Spot the Violation

PlumbingWater heatersLevel 32018 UPC

Gas water heater in the garage

Corner of a heated attached garage with taped drywall walls and ceiling. A 40-gallon gas water heater sits directly on the concrete slab, its gas control and burner access cover near the floor. A yellow-and-black sticker on the jacket reads FVIR, Flammable Vapor Ignition Resistant, next to the rating label. A yellow concrete-filled steel pipe bollard stands in front of the heater. A metal vent rises from the draft hood through the ceiling. The cold line drops through a ball valve and a tee with a thermal expansion tank hanging below it; the hot line rises into the ceiling. A black iron gas line with a gas cock and capped drip leg feeds the control. A copper relief valve discharge pipe runs straight down the side of the tank and ends about 6 in. above the slab. The front bumper of a parked car is at the lower right. FVIR FLAMMABLE VAPOR IGNITION RESISTANT
Heated attached garage, water heater replaced this week

What's wrong here?

  1. Nothing. This installation is compliant
  2. The burner and ignition source must be at least 18 in. above the garage floor
  3. A gas water heater may not be installed in a garage
  4. The relief valve discharge must be piped through the wall to the outdoors
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Show the answer and the code reference

The answer

Nothing is wrong. The heater is FVIR-listed, so it can sit on the garage floor, and the bollard keeps the car off it.

Correct choice: 1. Nothing. This installation is compliant

The 18 in. rule exists because gasoline vapor is heavier than air and pools near a garage floor, where a standing pilot or burner can ignite it. UPC 507.13 requires burners and ignition devices in a residential garage to be at least 18 in. above the floor unless the appliance is listed as flammable vapor ignition resistant. Gas storage water heaters built since the mid-2000s are generally FVIR-listed (their combustion chambers are sealed with a flame-arresting air intake), and this one is labeled. UPC 507.13.1 also requires protection from vehicle damage by a barrier, elevation or location out of the vehicle path; here a concrete-filled bollard does that. The rest checks out: shutoff on the cold, an expansion tank on the cold line, a sediment trap on the gas, and a full-size relief discharge ending near the slab.

How to fix it

No correction needed. On an older heater with no FVIR listing, the same spot would need a stand that puts the burner and ignition source at least 18 in. above the slab.

Code references

  • UPC 2018 507.13 — Installation in Garages

    Appliances in residential garages, and in adjacent spaces that open to the garage and are not part of the living space, shall be installed so that burners and burner-ignition devices are at least 18 in. above the floor, unless listed as flammable vapor ignition resistant.

    Drills citing 507.13

  • UPC 2018 507.13.1 — Physical Damage

    Appliances in garages and other areas subject to mechanical damage shall be guarded against it by protective barriers, by elevation, or by being located out of the normal path of vehicles.

    Drills citing 507.13.1

  • Other IFGC 2018 305.3 — Elevation of ignition source (Minnesota Fuel Gas Code)

    Appliances with an ignition source in private garages and similar locations shall have the ignition source at least 18 in. above the floor; an exception exempts appliances listed as flammable vapor ignition resistant. Minnesota adopts the 2018 IFGC with amendments as the Minnesota Fuel Gas Code (Minn. Rules ch. 1346).

    Drills citing IFGC 2018 305.3

  • UPC 2018 608.5 — Discharge Piping

    Relief valve discharge piping is full size, has no valves, traps or threaded end, and discharges by gravity through an air gap. The model code sends it into the drainage system or outside the building; Minnesota's amendment (Minn. Rules 4714.0608) is reported to let it terminate at a safe place of disposal or within 18 in. of the floor.

    Drills citing 608.5

Minnesota

MN status unverifiedConfidence: medium

Minnesota adopts the 2018 Uniform Plumbing Code with Minnesota amendments as the Minnesota Plumbing Code (Minn. Rules ch. 4714, effective Dec. 17, 2021). Minnesota deletes large parts of UPC section 507 because fuel-gas appliance installation is covered by the Minnesota Fuel Gas Code (Minn. Rules ch. 1346, the 2018 IFGC with amendments); search results indicate 507.13 is not among the deleted subsections, but that was not confirmed. The Fuel Gas Code's 305.3 carries the same 18 in. rule and the same FVIR exception, so the answer holds either way.

About the Minnesota Plumbing Code

Citation under review. (1) Confirm UPC 2018 507.13 and 507.13.1 survive in Minn. Rules 4714.0507 (a search snippet said 507.6-507.11 and 507.14-507.23 are deleted). The answer holds under IFGC 2018 305.3 either way. (2) This calibration drill is compliant only if Minnesota's amended 608.5 lets a T&P discharge terminate within 18 in. of the floor ('a safe place of disposal or within 18 inches of the floor', from search snippets). Under the model 2018 UPC 608.5(3) ('into the drainage system or outside of the building') a bare termination 6 in. above a garage slab would not pass. If the Minnesota wording is not confirmed, redraw the discharge to end over an approved receptor.

Why the other choices are wrong

  • The burner and ignition source must be at least 18 in. above the garage floor. UPC 507.13 (and fuel gas code 305.3) waive the 18 in. elevation for appliances listed as flammable vapor ignition resistant. The FVIR label shows this heater is, so it may sit on the slab.
  • A gas water heater may not be installed in a garage. No code bans them. UPC 507.13 sets the conditions: an elevated or FVIR-listed ignition source, plus protection from vehicles under 507.13.1, which the bollard provides.
  • The relief valve discharge must be piped through the wall to the outdoors. Minnesota amends 608.5 to let the discharge end at a safe place of disposal or within 18 in. of the floor instead of outdoors or in a drain, and this full-size, unthreaded pipe ends about 6 in. above the slab. A line run out through a Minnesota garage wall would also risk freezing, which 608.5 prohibits.
Safety hazardLevel 3 · Master#garage#FVIR#18 inch rule#bollard#gas water heater#calibration

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