Gas line sizing assistance - new pool heater

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pickerel

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Good evening, I am respectfully requesting assistance in the sizing of a gas line for a pool heater.

My local inspector will allow me to install the line on my own and once I get a licensed gas fitter to connect to the mainline, they would inspect everything. – hence the question to the experts in the form.

My plan

My plan is to run a trench 20 inches deep (gas line with 18 inches of cover) from the exit point of the house to the equipment pad where the heater will be located and use the direct bury DR 11 Underground Yellow Polyethylene Gas Pipe you can get at home depot with the proper risers to convert back to mip above grade at each exit point. Obviously, add tracer wire too.

Heater info

The pool heater is a Pentair 300,000 btu heater that appears to require a minimum flowing (dynamic) supply of no less than 4.0 in wc. If it helps, the pipe run chart says up to 200 feet “equivalent pipe length” with 1-1/4 pipe and 400’ for 1-1/2 so I was just going to run 1-1/2 from the house to the pad to make up for losses due to fittings, couplings, etc. Also, I may add a (50-60k BTU) patio heater on the line as well about the 1/4 way out from the house – hence the upsizing. But if I cannot, that is ok with me.

So in summary, directly from the meter to the heater I would have approximately 75 feet of 1-1/4 iron pipe and the remainder (125 ft or so) in 1-1/2 direct bury poly out to the heater.

Meter info

The meter is an Elster AL-800. I got the biggest meter I could get when I built. It says it has an MSOP of 20 psi, the meter outlet is 1-1/2 but is reduced to 1-1/4 coming into the hose.

Regulator info

The regulator is an Itron B531 IMRV

out pressure – 7 ihc

main spring is black

orifice size is 5/16 in

Additional loads that would run concurrently to pool heater:

only a typical water heater, and;

Perhaps a patio heater with an estimated load of 50k-60k BTU which would have its own TEE off of the mainline to the pool heater approximately 20-30 fet from the house or about 100 feet from the meter.

Questions

1. I am wondering if this setup is sufficient for size? Home flex says maximum capacity of 368k btu/hr for 125 ft of their pipe (and 333k BTU for 150 LF) @ 2 psi and 0.3 in w/c. On a side note, if I assume 10 equivalent feet of loss for every bend, tee, coupling, etc., used in their assembly the “equivalent length” adds up fast further pushing me into the 1-1/2 diameter range.

2. Can I combine other things in the same trench? I would like to add some irrigation main lines and some electrical conduit in the same trench for the pool electrical

3. Any restrictions regarding where the gas pipe outlets the house? (i.e., proximity to other vents, fresh air intakes, etc. I checked the IRC and I am not finding anything that says the gas line cannot exit the foundation above grade in proximity to furnace power vent exhausts, etc.

4. Am i missing something? I always miss something.....

Thanks to all for help. I want to learn about this and get smarter and do things right. Please let me know if you have any questions or need further information.
 

Jeff H Young

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360,000 btu and you are OVER 200 foot not under ( 75 ft plus 125) Whatever code you have pretty simple to figure. You could go smaller after tee possibly ( patio heater) save couple bucks . Anyway If you say its 1 1/2" sounds close I dont know which code you use. Id ask about a combined trench with inspector. Exit house where ever you want
 

pickerel

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Yes you are correct regarding overall length I apologize as the post left the overall length ambiguous. Yes There is likely over 200 leet of run not accounting for losses.

For sizing I was using both the pool heater chart and the chart for the specific gas line I would use outdoors for diameter sizing and looking at both to see what seemed reasonable

I will check the IBC and report back about what I think I can determine from that - I have that at home

2.0 understood regarding the combined trench. I will ask the inspector now that I know the terminology

thanks
 

Jeff H Young

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By the way. Your inspector might be going easy on you Our Inspectors sometimes ask for certification in the pipe process, Whether fusion weld, or even for the push fit fittings . Not that it matters but Your starting at meter going thru house then underground? I guess Gas fitter will decide how to join your 1 1/2 ' line and your house line (1 or 1 1/4 line im guessing) It might have a 2 inch tee and nipple at meter.
 

Reach4

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I have no answers, but you might consider planning for a potential whole-house generator while you are at it.

You might also ask your gas company about the possibility of of raising your incoming gas pressure from 7 inch water column (0.25 psi) to 2 psi. That would require a regulator at your various gas appliances, but it would make it much easier to send gas to the pool or whole-house generator.
 
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pickerel

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Yeah. Good point - he never said anything about reviewing and cents but that is a very good question.

To clarify , The 1-1/4 is already run in the basement as the furnaces are at the same end of the house as where I am coming out of the building .

all I have to do is size and install the additional footage from the house into the yard to the pool heater.

I got the genset already. When I built I called the gas company and told him what demands I needed and hence the big meter
 

Jeff H Young

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Natural Gas Generator? I dont think any mention of any other gas was wondering about the house being all electric or what but in any case nothing to do with this portion of work.
Congrats on the new house! exciting times and a lot of work no matter who actually does the work so many decisions!
 

wwhitney

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If you can draw up a diagram showing the different loads and the piping network with each segment labeled with the pipe type, size and length, and a link to the sizing tables for the different pipe types, I'd be happy to walk you through the sizing check.

Cheers, Wayne
 
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