Question about where to run underground pipe for IWB

shawnr

Member
Oct 13, 2012
6
Patterson, New York
Hi everyone,
I posted this in another sticky on underground piping, but wasn't sure if I was hijacking someone else's thread, so I thought I'd start a new one here.

I've been planning my wood boiler installation for next season and did some measuring yesterday and found that I can really save some underground distance depending on where I enter my basement to connect to the existing system and again where I enter the shed for the IWB. So I guess the question is...if I can save substantial length of buried pipe by entering a building at the closest point and then run the less expensive pex along the wall or ceiling to the boilers, is it a better option. I can always insulate the indoor pipe to reduce heat loss, and it will be in a heated space anyway. The difference in underground pipe length ( and cost) is significant. 115 feet vs. 170 feet. give or take a few feet either way.
Thanks for your thoughts on this.
Shawn​
 

wrightk20

Member
Nov 1, 2012
63
I would definitely go for the shortest under ground possible. Also make sure you use the correct size of piping for your load. Kevin
 

stee6043

Minister of Fire
Aug 22, 2008
2,624
West Michigan
Inside is almost always going to be better. Any heat lost from the pex inside the house is not really "lost". It's contributing to the heating of your home.

And as stated above don't fall into the 1" burried pex trap if your heat loads suggest you need more. Do some reading. Consider burying (4) 1" lines instead of two if you feel you're going to be on the edge with 1" line.
 

Tennman

Minister of Fire
Mar 4, 2009
983
Southern Tenn
Shawn, Stee summarized it. There are an number of users here that have undersized lines for their heat loads because they were ill advised by an installer. This results in high velocity flow (more electricity) in order to transfer the necessary btus/hr. So whatever you do don't skimp in the pex diameter. The Taco Data Sheet is a great tool for sizing your lines if you're inclined to do some math. Many systems here with enough experience given boiler capacity and run length whether 1" or 1.25" is your best route (or (4) of the 1"). And anywhere you can minimize energy leakage, either by shorter runs or better insulation all the better. I posted on the Underground sticky my recorded energy loss/ft of run (I now have very good underground insulation). Easy to compute how many degrees of energy you save by reducing line length. And absolutely if you want to "leak" energy anywhere do it in the house. This is the place to ask away to save pain later. Read my underground horror story to avoid my mistakes.
 

shawnr

Member
Oct 13, 2012
6
Patterson, New York
Thanks for the replies! I bought my IWB in October, with the intent of installing for next year. I asked a question on this site early on about my set-up and quickly realized I had many more questions than answers. I will spend some time on the Taco site to determine my load. If I run into some trouble, I'm hopeful that someone here can help me with the load calc's.
Tennman...I've read and re-read your post a half dozen times and have seriously considered the route you took with the closed cell spray foam.
Thanks,
Shawn
 

91LMS

Member
Oct 20, 2011
217
MAINE
make sure you do research enough to be sure how you will tie into your existing system as well. i got 50/50 feedback between local installers and replies here..... i would change it now if it were that easy.
 

Tennman

Minister of Fire
Mar 4, 2009
983
Southern Tenn
If you're handy with spreadsheets, I built a spreadsheet of the Taco TD10 datasheet used to compute head, line losses, and do Taco pump selection. If you want a copy of the spreadsheet just PM your email and I'll send it. It's very easy to use with color coded input and output fields. Just follow the steps in TD10 and populate the spreadsheet. For any boiler DIY'er I found the TD10 very educational for understanding the flow characteristics of your system whether you use TACO or not. AND has sometimes revealed sizing lines based on experience resulted in undersized pex resulting in way too high flow velocity. My system is on the edge as far as velocity which causes same effects as high speed aero flow skin friction... drag.... pressure losses.... and more horsepower required to push it the velocity to get the energy/time output capability of the boiler. For my system's distance and energy demands I should have used 1 1/2" so my recurring electrical costs could have been lower..... But that will only happen in my next life. Your total distance and boiler size gets you in the ballpark.