I'm looking at a Hayward 350k btu or 300k btu. On the brochure it says 3/4 inch pipe is what they take. Ive had conflicting suggestions from different HVAC people (licensed, good reviews). From our main, we get 1 inch. When we get to our basement (2007 home), it drops down to 3/4 inch to supply our dryer, furnace, fireplace (never used) and hot water. No stove. One guy said, "oh, I'll tee it off before it goes to 3/4 inch and use 1 inch bc its more efficient." I didn't know the actual specs for the heater we're going to use said to use 3/4. The other guy said he'll tee it off closer (where its 3/4 inch. Idk whats better for my home in the long run and if using one or the other will harm my gas-using appliances some time down the road.
Installing new heater but unsure of gas pipe size
- Thread starter hyperchord24
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Gas pipe size required is totally dependent on your gas pressure. Without knowing you're pressure need can't say if it is large enough. If the size is too small under your current pressure then the gas company can upgrade your pressure and you can have a gas contractor put regulators before each appliance to reduce to the proper pressure required, while still having enough pressure to reach your heater.
cptkirk
0
While it is true that the gas valve on the heater accepts a 3/4" pipe, the size of the supply line you need depends on whether it is a 1/2 PSI or 2 PSI system (high pressure), and how far it is from the meter to the appliance. It is worth a call to your gas company to discuss. They can tell you what type of system you have (if you don't already know), and they can also tell you whether your meter is appropriately sized to meet the new demand you will be adding. If there are regulators installed already between the supply line and each appliance, it's probably a high pressure system. If not, then it's probably not.
FWIW, I have the service manual for this series of heater, and it specs 1 1/4" for up to 100 feet from meter to heater and 1 1/2" for longer distances if it is a 1/2 PSI system. But for a 2 PSI system, 1" for most of the run would be fine and it probably doesn't matter that much where you tee off. If you don't already have a high pressure system, chances are you would need the gas company to upgrade it (and as mentioned above have regulators installed before each appliance).
FWIW, I have the service manual for this series of heater, and it specs 1 1/4" for up to 100 feet from meter to heater and 1 1/2" for longer distances if it is a 1/2 PSI system. But for a 2 PSI system, 1" for most of the run would be fine and it probably doesn't matter that much where you tee off. If you don't already have a high pressure system, chances are you would need the gas company to upgrade it (and as mentioned above have regulators installed before each appliance).
How/where can I find my pressure need? Is it estimated? And how can I tell if there are regulators before my appliances already?
cptkirk
0
Post some pictures of your gas meter including the dials and any visible labeling. The regulators should look something like this if you have them. There would probably be one somewhere between the main supply and each appliance if you have a 2 psi system.
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99% of residential gas appliances run at low pressure - under 0.5psi. But the manual will say for sure.
I did some checking. I have shut off valves prior to my appliances. No regulators. I have a 10' run of 1" pipe from meter. Then it drops to 3/4 for 15 feet, tees off to dryer, then elbows for 60 feet to furnace (Rheen Classic 90, still digging for BTU rating). Then tees off another 10 feet with some elbows to water heater and fire place. It looks like National Grid wants you to jump through some big hoops to get your hope upgraded to higher pressure. I'll keep looking
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You shouldn't need higher pressure, but you might need a larger service to accommodate all the appliances. Is there a regulator at the meter?
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The service is the pipe that connects from the main in the street to the riser at the meter. What size pipe comes up out of the ground?
Ok. From out of the ground, the outside diameter of the pipe is 1-3/4". That goes for maybe a foot and a half, then drops to 1-1/2" which connects to the meter itself
cptkirk
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Can you post a picture of the meter? Or a least post what the labeling on the meter says.
The Hayward manual has the correct gas line sizing charts.
Gas pressure is either low pressure (about 7” to 14” w.c) or high pressure (about 2 psig).
For low pressure, you use 1.25” pipe up to 100 feet, you use 1.5” pipe for up to 200 feet and 2” pipe up to 300 feet.
Natural Gas Pipe Sizing, Low-Pressure, Single-Stage Regulation.
Based upon an inlet gas pressure of 0.5 psig or less at a pressure drop of 0.5 in-wc
0.5 psig is 14” W.C (water column).
For low pressure, you do not have an additional regulator near the heater.
You reduce to 3/4” pipe right at the heater.
For high pressure, you use 3/4” pipe for the entire run, but you have a regulator to reduce the pressure from 2 psig to heater inlet pressure (4.5” to 10.5” w.c).
Natural Gas Pipe Sizing, High-Pressure, 2-Stage Regulation
Based upon an inlet gas pressure of 2 psig at a pressure drop of 1 psi.
