natural gas delivery pressure

rgar98

Hello,
We Just moved into a 45 year old house in Montgomery County, Maryland with an oil furnace and I want to convert to NG. Washington Gas needs to know if I want 0.25 psi or 2 psi delivery. I will have a 90K BTU gas furnace and 80K BTU range (these are both approximations); no other appliances are planned, for now. A contractor suggests the 2 psi option in case I want to add other gas appliances in the future. Does this sound reasonable? If I were to add a 40K water heater would that mean I would need to have a 2 PSI line? Obviously, I'm just learning about this subject and any suggestions would be appreciated.
Thanks.
Richard

doc_havoc

Not only will a 2 psi line provide lots of room for expansion in the future, but it will also require a smaller gas line to deliver the gas, making the installation easier. A .25 psi system will require a much larger gas line to move the same amount of gas, making installation much more difficult. I personally would go with the 2 psi system.

Jamie Hall

2 psi. As @doc_havoc said, it gives you room for expansion, and you can always regulate the pressure down -- in fact, you will anyway -- but you can't regulate it up.

Tim McElwain

As an old gas man 50 years in the business I would go with the lower pressure. With the appliances you have listed that is all you need. Keep in mind the regulator on the gas equipment is reducing the pressure typically down to 3.5" W.C. (27.6" W.C. is a pound pressure).

Is your gas range a commercial range? It seems that 80,000 is pretty high most ranges are 10,000 BTU's per top burner (40,000) the oven then is 25,000 so a total of 65,000 BTU's. You can still add the 40,000 BTU water heater. You will need a meter that allows approximately 250,000 so a residential America Meter AL-250 would be fine all operating at low pressure.

ChrisJ

I would never start out with 2 psi if you're running all new pipe.

If running new pipe size it for 1/4 psi and size it for some expansion.

If you ever had an issue down the road and need more gas you can then add regulators and go up to 2 psi.

mikeg2015

Regulators are one more thing to fail, leak or have someone install incorrectly and soot up the system or worse. Only reason would eb to save money. But you should be able to do it all in 3/4” black with maybe the initial header in 1” for future expansion. Easy to thread.

mattmia2

That really is a weird argument that the only reason to use 2 psig distribution is to save money. I would argue the only reason we use 7" wc distribution is historic, that it was sized for gas lighting, not for appliance service and to carry gas at that pressure to actual heating appliances requires insanely large piping. It is really more heavy wall duct work than piping at the traditional gas distribution pressure.

Zman

Maybe folks in other parts of the country think differently about this. I just can't imagine a house with a load of ~170k going to 2# gas. At 7" you would need 1" pipe max and just for the main piping. Would you go with 2# so you could use 1/2"pipe and then add step down regulators to the appliances? I am truly curious if folks are using 2# gas on small residential projects. Where I am, 2# is for commercial work and residential jobs where the contractor is bad at math. We do occasionally see 2# for really big custom homes where they are trying to avoid welded pipe.

ratio

I've never seen a house with 2# run inside, it's (AFAIK) 2# to the meter setting & then a regulator to drop it to ±7".

Personally, that's how I'd do it, that would open you up to a whole-house generator if desired (tap the 2" before the regulator) and still have low pressure inside the house.

Whatever you run, make sure to size the pipes properly.

ChrisJ

ratio said:

I've never seen a house with 2# run inside, it's (AFAIK) 2# to the meter setting & then a regulator to drop it to ±7".

Personally, that's how I'd do it, that would open you up to a whole-house generator if desired (tap the 2" before the regulator) and still have low pressure inside the house.

Whatever you run, make sure to size the pipes properly.

My boss originally had LPG and when we converted his house to NG the piping wasn't big enough. This wasn't an issue, except for a run from the basement to the attic. Since that was very difficult to swap we just converted the entire system to 2 pounds with a regulator at each appliance. All of it of course had to be inspected etc.

Zman

ratio said:

I've never seen a house with 2# run inside, it's (AFAIK) 2# to the meter setting & then a regulator to drop it to ±7".

Personally, that's how I'd do it, that would open you up to a whole-house generator if desired (tap the 2" before the regulator) and still have low pressure inside the house.

Whatever you run, make sure to size the pipes properly.

Pressure to the meter can be almost any pressure, 2# is not standard on the utility side. I believe that in my are it varies from 10# to 100#. On older systems it can be < 1#.

Zman

What I see as very common is a GC that goes with "bigger is better" and orders a 2# service. They then don't tell the heating, fireplace and appliance folks who just hook up there appliances as they normally would without step down regulators. Sure enough, the high pressure damages the appliances and ends up costing a bunch of $$$$

mattmia2

I have a question here. Is there any technical reason that the regulators built in to appliances couldn't be designed to handle anywhere from 4 " wc up to 2 psig and regulate it down to the 2 or 3 " wc the manifold requires?

pecmsg

mattmia2 said:

I have a question here. Is there any technical reason that the regulators built in to appliances couldn't be designed to handle anywhere from 4 " wc up to 2 psig and regulate it down to the 2 or 3 " wc the manifold requires?

Sure they could but in this cheap, cheaper, cheapest market no one is willing to pay for it!

Tim McElwain

@mattmia2 Regulators built into appliances are actually built into the gas valves. To change that would push the cost of gas valves through the roof.

The hybrid 2 pound systems are ideal if a typical regulator manifold is applied and then pressure is reduced to 1/2 lb or less to the equipment. Maximum pressure to all gas valves is 14" W.C.

ChrisJ

Tim McElwain said:

@mattmia2 Regulators built into appliances are actually built into the gas valves. To change that would push the cost of gas valves through the roof.

The hybrid 2 pound systems are ideal if a typical regulator manifold is applied and then pressure is reduced to 1/2 lb or less to the equipment. Maximum pressure to all gas valves is 14" W.C.

@Tim McElwain Isn't there a rule regarding venting such regulators as well? The 2 PSI regulators we installed had vent limiters, but it was really recommended and safer to vent them outdoors and I believe many places required it by code? Is that due to the pressure, or the style of regulator?

Zman

rgar98 said:

Hello,
We Just moved into a 45 year old house in Montgomery County, Maryland with an oil furnace and I want to convert to NG. Washington Gas needs to know if I want 0.25 psi or 2 psi delivery. I will have a 90K BTU gas furnace and 80K BTU range (these are both approximations); no other appliances are planned, for now. A contractor suggests the 2 psi option in case I want to add other gas appliances in the future. Does this sound reasonable? If I were to add a 40K water heater would that mean I would need to have a 2 PSI line? Obviously, I'm just learning about this subject and any suggestions would be appreciated.
Thanks.
Richard

Not sure if the OP is still with us but...
@rgar98
Given the information provided, I would recommend going with .25# gas and sizing your piping for modest future expansion. In the event you add a monster load to the system like a whole house generator, you can always change over to 2# gas and add regulators to each appliance.
KISS (keep it simple....)

ratio

Vent limiters will slow down the regulator. If you've only got one appliance on the regulator, when the valve closes the regulator may not be able to close fast enough to keep the pressure from overshooting. I've seen 12+ inches before on a regular set to ±7 inches.

I really wish vent limiters were illegal across the board.

ChrisJ

k

ratio said:

Vent limiters will slow down the regulator. If you've only got one appliance on the regulator, when the valve closes the regulator may not be able to close fast enough to keep the pressure from overshooting. I've seen 12+ inches before on a regular set to ±7 inches.

I really wish vent limiters were illegal across the board.

But as soon as the gas valve opens that pressure will drop immediately. So does it really matter?