Tankless water heaters: casing leaks versus connection leaks

Honestly, I’d argue a sudden connection leak can be just as nasty, if not worse. Had a supply line pop off once - came home to half an inch of water across the kitchen floor. Sure, insurance covered it, but the hassle was next level. At least with a slow drip, you *might* catch it before it turns into a full-blown disaster.

“Honestly, I’d take a connection leak over a slow box drip any day... at least you notice those before your shelf turns into pulp.”

Not always true in my experience. Sometimes those connection leaks go unnoticed until it’s too late, especially if you’re not home much. Either way, both are a pain.

Had both kinds over the years, and honestly, neither is a walk in the park. The connection leaks are sneaky - one time, a compression fitting under my bathroom sink loosened up just enough to start spraying behind the cabinet. Didn’t notice until I saw water pooling in the hallway carpet... not fun.

The thing with slow drips from the box is, yeah, you might spot them before they do major damage, but sometimes they’re hidden behind stuff or under appliances. Mold loves that kind of setup. At least with a big connection blowout, you know immediately (or as soon as you get home), and you can get to work drying things out fast.

I started putting leak detectors under sinks and behind appliances after my last fiasco. Cheap insurance for peace of mind. It’s wild how much damage a little water can do if it goes unnoticed for even a few hours or days.

Leak detectors are a smart move, especially if you’re trying to avoid a big repair bill down the line. I’ve always wondered if the slow drips are actually worse in the long run, just because of the hidden mold and rot factor. At least with a big leak, you know what you’re dealing with right away, like you said. Have you found the detectors reliable? I keep debating if they’re worth the upfront cost, but it sounds like they’ve saved you some headaches.

I’ve always wondered if the slow drips are actually worse in the long run, just because of the hidden mold and rot factor.

That’s exactly what worries me too. I had a tiny drip under my sink that went unnoticed for months - ended up with a patch of black mold behind the cabinet. The leak detector caught it, but only after some damage was done. As for reliability, mine’s been solid so far, though I do wish the battery lasted longer. Upfront cost stings a bit, but compared to what I paid for cleanup... yeah, I’d say it’s worth it. Have you looked into any that integrate with smart home systems? Those seem pretty handy for peace of mind.

ended up with a patch of black mold behind the cabinet

That’s the nightmare, right there. I had a tenant once who didn’t mention a slow drip under the bathroom vanity - by the time I found it, the whole bottom panel was mush. Honestly, those tiny leaks are sneaky. I’ve tried a couple of smart detectors that send alerts to my phone, but sometimes they’re too sensitive (false alarms from humidity). Still, better than missing something for months. The upfront cost hurts, but it’s nothing compared to gutting cabinets or replacing drywall.

Drips under the vanity are bad, but I’d argue leaks at the connections can be a bigger headache. At least with a slow drip, you sometimes get warning signs - swollen wood, musty smell. But a loose supply line or bad compression fitting? That can go from fine to full-blown flood in minutes.

I’ve tried a couple of smart detectors that send alerts to my phone, but sometimes they’re too sensitive (false alarms from humidity).

I hear you on the false alarms. Honestly, I still trust my eyes and hands more than any gadget. Do those detectors even catch fast leaks before it’s too late? Seems like by the time they go off, the damage is already done...

I get what you’re saying about trusting your own senses more than a gadget, but I’ve actually had the opposite experience. Those smart leak detectors saved my butt once when a supply line started spraying behind the washing machine. The alarm was obnoxious, but it went off before the water made it out from behind the unit - no way I would’ve noticed that on my own until it was way worse.

Yeah, they can be touchy with humidity, especially in the summer, but I’d rather deal with a few false alarms than come home to a soaked floor and a huge repair bill. I do agree that nothing beats checking under the sink every now and then, but for the price (some of those sensors are like $30), it’s cheap insurance in my book. Maybe not perfect, but better than nothing... especially if you’re not always home.

Honestly, I get the appeal of those sensors, but I’ve seen a few cases where folks relied on them and missed slow leaks - like tiny drips at the valve or connection that never triggered the alarm. Sometimes you only catch those by feeling around for dampness or spotting a little corrosion. Not saying gadgets are useless, just that they can give a false sense of security if you’re not still checking things by hand every now and then.

I’ve seen those sensors miss the slow stuff too, especially at compression fittings or old shutoffs. The tech’s getting better, but it’s not magic - sometimes you just need to get your hands dirty and check for that greenish corrosion or a bit of moisture. Out of curiosity, do you find more issues at the box itself or at the connections? I’ve always wondered if one’s more prone to sneaky leaks than the other.

Honestly, I’ve had way more trouble at the connections than the box itself. Those old compression fittings are sneaky - sometimes you don’t even notice a slow drip until there’s a weird smell or you spot that greenish gunk. The box seems sturdier, but maybe that’s just luck on my end? I do wish the sensors were better at catching those tiny leaks, though. It’s wild how something so small can waste so much water over time...

Yeah, those old compression fittings are a pain. I’ve had to redo a few after thinking I’d tightened them enough, only to find a slow drip days later. You’re not wrong about the box being sturdier - sometimes it’s just the luck of the install, though. Sensors missing tiny leaks is frustrating, but catching them early is half the battle. Keep at it, you’re definitely not alone dealing with this stuff.

Honestly, I’d take a box drip over a sneaky connection leak any day. At least when the box is dripping, you know where to look. Those compression fittings, though... they’ll have you questioning your life choices. You can swear up and down you’ve tightened them just right, but then you come back a week later and there’s that telltale crusty mineral ring. Drives me nuts.

