Finally got that rotted platform in the garage rebuilt

I dealt with almost the same thing two years ago, except mine was the air handler platform in the garage. Previous owner built it out of plywood and 2x4s right on the slab, and the condensate line had been dripping into a corner for who knows how long. By the time I noticed, the plywood was spongy enough that the whole unit rocked when I pushed it. I did the demo myself since it was just screws and rotten wood, but I went a slightly diferent route on the rebuild. Instead of framing a new platform, I set three 2 inch concrete pavers flat on the slab, leveled them with some shims, and sat the unit on those. The tech who came out for the annual service said it was fine and honestly better than wood since nothing can rot.

The part that actually mattered was fixing the drip itself. Mine was a clogged drain line, not a pan problem, so I ran some vinegar through it every few months and it has stayed dry since. Also moved the drain hose so it drains to the floor drain instead of over the platform edge. Cost me maybe sixty bucks total and an afternoon. Only thing I would add is to check where your drip is coming from before you rebuild, because a new platform with the same leak just starts the clock over again.

Mine was a hallway closet setup, water heater sitting in a wooden enclosure the previous owner built, and the drip leg on the gas line had been slowly wetting the baseboard for who knows how long. Instead of rebuilding anything I just pulled the old box out entirely and set the tank on a steel stand from the plumbing supply house, maybe forty bucks. Nothing to rot, nothing to absorb water, and the plumber had no complaints when he came out for the annual check. I also added a little float switch in the pan that kills power to the unit if water backs up. Cheap insurance after realizing how long that leak went unnoticed. For anyone with an AC air handler in a closet or garage, that switch has saved me twice allready when the condensate line clogged with gunk. One thing I'd add is to check under the tank itself before you assume the platform is the whole problem. Mine had been sitting in its own little puddle long enough that the bottom of the tank had surface rust, which pushed me toward replacing it a couple years earlier than planned. Better to know that before you pay to rebuild a stand for a tank that's on its way out anyway.

The kinked gas flex line detail is the part that stands out to me. I saw the same thing on a job I helped my brother with last spring, his tank had settled maybe an inch and a half on one side and the flex connector was doing all the structural work. Those connectors are not rated for that, so catching it before the rebuild was lucky. For anyone with a tank sitting low like that, shut the gas off before demo day and let the plumber hook it back up, it is a two minute job for them and a bad afternoon for you if you get it wrong.

First time posting here so bear with me. Our situation is a bit different, the AC condenser sits outside on a concrete pad that's sunk on one side over the years, so the unit leans toward the house and the lineset looks strained. Is that something a handyman fixes by pouring a fresh pad and resetting the unit, or is that an HVAC tech job? I honestly don't know who even handles that kind of thing. Reading this thread at least got me off the couch to go look at it with a level.

Agree with the point about fixing the drip itself before anything else. When I rebuilt the little platform under our air handler I had the tech add a float switch in the drain pan while he was out there, so if it ever fills up again the AC shuts off instead of quietly leaking all over the wood. That thing has tripped twice since, both times from a clog, and both times I caught it the same day instead of months later. Cheap little part and it basically turns a slow rot problem into a visible one.

Update: got it finished last week and everything's back up and running. Whoever pointed out the flex connector detail was spot on, the plumber said mine was stressed from the tilt and swapped it for a new one while the tank was out. Also went with a metal stand for the tank instead of framing another platform, which ended up cheaper and I can see under it now. No more soggy spots.