Outdoor Wood Furnace Info
All-Purpose OWF Discussions => Advanced Plumbing => Topic started by: morfem on August 11, 2017, 12:06:18 PM
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This is my attempt at designing a system for my house and pole barn running off the same OWB.
I have never done anything like this before so if you have any input of where I am going wrong or have an idea on how to make it better please let me know your thoughts.
I have looked at numerous webpages/videos trying to figure this out.
The Idronics catalogs and Coffee with Callefi videos had allot of good info.
https://www.caleffi.com/usa/en-us/technical-magazine (https://www.caleffi.com/usa/en-us/technical-magazine)
https://www.youtube.com/watch?v=-hEFzCCxz9s&list=PLuuV0ELkYb5VE0I4evUZ30b5U78CRlRdg (https://www.youtube.com/watch?v=-hEFzCCxz9s&list=PLuuV0ELkYb5VE0I4evUZ30b5U78CRlRdg)
The house will have about 250' or Logstor pipe to it and the barn has about 100'.
My thoughts are to have a Primary/Secondary loop system. With one outdoor reset that controls the water temp for both the garage and basement floor heat in the house. And another outdoor reset for the barn to control both concrete zones.
In the house I would like to heat the following.
2 water to air heat exchangers. Mounted in the existing ductwork. One is on the first floor and the other is on the second.
Domestic hot water with a Flat plat heat exchanger. Anti scald valve on top.
Attached garage concrete floor. 3 - 300 ft loops
Basement concrete floor. 6 - 300 ft loops.
Pole barn has the following.
Unit heater hanging from ceiling
Domestic hot water with a Flat plat heat exchanger. Anti scald valve on top.
Small baseboard radiator heater for small bathroom.
Main zone concrete: 8 - 300 ft loops
Secondary zone 1 - 300 ft loop.
Once I get a system design nailed down I need to figure out where to put all the valves, flanges,
drain ports, etc.....
Does anyone know of a free software that would help with system design and part specification?
Thanks for your time.
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Looks like one heck of a system, I would like to see placement of circus on the plans, then let's move from there.
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The small square boxes with the triangle in the middle are my crude representation of the circulating pumps with the triangle pointing in the direction of flow.
Is that what you are asking for Slim?
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Ok, I thought so but wanted to be sure, I haven't had a real chance to digest it, can we talk tommorow.
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Can I start out by asking why the distances to te house and barn are so far from the boiler? Also what boiler do you have, are you currently heating with another fuel source? What kind, how much per season and where do you live?
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The OWB placement is where it worked out the best with building placement any yard layout.
The boiler will be a Portage and main 34-44.
The house is currently heated with a heat pump and there is no heat in the barn.
Not sure on current usage.
Location is southern indiana.
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So a couple of things I see:
I would abandon the tertiary level to the cement loops, if done right there is no reason you cannot run all the cement in floor loops off one pump (secondary off the main loop).
I would also imagine you would want to mix down the water temperature for the cement in floor loops. Sending 160-180 degree water into the cement floor can make standing on top of it uncomfortable on the feet. A much lower temp for those loops would be a better design. 85-105 degree water is usually a good range for cement in floor loops.
There isn't really a reason to divide your primary loop up with the parallel branches. If you are doing a loop, make it a loop, not a bunch of cells. You could run into balancing/starvation issues if you make all those parallel paths in your primary loop. It would be simpler to keep all your secondary loops with close spaced tees off of one continuous primary loop.
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Thanks naturally aspirated. How would I go about having 2 zones in the concrete ran off 1 pump? That would be my preference. I added the tertiary loop in to get by with 1 outdoor reset to lower the water temp.
Are the parallel loops needed? I was thinking that route so the water temp would be the same for all loops and not be low at the last loop like it would be with a serial loop. Is that even a real concern?
What is considered "close" when spacing the t's? Planning on using 1" copper.
I have no real world knowledge about this. Just what I can find on the Ole interweb.
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Why 2 zones in the Crete, is it not an open building, is there separation of the Crete between the zones?
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The 2 zones for the house is 1 for the basement and 1 for the attached garage. And the 2 zones for the barn is the main area and then I have a block room in one corner that is sealed up pretty tight with a dehumidifier in it. I store some items in there that I want to keep secure and not rust. I don't necessarily have to have 2 zones there but thought it would be nice if possible.
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I'm just thinking 2 sections of Crete that are connected and running dramatically different temps Michu crack the Crete.
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Good point. I didn't think about that.
I am thinking about the main part being kept around 55-60 and the other section around 70.
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It's not the inside air temp that I would be concerned with but instead the water temp going into the slab. If you buy your product from a real supply house they will lay out your system for you for free, they will need overall size and placement of doors and windows then they can balance all your loops for you.
