400K BTU Gas Heater - Need Help with Meter Upgrade

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DSMinAtlanta said:
Is it just the total required load for all gas appliances in the home?
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Yes, that determines the meter size.

The meter is the same for either pressure.

The 425 class meter will be rated in the 425 (0.5" w.c pressure drop) to 583 CFH (1.0" w.c pressure drop) range.

The 425 class can be used up to about 898 SCFH if you allow for a 2" pressure drop.

If you go over 425 CFH, you can increase the regulator to 8" or 9" w.c before the meter to account for the higher pressure drop.

The 630 class meter will be rated in the 630 (0.5" w.c pressure drop) to 900 CFH (1.0" w.c pressure drop) range.

If you go over 630 CFH, you can increase the regulator to 8" w.c before the meter to account for the higher pressure drop.

If your load is over 900 CFH (900,000 btu/hr), you can move up to an 800 class or a 1,000 class meter.

I suspect that a 630 class meter will probably be sufficient unless you have a lot of gas load appliances.

The regulator before the meter determines the gas pressure.

You can do a 2 psi or 7" system.

The main difference is the size of the gas line going to the heater and if you need 2 more regulators.

The gas plumber needs to add up all gas loads and tell you which meter that you need based on the total load.

The gas plumber needs to decide if they want to use 2 psi or 7".
 
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The AC-630 can be used up to about 1,320 SCFH if you allow for a 2" w.c pressure drop.

You can use 9" at the regulator before the meter and that will give you 7" out of the meter at full flow.

If you use a 2 psi (55.4" w.c) regulator before the meter, then you still lose 2" at full flow, but that still gives you 55.4" - 2" = 53.4" w.c inches of water column out of the meter and a capacity of about 1,390 SCFH (1,390,000 btu/hr).

Most likely the 630 class meter should be plenty for your property.

You might even be able to use a 425 class meter up to about 898 SCFH if you allow for a 2" pressure drop, but the supplier needs to make that determination based on the total load.

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JamesW said:
Yes, that determines the meter size.

The meter is the same for either pressure.

The 425 class meter will be rated in the 425 (0.5" w.c pressure drop) to 583 CFH (1.0" w.c pressure drop) range.

The 425 class can be used up to about 898 SCFH if you allow for a 2" pressure drop.

If you go over 425 CFH, you can increase the regulator to 8" or 9" w.c before the meter to account for the higher pressure drop.

The 630 class meter will be rated in the 630 (0.5" w.c pressure drop) to 900 CFH (1.0" w.c pressure drop) range.

If you go over 630 CFH, you can increase the regulator to 8" w.c before the meter to account for the higher pressure drop.

If your load is over 900 CFH (900,000 btu/hr), you can move up to an 800 class or a 1,000 class meter.

I suspect that a 630 class meter will probably be sufficient unless you have a lot of gas load appliances.

The regulator before the meter determines the gas pressure.

You can do a 2 psi or 7" system.

The main difference is the size of the gas line going to the heater and if you need 2 more regulators.

The gas plumber needs to add up all gas loads and tell you which meter that you need based on the total load.

The gas plumber needs to decide if they want to use 2 psi or 7".
Click to expand...

Here is some rough math on what we have today in our house:
  • Tankless Water Heater - rated up to 199K BTU
  • Gas Furnace (4-ton unit) - rated up to 100K BTU (estimated)
  • Outdoor Grill - 32K BTU
  • Fireplace (which we never use) - 70K BTU?
  • Future: Pool Heater - 400K BTU
I thought that giving this list to the gas company would allow them to choose the correct meter. Perhaps if I give this to them and tell them the pool heater only need 7", then they can tell me if a new 7" meter is enough to support everything in the home including the pool heater.
 
Looks like you have about 800 SCFH total, which means that you can use an AC-630 meter.

At 800 SCFH, the pressure drop would be about 0.76".

The meter is rated for either pressure.

The difference is the regulator before the meter.

I would use an 8" w.c regulator before the meter and use 1.25" line for the gas line to the heater.

You could probably use an AL-425 with an 8" w.c regulator before the meter and that will give you up to about 740 SCFH with a 1.5" w.c pressure drop.

That's 6.5" at 740 SCFH.

The 425 class can be used up to about 898 SCFH if you allow for a 2" pressure drop.

That's 6" w.c out of the meter at full flow.

If you have a 0.5" pressure loss for the plumbing, the Dynamic gas pressure at the heater should be at least 5.5", which is 1.5" above the minimum of inlet pressure of 4" w.c.

You can probably use the 425 or the 630 meter, but the gas company should be able to tell you which is better.

The 630 is a safer choice.
 
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I would go with the AC-630 meter and about 7" to 8" for the regulator before the meter and a 1.25" line to the heater.

Can you tell the minimum and maximum gas pressure requirements for each appliance?
  • Tankless Water Heater - rated up to 199K BTU
  • Gas Furnace (4-ton unit) - rated up to 100K BTU (estimated)
  • Outdoor Grill - 32K BTU
  • Fireplace (which we never use) - 70K BTU?
 
We upgraded to the AC-630 meter at 2psi - with 2 regulators to lower to the equipment required 7"w.c. My distance to the pad was about 120' thru the house. Our gas plumber went with corrugated stainless flex line thru the house with only one coupling in the house. Our pad is on the complete opposite side of the house from the gas meter. So there is the main line to 2psi regulator supplied by the gas company in front of the AC-630 meter and then the output of the meter splits into the line to the pool heater and the original plumbing for the house. The first 2psi to 7"w.c. regulator was placed on the original house plumbing and the second 2psi to 7"w.c. regulator was put at the pool heater side at the end of the corrugated stainless flex line.

