2-psi Gas Service With Pool Heater and Outdoor Kitchen Added
A 2-psi natural gas service enters a 3,000-square-foot house through a 1-inch polyethylene yard line and a line regulator at the foundation that reduces pressure to 7 inches water column. The existing 3/4-inch black-iron manifold serves a 120,000 Btu/h furnace, a 40,000 Btu/h range, and a 50,000 Btu/h water heater. The homeowner is adding a 150,000 Btu/h pool heater 90 feet from the meter and a 75,000 Btu/h outdoor kitchen 45 feet away. A handyman proposes teeing both new appliances off the existing 1/2-inch line to the water heater and using 3/4-inch CSST for the pool run. The pool heater will be in a below-grade vault, and the outdoor kitchen will have a side burner. The local utility’s meter capacity is 425 cfh, and the gas company will not upgrade the meter.
1. Evaluate the total load and the handyman’s piping proposal. What sizes and pressure arrangement are needed?
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Convert the loads to approximate cfh at 1,000 Btu/h per cfh: 120 + 40 + 50 + 150 + 75 = 435 cfh. The utility meter is limited to 425 cfh, so the connected load already exceeds meter capacity before any diversity allowance; the plans must be revised to reduce load or the utility must approve a larger meter. The handyman’s 1/2-inch tie-in is clearly inadequate and unsafe. Downstream of the line regulator, the system is at 7 inches water column; a 3/4-inch CSST run of 90 feet cannot carry 150,000 Btu/h with an acceptable pressure drop, so the pool heater needs a larger line, likely 1-inch or a dedicated 2-psi line with an appliance regulator at the heater. The outdoor kitchen at 45 feet also needs its own properly sized branch and appliance regulator if served at 2 psi. Do not tee both appliances off the water-heater branch. Size each run by the longest-length method using the available pressure drop, include fitting allowances, and provide a regulator at each appliance on a 2-psi system.
2. What safety and code details are critical for the pool heater vault and the outdoor kitchen?
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The below-grade pool heater vault is a gas-accumulation hazard. It needs adequate ventilation at high and low points, protection from water entry, and a gas detector or other approved safety means if the authority requires it. The appliance must be listed for that location, and the gas piping must not pass through the vault in a way that can trap gas. Provide a sediment trap at each appliance, a union and shutoff valve at the appliance connector, and proper support and protection for CSST. The outdoor kitchen side burner needs an appliance regulator, a sediment trap, and clearances from combustibles. CSST must be bonded to the grounding electrode system per the manufacturer’s instructions, typically with a listed bonding clamp and conductor sized by the manufacturer; bonding is not a substitute for the equipment grounding conductor. All concealed joints should be minimized, and the piping must be protected where it emerges from grade.
3. The homeowner wants to keep the existing meter. What options would you present, and what would you refuse to do?
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Present load-reduction options: replace the pool heater with a lower-input or heat-pump model, eliminate the side burner or use a smaller outdoor appliance, or interlock appliances so the pool heater and outdoor kitchen cannot operate at the same time if the authority accepts a load calculation with demand diversity. Even with diversity, the meter capacity and the 7-inch w.c. piping must be checked; a 425-cfh meter leaves little margin for 435 cfh connected load. Refuse to tee 150,000 and 75,000 Btu/h appliances off a 1/2-inch line, refuse to use 3/4-inch CSST for a 90-foot 150,000 Btu/h run at 7 inches w.c., and refuse to install a pool heater in an unventilated vault. Also refuse to rely on the existing line regulator for appliances that require their own appliance regulators. The correct path is a engineered load calculation, a utility-approved meter size, dedicated regulated runs, and a permit inspection.