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Anybody else want to take a stab at this?
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So a couple of things I see:
There isn't really a reason to divide your primary loop up with the parallel branches. If you are doing a loop, make it a loop, not a bunch of cells. You could run into balancing/starvation issues if you make all those parallel paths in your primary loop. It would be simpler to keep all your secondary loops with close spaced tees off of one continuous primary loop.
I agree, make the primary loop a loop. Place the tees as close as possible to avoid ghost flow. Webstone's P/S purge tees are nice.
I would stack the secondary loops in the barn in this order: domestic FPHX (so it has priority), baseboard rad, unit heater, floor heat. Basically in order of water temp required.
House secondary loop order: Domestic, air handler loop, floor heat. Again in order of priority and temp needed.
Slab water should be able to be close enough in temp to avoid any issues, piping can be spaced to use the same temp water I would think. Separate pump pumping mixed water for each room should be fine unless I'm missing something.
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Any ideas on how I would control 2 concrete zones with 1 outdoor reset?
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Chirp chirp.....
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I guess I missed that but typically an outdoor reset is wired into a relay and it controls all the zones.
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The purpose of outdoor reset is to reduce energy use and cost without sacrificing comfort. The controller lowers boiler water temperature when the outdoor temperature is warmer and increases it when the outdoor temperature is colder. It is for controlling the fuel oil ,propane ,nat gas furnace only not for controlling outside wood furnace temp. The inside boiler should not be heated in the winter. It will be a negative energy flow. When you shut down the wood furnace then it comes into play. Mostly the shoulder months.
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Maybe I am calling it the wrong thing. I had seen one at an outdoor furnace dealer where they had what I thought was an "outdoor reset" hooked into the plumbing before the radiant manifold. It controlled the mixing valve to give warmer water on cold days and cooler water on warm days.
I'm struggling with how the plumbing would be setup to have 1 of them control 2 separate zones with 2 pumps without doing a tertiary loop.
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Tekmar 356 control is what you seen. It senses outside temp and controls a mix valve. Or circulator to do injection mixing in a secondary loop.
Also you will need a heat exchanger for the house. Or you could get steam flash and a lot of air from that upstairs ️HX.
Your primary loops won't work how the cad drew them out. Draw a circle and t off of it. ___|_|____|_|___|_|____.
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I modified the drawing to show a series primary/secondary loop rather than the parallel that I had originally drawn per the recommendations. Drawing attached. Does anybody see any problems with this layout?
I am still struggling to envision how I can use one outdoor reset to control the water temp for 2 different radiant heat zones.
The outdoor reset that I have seen in the past is one from Viega. Attached picture.
Thanks
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I modified the drawing to show a series primary/secondary loop rather than the parallel that I had originally drawn per the recommendations. Drawing attached. Does anybody see any problems with this layout?
I am still struggling to envision how I can use one outdoor reset to control the water temp for 2 different radiant heat zones.
The outdoor reset that I have seen in the past is one from Viega. Attached picture.
Thanks
That primary/secondary loop design looks much better. :thumbup: However see below...
First off, I apologize for not going over your first post a bit closer.
Now, as for the outside reset, I think you may want to reconsider using it at all. You may be far more happy if you use thermostatic mixing valves for your concrete loops, instead of trying to turn your OWB down so low as to have cool enough water for your loops. You will get a couple of major problems if you try to operate your OWB at such low temps, 80-120* depending on the BTU/sq. ft. you are aiming for.
Firstly, flue gas condensation ( https://en.wikipedia.org/wiki/Flue-gas_condensation ). Also check out idronics 10, page 8. One of the primary functions of the new gasification OWBs (your G200 is one) is to burn extremely HOT so as to fully and efficiently combust all the hydrocarbons possible. This is counter in theory to running the stove in a setback or turndown, from a reset. Reference idronics 7 p.9-10 & fig 3-5. This has even caused a bit of a paradigm shift in OWB use in general, With regular non-gasification stoves, you could damper down, and let the stove smolder away when everything was up to temp and no major BTUs were required. Since gasification stoves don't operate in the same turndown capable way, that smoldering style has given way to quick batch burn, and best when thermal storage is used. This is something you may consider implementing to replace the out door reset/turndown problem. The addition of a thermal storage tank will allow you to load up the G200, do an efficient, hot burn, and store all those BTUs in a tank. Reference idronics 10, p.28 fig. 6-12
Secondly, being that you may be unable to turn down the G200 far enough to have cool enough water for the loops, they will end up overshooting your BTU/sq. ft. target. In addition, trying to run your stove so low will make the forced air, radiator, and hot water generation systems extremely inefficient. All of those like the, "hotter is better" for water temperature.
