Gas line to outbuilding - sizing questions

ururk

I posted on another website and the recommendation was for a 1" line, but when I called the local HVAC place (without sizing anything) the guy I talked with said to go with 1-1/4" pipe. This is my situation:

Maximum 150' run (after everything is installed, probably 130'), 1" SDR-11.
7" WC at meter
1" meter outlet
Meter rated for 400K BTU
Currently using 130K BTU total - water heater & furnace

I want to provide a gas line for a boiler - Viessmann B1HA 26 in an outbuilding for radiant heating. Boiler is rated up to 94K BTU.

When I look at charts for SDR-11 sizing, 1" appears to be sufficient... but 1 1/4" provides a significant increase of capacity so I'm leaning towards installing the larger pipe. However...

The meter has just a 1" outlet - to use a 1-1/4" pipe, will I have to increase the meter size? Would I be better off requesting a pressure increase and adding regulators at the house and outbuilding?

I'll be installing the gas line - pulling a mechanical permit - and will have an HVAC company connect the line once approved.

Alan (California Radiant) Forbes

One inch schedule 40 steel or polyethylene will carry well over 100K BTU for 150'. Don't have tables for SDR-11.

I'm like you and will (almost) always oversize although as I see it, 1" is already oversized for you unless you want to add a few more appliances.

If you use 1-1/4" pipe, just come off that 1" fitting with an increaser. The small length of 1" will not impede flow. What kills flow is the friction loss/pressure drop of long lengths.

ururk

SDR-11 is listed at 127K for a .3" drop, 168k for a .5" drop.

I will be installing an electric point of use water heater, as I don't expect to use hot water that often (maybe to wash my hands).

EBEBRATT-Ed

Make sure your meter will handle the additional flow. You only have 6" wc , what is the rated inlet pressure of the of the boiler?

Ironman

Proper design is the foundation and key to having a radiant floor that's efficient and functions properly. Make sure you have that before doing anything else. There's a lot more to it than just laying tubing.

Tim McElwain

Is this line being buried? If so minimum size is 1 1/4" per code.

Zman

Tim McElwain said:

Is this line being buried? If so minimum size is 1 1/4" per code.

Which code?

GroundUp

Tim McElwain said:

Is this line being buried? If so minimum size is 1 1/4" per code.

Maybe YOUR code, but certainly not mine. There is 1/2" buried statewide in MN

ururk

1) Ironman - I had a radiant heat company draw up (paid) plans and I installed in-floor (concrete) pex according to those plans. They sized the boiler according to my structure's insulation and layout.

2) EBEBRATT-Ed - I called the gas company and they told me 7" WC. Meter is rated up to 400K BTU/h. Boiler is rated for a minimum of 4" WC.

3) Line is being buried. 1" is acceptable - provided it provides enough BTUs.

Ironman

I hope you're not direct burying iron pipe. It has to be coated.

ururk

Ironman said:

I hope you're not direct burying iron pipe. It has to be coated.

No - I'm using gas-rated yellow poly line, SDR-11, with proper tracer wire, anode-less risers (the pipe slips into the risers so there are no underground joints).

Alan (California Radiant) Forbes

Polyethylene? Do you have a link to the specifications? Just curious.

What's the burial depth? 36" usually.

ururk

Alan (California Radiant) Forbes said:

Polyethylene? Do you have a link to the specifications? Just curious.

What's the burial depth? 36" usually.

https://www.cresline.com/uploads/pe161yg.pdf

1" IPS

As for burial depth... need to find out. I've been told everything from 12" to 24" by different tradesmen in my area, trying to get in touch with the inspector to find out for sure.

STEVEusaPA

Don't forget tracer wire...

mattmia2

Look in the code, it will tell you what the depth needs to be for your application.

Tim McElwain

Here is some good info from Dave Yates:
Does pool need own gas line?
VIA E-MAIL I saw Dave Yates' column about swimming pools at contractormag.com and have a question about gas lines for pool heaters ("Spring means it's pool heater mania time," May, pg. 52). We plan to install a 333,000 Btuh heater and feed it natural gas. Do we need a dedicated gas line from the meter, or can we just splice into the existing gas lines in the house? I have heard that a unique line

NOV 01, 2006

VIA E-MAIL — I saw Dave Yates' column about swimming pools at contractormag.com and have a question about gas lines for pool heaters ("Spring means it's pool heater mania time," May, pg. 52).

We plan to install a 333,000 Btuh heater and feed it natural gas. Do we need a dedicated gas line from the meter, or can we just splice into the existing gas lines in the house? I have heard that a unique line prevents heater startup from sucking all the gas out of the lines and extinguishing pilot lights. Is this a valid issue these days?

The heater will be about 60 ft. from the nearest gas users (furnace and water heater). We live in California and will not use the pool heater that often.

PETER MCINTOSH

Dave Yates replies: Two primary issues come into play:

Can the existing gas meter support the load? In other words, can it pass enough gas (no pun intended) if all appliances connected are "on"?
Is that existing gas line large enough to carry the total connected load? I doubt it is, in which case a dedicated line is typically the easiest and least expensive route.
Also important is the Btu content of your natural gas and the pressure at which it's delivered. For my area, a 60-ft. run of natural gas for that load would dictate we utilize 1.25-in. plastic piping with risers at both ends (outdoors) and then black iron piping at both ends to connect to the pool heater and gas meter or existing piping.

If your furnace is 80,000 Btuh and you have a gas water heater (tank style) with 50,000 Btuh, you'll have a combined load of 463,000 Btuh. If you have 40 ft. of gas piping (each ell = 5 ft. of straight piping) up to the branch lines serving the furnace, that portion (in my area) would need to be 1.25-in. diameter. The additional 60-ft. run would transition to 1.25-in. SDR-35 plastic pipe that's buried with a bed of crushed rock dust, with a barrier warning tape on top of that bed and a tracer wire for electronic line detection laid in the trench prior to backfilling.

Attaching a large load to an undersized line can indeed pull enough to cause pilot outages, but the larger concern is the potential for starving other appliances and creating potential combustion issues that could ruin the equipment or create a carbon monoxide incident within the home.

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Zman

I am not sure ehat Tim is getting at.

Tim McElwain said:

Is this line being buried? If so minimum size is 1 1/4" per code.

In the example Tim posted from 2006, 1 1/4" was correct. As for this post, 1" would be sufficient. There is no harm in going with the bigger size.
https://www.pexuniverse.com/uploads/literature/pf-pe-man.pdf