Brazing a Filter Drier Beside a Standing-Pilot Water Heater
A basement mechanical room, 9 ft by 11 ft with an 8 ft ceiling, contains a 30-year-old R-22 split system with about 7 lb of charge, a natural-draft gas water heater with a standing pilot, and a gas furnace with a draft hood. Both gas appliances vent into a shared masonry chimney. A liquid-line flare fitting is leaking oil and bubbles under soap solution. The plan is to cut out the flare and braze in a new filter drier. Ambient is 85°F, there is one small window, no mechanical ventilation, and the water heater pilot is lit. The van has a recovery machine, a nitrogen regulator and tank, a torch, a refrigerant detector, and a combustible gas detector. The homeowner mentions that the last company 'just added a little Freon and it was fine.'
1. Identify the hazards in this room and explain what makes each one dangerous during this specific job.
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Refrigerant accumulation. R-22 vapor is heavier than air and this room is below grade with one small window. At 85°F the system holds roughly 150 psig, so any release forms a large, cold vapor cloud that pools at floor level, displaces breathing air, and can cause asphyxiation and frostbite.
Thermal decomposition. An open torch flame touching R-22 produces phosgene, hydrogen chloride, and hydrogen fluoride. In a low, poorly ventilated basement those products linger at exactly the height a technician is working.
Ignition and carbon monoxide. A standing pilot and a draft-hood furnace are open ignition sources inches from where the torch will be. Combustion products can also spill from the draft hood if a fan is placed without makeup air, and the flame from the torch can ignite accumulated gas if a fitting is leaking.
Pressure and oil. Brazing a closed system with refrigerant or oil inside can rupture the line; heated oil forms carbon and acid that later plug the drier and damage the compressor. Add hot-work burns, confined-space access, and the 30-year-old flare that may not reseal.
2. Write the sequence you would follow from arrival to torch-off, including what you do about the gas appliances.
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Notify the homeowner and isolate the ignition sources first: shut the gas valve at the water heater and extinguish the pilot, and shut the furnace gas valve and switch off its power. Tag both. Open the window and set a fan to exhaust, confirming the draft hoods do not spill combustion products before you light anything.
Recover the R-22 into a clean recovery cylinder - no venting - and record the weight. Cut out the flare, remove Schrader cores, and purge with nitrogen at 2–3 psig with flow confirmed at the outlet before the torch is lit, keeping flow through the braze. Shield the gas appliance and any combustibles with a heat shield and wet rag. Braze the new filter drier with the arrow in the direction of flow, cool the joint, then pressure-test with nitrogen to the manufacturer's test pressure and leak-check every joint. Evacuate to 500 microns and perform a decay test, then charge by weight to the recorded amount plus any nameplate adjustment.
Leak-check, restore gas, relight the pilot, and verify draft and CO at both appliances before leaving.
3. The homeowner says, 'Just top it off like last time - the pilot is fine.' How do you handle it?
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Do not treat it as a scheduling preference. Explain in plain terms: the leak is at a flare that will keep losing refrigerant; topping off a leaking system is not a repair, and with a lit pilot in a basement the combination of refrigerant and an open flame can create phosgene and hydrogen chloride. That is a health and safety issue, not a cost issue. Also note that refrigerants must be recovered, not vented, and that a system with a known leak should be repaired rather than repeatedly topped off.
Offer the repair with the price, and offer the alternative of pumping down or recovering the charge and returning when the customer is ready - but not a top-off with the pilot lit and a torch in the room. If the customer refuses the repair, document the refusal, the leak location, and the safety conversation on the invoice. Do not perform hot work in that room until the ignition sources are controlled.