Outdoor Wood Furnace Info
All-Purpose OWF Discussions => Plumbing => Topic started by: Midnight Farms on January 05, 2015, 10:52:56 PM
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I have enjoyed reading the posts on here, so first, a thank you to all the experienced contributors.
I have been looking at Heatmor and Earth Outdoor Furnaces.
I will be heating a 5300 sq ft home (currently with two residential furnaces) and hot water tank. I also want to run a second line to my greenhouse and pool to utilize the furnace in the late summer/fall and early spring. (Northeast Ohio weather)
My question is specific to the capability of utilizing a manifold system, similar to what they use on radiant floor heating systems. I'd like to bring an 1 1/4 line to the house from the burner, and run a manifold off that with separate lines to the plate exchanger for dhw and each furnace. I'd also like to have the capability of putting an air handler in the garage eventually, and possibly another small greenhouse attached to the house.
Is this commonly done? Successfully? I haven't had good luck with dealers/installers in this area, so I am reaching out to this forum. If you recommend a good / knowledgable dealer / installer in Northeastern Ohio, I'd like to know.
Thanks!
Nick
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5300 square feet and it now takes two furnaces to heat it. I am having doubts if you can even get enough water to the home to heat it. take an average of 10 to 20 btu per square foot on average winter days 106,000 btu an hour on extreme cold nights when the wind is howling, maybe 30 or 40 btu per square foot? 40 = 212,000 if this is true then your 1 1/4 pex is not going to give you enough water for that kind of btu
perhaps your btu need is less but with 2 furnaces I am thinking not. do you know the btu output of your furnaces or your total heat bill from last year, this could go a long way in figuring out what your btu usage would be. an average house likely requires about 80 to 120 million btu for a heating season in your area, and I am guessing you have the equivalent to at least 2 if not 3 average homes!
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I would agree with willie on the BTU's but with proper switching and manifold setup, the existing units allowed to fire whenever they are needed, then the oil or gas bill can be drastically reduced at the very least. The thing we should all realize is that the demand for full BTU requirements are not there all the time and any BTU's that can be put into the equation are reduced from the heat load on the existing unit!
Please post up a drawing of what you would like to accomplish and let us all ponder on a solution, sounds like a great project to me.
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sorry if I sounded like I was trying to scare you off. Slim has hit the nail on the head about reducing your heat bill drastically. I was just trying to point out that your demand for heat from an OWB at times will not likely be able to keep up and your current heating system will be called upon to "top off" the demand
have you also considered a house of 5000 plus square feet, how much wood you will need
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Assuming you have enought BTUs from OWB...
In regards to using a manifold to distribute to DHW & Furnaces, I do not think that there very many out there; as I have not heard of one.
The main problem you would run into is not the manifold, but the max GPM per loop. Most manifolds used for radiant application, max out at 2-3 gpm, with a few Commercially sized manifolds at 3-5 gpm for Snow Melt application (but then again these are genereally custom designed and built per job.
My best advise, closely spaced tees (off of main line) and indivisually pump each application; you may be able to get both furnaces on one set of tees, but I have never installed a water to air HX
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I used a manifold system. I had Earth Lee make them for me - 1-1/4" main body with five 3/4" taps and two 1" taps. I only was using one of the 1" taps for my furnace and two of the 3/4" taps for water heater and a small radiator for the dog's sleeping area in the basement. I had plans to expand and I never did. I also had a device on one of the 3/4" taps that opened when the zone valve on the furnace coil closed to allow the extra flow go through. The system worked very well and I had each device isolated with ball valves on both sides.