Before:
PXL_20220929_203154536.jpg

After:

PXL_20221021_184922158.jpg

I can turn off the whole system with one gas valve, or turn off just the pool heater line with the other. Very satisfied with the AC-630 for our needs.

-Tom
 
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The 2 psi is also a good choice.

You can run a 3/4" line to the heater with 2 psi, but you need 2 additional regulators.

Either way will work.

Maybe the gas plumber can send us a check for design services.

:goodjob:

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Note: 1/2" line can be used up to 50 feet (400,000 btu/hr at 2 psi), but the total equivalent length with 90s and vertical pipe is probably over 50 feet, so you would go with 3/4" pipe, which is good to 150 feet.
 
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tommelton said:
We upgraded to the AC-630 meter at 2psi - with 2 regulators to lower to the equipment required 7"w.c. My distance to the pad was about 120' thru the house. Our gas plumber went with corrugated stainless flex line thru the house with only one coupling in the house. Our pad is on the complete opposite side of the house from the gas meter. So there is the main line to 2psi regulator supplied by the gas company in front of the AC-630 meter and then the output of the meter splits into the line to the pool heater and the original plumbing for the house. The first 2psi to 7"w.c. regulator was placed on the original house plumbing and the second 2psi to 7"w.c. regulator was put at the pool heater side at the end of the corrugated stainless flex line.

Before:


After:



I can turn off the whole system with one gas valve, or turn off just the pool heater line with the other. Very satisfied with the AC-630 for our needs.

-Tom
Click to expand...

Wow, that's impressive. I see you are in Atlanta as well. Did you have the meter replaced by AGL? Did they have to run a new line from the street to your house? Are these gas meter model numbers pretty standard and I should expect something like the AC-630 to be part of the install if I request 2psi from AGL? Thanks for the pictures!
 
My provider is Lawrenceville Gas. Per the installer, line from the street is over 7psi and no change needed there for me. For you, only AGL can answer based on your supply line size and pressure. I was told this model is a light commercial unit. I had to collect the BTU ratings of all my gas appliances so my gas company could size appropriately. The gas company side was pretty painless. They are happy to upgrade the meter for free, since the usage will certainly go up. If you need a gas plumber, let me know. I got quotes from 3 or 4 before choosing the one I used.

-Tom
 
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The O.D (Outside Diameter) can identify the pipe size.

Measuring the OD of a pipe can be tricky unless you have a caliper.

You also need to know the line pressure from the street to the regulator.

Most likely, the line will not need to be replaced.

Do you know who the licensed gas contractor is and have you contacted them directly?
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It looks like an OD of about 1", which is probably a 3/4" line.

It depends on the pressure.

I suspect that the pressure from the street is probably between 2 psi and 10 psi.

The gas supplier will have to determine if the line will supply the correct volume of gas.

The AC-630 meter will probably be the best choice.

The plumber needs to decide if they want to go with 2 psi or 7" w.c pressure.

I would say that the two methods are about equal, so the one that costs less will probably be the deciding factor.
 
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If you have 2 psi, the 3/4" pipe is good for about 836 SCFH up to about 125 feet.

As long as the line is less than 125 feet from the street to the meter, the line is probably fine assuming a 2 psi pressure.

If the pressure is higher than 2 psi, then it is almost definitely ok.

3PSI = 250+ feet.
5 psi = 500+ feet.



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C. Basic Delivery Pressure and Exceptions

The Company is not obligated to deliver Gas at a pressure in excess of the pressure available from its distribution system or in excess of four ounces or 0.25 PSIG.

The Company may, at its sole option, contract to deliver Gas to a particular Customer at a higher pressure without a pressure charge if each of the following conditions is met:

1. Such pressure exists in the lines of the Company used to serve the Customer by reason of the pressure at which the Gas is supplied to the Company by its pipeline supplier;

2. It is not necessary for the Company to install any additional facilities in order to maintain such pressure; and,

 
JamesW said:
I would go with the AC-630 meter and about 7" to 8" for the regulator before the meter and a 1.25" line to the heater.

Can you tell the minimum and maximum gas pressure requirements for each appliance?
  • Tankless Water Heater - rated up to 199K BTU
  • Gas Furnace (4-ton unit) - rated up to 100K BTU (estimated)
  • Outdoor Grill - 32K BTU
  • Fireplace (which we never use) - 70K BTU?
Click to expand...
Here is what I could find for the min and max pressure requirements:
 
Tankless Water Heater 3.5 " WC to 10.5 " WC.

Pool Heater 4" w.c to 14" w.c.

I think that the AC-630 will work for you.

You can go with 2 psi or 7".

Have you checked with the gas plumber?
 
JamesW said:
Tankless Water Heater 3.5 " WC to 10.5 " WC.

Pool Heater 4" w.c to 14" w.c.

I think that the AC-630 will work for you.

You can go with 2 psi or 7".

Have you checked with the gas plumber?
Click to expand...
Thanks. I plan to call the pool builder first thing tomorrow morning to discuss this. I'm not sure who they are going to sub the gas line work out to. I just know that they want to run the line this week along with the other utilities so I need them to tell me to request either 7" or 2 PSI so I can call AGL and get the meter install scheduled.
 
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Do we know for sure that the gas supplier can do 2 psi service?

The best default choice would be to use 7" service with a 630 class meter and 1.5" plumbing from the meter to the heater.
 
JamesW said:
Do we know for sure that the gas supplier can do 2 psi service?

The best default choice would be to use 7" service with a 630 class meter and 1.5" plumbing from the meter to the heater.
Click to expand...
Yes, the form I have to fill out wants me to choose between 2 psi and 7”. I can ask them about the 630 meter but should I expect the ‘sales rep’ to know what a 630 class meter is?
 

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