3/4" tub/shower mixing valves?

[Steve hartman]

As an old man (71), I'm beginning to love baths. The one single drawback to baths is that I have a large tub and it takes too long for the water to rise to the level I like. So I immediately get discouraged and just take a shower instead.
So, it finally dawned on me. Could I buy a complete mixing valve w/trim setup where I could feed the mixing valve with 3'4" water lines and a 3/4" output flow tub spout; but just have a 1/2' line out the top of the spout for the shower? The shower doesn't really matter, but I figure the tub would fill a whole lot faster - like before I get discouraged.
Is this possible? I'm on a fixed income so I can't afford a lot of money, but the good news is, I can do the work myself. Well, I can get down on my back to scoot under the house to do the work. Getting out from under the house and standing again "may" be a problem!
Would you have some products or know of two or three that would fit my needs?
Thank you very much!

 

[WorthFlorida]

Yep, I'm 71 with back problems also and every year it does get harder to stand back up after working at ground level. Your water heater recovery rate may not be able the handle the higher flow. It could be your flow is too slow even for a regular tub and by going to 3/4" may not give you the results you're looking for.

Your water source and pressure will have a lot to do with it. If you are on city water usually no pressure problems. Well water you are limited to what the the system can deliver plus it is usually much colder water that will impact recovery rate.

Usually the biggest complaint is not enough hot water for filling spa size tubs. What type of water heater do you have?

I'm not sure if a 3/4" valve body has 3/4" shower or tub outlets. This one is rated a 13 gallons a minute but most homes may get 5-8 gallons on a good day. To test your current flow rate get a 5 gallon bucket and using a 5/8" garden hose fill the bucket and time it, then do the math for flow rate per minute, however, hot water is always a slower rate. Kohler is a bit expensive and it may bust the budget. There are lower cost ones. Do you have access behind the wall to change out the valve body?
https://www.us.kohler.com/us/rite-t...wdriver-stops/productDetail/valves/428382.htm

 

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[Jadnashua]

If you can run 3/4" lines to the new tub filler, it will fill faster. A 3/4" line has double the cross-section of a 1/2" line, so can move more water with less friction losses.

1/2" line to the showerhead is more than enough. Bigger might work better if you had multiple heads, but is more than enough for one.

You can tend to get about 70% of the volume of a WH before it starts to cool off. If you have a large burner or heavier electric elements, you might get a bit more. First hour delivery isn't as much of a thing, as when filling a tub, it's normally way over in the first 10-minutes or so, so what it can do in the first hour is sort of useless (helpful on say taking a shower as that could last longer, but not a full-volume, dump like filling a tub). To help with keeping the desired temperature, consider a thermostatically controlled valve, as it will adjust the hot/cold balance to try to keep the temperature constant until there's not enough hot water left, and, as a class, it tends to flow more than a simpler pressure balanced valve, so you can kill two birds (speed, and temperature without having to babysit and adjust to more hot as you start to run out of hot).