As best I can tell, Earth Lee isn't in business anymore. It looks like you can still buy her products from here though:
http://www.designheating.com/catalog/subcat.cfm?Category=31&SubCat=63 (http://www.designheating.com/catalog/subcat.cfm?Category=31&SubCat=63)
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I also use a manifold
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My mistake, JUDDSPAINTBALLS, :bash:
..sorry but when I heard manifold I was think those fancy things with valves and flow meters that you typically see in mechanical rooms. I think a better definition of what you describe is a HEADER, independent of the name it should work
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Header or manifold, it's just a name depending on who you talk to. I've even seen them called header manifolds. It all works the same. Unless all you're gonna run is one heat exchanging coil and a water heater setup, I prefer a header/manifold setup so each appliance gets full temperature water to run at it's peak efficiency as opposed to a one-loop setup where each successive appliance gets progressively cooler and cooler water after it passes through the prior appliance.
So, like LittleJohn said, if you have enough BTU's, it should work just fine. Worst case, you're just going to supplement your system and spend less on heating bills.
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I used a manifold system. I had Earth Lee make them for me - 1-1/4" main body with five 3/4" taps and two 1" taps. I only was using one of the 1" taps for my furnace and two of the 3/4" taps for water heater and a small radiator for the dog's sleeping area in the basement. I had plans to expand and I never did. I also had a device on one of the 3/4" taps that opened when the zone valve on the furnace coil closed to allow the extra flow go through. The system worked very well and I had each device isolated with ball valves on both sides.
As best I can tell, Earth Lee isn't in business anymore. It looks like you can still buy her products from here though:
http://www.designheating.com/catalog/subcat.cfm?Category=31&SubCat=63 (http://www.designheating.com/catalog/subcat.cfm?Category=31&SubCat=63)
Did you utilize only the main pump for this setup or did you have individual pumps off the taps. Also, when you say "device" what do you mean?
Thanks!
Nick
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I used only one pump, a fairly large Grundfos (model I can't remember right now). I had an electronic ball valve on the HX for the plenum so it didn't always put heat in the duct work when the fan wasn't running. I had an adjustable bypass valve tied in so when the HX in the plenum was closed, the additional flow was able to bypass through that valve. I had two manifolds/headers so one was a "supply" and one was a "return" where the appliances (which I also called devices) were the path between supply and return. My water heater and dog heater were always open and running unless I manually shut them down with the ball valves I had at the manifolds/headers. I used to have pictures of the setup, but ImageShack decided to lock my account out unless I forked over money to them, and I'm not likely to do that.
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I have enjoyed reading the posts on here, so first, a thank you to all the experienced contributors.
I have been looking at Heatmor and Earth Outdoor Furnaces.
I will be heating a 5300 sq ft home (currently with two residential furnaces) and hot water tank. I also want to run a second line to my greenhouse and pool to utilize the furnace in the late summer/fall and early spring. (Northeast Ohio weather)
How large of furnaces are they? Was the house originally set up as a duplex?
How good is the insulation?
When a friend bought a house in town and told me he had two furnaces in the basement I was lost originally as I couldn't remember a house in town that was large enough to need two furnaces, all made sense when he said it used to be a duplex. I think the furnaces in his basement aren't even 70,000 BTU each.
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The house is a large house. No mistaking that. The BTUs on each of the furnaces is either 113K or 142K - Not sure. The house was built with many redundancies, and each furnace supports a zone of the house. One Furnace covers the living room, kitchen and dining room. The other supports the bedrooms and library. When one system was down, the other was able to cover the entire house - decently. The house structure is robust and the insulation is beyond standard.
Seems I can't upload a file - I will list it here...
Burner - Still deciding (Looking at Heatmor 400DCSS and Earth Outdoor 505)
- System #1
--- 170 ft to the house under ground
--- 50 ft in basement to the wall I plan to put the manifold on, 5 ft from each furnace and water heater.
--- Manifold
----- Furnace #1 - Water/Air 20" x 20" - 145K BTU
----- Furnace #2 - Water/Air 20" x 20" - 145K BTU
----- Hot Water - Plate Exchanger - 20 Plate - 5" x 12" - 95K BTU
----- Garage - Water/Air 18" x 18" - 120K BTU w/box fan
----- Extra position for expansion or bypass return (Thanks Judds)
- System #2
--- 40 ft to the Greenhouse
----- Hot Water - Plate Exchanger - 20 Plate - 5" x 12" - 95K BTU
----- Note: I will be utilizing a manifold system from the Hot Water tank to service the under-bed heating system. "Think" radiant "bed" heat for gardens.
