The Tankless Sat Over a Paint Bucket

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The hallway felt fine. Reed’s spare-desk note this morning is vapor in a closed work room: the spare desk room held overnight air. The garage told a different story. A wall-hung tankless still made the shower. A thin white tube dropped from the bottom of the cabinet into a one-gallon paint pail. The pail was half full. The slab had a dark ring.

That is condensate from a condensing heater. Not a humidity complaint. Not the tank pan I already wrote. Not the air-handler closet.

I already walked the tank that sits in a dish with no pipe: the heater pan had nowhere to go. Today is the other heater in that bay. The one that makes its own water when it burns.

Why a tankless makes a bucket

A condensing tankless wrings water out of the flue. September showers in coastal Florida mean long hot-water runs after work. That water is not a leak in the city line. It is condensate. It is supposed to leave the garage through a trap and a pipe you can name — to daylight, a floor drain, or a pump that actually dumps.

What I find instead: a tube aimed at a paint pail. Or a pail that walked two feet during last week’s load. Or a tube that drips on the slab because nobody put a receptor under it.

A paint pail is a plan until someone forgets it. Then the shared wall drinks. Then the hallway smells closed and someone shops for another portable machine.

If the first six inches of the shared wall already look stained, pin it. Looking dry is not a reading: moisture meter after a leak.

After-work check (five minutes)

You do not need to pull the heater on night one. You need a look at the tube.

1. Open the garage. Flashlight the bottom of the tankless, the white or clear tube, and whatever sits under it.
2. Look in the pail. Standing water, algae film, or a dry pail with a wet ring on the slab is the diagnosis. A dry tube after a long shower is a different problem — the drain may be plugged upstream of the dump.
3. Follow the tube. If it dies in the bucket, on the slab, or in a hose that ends at the weatherstrip, the heater has no honest drain.
4. Look at the first six inches of slab and the shared wall. Dark concrete or a soft baseboard means the bucket already lost.

If the tube is tight, the dump is a real pipe you can see leave the bay, and the slab is dry, close the door. Do not invent a project.

If the tube is hanging in a pail, stop treating the hallway air as the first job.

What that bucket usually is

A lot of coastal Florida tankless swaps keep the old “we’ll add the drain later” pail. The unit hangs. The shower works. The installer leaves. The pail stays because it is cheap and it looks like a plan.

I will not walk you through cutting a live gas line. I will not tell you to cap a relief discharge into that same pail. Look. Photograph. If you can name the heater shutoff and the pail is overflowing onto the slab, you can empty the pail so it stops walking. That is not a drain.

A real drain needs fall or a pump. If the tube has no downhill run to daylight, a pump at the wall is ordinary work when a licensed plumber or HVAC tech sets it. This note is not a dispatch.

The future is still a text. A puck on the slab where the ring already is — pads down, not taped to the heater jacket. Test with a wet finger. Confirm the phone buzzes from the driveway: your phone knows before the ceiling. Same witness list as the tank pan: five places a leak puck earns rent.

If the tube has no fall to a floor drain, an assembled-USA condensate pump is the continuous dump I will point at. Not a bigger pail.

FloridaDamp is an Amazon associate — we earn from qualifying purchases. I still point at this one because it is an assembled-USA condensate pump that will actually drain when the garage slab has no fall, not because anyone paid for a review.

What not to do

• Do not treat a wet paint pail under a tankless as “just garage humidity.” Vapor is Reed’s meter. Standing water under a heater is a drain.
• Do not keep running long showers “to use the new unit” while the pail is full and the slab is dark. You are making more water into a failed receptor.
• Do not pour the pail onto the shared-wall side of the slab and call the bay dry.
• Do not tie the tankless tube into an air-handler dump you cannot see the end of. Two sources, one mystery outlet, is how a closet pan fills on a Saturday.
• Do not buy another portable dehumidifier for a garage that has a bucket under a heater. Give the water a path. Then measure the air.

If the water is in a wall, you smell gas, or you cannot name the shutoff, stop. Licensed plumber or HVAC tech on site.

After the tube is honest

Once the dump stays dry through a hot afternoon and one long shower you can watch, the air is Reed’s job. Log indoor relative humidity (RH) on an interior living-room wall, not on the garage door: hygrometer guide. If the house still sits above 60%, that is capacity, not a pail. Hand it to Reed’s pint chart.

A garage that still rusts tools after a dry dump is its own climate: Florida garage dehumidifier. Reed’s desk-room note from this morning is the vapor half of a closed September house: the spare desk room held overnight air. A dry pail does not dry a shut work room.

After a pulse that wet assemblies: after-storm sizing. Florida humidity home guide.

Run this

1. After work tonight, flashlight the tankless and whatever sits under the tube. A paint pail, a wet ring, or a hose that dies on the slab is the diagnosis.
2. Empty the pail so it stops walking. If you can name a real pipe to daylight, use that. If the tube has no fall, call a licensed plumber or HVAC tech for a trap and a dump that leaves the bay — or a pump that actually drains.
3. When the slab stays dry, drop a leak puck where the ring was and confirm the phone buzzes. Then log relative humidity (RH) for a week. Reed’s spare-desk note from this morning is the vapor half: the spare desk room held overnight air. A dry heater tube does not dry a closed desk room.

Carlo DeLuca is a third-generation master plumber. Family trade from Long Island, writing from coastal Florida. This note is not a service call. If the tube is in a wall or you smell gas, get a licensed plumber or HVAC tech on site.

If it’s useful, it’s beautiful.