Need help with my setup (OWB)

[wise8706]

Guys I've researched and researched, I'm still not finding the answer I'm looking for.

Here's the lowdown and layout.

I am building a house right now. It's a 1400sq ft ranch with radiant infloor heat in the basement. I have a CB 6048 ready to install. I will heat the infloor heat, DHW, a 24'x24' attached garage, and also run a heat exchanger in the furnace.

The problem I have is I'm not exactly sure what size thermopex line I need to run to my house. The run will be around 120ft. No elevation on the run. Can I just go with 1" thermopex or should I check on the 1.25"?? I have read that the smaller the line the more friction and less flow I will be able to get. Any help would be appreciated.

The stove will also be heat the polebarn I'm building with infloor heat. (32x56x12'walls)

Main question is how big of thermopex I should run to house.
2nd question is am I overloading this stove by heat in this much area? The polebarn will be zoned and more than likely partitioned off and only heating half of it.




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[Oxford]

Get and read the book "Pumping Away" by Dan Holohan. It's aimed at pressurized systems, but it covers the principles of primary/secondary pumping, which is how you're going to want to pipe your system. There are useful formulae in it that will assist you in your sizing and flow questions.

Search the forum for @Kevin in Ohio and his system. He really did his right, and if everyone did it as well as he did, the forum wouldn't get nearly so many "I have a 350000 BTU/hr OWB and my house is still cold- why?" questions.

 

[mohick]

you are asking-expecting a lot out of your O W B. you'r location wasen't listed but if you are in the cold north you'r screwed!!!!!!!!!

 

[wise8706]

Im in Michigan. And I'm not screwed I will just have to heat less of my polebarn with the OWB and use an IWB.

Also mohick, I beleive after a lot of research the 6048 will be a plenty big enough stove for my needs. Even if I wanted to heat the hole 32x56 polebarn.
The calculation I come up with heat everything is 300,000 btus. The stove has a max of 500,00. Hence the reseason I beleive I have plenty big enough stove.
House 1400sqft x2 for basement floor heat
576sq ft attached garage.
1800sq ft polebarn
=5176 total sq ft.
Considering 50btu's/sq ft per my climate.

=285,000 btu's total.

Someone please correct me if my calculations are wrong.
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[Oxford]

In my experience, the higher the load, the better your system will run. In particular, you'll have less smolder time and so less smoke and smell. Again, the numbers will tell the story.

 

[NSMaple1]

IMO 1" would be waaayy too small.

Don't really know the layout though. Will the heat be going 3 different ways from the OWB, or all only one way to a central manifold/HX, or some kind of combo?

If you check this out:

http://www.taco-hvac.com/uploads/FileLibrary/SelectingCirculators.pdf

you can get a handle on some things.

Using your 300,000 BTU/hr figure, 2" pex would be marginal at acceptable flow rates and dT of 20° (considered a decent dT to run). I suspect though that 300,000 is an overestimation.

Using the same 20°dT assumption, you can also deduce from the first step there, that 1" pex is only good for transfering 75,000 BTU/hr at acceptable flow rates.

OWB installs are notorious for undersizing their underground piping.

 

[wise8706]

IMO 1" would be waaayy too small.

Don't really know the layout though. Will the heat be going 3 different ways from the OWB, or all only one way to a central manifold/HX, or some kind of combo?

If you check this out:

http://www.taco-hvac.com/uploads/FileLibrary/SelectingCirculators.pdf

you can get a handle on some things.

Using your 300,000 BTU/hr figure, 2" pex would be marginal at acceptable flow rates and dT of 20° (considered a decent dT to run). I suspect though that 300,000 is an overestimation.

Using the same 20°dT assumption, you can also deduce from the first step there, that 1" pex is only good for transfering 75,000 BTU/hr at acceptable flow rates.

OWB installs are notorious for undersizing their underground piping.

Nsmaple,
Thanks a lot for the response. The polebarn will be a 50' run from the stove facing 11oclock from the stove door.
The house will be 120' facing 2oclock from the stove door.


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[NSMaple1]

You should do or have done some heat loss calcs on everything in order to come up with a reliable answer. 50btu/sq.ft. sounds excessive for new construction.

A partially heated pole barn with flexibility in how much of it you are going to heat, like you are describing, sounds like an ideal place for an indoor gasifier and your entire winters wood. With storage either also there or in the house or garage. You would see a big reduction in wood useage, and all that goes with that, over its life cycle.

 

[Oxford]

Nsmaple,
Thanks a lot for the response. The polebarn will be a 50' run from the stove facing 11oclock from the stove door.
The house will be 120' facing 2oclock from the stove door.


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You might want to consider putting a manifold with a pump for each building at the boiler and distribute heating water to each load individually.

 

[wise8706]

You should do or have done some heat loss calcs on everything in order to come up with a reliable answer. 50btu/sq.ft. sounds excessive for new construction.

A partially heated pole barn with flexibility in how much of it you are going to heat, like you are describing, sounds like an ideal place for an indoor gasifier and your entire winters wood. With storage either also there or in the house or garage. You would see a big reduction in wood useage, and all that goes with that, over its life cycle.