The line for the heater has to T off before all other lines.
Gas pressure is either low pressure (about 7” to 14” w.c) or high pressure (about 2 psig).
For low pressure, you use 1.25” pipe up to 100 feet, you use 1.5” pipe for up to 200 feet and 2” pipe up to 300 feet.
Natural Gas Pipe Sizing, Low-Pressure, Single-Stage Regulation.
Based upon an inlet gas pressure of 0.5 psig or less at a pressure drop of 0.5 in-wc
0.5 psig is 14” W.C (water column).
For low pressure, you do not have an additional regulator near the heater.
You reduce to 3/4” pipe right at the heater.
For high pressure, you use 3/4” pipe for the entire run, but you have a regulator to reduce the pressure from 2 psig to heater inlet pressure (4.5” to 10.5” w.c).
Natural Gas Pipe Sizing, High-Pressure, 2-Stage Regulation
Based upon an inlet gas pressure of 2 psig at a pressure drop of 1 psi.
The line for the heater has to T off before all other lines.
Your meter is a 250 cfh (cubic foot per hour) model. A 350,000 btu/hr heater needs at least 350 cubic feet per hour.
Each cfm is 1,000 btu. So, 250 cfh is 250,000 btu/hr.
The meter would need to be replaced with one that can supply 350 cfm plus all other appliances.
350 + 250 is 600 cfh.
I suspect that the new meter will need to be at least 500 cfh, or bigger, depending on the total maximum possible load.
The meter output can be low pressure or high pressure, whichever your supplier recommends.
The pipe size from the meter to the heater will depend on the pressure.
Each cfm is 1,000 btu. So, 250 cfh is 250,000 btu/hr.
The meter would need to be replaced with one that can supply 350 cfm plus all other appliances.
350 + 250 is 600 cfh.
I suspect that the new meter will need to be at least 500 cfh, or bigger, depending on the total maximum possible load.
The meter output can be low pressure or high pressure, whichever your supplier recommends.
The pipe size from the meter to the heater will depend on the pressure.
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You are on a high pressure main, so the gas company should be able to supply all the gas you need without digging anything up. This is the gas regulator that drops the high pressure in the main to <0.5psi for your house.
The gas company should be all too happy to tell you whether the meter is big enough (probably not, it lists its capacity as 250CFH, which is less than the pool heater alone) and supply a larger one, if necessary.
Given that your house piping is low pressure, you're going to need big pipes to carry the load from the meter to the heater, as JamesW describes above.
The gas company should be all too happy to tell you whether the meter is big enough (probably not, it lists its capacity as 250CFH, which is less than the pool heater alone) and supply a larger one, if necessary.
Given that your house piping is low pressure, you're going to need big pipes to carry the load from the meter to the heater, as JamesW describes above.
Attachments
I think that you need a bigger meter.
Assuming the output from the new meter is low pressure, you would use 1.25" pipe from the meter to the heater and then reduce to 3/4" right near the heater.
The line from the meter to the heater has to be Teed off before any other lines.
Your gas contractor or gas supplier should be able to recommend the correct gas meter size and the gas supplier can replace the meter.
The gas contractor would connect everything from the output of the meter.
Assuming the output from the new meter is low pressure, you would use 1.25" pipe from the meter to the heater and then reduce to 3/4" right near the heater.
The line from the meter to the heater has to be Teed off before any other lines.
Your gas contractor or gas supplier should be able to recommend the correct gas meter size and the gas supplier can replace the meter.
The gas contractor would connect everything from the output of the meter.
My gas guys and my pool guy say 3/4" is fine. My pool guy says "you can run 7 stoves from your meter without a problem." Yikes. So does the line have to come directly from the main? And why do these people say smaller is ok if it isn't ok? These guys are licensed and do this all the time, heck even my pool guy for 20 years, so what gives? I'm on national grid. Do I call them now? Or when its installed? I called before and they had no idea what I'm talking about. But this is national grid and they suck
You need a new meter.
You need to call National Grid and get them to replace the meter.
Once the new meter is installed, have the contractor install a T at the output of the meter.
From one leg of the T, run 1.25" pipe to the heater.
The line size is specified in the manual, and you have to follow the manual.
From the other leg of the T, connect the old line going into the house.
Note: This assumes that the output of the existing meter is low pressure (7" to 14" w.c) and the output of the new meter will also be low pressure.
That's just stupid.
A "stove" is not a unit of measurement.
Your meter is rated for 250 cfh.
The number of "stoves" depends on the stove.
A "stove" might take 2 cfh or 2 thousand cfh.
