ACHR News reported that a Missouri ice rink "replaced its aging R-22 refrigeration system with ammonia" as part of a $5.2 million renovation completed in five months (read the ACHR News ice rink report). The refrigerant choice does not transfer to a house, and nobody should read a commercial ice plant as a template for a home system. The part that does transfer is the schedule. A job that runs five months was planned around shutdowns, handoffs, and dates, and a homeowner planning a refrigerant-side replacement can use the same discipline.
Why the Ammonia Choice Stays at the Rink
Ammonia is toxic and flammable, and it is handled in industrial plants built around those hazards, with specialized equipment, detection, and trained operators. Residential split systems and heat pumps are designed around other refrigerants and other equipment. Your job is narrower. Confirm what the installer proposes, confirm it matches the equipment you actually own, and do not let a story about a different building set expectations for yours. If a contractor starts talking about switching refrigerant types as a casual upgrade, ask for the equipment rating sheet and the manufacturer's written position before agreeing to anything.
Plan the Downtime Before the Crew Arrives
A house has one thing a rink does not have in the same form: a household that needs heat on a cold morning. That makes timing the first decision. If the system is your only source of heat, pick a shoulder-season window and write down what happens if the job runs past the planned days. Ask which rooms stay usable, what the temporary heat source will be, and where it will plug in. Check the breaker rating before anyone plugs in a space heater, and if you own a clamp meter, measure the circuit under load so you know whether it can carry the heater with the blower and the kitchen appliances running at the same time.
Map the Refrigerant Handling Before the Lines Are Cut
Refrigerant in the existing system has to be recovered, not vented, and the technician doing the recovery needs EPA Section 608 certification. Ask for the certification of the technician who will handle the charge, and ask where the recovered refrigerant goes after the job. Then ask for the old system's service history, including past leak repairs, charge adjustments, and any coil or line work. That history tells the installer what the existing lines and coil have already been through, and it tells you what a future technician will need to know.
Plan the Roof and Attic Side as Its Own Phase
New line-set routes often cross the attic or pass through a roof penetration, and any work at the roof edge belongs on the calendar as its own phase. If the swap touches roof penetrations or flashing, a roofing contractor such as a roofing contractor such as Keys Roofing can handle that side, and the flashing work should be finished and inspected before the refrigerant goes in. Schedule that phase in dry weather and before the heating season starts, not in the middle of it, so a rushed roof detail does not become the next leak you chase in the attic.
Get the Schedule in Writing
Ask for a written schedule with a start date, milestones, a removal date for the old unit, a commissioning date, and a named person responsible for each step. Ask what happens if parts slip and whether the contract sets a limit on how long the house can go without its primary heat source. Keep the signed schedule, the refrigerant recovery paperwork, and the final invoice together in one folder with the equipment manual, so the next technician can see what was done, when it was done, and by whom.
The rink's five-month renovation is a reminder that a major equipment change is a calendar problem first. Put the downtime plan, the handling records, and the roof-side work on one timeline, and the refrigerant decision becomes one line on that timeline instead of the thing that controls everything else.