Natural Gas Black Pipe Sizing question

Users who are viewing this thread

gwdew

New Member
Messages
3
Reaction score
0
Points
1
Location
New Jersey
Can someone give me advice on the attached as-built drawing. I'd like to know if the piping after the attic furnace is sufficient? I'm thinking it should be 1 1/4" instead of just 1" to carry the 344k load after the attic furnance. My plumber says it is, but I'm thinking the furnance or the tankless water heater will starve if other appliances are used.
 
Last edited by a moderator:

hj

Master Plumber
Messages
33,599
Reaction score
1,037
Points
113
Location
Cave Creek, Arizona
Website
www.terrylove.com
It is almost impossible to read, but in order to use any table, you have to add the lengths of EVERY section between the meter and the farthest appliance, plus the "equivalent lengths" of every fitting in the run. THEN you can compute the required sizes for each section.
 

Dj2

In the Trades
Messages
2,611
Reaction score
258
Points
83
Location
California
If you have similar natural gas pressure as in my city, it would be plenty enough. Listen to your plumber. Contact your natural gas provider and ask them, they know what pressure they have in the supply pipes.
 

Jadnashua

Retired Defense Industry Engineer xxx
Messages
32,771
Reaction score
1,191
Points
113
Location
New England
There's a regulator at the gas meter. Both that and the meter must be capable of the volume of gas you require. Usually, the input to that is of high enough pressure that you would be unlikely to overload the supply. THen, the gas moving through pipes and fittings in the house will experience friction, which will limit how much volume can flow through. The regulator will keep the inlet pressure constant as long as you're not asking for more than it can provide, but friction to the devices through the piping will determine if the pressure drop is out of spec for the volume of gas the devices are designed for. Longer pipe, smaller diameter, more fittings, all affect how much can flow through the pipes. It should be designed for worst case when all devices are calling for maximum at the same time. That takes some calculations.

Ever tried to drink a milkshake with a small straw? Really tough. Your gas appliances don't 'pull' the gas through, but the pressure is quite small...the opening must be large enough, or it won't work well, if at all.
 

Jadnashua

Retired Defense Industry Engineer xxx
Messages
32,771
Reaction score
1,191
Points
113
Location
New England
The pressure in the "supply pipes" is irrelevant, because it more than adequate and many, many, many times higher than your house piping.
I think, that's what I said!

But, adding more devices IN the house or not having those pipes of sufficient size, or having a meter and regulator not designed for the intended volume, all could affect the home's gas appliances' performance. FOr example, I think I remember my gas meter having a cast in legend saying up to X cuft/min maximum. Regardless of the input pressure from the utility, asking it to provide more than that is asking for problems, just like having too small pipe inside the house to feed them all. FWIW, my supply is on a quite high gas pressure main, so it would never be a utility supply issue, at least for a typical home, but the meter, regulator, and internal supply lines ARE part of the potential problem that may limit the operational capability. Use the tables to account for the BTU demand, the distance and size of pipe and the quantity and type of fittings, and match or exceed that, and it will work. Otherwise, you may have intermittent problems as the combination of things combine to maybe exceed the capacity of the system to work. Take a cold day in winter...cooking Christmas dinner, all burners going, a turkey in the oven, furnace blasting, doing a load of laundry, everyone taking their showers, your gas delivery needs to be adequate. Most other days, you may never notice.
 

gwdew

New Member
Messages
3
Reaction score
0
Points
1
Location
New Jersey
Thanks for all the input guys....Well, to give you a bit more info the longest run of piping from the meter to the furthest appliance is about 60 ft and the total load is 755,000 BTU's. If you guys can provide any additional info I'd really appreciate it. I'd hate to have appliances starving for fuel and then cutting out, leaving me with no hot water, or heat, or electricity, etc...
 

gwdew

New Member
Messages
3
Reaction score
0
Points
1
Location
New Jersey
My gas service provider is coming out next week to install an "800 meter", if that means anything to you guys. I have to have my rough inspection (which I passed) and one appliance hooked up prior to them coming out to change the meter.
 

Jadnashua

Retired Defense Industry Engineer xxx
Messages
32,771
Reaction score
1,191
Points
113
Location
New England
My gas service provider is coming out next week to install an "800 meter", if that means anything to you guys. I have to have my rough inspection (which I passed) and one appliance hooked up prior to them coming out to change the meter.
It sounds like it's rated for 800SCFM (standard cubic feet per hour). A cubic foot of natural gas has about 1,000BTU, so 800*1,000 = 800K BTU approximately. The actual energy varies by the mix of components in the gas.
 
Top
Hey, wait a minute.

This is awkward, but...

It looks like you're using an ad blocker. We get it, but (1) terrylove.com can't live without ads, and (2) ad blockers can cause issues with videos and comments. If you'd like to support the site, please allow ads.

If any particular ad is your REASON for blocking ads, please let us know. We might be able to do something about it. Thanks.
I've Disabled AdBlock    No Thanks