Racking

Installing Racking in a Running Freezer: The Contractor Rules I Learned the Hard Way

By the operator · November 4, 2026

Putting racking into an empty warehouse is a construction job. Putting racking into a freezer room that’s already running is a construction job inside an operating plant, and the plant doesn’t stop needing you just because the crew showed up.

I run an underground freezer, a two-stage ammonia plant feeding a calcium chloride brine loop, with rooms held anywhere from about -15 to 8 °F. In the summer of 2025 we were finishing a new freezer room, and the drive-in racking went in while the refrigeration was on. Here’s how it actually went, and what I’d tell any operator before a crew starts in their cold space.

How the install actually went

These are straight from my daily notes that summer.

• Late May: the drive-in racking started showing up.
• July 2: the crew started the install. They were going to work through the weekend, and the estimate was that it would take a couple of weeks.
• July 15: the racking crew was still there. That afternoon I had some head-pressure trouble and ran defrosts on a few units to bring it back down.
• July 22: the crew was about two-thirds of the way down the room. Head-pressure alarms started around 1:30 in the afternoon, and I was defrosting units in the new freezer to work through it.
• July 24: I found a door in the new freezer cracked open to the outside. Closing it started helping the temperature in that room.
• July 25: I found the crew had switched off half the units in the new freezer. I turned them all back on, and then the rest of that day happened. I wrote that one up separately as The Day From Hell.
• Mid-August: the good news. They were able to fit more racking than we had originally planned for.

So a “couple of weeks” job was still going more than three weeks later, right through the hottest part of the summer. That’s not a knock on the crew. Big installs run long. But it means you need rules that hold up for a month, not a few days.

Why a crew in a freezer is different

A racking crew thinks about uprights, beams and anchors. They don’t think about what an open door or a quiet evaporator does to a freezer, and there’s no reason they would unless someone tells them.

• An open door lets in warm, wet air. In a freezer that moisture ends up as frost on coils and product, and as ice on floors and ceilings. Even a door that’s just cracked open adds up over a shift.
• Units that are off aren’t pulling heat or moisture out. People turn them off because they’re loud, cold, or blowing on them while they work. Every unit that’s off is temperature you’ll have to win back later.
• The timing is the worst possible. Summer installs land in head-pressure season. We were already juggling defrosts to keep head pressure down, and doors left open and units switched off made that job harder.

The rules I’d set before the next crew walks in

1. Nobody touches a unit but us. Not the disconnect, not the controls, nothing. If a unit is in the way or blowing on someone, they come get us and we decide what to do with it.

2. Doors stay closed. No propping, no cracking open “for a minute,” especially any door to the outside. If they need a door open to move material, they ask, and someone closes it after.

3. Say who’s in charge, on both sides. When I found the units off, the person in charge said he didn’t do it. Maybe he didn’t. Name one contact on the crew who answers for the whole crew, and make sure they’ve passed the rules on.

4. Walk the room yourself, every day. Telling the crew once isn’t enough. I ended up just checking the doors myself, and I’d make a walk-through of doors and units part of the daily rounds for as long as a crew is on site. Our daily, weekly and monthly checklist is a good place to add it.

5. Plan for it to run long. Take the crew’s estimate and assume it’ll stretch. If that pushes the work into the hottest weeks of the year, plan your defrost schedule and head-pressure strategy around having the crew there.

6. Watch the temperature log closer while they’re there. A room that drifts up a degree or two with no other explanation is often a door or a unit. A temperature log makes that drift easy to see and easy to tie to a day.

7. Expect cleanup after. If doors were open or units were off, frosted coils and ice on floors and ceilings don’t go away when the crew leaves. Budget a few defrosts and some time with a scraper once they’re gone.

The short version

Racking crews are good at racking. Your job is to protect the freezer while they do it: units off-limits, doors closed, one contact who answers for the crew, and you walking the room every day until the last beam is in.

Related: The Day From Hell, the day the units got switched off, and Snowstorm Behind the Racks, what warm air getting into a freezer can look like once it’s racked and full.

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