized pumps, one for each loop ?
The exchanger for the furnace is 16 x 18. Haven't looked into the plate exchanges yet for DHW.
-
You’ll need a tempering valve for in the garage regardless. Won’t be such a thing as too hot with the proper valve.
-
That's right..forgot about the mixing tempering valve ...there is a lot to try and keep straight for a novice.
So, it would be best to make both pumps the same ?
The garage and the house will be real close to the same distances to the OWB, the only difference will be the pipe in the floor of the garage. Nobody answered that question. Do I count the pipe in the floor as part of the garage loop or just to the manifold for the radiant heat .
-
Refresh my memory, is the garage already built and has a source to heat it or will it be a new construction?
If it already has a heat source you will be using a flat plate heat exchanger to tie your wood boiler into the garage heat. In that scenario you will only count the loop directly to the garage and back since you would already have a pump in the garage.
To be perfectly honest this is the only types of radiants I’ve encountered, your insurance company may require you to have another heat source in the garage as a backup, think mini boiler or on demand water heater.
-
The garage will be a new build. The garage doesn't even need to be heated. Don't think the insurance companies here care..
I will have two pumps on the boiler itself. One for the garage and the other for the house. The Polar comes with an EZ manifold built right on the boiler with two adapters for pumps and two returns.
-
Dave, I think you said that you were doing radiant in the garage slab, if so, your primary loop to the garage should run its circ constant and either a zone valve or additional circ should control flow from the primary loop to the floor, not a bad idea to separate the floor from the primary loop with a plate exchanger and expansion tank as well so that it could be anti freezed.
-
Yes, the garage will have radiant in the floor. It's not a floating slab though, it will have frost walls around the outside, plastic and rigid foam insulation under floor. Both pumps for the house and shop will run all the time. I was planning on a mixing valve in the floor loop controlled by a zone valve. Didn't think I could put antifreeze in the garage loop and not the house loop ? Would I need antifreeze ?
-
First, remember that about 80% of heat loss from a radiant slab comes from the perimeter walls, that is the most important place for insulation and yes being from the North country I would certainly use anti freeze in the slab,
-
First, remember that about 80% of heat loss from a radiant slab comes from the perimeter walls, that is the most important place for insulation and yes being from the North country I would certainly use anti freeze in the slab,
The frost walls around the garage will be ICF so there will be foam around the perimeter. So, you suggest running antifreeze in the entire system, 50/50 ?
If so, that will change my calculations for the pump a bit. The addition of antifreeze changes flow rates I believe.
-
It does and you won't need it in the entire system, I would use a plate exchanger to separate the garage heat loop from the boiler primary loop and probably install the plate exchanger in the back of the boiler if there is room.
-
I think I am slowing getting this...If I install a plate exchanger for the slab loop I would actually be creating a closed system for the slab right ? That's why the expansion tank in the loop and a pressure relief valve and another circulation pump too I would guess.
I don't know if there will be enough room in the back of the furnace with the two sets of pipes and pumps...don't know but, it could be installed in the garage too right ? The a small circulation pump on the floor loop ?
-
You are starting to grasp it now!
-
Something you might want to consider when setting up your system is your electric cost. I have heard that some places in Canada it is really high. If it is where you are, I would use larger piping so you can use ECM pumps.
-
Something you might want to consider when setting up your system is your electric cost. I have heard that some places in Canada it is really high. If it is where you are, I would use larger piping so you can use ECM pumps.
:post:
-
That is the way I heat my 50x60x16 shed. Primary loop from the boiler to the shed which has a 40 plate heat exchanger feeding a 10 loop manifold. I switched to a Gundfus Alpha ECM pump and cut my electric usage for that pump by 75% and flow is excellent. I have antifreeze in the in floor system only just in case of problems.
-
That is the way I heat my 50x60x16 shed. Primary loop from the boiler to the shed which has a 40 plate heat exchanger feeding a 10 loop manifold. I switched to a Gundfus Alpha ECM pump and cut my electric usage for that pump by 75% and flow is excellent. I have antifreeze in the in floor system only just in case of problems.
Thanks..my garage will only be 30x40x12. So, a 40 plate should do for me as well. Did you use the 1" MPT ? From what I can find a 40 plate is the smallest in the 1".
What model of Grundfos did you use on the primary and the floor system ?
-
Something you might want to consider when setting up your system is your electric cost. I have heard that some places in Canada it is really high. If it is where you are, I would use larger piping so you can use ECM pumps.
I would like to use ECM pumps. How do I determine what size pump I need ?
I know they are by GPM and Head but how do I figure that out ?
-
Dave, really look at the plate exchangers, the more plates and larger plates give you more BTUs and require cleaning less often, they are so close in price that it's not worth cutting yourself short.
-
Dave, really look at the plate exchangers, the more plates and larger plates give you more BTUs and require cleaning less often, they are so close in price that it's not worth cutting yourself short.
Kinda like building a garage or shop, go to small and you’ll regret it, least with the heat exchanger all you have to do is change it out for a bigger one, clean the too small one up then sell it on Ebay or Craigslist.
-
My 40 plate is a 5"x12" with 1 1/4" mpt ports. The specs on it were way over sized for my need but I wanted the least flow restriction and like Slim said the cost isn't that much more for a larger one.
My in floor pump is the Grundfus Alpha ECM which has multiple settings and works just fine for my 10 loop manifold. My pumps on the back of the boiler are Bell and Gossett 3 speed pumps but I can't remember the model right now but are comparable to the 26-99. I am able to run my shed on medium and my house on low to save power and still get adequate gpm for my G200.
-
Another way too save a little juice, look into the Delta T pumps from Taco. Uses two sensors, one on the supply and another on the return, then pump speed adjusts to keep the differential wherever you set it. I run one Delta T and one 26-99 on my G200, I’ll have to ask, but now wit the built in circulation pump on the G series two Delta T’s might be able to be used and still have sufficient flow.
-
mlappin, do you know what pump they are using on the back of the G200 now and how many GPM it is supposed to be delivering? Do you have a picture of how that setup looks?
-
mlappin, do you know what pump they are using on the back of the G200 now and how many GPM it is supposed to be delivering? Do you have a picture of how that setup looks?
Yep, have one hooked up and was running it less than a week ago. I’ll snap a picture tomorrow.
-
It's the Grundfoss 15-58
-
Thanks Slim, does that pump move enough gpm so just about any gpm in the other circuits will meet the total gpm requirement? I was wondering about shutting down one feed, say my shed and keep the house going in milder weather and still get DHW also.
-
Yes, because of its pipe size and short distance it will move enough to keep the water temps balanced.
-
Thanks