70 gallon tub. Need advice on shower/tub controls

[Lordoftheflies]

I have been searching high and low for the perfect shower/tub control trim/valve for my high volume 70 gallon Hydrosystems Sydney 66"x 32"x 22" tub.

It seems nearly impossible for me to find the following:

Things I want:

Pressure balanced valve
Single handle
High flow (i.e. somewhere in the neighborhood of 10gpm)
Built in diverter into trim.

Things I do NOT want:

Diverter built into spout - those things leak all the time.
Thermostatic valve - I want to be able to set it to 100% hot water. My water heater is set to 130F and I like turning it full hot at the end of a shower.

I am going to be installing a 1/2" manabloc with dedicated 1/2" lines to the shower and will use copper tubing from the diverter to the spout to maximize flow.

I have city water, a Rinnai RU98i tankless hot water heater, 3/4" main, ~100psi of static pressure incoming with a PRV set at 75psi, and a 3-stage whole house water filtration system (100mesh/150micron stainless steel sediment trap, 5micron sediment filter, 5micron granular carbon activated chlorine taste/odor filter).

Stupid me did not do my research properly and had already purchased an Artos-Westover F903-14CH valve. This valve does a max of 5.5gpm flow for the tub and 70 gallons / 5.5gpm = almost 13minutes for it to fill.

Is that too long of a time or do you think that's reasonable? Obviously won't be filling it to 100% capacity every time but when you want a soak, you want a soak.

Click on the pic for the specs of the valve. It has 1/2" FNPT connections for inlet and shower outlet and a 3/4" FNPT connection to the tub.
I like how this diverter button operates - you turn on the water, then press the button and the shower comes on. To get back to filling a tub you have to shut the water and the button will reset itself.

Any input is greatly appreciated.

 

[Lordoftheflies]

A similar shower trim I found from Grohe is the Concetto but that's also maxed out at 5.8gpm.

 

[Sponsor]

 

[Jadnashua]

TO get more volume, you're going to need a larger valve. Throw in the Copper Institute's recommendations, and with a nominal 1/2" pipe, with hot water, they recommend NGT 4gpm (which equates to 5fps - it's the higher velocity that can be problematic and also creates more friction). WIth a 3/4" valve, the hot line's max flow is 8gpm. Now, you'll also be mixing that hot with some cold, so you can see higher volume. A thermostatically controlled valve does allow you to get to (almost) full hot, but on most of them, you have to press an override control to achieve it. In the meantime, it will keep the same temperature even if the source ends up cooling off, at least up to a point.

 

[Lordoftheflies]

Thanks for your input.

Manabloc doesn't come with 3/4 loops though. Only 3/8 and 1/2.

I could just tee the 3/4" main and split it to the two tubs and the manabloc.......

I don't plan on running a bath on a daily basis so I suppose it's not the end of the world if it takes a little longer once in a while to run a bath.

That said I do have a 5 year old who still likes to take a bath and when I finish the upstairs the downstairs bath will be taken out.

I tried to search for how long it takes to fill a typical deep soaker tub on youtube and all I could find were stupid videos with ASMR.

 

[Jadnashua]

5-8gpm is about the limit at code limited supply pressure with a 1/2" valve. I did find one 3/4" valve rated at about 18gpm a long time ago, or nearly 3x as much. You need a good sized tub spout to prevent backup (and potentially push it up to the showerhead). Some valves actually have an opening to both ports (head and spout) but because of gravity, it goes out of the spout unless there's too much friction. Close that port off, and it then flows up instead. It sounds like that's how your valve works...similar to that tub spout you don't like. They aren't all created equal, some tub mounted diverters do work well. An alternative would be a separate diverter valve. Just like anything, they do eventually need servicing to maintain their proper function.

The Copper Institute's guidelines take into account that higher velocity can, over time, literally wear out the pipes, but more practical problem with it in the shorter term, is that the water flow starts to get noisy and the effective (not static) pressure drops. That 8gpm on hot at 3/4" valve is the same 5fps as on the 1/2" line. They allow it to go faster with cold water by about 60%.

 

[Lordoftheflies]

So I could just get a 3/4" single handle pressure balance valve/trim with no integrated diverter (3/4" inlets, 3/4" tub outlet, 1/2" shower outlet) and add a separate diverter valve.

 

[Lordoftheflies]

I think I have a solution:

Click on each pic to be taken to the kohler site.

K-2971-ks-na pressure balance 3/4" inlets and outlets. Will cap off shower outlet. 13gpm flow rate. 70 gallons should take roughly 5.5 minutes to fill to the max.



K-ts14423-4 Purist trim for rite temp.



K-737-K 2-way 3/4" diverter



K-t14491-4 Purist trim for diverter 2-way



K-14426 Purist tub spout 1/2"



I think the tub spout will be fine even though it's only 1/2". It's unrestricted and the distance from the diverter will be less than 2'.

Kohler does not seem to have 3/4" tub spouts and of course the online retailers just pass the buck off to the manufacturers.

I might even just keep the longer Artos 9" tub spout I already have.

 

[Lordoftheflies]

Now the question is should I supply the valve with dedicated 3/4" lines for hot and cold by tee-ing off the main water line and the hwh before the manibloc or should I just run 1/2" supply lines. Hm. I will only need one fitting at each end of the pex from manibloc to the valve.

 

[Jadnashua]

You definitely want to run 3/4" if it is in pex. Keep in mind that 3/4" pex's ID is not much larger than 1/2" copper. Minimize the number of fittings you use on the pex. It doesn't have to be pretty, it will be covered up. SOme try to run it really neat and use lots more fittings than needed. Each one of those adds more restrictions. Just don't try to bend it in a smaller radius than it allows or it can kink. If you want to make the sharpest bend, use a bend support.

Personal opinion, I tend to avoid Kohler. It may look and last, but when it does need service, at least on some of their things, it can be tough to get repair parts. They have this NIH attitude, and tend to change things frequently making trying to stock repair parts tough, so you have to go back to the factory which can take a long time. Not good if you need it now.

Note that those specs on the valve are for copper...it will be less with pex because of the ID.

 

[Lordoftheflies]

Thanks. I have a pretty clear run to the bath upstairs so I am planning on using bend supports and only one fitting on each end.

I will be using sharkbite fittings for my transitions - drops ear for vanity, toilet, mnpt for bathtub valve - so at least I'm using the full diameter of the 3/4" pex. I could upsize to 1" just for the bathtub.

The plumber who transitioned from the 3/4" copper main used 3/4" pex......so I could just buy a 100' roll of 1", replace what he did, feed the water heater, tee off to the manabloc and also tee off direct for the 2 bathtubs (1st floor bath is the next project).

On top of that I have a 5/8" water meter. The city wants $300 and a permit filed to change that to 3/4". I think I should do it, although I could always do it at a later date.

 

[Lordoftheflies]

Now that I think about it more since I'll be running a 1" line direct to the bathtub anyways, I might as well save some $$$ and just not even bother with the manabloc. I can just trunk and branch off of the bathtub line with 1/2" pex for the toilet and vanity.

 

[Lordoftheflies]

Why is it that tub spouts are typically a 1/2" connection? I guess I will just use 3/4" copper down to a 3/4" drop ear and the insert a 3/4"=>1/2" bushing for the tub spout. There are not a lot of 3/4" tub spouts to choose from. I don't get it.

 

[Lordoftheflies]

Just got the parts.......and am befuddled........because the diverter has 3 1/2" outlets with a 3/4" inlet. WTFEOPHJER)*&#$@.

It says that the unit can do 18gpm using one outlet so this should max out the mixing valve's output of 13 gpm.

That makes sense if you are going to a shower head and two body sprayers or two showerheads and a body spray......

But this particular model is for one output at a time......so there's no sharing of the ports. You also have to remove a plug inside of the outlet you are not using BEFORE you close up the walls or else you're gonna have to retile.......

So looking at the tub spout it looks extremely roomy, larger than the 1/2" connection for sure. I think I'll be alright and this makes life easier so I can just go 1/2" copper from the diverter to the shower head and the tub spout.

 

[Reach4]

So looking at the tub spout it looks extremely roomy, larger than the 1/2" connection for sure. I think I'll be alright and this makes life easier so I can just go 1/2" copper from the diverter to the shower head and the tub spout.

I see many tub spouts say
3/4" x 1/2" FIP Base Connection

I'll bet many people can tell you what you have to do to use 3/4 with such a spout.

 

[Lordoftheflies]

Also the K-2971-KS pressure balance valve has only one 3/4" output - there is no high-flow-tub-output-so-you-have-to-flip-it-upside-down-and-flip-the-cartridge-and-or-reverse-the-lines-so-you-can-not-use-the-smaller-shower-output situation going on here.

 

[Lordoftheflies]

I'm not sure I understand Reach - originally I thought I was going to have a 3/4" output on the diverter to the tub (silly me for going blind reading spec sheet after spec sheet and not catching this) and was worried about the transitioning to a 1/2" tub spout from the 3/4" output of the diverter..........but now the specs on it clearly state that it can do 18gpm using one of the outlets.......and since they are all 1/2"..........I think I'm good.......

So what I don't understand is if it *really* makes that much of a difference if it had been a 3/4" spout....and it would seem that it doesn't unless you're trying to fill a jacuzzi or something with massive capacities......

 

[Reach4]

There are not a lot of 3/4" tub spouts to choose from. I don't get it.

You are the one who brought up a 3/4 inch tub spout. I had got the mistaken impression that you kinda wanted one.

So what I don't understand is if it *really* makes that much of a difference if it had been a 3/4" spout....and it would seem that it doesn't unless you're trying to fill a jacuzzi or something with massive capacities......

70 gallons seems pretty big.

 

[Jadnashua]

The longer the path, the more resistance to flow, regardless of the size of the pipe. The smaller it is, the resistance increases . Keep in mind that the ID varies by the radius squared, so a small difference creates a bigger change than you might think. That's why a 3/4" pipe can deliver twice the flow of a 1/2" one...the pipe's opening has twice the area.

 

[Lordoftheflies]

I remember my πr² - math was my best subject.

It would seem to me that 3/4" spouts are not common and I guess I thought they would be more common.

In any case, all the Kohler stuff is here except for the shower head and valve trim which somehow never got picked up from UPS. I've already reconfigured the diverter for 2-way operation and I find it funny that it has no OFF position - it looks like it will be shower, tub, shower+tub. I can see if you wanted to use it for a shower head and a handheld or second spout.....I would have preferred just an A or B diverter (again, probably something I would think is common that probably isn't).

Now I've got another few problems - my 5/8" water meter, my 4gpm GAC 20" BB whole house chlorine filter, and I've got to shim two floor joists (one 3/4", one 3/8") to flatten the floor.

This is certainly a can of worms I've opened up. But fun indeed........Thanks for all the help.

 

[Jadnashua]

Shims can work, but you might find that if you can sister a straight 2x something on the side, you can make that more solid easier. Glue and screw it, but it does not need to be the full height. Trying to cut tapered, maybe crowned shims can be a tough challenge. If they are crowned, and you can afford losing some height, a power planer works. I did a combination of all three when I remodeled my first floor.