--- 130 ft from Greenhouse to 35K Gallon Pool (Equipment location)
----- Shell & Tube Exchange - 600K
--- 170 ft back to burner
I was planning to utilize 1 1/4 inch insulated in ground for all outdoor lines. I assumed I would need large pumps on both as well.
I don't expect to run both systems at the same time. The house will be Late Fall through Early Spring. The Greenhouse will be Early Spring and the Pool will be Spring and Late Summer.
The other option I have is to run two sets of lines to the house. Can manipulate how the loop is done based on the pull. IE, set it up from Furnace #1 to Furnace #2 on the first, and Hot Water to the garage on the second. If the return temps don't work out... do some swapping.
What other information can I provide?
Once I get set on a "design", I will be asking for help on what specific equipment.
Thanks for your help!
~Nick
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I was thinking along the same line as your last post Midnight, instead of one 1-1/4" loop, what about dropping 2 1-inch loops in the trench to the house. Plumb one loop to each individual furnace (one loop/furnace) and than add the hot water to one of the loops and garage heater to the other loop.
I am thinking then you could use one of the loops where it leaves the stove to feed the green house and the 2nd loop to feed the pool, i.e. put your pumps at the stove then split each loop at the stove (after the pumps) and valve them to allow use of only one or the other (house or pool and house or green house). Hope that theory makes sense.
That would allow you to still feed one of the furnaces in the house and shut the 2nd furnace down from the OWB and start heating the greenhouse during that transition season.
Without details of your setup, there is a bunch of assumptions going on here!
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Are there any flow issues created by plumbing a valve right at the back of the furnace (after the pump)?
This idea would allow the use of only two pumps, however you would have to figure out how to have two different sensors driving the same pump (one on the house lines and one for the greenhouse or pool lines). May be that you just flip a switch there too.
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I have a ball valve on my DHW side that has one inlet and two outlets and flow cannot be shut off, only diverted one way or the other (not both). That might be an option for diverting the flow, you would essentially have 4 loops but only be able to flow thru only two of them, i.e. between Loop 1A or 1B and Loop 2A or 2B
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Thanks Wood Nutt... that helps. I guess my question about that ball valve specifically is do you lose much (if any) flow from it?
This option with basically 4 loops is great, however, that is a lot of extra insulated pipe. And at $5 to $10 a foot for it, and lengths of 150 feet to the house, it starts to add up. If I could do it with a large line to the Manifold at the house, I am assuming it would be cheaper, and potentially a more controllable option.
Any other thoughts about Manifolds at the house? Anyone have pictures or other links for these?
Thanks!
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I don't know were all 4 of the heating places are in relation to each another, but you can basically put the pumps wherever you have electricity and protection from freezing when not in use (back of OWB, house, etc). Hopefully, that would minimize the amount of insulated pipe you would need. You should also be able to get a single insulated set with 4 each 1-inch lines in it if that works better and at a lower unit price than 2 sets with only 2 each 1-inch lines in them.
Here is a link to one of the valves
http://www.zoro.com/g/3-Way%20Bronze%20Ball%20Diverter%20Valves/00060026/None (http://www.zoro.com/g/3-Way%20Bronze%20Ball%20Diverter%20Valves/00060026/None)
and it comes in both 1 and 1-1/4". I actually have the 3/4" valve but it is on my DHW side and I bypass my plate exchanger with it in the summer when the OWB is not in operation.
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I have continued to look into the Manifold idea. Unfortunately, I can't find any that are rated for more than 2.3 gpm out of each line. The Manifold itself is rated for a total of 15 to 18gpm. I am assuming, 2.3gpm to a furnace probably isn't enough. Thoughts?
