The Gas Appliance Removal and Venting Check SOP

Purpose

When one gas appliance leaves, every vented appliance left behind runs under conditions nobody tested: a cooler chimney, different room air, an open hole where a connector was. This SOP guarantees no crew leaves after a removal without testing each remaining vented appliance for draft, spillage and carbon monoxide (CO), checking its vent, and writing it down. Without it, the failure surfaces weeks later as a CO alarm.

Scope

Covers: any removal of a gas or propane appliance (furnace, boiler, water heater, dryer, range, fireplace insert) from a house where at least one vented gas appliance remains, run the same visit as the removal.

Does not cover: how the gas line is capped (See related: How to Cap and Abandon a Gas Line Correctly), closing the account and meter with the utility (How to Close Out Gas Service with the Utility), what to do with a chimney nothing uses any more (How to Handle the Chimney a Furnace Left Behind), or why a remaining appliance fails (What Removing a Gas Appliance Does to the Ones Left owns that). If the last gas appliance in the house is the one coming out, steps 4 to 7 do not apply; record that and run step 8.

Roles and responsibilities

The handoff that fails is the removing tech leaving before the tester arrives. The removal is not complete until step 8 is signed.

Procedure

1. Put on a personal CO monitor and take a baseline on every remaining vented appliance before anything comes out. Zero the monitor outdoors, then fire each remaining vented appliance under normal conditions and read CO at the draft hood or vent connector and in the room. Acceptance: room CO under 9 ppm and each appliance's baseline recorded with its input rating from the rating plate. Wrong looks like room CO rising toward 35 ppm, soot at a draft hood, or an appliance already spilling. Stop rule: an appliance that fails before the removal is shut off at its own gas valve, tagged, and recorded as a pre-existing condition, and the removal goes ahead only once the customer has that in writing. Hazard: you are firing appliances with unknown venting, so the monitor is on before the first one lights, and at 35 ppm in the room everyone leaves the house and the appliance is shut off from its valve on the way out.

2. Isolate and remove the appliance, then leak-test the cap. Close the appliance's shutoff valve, disconnect, and cap the line per the capping card. Leak-test the cap with a listed leak detection solution or a combustible gas detector at the cap and every joint disturbed. Acceptance: no bubbles over the observation time on the solution, or no detector response at the cap. Wrong looks like bubbles, a detector alarm, or a gas odor. Stop rule: on any leak, close the next valve upstream; if the odor persists or you cannot find the source, everyone leaves the house without operating switches, lights or phones inside, and you call the gas utility's emergency line from outside. Hazard: an open gas line, so any standing pilot in the room is off at its valve and nothing that sparks is used until the cap tests tight.

3. Seal the vent opening the removed appliance leaves. Remove its vent connector, then close the chimney thimble or the open tee in a shared vent with a noncombustible seal appropriate to the vent (a masonry thimble cap, a listed cap on a metal vent). Acceptance: no opening into the vent from the room, confirmed by eye and by a smoke pencil held at the seal showing no draw. Wrong looks like smoke drawing in at the seal, or a connector still feeding into a common vent from the removed side. Stop rule: an unsealed opening means the remaining appliance's test in step 6 is not valid; seal it before testing. Hazard: old thimbles sometimes carry asbestos-containing paper or tape; if you see any, stop this step, do not cut, scrape or pull it, and record it for a licensed abatement contractor. Soot is bagged, not brushed into the air.

4. Check the vent each remaining appliance is now left on. Record chimney height, interior or exterior, flue size, liner, connector rise and length, and the remaining input, and look the combination up in the Category I venting tables of NFPA 54 Chapter 13 or International Fuel Gas Code Section 504, in the edition your jurisdiction has adopted. Acceptance: the remaining appliance's input sits between the table minimum and maximum for that vent, with the table and edition written on the card. Wrong looks like an input below the minimum, a combination the table does not list, an unlined masonry flue, or a connector sloping down toward the chimney. Stop rule: a table failure is recorded as a mandatory vent fix with a date; the appliance may stay in service until then only if it passes steps 5 to 7 and a working CO alarm is present, and the office schedules the fix within 14 days, a shop default your inspector may tighten. Hazard: none at the table, which is a desk task, but reading the chimney from a ladder or a roof is height work under the shop's fall protection rules.

5. Set up worst-case depressurization in the combustion appliance zone. Close exterior doors and windows, run every exhaust appliance (bath fans, kitchen hood on high, dryer) and the air handler, and set interior doors to whichever position makes the appliance room most negative. Measure the room against outdoors with a manometer. Acceptance: the worst-case pressure recorded in pascals, at or less negative than the limit your test protocol sets for that appliance's venting type. Wrong looks like a reading more negative than the limit. Stop rule: over the limit, finish step 6 to see whether it spills, but the appliance cannot pass this SOP until the depressurization is corrected. Hazard: you are deliberately creating the condition that pulls flue gas into the room, so the monitor stays on you and the test is never left running unattended.

