I am being asked by the local utility company how much gas do I want. Well... not in so many words, but they're asking for estimated BTU's/hr which is simple enough to arrive at, or so I thought:
Detached Garage
They also want to know about pressure requests, e.g. 6 or 7 inch water column, or 2 lb, and here's where I get confused.
The natural gas service is at the corner of our 2 acre lot, and the utility company will place the meter on the detached garage as it is closest. I am desirous of one service for both garage - being built this summer - and house - being built a year later. Now, for the questions (which, sadly, the utility company was not very responsive to answering...)
1. That's a lot of gas... is residential gas supply sized to "typical" use? Or to "maximum possible" use?
2. Do I need to request a high pressure service, e.g. 2# service, or even 6" or 7" WC?
As mentioned, gas arrives at the garage, and will be run from there to the house. The house will be 125 face-to-face feet from garage, and from meter to utility room in house the distance will be roughly 200 feet.
If I am understanding the physics properly (and there's no guarantee of that!) it would seem that standard service, pushed through a 1" pipe 200' from garage to house will only supply about 125 CFH. (Spitzglass formula for less than 1 psi) At roughly 1000 BTU per cubic foot, I'm ONLY meeting my heating needs at the house, with no gas left over for anything else.
Thus, I must increase pipe diameter, or inlet pressure, right? Increasing to 1.5" pipe nearly triples CFM, it would seem, thereby meeting my needs? It wouldn't seem so, as there will be further loss of flow when routing pipe about within the house itself, right? Maybe I need a 2" nominal sched 40 steel pipe?
Or would I be smarter to look to increase the pressure in the line, and use smaller (cheaper?) pipe. Can pressure be left higher after the gas company's meter/regulator? Will 2 lb service suffice?
It seems like it should be a simple issue, for someone with knowledge and experience. I fear I am overthinking the problem and getting myself unnecessarily hung up on "optimizing" the solution.
Detached Garage
- Heating = 82,000 BTU/hr
- Hot H2O = 32,000 BTU/hr
- Gas Grill Connection = 48,000 BTU/hr
- Total = 162,000 BTU/hr
- Heating = 122,000 BTU/hr (unless I go geothermal GSHP)
- Hot H2O = 60,000 BTU/hr
- Cook Stove = 58,000 BTU/hr
- 2nd Gas Grill Connection = 48,000 BTU/hr
- Clothes Dryer (?) = 22,000 BTU/hr
- Fireplace (x2) = 96,000 BTU/hr total
- Attached Garage Heating = 33,600 BTU/hr
- Total = 391,600 BTU/hr
They also want to know about pressure requests, e.g. 6 or 7 inch water column, or 2 lb, and here's where I get confused.
The natural gas service is at the corner of our 2 acre lot, and the utility company will place the meter on the detached garage as it is closest. I am desirous of one service for both garage - being built this summer - and house - being built a year later. Now, for the questions (which, sadly, the utility company was not very responsive to answering...)
1. That's a lot of gas... is residential gas supply sized to "typical" use? Or to "maximum possible" use?
2. Do I need to request a high pressure service, e.g. 2# service, or even 6" or 7" WC?
As mentioned, gas arrives at the garage, and will be run from there to the house. The house will be 125 face-to-face feet from garage, and from meter to utility room in house the distance will be roughly 200 feet.
If I am understanding the physics properly (and there's no guarantee of that!) it would seem that standard service, pushed through a 1" pipe 200' from garage to house will only supply about 125 CFH. (Spitzglass formula for less than 1 psi) At roughly 1000 BTU per cubic foot, I'm ONLY meeting my heating needs at the house, with no gas left over for anything else.
Thus, I must increase pipe diameter, or inlet pressure, right? Increasing to 1.5" pipe nearly triples CFM, it would seem, thereby meeting my needs? It wouldn't seem so, as there will be further loss of flow when routing pipe about within the house itself, right? Maybe I need a 2" nominal sched 40 steel pipe?
Or would I be smarter to look to increase the pressure in the line, and use smaller (cheaper?) pipe. Can pressure be left higher after the gas company's meter/regulator? Will 2 lb service suffice?
It seems like it should be a simple issue, for someone with knowledge and experience. I fear I am overthinking the problem and getting myself unnecessarily hung up on "optimizing" the solution.
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