Second question: The dual loop idea. Is there calculators I can use to determine if my pipe diameter, distance from burner, and devices will pull too much temperature, thus sending the water back to the OWB to cool? The information is 150ft x 1 1/4inch from burner to house, 50ft x 1 1/4inch from wall to furnace (160K BTU Water/Air Exchanger), 10 ft x 1 from furnace to water heater (Brazed Plate Exchanger 5 inch x 12 inch x 20 plate, 97K BTU), 50 ft to wall, then 150ft back to burner.
Lastly- Is there any issue/advantage/disadvantage of going from a 1 1/4 supply and return line, down to the 1 inch for the heat exchange devices? Or is it best to utilize a 1 inch supply and return line to match the equipment?
Thanks!
~Nick
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I have continued to look into the Manifold idea. Unfortunately, I can't find any that are rated for more than 2.3 gpm out of each line. The Manifold itself is rated for a total of 15 to 18gpm. I am assuming, 2.3gpm to a furnace probably isn't enough. Thoughts?
With this manifold/header (whatever you want to call it) flow for each loop would be about 5.5 GPM (3/4" Copper at 4ft/s) and the whole manifold at about 15.3 GPM (1-1/4" Copper at 4ft/s): http://www.pexuniverse.com/sioux-chief-12-port-copper-manifold-6795l-12333 (http://www.pexuniverse.com/sioux-chief-12-port-copper-manifold-6795l-12333)
There should be no perfomance issue necking down 1-1/4" to 1" for heat exchanger, other than more water in system and that your system will see less head pressure with the larger 1-1/4" feed lines versuses 1" lines, at a same GPM. One down side is 1-1/4" is $$$ more than 1" ;D
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buy one of those for 85 bucks, cut it in half and you have about the cheapest manifold you will find and likely more ports than you could deliver water too (unless you were cutting them down to 1/2 inch)
1.25 pex at 4 feet per second is 11.2 gpm
if after the header you were using 3/4 copper it is rated at 6.5 gpm at 4 feet per second
so, 2 copper runs off the main header could draw all the water (more actually) then the 1.25 pex could deliver. However if the delivery water was 180 degrees and figuring your delta of 20 degrees you could expect to have 110,000 btu per hour to divide amongst any outlets you add to the main header.
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Willie, you can run PEX faster than 4ft/s; 1-1/4" PEX at 8ft/s if like 21GPM or something. Velocities over 8ft/s IN ANY HYDRONIC SYSTEM can be an issue of noise and/or turbulence.
NOW THAT BEING SAID, the velocity (over 4ft/s) is only an issue with METALLIC parts. Because as you exceed a water temperature of 140f, erosion of metal can occur if the velocity is over 4ft/s and you can develop pin hole leak eventually (typically after a sharp bend in the pipe).
I personnally do not run water than fast in any of my systems, but I also have a lot of inslab, which does not require a high flow rate
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I understand you can pump more water than the number I used but I think(if I was figuring right) 20 gpm through 200 feet of 1 1/4 pex would be a head pressure of about 30 feet, that would take a large pump and lots of electricity. (here in Ontario where we have ((I think) the most expensive electricity in the world) that would cost a lot to operate so I used a number that would put you at about 12 feet of head in that length of pipe
I think 20 gpm was 30 feet of head
16 gpm was 19 feet of head and
12 gpm was 12 feet of head
I think a grundfos 26-99 would do the 12 or 16 gpm
I never looked to see what type of pump you may need for the 20 gpm
here in my part of Ontario Canada we are up to right now (and another price hike coming soon) about 22 to 25 cents per KWH
for me to run this pump 24/7 would cost me about 1.20 per day
I think power in the states is likely about a quarter the cost?
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Willie I agree, just BECAUSE YOU CAN DOES NOT MEAN YOU SHOULD, run that fast (8ft/s), that is why I added the note about erosion of metal parts in hydronic system when velocities get above 4ft/s and the issues of turbulance and noise.
BTW, I also like smaller pumps ;D, electicity isn't as bad as Canada's, YET