Makeshift tub faucet, Is this allowable?

[Kenji S]

I've got a freestanding tub and have been struggling to find high-flow filler options at (to-me) reasonable prices. While looking around the web, I found this image (http://www.remodelista.com/wp-content/uploads/2016/03/niki-turner-stroud-remodelista-25.jpg) and would love to do it if it would pass code. What do you all think? Can I run bare copper pipes in from the ceiling (or wall) and fill the tub with just a valve on each line?

Really appreciate this forum by the way, it's been my go-to resource for all my many plumbing questions

 

[Reach4]

In case some don't want to follow your link, here is a shrunk down version of the picture

 

[Sponsor]

 

[Smooky]

What do you consider a reasonable price?

 

[Kenji S]

Thanks, Reach4, appreciate the help!
Smooky, for high flow (10 GPM+) floor or wall mount fillers with a hand shower, mostly what I've been able to find has been 1.5k - 3k+. An order of magnitude less would be nice! spending $20 on the filler and 200 on a separate, dedicated hand shower would be ideal for me
Cost is part of the calculation, but I also really like the aesthetic and the space-savings of just piping in 3/4" copper lines. I'm asking because I couldn't find anything in my local code on exposed piping or filler requirements.

 

[Jadnashua]

You don't need an anti-scald valve for a tub filler, but you do for any shower. So, you could add an in-line valve to do that for your shower, while having it go straight in for the tub.

Note, while you can get more volume out of it than this, the copper organization trade group publishes a handbook that states for a hot water line, your flow rate should not exceed 5fps, which, on a 1/2" copper pipe equates to 4gpm! You can double that with a 3/4" pipe and still maintain that maximum flow rate. Depending on how hot your water is, and how much cold you would mix in to it, you'd probably want 3/4" lines. Bigger valves do cost more, especially if they are designed to minimize internal restrictions.

 

[Stuff]

That picture is pretty neat but may not pass as I believe there needs to be a 3" air gap to prevent any backflow.

 

[BillTheEngineer]

if you did that I would think the water would go in one side, wrap around the tub and fly out the other side. Unless you have really low water pressure.

 

[Reach4]

20 ft of open 1/2 inch can give more than 10 GPM. http://www.engineeringtoolbox.com/hazen-williams-water-d_797.html

Would the fill water wrap and fly? I don't know.

 

[Kenji S]

Interesting point about the air gap. I think i'll just take a picture to the permit office and see what they think. Even if they say 'no', I'll set it up temporarily just to find out if it really does wrap and fly! I hadn't even thought of that possibility. I've got 1" wirsbo coming into the house at ~80psi, so I think it'll be a good test. Definitely going with 3/4". If this works, I'll probably T off the lines in the ceiling and bring them down inside the wall and connect them to a simple handshower with a code-approved mixing valve.
And if it doesn't work/pass, I'll probably just get a tried and true wall-mount tub filler and grumble to myself. Thanks for the comments, all!

 

[Jadnashua]

20 ft of open 1/2 inch can give more than 10 GPM. http://www.engineeringtoolbox.com/hazen-williams-water-d_797.html

While, yes, a 1/2" copper pipe can flow more than I mentioned (and I said as much), good design dictates that you should NOT flow that much with hot water as indicated in the Copper Industry guidelines for the reasons indicated.

https://www.copper.org/publications/pub_list/pdf/copper_tube_handbook.pdf

(see page 76, and note there's a difference between that rate for hot verses cold...slower for hot than cold)

 

[Terry]

There always needs to be an air gap. It's been that way for the last fifty years.
Some places want to see a restriction on water temperature to 120 or less on a non balanced system. Some homes have tempering valves for tubs.
HansGrohe makes an i-Box with 3/4" in and out.

 

[Smooky]

The minimum air gap is usually twice the diameter of the pipe or 1 inch, whichever is greater.

 

[Kenji S]

Quick update for posterity: Terry was completely correct about the max temp on the line - I could hide a mixer somewhere upstream but I'll probably just go with a standard wall-mount faucet with diverter for hand shower. The Lost Boys bathroom can wait for a cabin or farmhouse somewhere. thanks for the advice, and I'm still going to see if I can get some acrobatic water jets once the kerdi is in...