I’ve seen folks crank down so hard on those fittings they end up crushing the ferrule or splitting the pipe, thinking more muscle means less leak. Spoiler: it doesn’t. Sometimes it’s just about getting the angle right and using a dab of pipe dope if you’re feeling fancy.

Sensors missing leaks is a whole other headache. I’ve crawled under more sinks than I care to admit, chasing a “phantom” drip that only shows up when nobody’s looking. At least with a box drip, you can slap a towel under it and buy yourself some time. Connections? They’ll ruin your day and your drywall if you’re not careful.

At least with a box drip, you can slap a towel under it and buy yourself some time. Connections? They’ll ruin your day and your drywall if you’re not careful.

Totally get where you’re coming from. Connection leaks are way sneakier and can do a lot more damage before you even notice. Here’s what I’ve picked up:

- Box drips are usually obvious - water right under the box, easy to spot, quick to contain.
- Connection leaks, especially at compression fittings, can run down the pipe and show up somewhere totally random. Had one that wicked along the supply line and started staining the ceiling below... took forever to track down.
- Over-tightening is a classic mistake. I’ve seen more than one ferrule get mangled because someone thought “just a little more” would fix it.
- Pipe dope or Teflon tape helps, but only if you’re using it on the right threads. Some fittings actually seal better dry.

One thing I’d add: sometimes those box drips are just condensation, not an actual leak. Easy to misdiagnose if you’re in a hurry. But yeah, given the choice, I’ll take the obvious drip over a hidden connection leak every time.

Had a call last winter - customer thought it was just a “little drip” at the washer box. Turned out the real problem was a pinhole leak at a connection upstairs, water running down the stud bay. Drywall repairs cost way more than fixing the actual leak. I’ll take a puddle I can see any day.

Honestly, those sneaky leaks behind the walls are the worst. At least with a drip at the washer box, you know where it’s coming from and can throw a towel down while you fix it. Hidden leaks just quietly destroy everything... drywall, insulation, sometimes even framing. I’d rather deal with a visible mess than hunt for a mystery leak any day.

- Had a job last year where a slow leak behind the laundry wall went unnoticed for months. By the time anyone caught it, the bottom plate was rotted out and there was mold in the insulation. Ended up being a full gut job for that section. Not fun, and definitely not cheap for the homeowner.

- With visible drips at the washer box or exposed connections, you can usually spot them early. Quick shutoff, maybe swap a hose or tighten a fitting, and you’re done. Worst case, you mop up some water.

- Hidden leaks are dangerous because they don’t just damage what you see - they can compromise electrical wiring if it runs through those walls. I’ve seen outlets short out because of this. That’s a real safety hazard.

- One thing I always recommend: install water alarms near washer boxes and under sinks. They’re cheap and can save you from a nightmare down the line.

- Not saying visible leaks aren’t annoying, but at least you know what you’re dealing with right away. The unknowns behind drywall? That’s where things get expensive fast.

- If you ever smell mustiness or notice paint bubbling near plumbing lines, don’t ignore it... could be a sign something’s going on behind the scenes.

Guess I’m with you - give me a mess I can see over one that sneaks up on me any day.

You nailed it - hidden leaks are the real nightmares. I’ve seen folks spend thousands fixing what started as a tiny drip behind drywall. The visible stuff? At least you get a fighting chance to catch it before it turns into a disaster. Water alarms are underrated, honestly. People spend big on fancy appliances but skip the $20 gadget that could save their floor. Wild. I’d rather deal with a puddle than mold and electrical headaches any day, too.

Couldn’t agree more about water alarms - those little things have saved my bacon more than once. I remember a job where the homeowner ignored a faint musty smell for months. By the time we opened up the wall, the whole bottom plate was rotted out and there was mold everywhere. A simple alarm could’ve caught it early and saved them a fortune. It’s funny how folks will spend big on the latest fridge but skip basic protection. I’m with you - give me a visible puddle over hidden trouble any day.

It’s funny how folks will spend big on the latest fridge but skip basic protection.

That always gets me too - people love their gadgets but ignore the boring stuff that actually prevents headaches. I’m curious, though: do you think leaks at the connections are more likely to go unnoticed than a drip from the box itself? I always wonder if those slow, hidden leaks are worse for long-term damage, especially with all the eco-friendly materials that can be more sensitive to moisture. Anyone ever had a connection leak sneak up on them?

I always wonder if those slow, hidden leaks are worse for long-term damage, especially with all the eco-friendly materials that can be more sensitive to moisture.

Honestly, I think the slow leaks at connections are a bigger headache than a drip from the box itself. Here’s why:

- Drips from the box are usually obvious. You see a puddle, you know something’s up, and you fix it.
- Connection leaks? They’re sneaky. Water can run along pipes or wires and end up soaking insulation or subflooring before you even notice.
- With eco-friendly materials (like bamboo or recycled cellulose), even a little moisture can cause swelling, warping, or mold way faster than traditional stuff.

But I’ll push back a bit - sometimes people overestimate how “sensitive” green materials are. A lot of them are treated to resist moisture, but yeah, they’re not bulletproof. Had a slow leak behind my fridge once... didn’t spot it until the baseboard started to buckle. Took ages to dry out.

Bottom line: both types of leaks suck, but the hidden ones at connections can really mess with your house before you even know there’s a problem.