6. Fire each remaining appliance under worst case and test it for spillage and flue CO. Start with the smallest-input appliance on a common vent, then add the next. Test for spillage at the draft hood with a smoke pencil or a mirror at 5 minutes of main burner operation, and read CO air-free in the flue ahead of the draft hood. Acceptance: smoke drawn into the hood, no condensation on the mirror, and flue CO under 100 ppm air-free, a common shop default taken from widely used combustion safety protocols. Wrong looks like smoke rolling out at 5 minutes, flue CO from 100 to 400 ppm (service needed), or over 400 ppm. Stop rule: spillage that does not clear, or CO over 400 ppm, means the appliance is shut off at its gas valve, red-tagged, and the customer told in writing before you leave; 100 to 400 ppm is recorded as a service item. Hazard: this is a burning appliance in a negative room, so room CO at 35 ppm on your monitor ends the test, the appliance goes off, and the space is ventilated before anyone continues.

7. Return the house to normal and re-test under normal conditions. Turn off the exhaust fans and dryer, restore doors and the thermostat to how you found them, and fire each appliance that passed step 6 once more. Acceptance: draft established within the first minute and no spillage at 5 minutes, and a working CO alarm on the appliance's level and outside sleeping areas, proved by its test button. Stop rule: spilling under normal conditions is a red tag; a missing alarm is installed or written up before you leave, and where your state requires alarms on a fuel-burning installation, the work is not complete without one. Hazard: you are relighting appliances you just stressed, so the monitor stays on until the last one has run 5 minutes clean, and an appliance red-tagged in step 6 is not relit here for the customer's convenience.

8. Complete the record card and walk the customer through it. Fill every field, photograph the sealed opening and each appliance's rating plate, and read any red tag to the customer with the reason and the next step. Acceptance: card complete, red tags signed, and the office has the card the same day. Stop rule: a blank field or an unsigned tag means the job is not closed in the system until it is fixed. Hazard: none at this step beyond confirming every valve you closed for testing is in the position the card says it is.

The record this produces

One card per removal, filed to the customer, read by the office scheduling any fix and by the next tech on any gas appliance in the house.

REMOVAL AND VENT CHECK  - 2 story, interior chimney
REMOVED   boiler 120,000 Btu/h, capped, leak test OK
SEALED    thimble cap, smoke pencil no draw
REMAINING water heater 36,000 Btu/h nat draft
VENT      interior masonry, 28 ft, lined 6 in round
          NFPA 54 Ch.13 table, adopted ed.: in range
BASELINE  flue CO 22 ppm AF, room 1 ppm
WORST     -4 Pa (limit -2), fans+dryer+hood+AH
SPILL 5m  FAIL, smoke rolling out, did not clear
ACTION    WH off at valve, red tag, signed
DIAG      air handler off mid-test: draft in 40 s
ALARMS    basement + hall, both tested OK
FIX       seal return leaks, or sealed-comb. WH

Worked pass

The card above is one run on a house where a boiler was replaced by heat pumps and a natural-draft water heater stayed on the chimney.

Step 1: monitor zeroed outdoors. Water heater baseline under normal conditions: flue CO 22 ppm air-free, room 1 ppm. Pass.

Steps 2 and 3: boiler capped, solution leak test clean on the cap and the union. Thimble closed with a masonry cap; smoke pencil at the seal showed no draw. Pass.

Step 4: interior chimney, 28 feet, with a 6 inch round liner sized years ago for the water heater alone. The water heater's 36,000 Btu/h falls inside the adopted table's range for that liner and height. Pass.

Step 5: bath fans, the kitchen hood on high and the dryer running, air handler on. The basement measured -4 Pa against outdoors, against an illustrative -2 Pa protocol limit for an orphaned natural-draft water heater: 2 Pa more negative than the limit. This step failed its acceptance. Per its stop rule, the tester ran step 6 to see what the appliance did.

Step 6: the water heater was still spilling at 5 minutes, smoke rolling out of the draft hood, flue CO 48 ppm air-free, room CO peaking at 6 ppm on the monitor. Before shutting it off, the tester switched off only the new air handler with the burner still lit: draft established in 40 seconds. The hydronic boiler had no blower; the ducted heat pump that replaced it put an air handler with leaky return ducts in the basement, and those returns were pulling the room negative. Failed, and took its stop rule: shut off at its gas valve, red-tagged, and the customer told in writing it stays off until the returns are sealed and it retests, or it is replaced.

Step 7: the water heater stayed off, because a red-tagged appliance is not relit here. Both CO alarms tested with their buttons. Pass on the alarms.

Step 8: card filed; the office booked the HVAC crew to seal the returns two days out, with a retest of steps 5 to 7 before the tag comes off.

References

• NFPA 54, National Fuel Gas Code, Chapter 13 venting tables and Annex G (an informative safety inspection procedure), in the edition your jurisdiction has adopted; International Fuel Gas Code Section 504 where the IFGC is adopted instead
• NIOSH recommended exposure limit for carbon monoxide (35 ppm, 8-hour time-weighted average), used here as a room-level stop default
• See related: What Removing a Gas Appliance Does to the Ones Left
• See related: Combustion Safety After a Partial Conversion