So..... to remedy these issues is probably going to be somewhat expensive. :-[
Being that you are a Caleffi fan (as am I), they offer some storage tanks with the Thermocon line: http://www.supplyhouse.com/Caleffi-NAS20120-119-Gallon-ThermoCon-Storage-Tank-without-Heat-Exchanger
Now, you are still stuck with the problem of having a vast quantity of hot water (in the storage tanks), yet needing cooler water for your concrete loops. There are a couple options here:
Adding a motorized mixing valve before each of the circulators for each loop manifold feed is one. Reference idronics 10, p.37 fig. 7-2 (a fairly close system to which you wish to implement). This can be used with a reset control. It's intelligent, as it can respond to changes in your thermal storage temperature (tank may fall from 180*-160* before a new batch burn. It is also one of the more complex ways to go about things (that's usually what I prefer, but I'm a bit of geek, and a glutton for punishment! :bash: )
There is the option of having a thermostatically controlled (maintains output), but using a cartridge style mixing valve, Reference idronics 7, p.19-20 fig. 4-8. This gives a similar ability to react to input temperatures to maintain the set output temperature. This does so without so many of the fun doo-dads. This is what I play to deply for a system expansion this fall. I'm constructing a heated dog kennel for our new dogs, and have a force air heater for the enclosed house part of the kennel, and a single loop for the pad, both inside the house and out on the exposed pad of the kennel. See attached pdf. :thumbup: This option is fairly reasonable, as the valves are not hugely expensive, and a little more plumbing is all that is required from what you already have.
You could also deploy a complete mixing station, something along the lines of Caleffi 172 series: https://www.caleffi.com/usa/en-us/catalogue/manifold-mixing-station-high-efficiency-pump-1725c1ahe Reference idronics 7 p.34 fig. 6-5. You can find them in most any configuration of port numbers you may need.
Sorry to be a bit of a rain cloud, but starting off with a well designed system seems to be better than trying to come in and modify something you may not be happy with.
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Than you for the detailed response.
I have been calling it an outdoor reset but what I think I mean is an automatic thermostatic mixing valve. I want to lower the temp of the water running through the concrete loops on warmer days and raise it on the cooler ones.
I am on the same page as you on keeping the boiler water at the high temp all the time.
I was hoping to use just one valve for multiple zones to try and cut down on the cost.
I am looking at your diagram for your dog kennel and have a few questions.
The primary/secondary loop going to the house and towel warmers makes sense to me but can you elaborate on the other loop going to the garage and dog kennel?
It looks like there is a mixing valve "ZV999" just after the pump in the primary loop..... and also one before the pump "TMV999" in the secondary zone.
Also do you have a special software to make these diagrams or just using autocad?
No problem on correcting my errors. I only want to do it once!
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Than you for the detailed response.
I have been calling it an outdoor reset but what I think I mean is an automatic thermostatic mixing valve. I want to lower the temp of the water running through the concrete loops on warmer days and raise it on the cooler ones.
I am on the same page as you on keeping the boiler water at the high temp all the time.
I was hoping to use just one valve for multiple zones to try and cut down on the cost.
I am looking at your diagram for your dog kennel and have a few questions.
The primary/secondary loop going to the house and towel warmers makes sense to me but can you elaborate on the other loop going to the garage and dog kennel?
It looks like there is a mixing valve "ZV999" just after the pump in the primary loop..... and also one before the pump "TMV999" in the secondary zone.
Also do you have a special software to make these diagrams or just using autocad?
No problem on correcting my errors. I only want to do it once!
The ZV999 is a 3 way zone valve that will redirect the second main loop back into the stove to keep the return water above the minimum set point. As you can see the two returns have thermocouples just before going back into the stove. That is what will determine if the valve needs to return the hot output directly back in the return, or if the returns are hot enough to provide service to the entire second main loop. It works like a boiler protection valve, and can be replaced with one instead of the zone valve. If you look just to the right of the pink and the T you will see a check valve that forces the flow back into the stove and prevents it from going down the cool return line. I don't anticipate a lot of movement of any valve that is used for boiler protection, as I have a Central Boiler Maxim M250 corn/pellet stove, and not a gasification stove. The M250 can turn down and idle when the high water temp set point has been reached.
The TMV999 is a thermostatic mixing valve (I have not yet finished setting the labels numbers) to mix down the temp for the slab loop.
I am using Microsoft Visio, and some of the Caleffi stencils for it. If a stencil does't exist I use commonly used industry symbols (thermometer/flow meter, ect.) :thumbup: