Add diverter and body sprays to typical tub/shower combo kit

[Tim Coffey]

I have it in my head that I might like to add 2-3 body sprays to a tub/shower standard combo kit, by placing a 3-way diverter valve fed from the "shower out" of the single handle temperature valve. The diverter would be the kind that sends water to either the shower head, the body sprays, or both. It would not have an 'off' position (from what I know).
Is this possible to do? Would I need to install my own pressure loop with the body sprays?
Thanks

 

[Jadnashua]

Do you have access to the back side of the wall(s) involved?

Is the shower tiled? If you don't have access, or a few new tile, it won't really be able to be done easily. YOu can cut access holes in the tile, but would need to buy a diamond core drill to do it.

Note, there are some shower systems that would be easier to install that combine all of those things.

 

[Sponsor]

 

[Tim Coffey]

Do you have access to the back side of the wall(s) involved?

Is the shower tiled? If you don't have access, or a few new tile, it won't really be able to be done easily. YOu can cut access holes in the tile, but would need to buy a diamond core drill to do it.

Note, there are some shower systems that would be easier to install that combine all of those things.

Thanks for replying.
This is a complete bath remodel, so at this moment I am looking at bare studs. I have free reign to do whatever I can afford, and accomplish with my very limited, but learning, plumbing skills (I sweated two shutoff valves after I removed the old tub/shower Moen valve, and they aren't leaking after 5 days).

I had been looking at shower systems, but I don't really care for the outside-the-wall look. Would rather have the more traditional trims with rough-ins behind the cement board.

Also - I was able to finagle some new Kohler trims off of craigslist ($200 off retail, but I had to drive an hour away to get it). Also, I bought both a Kohler K 704 mixer, and a K 728 3-way diverter (both at 1/2 normal price). I only need to buy 2-3 body sprays that match the trims - and I think 3 is my limit. Since I am getting a little concerned about GPM, etc (I can only feed this with 1/2 inch piping, not 3/4) I am trying to find body sprays that use less than 2 GPM each. Would hate to solder all this, then have my first pressure test with nozzles and spray head on look really weak.

Also, when plumbing the pressure-balancing loop between the sprays, should I use 3/4 pipe, or 1/2?

 

[Tim Coffey]

Update:
Got an email from Kohler. They recommend I use the K 2971 valve, instead of the K 304. 13 GPM, versus 5GPM. They said I can use 1/2 pipe into the K 2971, using 1/2 to 3/4 reducers. It seems strange to me, admittedly as a non-plumber, that the flow from 1/2 pipe into a 3/4 inch valve (like the 2971) can magically give the 2971 enough water to feed out 13 GPM. Or am I missing something?
Anyway, that 2971 valve is $200. I will switch to it if it will work with the 1/2 inlet copper.
Any advice? Should I save my money and stick with the 5 GPM K 304 valve I already purchased?
Thanks

 

[Terry]

A lot has to do with the cartridge itself. There can be a lot of restriction in the valve. Also, the top of the K304 is restricted too.

 

[Jadnashua]

FWIW, the copper institute highly recommends you limit the maximum velocity in supply pipes with hot water to 5fps, and on a 1/2" copper pipe, that's only 4gpm. Yes, if the valve doesn't have a lot of restrictions, you can exceed that value but at your peril. Higher velocities tend to cause water flow noises, and can, over time, literally erode the inside of the supply pipe (especially after fittings and changes of direction). Depending on how cold your supply is, especially in the winter, you may be using mostly hot water and would easily exceed that recommended maximum when using a 1/2" supply pipe. It might be close in the summer when you'd be mixing more cold water into the stream.

 

[Tim Coffey]

FWIW, the copper institute highly recommends you limit the maximum velocity in supply pipes with hot water to 5fps, and on a 1/2" copper pipe, that's only 4gpm. Yes, if the valve doesn't have a lot of restrictions, you can exceed that value but at your peril. Higher velocities tend to cause water flow noises, and can, over time, literally erode the inside of the supply pipe (especially after fittings and changes of direction). Depending on how cold your supply is, especially in the winter, you may be using mostly hot water and would easily exceed that recommended maximum when using a 1/2" supply pipe. It might be close in the summer when you'd be mixing more cold water into the stream.

Thanks for your advice.
So you recommend sticking with the 5 GPM K-304 (which uses 1/2 inch inlet piping)? It would certainly save me money (and it just arrived today).

 

[Jadnashua]

A 5gpm valve will have very poor performance if you want to run 3, 2gpm body sprays. If you insist on using them, IMHO, you'd want the larger valve, but you will be going against the recommendation on maximum velocity of the water in the supply pipe. Since that won't be a constant use, it may not be a significant issue, but keep in mind, while you may not hear the water flow in the bathroom while showering, others may.

 

[Tim Coffey]

A 5gpm valve will have very poor performance if you want to run 3, 2gpm body sprays. If you insist on using them, IMHO, you'd want the larger valve, but you will be going against the recommendation on maximum velocity of the water in the supply pipe. Since that won't be a constant use, it may not be a significant issue, but keep in mind, while you may not hear the water flow in the bathroom while showering, others may.

Thanks again for your input.
With the K304, it sounds like I should limit the number of sprays to 2. I can even get some that are less than 2 GPM.
The showerhead is 2.5 GPM, so if I add 2 sprays 1.75 GPM each, I am at 6 GPM when both are running. So that is over the 5 GPM max outout of the K-304,which I assume means that both will be underpowered somewhat. But if I use the larger valve, I could put the elbows in the pipe at risk of failure. That sounds really bad (although I am really lucky in that the entire wall is accessible from the back, as it is shared with a linen closet. So if I (or better, a professional, should I get into said “bad situation”) had to access all the connections, it is possible to do without opening up the tiled wall.

And one more update: It appears that the bathroom do3s have 3/4 going up to it from the basement. Then it splits into 1/2 feeds to the shower, sink, and lav. But I would have to open the subfloor to get at that split if I wanted to feed the shower with 3/4 piping instead.

 

[NickK]

The 5GPM is almost certainly going to be under-powered. It sounds like you would be really better off spending a little more and getting the higher water pressure. Alternatively, I think you should consider skipping the body sprays entirely. If they don't work well, you will definitely not use them. For a more affordable shower system you might want to consider Delta. Here's an article that explains a bunch about building a delta shower system