I'm looking for some kind of floor plug/gasket/grommet/valve/drain

[musigenesis]

My floor has two lowered boxes (one for a tub, the other for a closet) that extend below the rest of the floor. If I have any leaks inside the bus, water is going to tend to accumulate in the bottom of these. Is there some sort of small plug/gasket/grommet/valve/drain type of doohickey I can put in the bottom that will allow water to drain out but not allow water in from the underside?

[banman]

Originally Posted by musigenesis

My floor has two lowered boxes (one for a tub, the other for a closet) that extend below the rest of the floor. If I have any leaks inside the bus, water is going to tend to accumulate in the bottom of these. Is there some sort of small plug/gasket/grommet/valve/drain type of doohickey I can put in the bottom that will allow water to drain out but not allow water in from the underside?

Like a drain plug...?
(sorry I couldn't resist...)

How about a pipe plug (¼"NPT) like you have to drain and fill your diff cover?

You just weld it wherever you want it.

[musigenesis]

Originally Posted by banman

Like a drain plug...?
(sorry I couldn't resist...)

How about a pipe plug (¼"NPT) like you have to drain and fill your diff cover?

You just weld it wherever you want it.

That would be like something where I'd have to go under the bus and open it to drain, right? I'm hoping to find something like a passive drain that would let water out with my having to do anything.

I've seen marine drains but I think they're also something you turn from the outside to allow drainage to happen (for obvious reasons, I guess). They're also of a thickness meant for wood, so if I attached one through my sheet metal, the water would have to be 1/4" deep or more before it started to drain.

[sepudo]

Not sure if it would help but in my rig I installed a drain straight through the floor and used a kayak 4 inch deck plate.

Worked for my needs

[keithgugliotto]

Would a Hepvo valve work?

[musigenesis]

Originally Posted by keithgugliotto

Would a Hepvo valve work?

That's the idea, but those are too huge. I'm thinking of just some tiny thing that only needs to allow a small flow of water to drain.

[musigenesis]

Originally Posted by banman

How about a pipe plug (¼"NPT) like you have to drain and fill your diff cover?

You just weld it wherever you want it.

Could you tell me more about this or maybe give me a link to what I would need to buy? I see these plugs that are like a short piece of threaded rod with a square nut on one end, and you screw these into a tapped hole.

[banman]

Originally Posted by musigenesis

That's the idea, but those are too huge. I'm thinking of just some tiny thing that only needs to allow a small flow of water to drain.

All the float valves I can think of require some room inside your box -- like the valve on the bottom of a dishwasher.

Welding a bung to the bottom of the 'box' gives you the lowest possible drain point but has the hassle of getting under the bus to remove the plug.

Aha, a flapper valve in the bottom-side-edge of the 'box'.
https://www.amazon.com/Moeller-05101.../dp/B003E1ZGKG

Or,
Automotive application has what I've always known as 'duck bill valves'. You'd find them on a/c evaporator drain lines. The air filter housing on my bus has one on the bottom of it in case water gets inside -- the weight of standing water will open it but the rubber 'duck bills' want to stay closed to keep bugs and crud from coming in...

[banman]

Originally Posted by musigenesis

Could you tell me more about this or maybe give me a link to what I would need to buy? I see these plugs that are like a short piece of threaded rod with a square nut on one end, and you screw these into a tapped hole.

Yes, the 'hole' would be called a "bung fitting" or bung hole.

Numerous sources but
https://www.summitracing.com/search/...ize/1-4-in-npt

[musigenesis]

Do these things work like I think? https://www.amazon.com/dp/B0718Z7VKV

You drill a hole, stick this in from the outside and push the lever down, and it expands and fills the hole and waterproofs it? Would something like this work on the underside of a bus?

[banman]

Originally Posted by musigenesis

Do these things work like I think? https://www.amazon.com/dp/B0718Z7VKV

You drill a hole, stick this in from the outside and push the lever down, and it expands and fills the hole and waterproofs it? Would something like this work on the underside of a bus?

Yes, and no... I think they're meant to go into material far thicker than sheet metal -- like a plywood hull. And usually you'd have it on the inside. I don't know how well that metal bit would hold up to road crud and if it came loose it would fall out and be gone leaving an open hole...

[banman]

It's not just me -- the rest of the world calls 'em duckbill valves too!
I think these are your best bet for set & forget drainage.

https://www.google.com/search?q=duck...hrome&ie=UTF-8

[musigenesis]

Decided to go with these little MNPT drain cocks: https://www.grainger.com/product/PAR...in-Cock-21VL69

My plan is to weld a nut on the underside and to run these through that and a hole in the 14 ga sheet, so that the drain is flush with the bottom of the floor. I explained what I was trying to do to the tech person at Grainger and they said this was pretty much the only way to do it.

[banman]

Originally Posted by musigenesis

Decided to go with these little MNPT drain cocks: https://www.grainger.com/product/PAR...in-Cock-21VL69

My plan is to weld a nut on the underside and to run these through that and a hole in the 14 ga sheet, so that the drain is flush with the bottom of the floor. I explained what I was trying to do to the tech person at Grainger and they said this was pretty much the only way to do it.

Those will work -- coat the threads with anti-seize (I especially mean the valve threads) in that environment they will corrode and then the wing spins on the threads

The install method you describe is what I was trying to suggest before but with some type of duckbill valve so gravity drains it for you as needed.

[o1marc]

I would flare one end of a 1/2" pipe copper about 2" long, drill a hole in the corner of the box and glue it in. This way it constantly drains with little chance of water coming up the tube if it is angled rearward.

[banman]

Originally Posted by o1marc

I would flare one end of a 1/2" pipe copper about 2" long, drill a hole in the corner of the box and glue it in. This way it constantly drains with little chance of water coming up the tube if it is angled rearward.

You'll get vermin coming in your bus with a hole that big -- till a muddauber next plugs it up...

[Maligator.]

Is there a reason you cannot use Scupper valves or self-bailing valves?

https://www.amazon.com/Invincible-Ma...KSYNS68K2G1FEX

https://www.amazon.com/dp/B0000TX760...xpY2s9dHJ1ZQ==

[musigenesis]

Originally Posted by Maligator.

Is there a reason you cannot use Scupper valves or self-bailing valves?

https://www.amazon.com/Invincible-Ma...KSYNS68K2G1FEX

https://www.amazon.com/dp/B0000TX760...xpY2s9dHJ1ZQ==

Just ignorance on my part about how they work. I've been looking at tons of this type of gadget, but none of them ever shows a picture of how it works in terms of how it goes through something, so I'm never really sure of which end goes where.

So I'm sure of nothing about these things, but it seems like scupper valves a) project a little bit above the surface they're draining, so they won't allow all of the water out, and b) they require a certain weight of water above them for the flap to open? They also generally seem to handle a much larger flow of water than what I'll need.

[BarnYardCamp]

I don't see where or why you would need a valve. Just use a couple short pieces of small pipe with a couple of 90's in it...
straight pipe down from your drain pan...maybe 1 inch drop, then a 90 with another straight pipe for a few inches then another 90 straight down. Not likely that the wind would force the water up and not likely to get splashed water to navigate it either. Maybe put some kind of screen over the end to keep bugs out.

[Maligator.]

They are placed on the Aft transom and use the vessels forward momentum to drain the water. Assuming you position them properly, anytime you're 'underway' the water will push toward the aft of your boxes and physics does the rest through the one way valve. I see no reason (since the bus won't actually be in water) that you couldn't just mount them on the bottom of your boxes. After the water drains, the valves close from lack of downward or backward water pressure.