Refrigerant handling: General tips (part 1 of 2)

Short, practical technician tips on refrigerant handling for general. Check each one against the manual for your exact model before acting.

Absorption terminology

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"strong"/"weak" solution means ratio of refrigerant to absorbant in this book; other publications flip it.

Air band adjustment only with instruments

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A flame that "looks" air-starved may be a dirty nozzle or after-drip; don't eyeball.

Air-in-fuel test

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Gauge on pump port: fluttering needle = air; for small leaks, bleed tube into a bottle of oil and watch for bubbles.

Ammonia leak checks

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Smell, or wet litmus turns red; soap bubbles don't work (ammonia dissolves into the water).

Analyzer probe near hottest part of flue; let it cool 5 min before touching.

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Analyzer probe near hottest part of flue; let it cool 5 min before touching.

Bleeding a one-pipe oil burner

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Loosen bleed/gauge plug, 1/4" tube to container, open fully, run burner until solid oil, stop, tighten, restart.

Blow out oil lines with nitrogen only

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Never compressed air or oxygen; use regulator and relief.

Booster pump placement

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Near the tank (push, not pull); use a vacuum safety valve on the pump inlet, not a check valve (check valves blow pump seals).

Break the vacuum pump's vacuum before storing

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Otherwise oil floods the cylinder and the pump oil-locks. Change pump oil before every evacuation; white/foamy oil = water. Test the pump alone to 500 microns via a tee.

Cad cell must have line of sight

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Mount per burner mfr.

Centrifugal rotation direction is critical

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Wrong rotation damages the compressor; run at reduced load after start until oil foaming subsides; sump heater limits migration.

Charging absorption solution

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Purge vapor from solution cylinder into a pail of water to let liquid NH3 flow in; discard solution if white precipitate forms.

Check a cylinder float switch by inverting it with the cord connected

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Machine should alarm/shut off; if not, the overfill protection is dead.

Check all three oil filters

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Line filter, pump strainer, nozzle strainer.

Cold fan motors

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Outdoor fan motors idle in cold weather thicken their oil and may not start/trip overload; use oil that stays fluid at the lowest idle temperature.

Combustion head has many names

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End cone, burner head, fire ring, retention ring. Flame-retention heads are hotter/cleaner; check chamber refractory each visit when retrofitted.

Compound gauge scales are per-refrigerant and colour-coded

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Read the right ring; digital manifolds avoid this.

Cross-break big panels

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Prevents oil-canning when the blower starts/stops. Fabric joints at furnace absorb expansion and noise (check fire code).

Damp fluctuating pressure with a small-bore connector or liquid-filled gauge

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Pulsations ruin gauge accuracy quickly.

Date-tag service

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On the furnace/condenser; log charge, suction and head pressure whenever the system was opened.

Draft test: overfire first, then flue (between draft regulator and furnace)

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; zero the gauge on a level surface, read after 30 s; low = move barometric weight to increase draft. Sealed-combustion oil units may have no regulator.

Duct leaks are not equal

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A leak into unconditioned space hurts far more than one inside the envelope; seal ducts in attics/crawlspaces first.

Electrodes must not touch the spray

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They carbon up and cause delayed ignition/blowback.

Find leaks under depressurization

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With house at −50 Pa, leaks are exaggerated — use smoke sticks or thermal imaging.

Heavy extension cords, as short as possible, for recovery machines

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Plus: drier per schedule, fittings leak-checked every 3 months, verify overfill shutoff, check gauge calibration, tank recert dates (5 or 10 yr; >300 psig cylinders every 5).

Humidifier commissioning/maintenance

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Level in all directions; check leaks; grounded receptacle; monthly check for bacteria/scale; treat reservoir water.

IAQ interview clues

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Complaints that fade when the occupant leaves the house, RH >60% or <40%, musty odor, stuffy rooms, condensation on windows/pipes. Walk-through checklist in Fig. 28-8 (dust, pests, leaks, stains, soot near furnace/water heater, gas/oil odor).

Inspection checklist habit

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Written periodic inspection (connections, safeties, noise, charge, moisture indicator, oil level, water flow, coils, supports, cleanliness; belts/coupling on open drive; overload/relay/capacitors on hermetics) — give the owner a copy.

Insufficient draft causes

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Too many appliances on one flue, soot/nest/bricks in chimney, tight house (add dedicated combustion air pipe).

Interrupted vs intermittent ignition

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Interrupted sparks only at start (then ignition carryover); intermittent sparks all cycle; field slang mixes these up.