Most everything I have read on hVac forums has suggested that my area is around 50-55btus/ sq ft. However there was multiple posts stating that that number is very high and its more than likely somewhere in the range of 35-40.


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[wise8706]

You might want to consider putting a manifold with a pump for each building at the boiler and distribute heating water to each load individually.

I was considering this. One pump for hx in forced air furnace, DHW, and radiant in floor heat.
Run another pump for attached garage.
Finally run another pump for the polebarn.


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[Kevin in Ohio]

I'm heating a 36' x 50' 2 story farm house with full basement, fully insulated 36'x 50' attached garage with radiant floor heat and DHW with a Central boiler 5648 stainless version. I used a 1 inch feed line from boiler and it has been able to keep up for 13 years now. I'm in Ohio a too. I will say this on your barn, Insulation is a HUGE variable here. First year house had ZERO insulation and used 28 cord and it was chilly inside. Redid the house the next year and I've averaged 13 cord since then with everything going. Ask away if you have ?'s

No expert but I have done it with real world experience and solutions.

 

[wise8706]

I'm heating a 36' x 50' 2 story farm hose with full basement, 36'x 50' attached garage with radiant floor heat and DHW with a Central boiler 5648 stainless version. I used a 1 inch feed line from boiler and it has been able to keep up for 13 years now. I'm in Ohio a too. I will say this on your barn. Insulation is a HUGE variable here. First year house had ZERO insulation and used 28 cord and it was chilly inside. Redid the house the next year and I've averaged 13 cord since then. Ask away if you have ?'s

No expert but I have done it with real world experience and solutions.

I looked all over on here trying to find ur pics and ur setup. I knew I saw it a few months ago on here but wasn't able to locate it! Thanks for the pics and info! This is a brand new house. We have pretty strict codes here and energy codes are strict also. Spray foam 2x6 walls and then 14" of blown in on the ceiling. This is only for the house.
The barn will be completely spray foamed. On the walls and blown in in the attic.

Thanks Kevin


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[NSMaple1]

Make sure you insulate under & around the edges of your slabs very well.

 

[Kevin in Ohio]

I looked all over on here trying to find ur pics and ur setup. I knew I saw it a few months ago on here but wasn't able to locate it! Thanks for the pics and info! This is a brand new house. We have pretty strict codes here and energy codes are strict also. Spray foam 2x6 walls and then 14" of blown in on the ceiling. This is only for the house.
The barn will be completely spray foamed. On the walls and blown in in the attic.

Thanks Kevin


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Pics were lost in the hacking they had.

email me for a link

 

[wise8706]

Pics were lost in the hacking they had.

email me for a link

Message sent


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[Jon E]

I have been heating my house in VT for 11 years with a CB 5648, with an 80' run of 1" PEX and less than 2' elevation change. My circulator pumps are Taco 007's - off the shelf at any plumbing or big-box store. The house is a basement with radiant tubing in the slab, plus two currently unheated floors above. The entire house, with the exception of two second-floor bathrooms, is heated with the slab tubing. It's 4300 square feet total including the finished basement. That means that occasionally it's 72 degrees in the basement and only in the low 60's upstairs, but we like it that way. Not once in that time has there been a problem with the system "keeping up". I should add that ALL of my domestic hot water comes off this setup too, so I burn 365 days a year.

However, this year I am adding a 2-story, 24' x 36' garage/workshop to the heat load, also with radiant tubing in the slab. I also will be adding supplemental heat to my 18' round aboveground pool with a tube-style heat exchanger off the same loop. When the pool is being heated the garage loop is shut off, and vice-versa. I plan on adding several components to my system this year to ease up the wood demand. First will be a small electric or propane heater for DHW so that I can shut down the system in the summer for easier maintenance of the OWB. I am also going to finish hooking up all the under-floor staple-up tubing that I was supposed to be using for upstairs heat (and wasn't).

I average 10-12 cords of wood per year including DHW. It will go up a little bit when I start heating my garage, maybe another 2-3 cords.

 

[lindnova]

I heat a 1500 Sq.Ft. ranch (2 levels = 3000 SF) plus a 1200 SF attached garage. In floor heat in basement and garage, forced air furnace and DHW. Spray foam insulation in house and fiberglass in garage (most heat loss there obviously). 1" Pex-Al-Pex and an 011 pump 60 ft from house with a 7 ft elevation drop. I have 1.5" lines out of my Heatmor with a tee and valves for a future detached garage that I probably will never build. I keep the house 68° and garage normally around 55°. Works fine even on the -30 days.

I am no fluid mechanic - sizing was chosen by my furnace dealer, but my system has worked great for 9 years. Everyone I know around here uses 1" pex. Larger pipes mean less resistance and very well may be a good idea especially with the longer distance.

Also, I use between 10 and 14 cords of elm/oak/boxelder mix a year depending on winter.

 

[Timbercreek]

I would use the 1.25" on 120' run.
Your getting up there on friction and head loss. It wont hurt thats for sure.
I had a struggle this winter due to pump sizing and aquastat, and there was lots of finger pointing at the 1" pex on my 125' run.
I inherited the install, but if it was up to me to do over again, i wouldnt hesitate to run bigger lines.

 

[Timbercreek]

Kevin in ohio,
How many plate heat exchanger is that? Looks thin.