Pipe Sizing For Boiler System

[Countryboy1966]

Hello everyone. Long story short, I recently moved and the OWB I used to heat my old house will be used to heat my detached garage. I am in the middle of building a system. Fun exciting times!


I did heat loss calculation and I am right around 30,000 BTUs for the current garage.


At some point I am increasing my shop size over the next two years and what was 30,000 BTU's will become approximately 90,000 BTUs. That number is correct as I'm adding on quite a bit of space.


In the end I also plan to tie my house into this system so I'm guessing I'll be somewhere around 160,000 BTUs total once the plan is complete.


In the end all sorts of things need upgraded including my boiler and HX as they will become the constraints. I plan to upgrade to a gasser.


My question is instead of building my system to what I need now, is there any issue I’m not seeing with building my system to how I want it for the long term? I.e. Because my HX and supply lines are 1” I was going to use 1” Copper for everything however I quickly realized I can build a system out of 2” Black pipe for cheaper than my system with 1” Copper. Granted I can build the system on the cheap and get by now, but I wan to do things right.


So I was going to build everything from either 1-1/2” or 2” and then bush down to the 1” lines on the HX so that over time I can replace the HX and the Boiler. I think I’ll have to re-consider the circulation pump sizing as well.


In the end there will be 500-1000 gal pressurized storage involved.


Anyone else have a heat loss of 160,000 BTUs and are covering it just fine with 1-1/2 Black Pipe Lines?

 

[heaterman]

If you're talking about pipe size for your main manifold you'll be fine with 1-1/2" steel. Given the right temp drop from supply to return it's pretty easy to carry 250-300,000btu's in that size pipe.
What you want to pay attention to is the pex runs that will go to all the various loads. Most dealers/installers tend to run 1" to everything just because.........
Often time this is not going to do what you need especially if length gets much past 100' between buildings.

 

[Countryboy1966]

Thank you for the feedback. After looking into this more:

Assuming I would go with an EKO-60 or equivalent the outlet pipe size is 2.5" If I was to maximize my btu transfer would I need to go with a 2.5" main supply manifold or would I be fine with a 1-1/2"?

I tried searching for btu capacity of different diameter iron pipe and struck out. I'm certain there are equations and all that could do.

 

[jebatty]

Your heat loss numbers look quite high to me. My 32 x 48 x 14 shop has a calculated heat loss of about 40,000 btuh, but the highest I have ever actually measured in less than 20,000 btuh when temps are in the -20 to -30'sF range. More normal temp heat loss (temps in the 0-15F range) is around 12-15,000 btuh. Your climate is much warmer than mine. Might your structures be quite poorly insulated, large overhead doors open a lot, etc.? 160,000 btuh heat with wood will take about 30 lbs of wood/hour with an assumed efficiency around 85% at delivering heat to the structure. That's around 1/3 to 1/5 of a full cord of wood per day.

 

[pbvermont]

to jebatty: good questions. the math tells all.

 

[Countryboy1966]

I will re-calculate. I will be heating a well insulated (done by me but I guess I shouldn't assume my insulation job is good) building that is 3,600 square feet. L - shaped. 24X 50 X 9 and the other part 40 x 60 x 16. I'm then considering my 1,800 sq foot house as part of the total heat loss calculation.

 

[jebatty]

Nothing wrong with using lots of wood if that is your need. An environmental learning center where I volunteer, same temperature considerations which affect me, heats 56,000 sq ft at 500,000 btuh delivered to the system from a Wood Gun E500 and that will use one full cord of wood per day at that burn rate and heat the facility at temps down to -10F. It has a separate 6000 sq ft structure, not well insulated, which is heated (including dhw) by a Froling FHG L50 (170,000 btuh rating) and that meets all needs down to the -30'sF.