400K BTU Gas Heater - Need Help with Meter Upgrade

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DSMinAtlanta

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Jun 27, 2023
192
Atlanta, GA
Well we are finally in the middle of our pool build with shotcrete getting done earlier this week. The next step is to run the needed utilities for the equipment which I thought would be one of the easier steps in this build. We will have a Pentair 400K BTU gas heater as part of the build. I called Atlanta Gas Light since we need a meter upgrade. Here is where we are on that process:
  • The gas company is asking me for the delivery pressure requirements of the pool heater - either 7” W.C. or 2PSI
  • The pool builder is asking me for the meter specs so they know what size line to run for the heater
  • The gas company is telling me we are already over the capacity of our current meter without the pool heater so we definitely need a new meter
  • When I reached out to the pool builder again about the above, one of the project managers said the low pressure meter may be fine while the other project manager said to go with the 2PSI option
It feels like they are pointing fingers at each other with no clear path forward. How do I determine which is needed since I'm not getting a confident answer from the builder? Is this something I should be able to calculate on my own based on the BTUs of all the appliances in our house? We currently have a gas tankless water heater, gas range, gas fireplace, gas furnace, and we have gas connected to our outdoor grill. The gas company says our current meter only support 397K BTU and they didn't say what the new ones will support. Is there any harm in requesting the higher pressure 2PSI meter over the other?
 
You can use 7" or 2 psi.

The only difference is the line going to the heater.

The heater needs 7" wc pressure.

So, you can use 2 psi with a smaller line and a regulator near the heater or 7" with a bigger line and no regulator.

The meter should be sized for the total load.
 
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JamesW said:
You can use 7" or 2 psi.

The only difference is the line going to the heater.

The heater needs 7" wc pressure.

So, you can use 2 psi with a smaller line and a regulator near the heater or 7" with a bigger line and no regulator.

The meter should be sized for the total load.
Click to expand...
Thanks for the quick reply! So the heater needs 7" wc pressure, that's good to know.

How do we determine the total load? Do I need to look up the max BTU for the water heater, grill, furnace, etc.? You'd think the gas company would be able to do this since I told them about everything we have currently using gas. Are there any downsides in choosing one over the other? I do know that going with the larger meter could require them to run a new line from the street which will extend the lead time quite a bit.
 
Meters are sized partly by the pressure drop.

For example, the AL-425 can deliver different flow volume based on the allowable pressure drop.

The meter will deliver 425 CFH at a 0.5" pressure drop.

The meter will deliver 583 CFH at a 1.0" pressure drop.

If you allow for a 1.5" pressure drop, the meter will provide about 740 CFH.

If you allow a 2" pressure drop, the meter will provide 898 CFH.

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Heater issue?

Hi All - I haven’t updated my signature with pool size, equipment, and all other necessary things but I will eventually. Anyhow, we’re having an issue with our heater, it’s a new Raypak Avia 404, that shuts off after roughly 10 min. The digital screen says two things: Flue Extremely Low...
www.troublefreepool.com www.troublefreepool.com
DSMinAtlanta said:
Do I need to look up the max BTU for the water heater, grill, furnace, etc.?
Click to expand...
Yes.
 

Attachments

  • AC630.pdf
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Some gas companies use the 0.5" w.c pressure drop rating, which is conservative and some use the 1" pressure drop rating.

If your pressure before the meter is 7" and you have a 1" drop, then your pressure out of the meter is 6" and then you have a 0.5" w.c pressure drop through the gas line, which leaves you 5.5" w.c.

Do you have a Licensed qualified gas contractor who will do the installation?

Can't they figure this out and advise you?
 
If you use a 2 psi meter, then your pressure out of the meter is about 2 psi and you need a regulator before sending gas to the house and you send 2 psi towards the heater and use a regulator near the heater to lower the pressure from 2 psi to 7" w.c.
 
JamesW said:
Some gas companies use the 0.5" w.c pressure drop rating, which is conservative and some use the 1" pressure drop rating.

If your pressure before the meter is 7" and you have a 1" drop, then your pressure out of the meter is 6" and then you have a 0.5" w.c pressure drop through the gas line, which leaves you 5.5" w.c.

Do you have a Licensed qualified gas contractor who will do the installation?

Can't they figure this out and advise you?
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Atlanta Gas Light (our gas provider) would be the one replacing the meter at no cost to us. They just need to know "What delivery pressure is your gas plumber requesting? Either 7” W.C. or 2PSI?" so they can prepare the work order to have a site survey done in order to determine what is necessary to install the meter we request.
 

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Most likely, you will need the AC630 or the AL1000 depending on the total load.

The AC630 can do 630,000 btu/hr (630 CFH) at 0.5" or 900,000 btu/hr (900 CFH) at 1".

The AC 630 is probably big enough as long as the regulator before the heater is at 8" w.c.
 
JamesW said:
Most likely, you will need the AC630 or the AL1000 depending on the total load.

The AC630 can do 630,000 btu/hr (630 CFH) at 0.5" or 900,000 btu/hr (900 CFH) at 1".

The AC 630 is probably big enough as long as the regulator before the heater is at 8" w.c.
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I have no idea which make/model meters Atlanta Gas Light installs. I'm not confident the people on the phone know or care to know those details. I guess I'll do some calculating of our BTU requirements for everything in our house and see if that helps us decide.
 
JamesW said:
You can do it either way.

Ask the gas plumber which way they want to do it.

Can't the plumber tell you what they prefer?
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So you're saying the pool builder should be able to answer that? That's what I had assumed as well. Since I got mixed messages from the pool builder project managers I wanted to do a little research here before I respond to them. Thanks.
 
DSMinAtlanta said:
So you're saying the pool builder should be able to answer that?
Click to expand...
The licensed gas contractor needs to make a decision on if they want to use 2 psi or 7" w.c.

They can do it either way.

If the pool builder is subcontracting the work out, get the gas contractor's number and ask them what they want to do and what size meter you need.

Contact the city and ask for copies of all building permits issued for the project and see who pulled the gas plumbing permit.
 
Here are the two ways that you can do it.

With a low pressure 7" system, you use 1.25" pipe up to 100 feet or 1.5" pipe up to 200 feet.

With a high pressure 2 psi system, you use 3/4" pipe up to 150 feet and you put a regulator on the line going to the house and a regulator near the heater.

The benefit of the 2 psi system is that you can run a smaller line, but you have to buy 2 regulators, which partially offsets the cost savings.

You can do it either way.
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DSMinAtlanta said:
The distance from the meter to the center of the equipment pad is ~35 feet
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You also have to account for 90s and vertical pipe, so the total "equivalent" length will be about 70 feet.

You can do low pressure (7") and run a 1.25" line or high pressure (2 psi) and run a 3/4" line.

The heater needs 4" to 14" w.c at all times.

If you allow for a 1" drop across the meter and a 0.5" drop for the line, then that is a total of 1.5" w.c.

If you us a 7" regulator before the meter, then the heater should get at least 5.5" w.c.

You can adjust the regulator before the meter to 8" w.c and then the pressure at the heater will be at least 6.5"

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This is a lot of information to take in but thank you for all the help. So either meter could work fine and now I see why the builder needs to know which one so they can run the correct diameter piping. What dictates the need for one meter over the other? Is it just the total required load for all gas appliances in the home?
 

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