I am in the process of remodeling a bathroom and am installing a shower system with 1 shower head, one hand shower, three jets and one rainshower overhead. The thermostatic valve is 3/4" and the volume control valves are also 3/4" BUT the hot water supply is 1/2" and the existing shower has both cold/hot 1/2" copper pipes/The plumber says he can bring and connect a 3/4" COLD to the thermostatic valve and of course connect the HOT 1/2" pipe to the valve. Is this advisable?
Can he run the COLD water 3/4" also to the volume control valves even though the hot water would be 1/2" pipes?
Would appreciate your advice!

HI Remodgal...

In my opinion, if you want the full benefit of the 3/4" valves you paid for, spend a little extra and have the plumber run full size 3/4" cold and 3/4" hot copper tubing to the thermostatic mixing valve. If he wants to reduce to 1/2" for the volume control valves then that would be OK as long as the hot and cold water into the thermostatic mixer valve are both 3/4". In this way you can run more than one of the units (shower head, jets, rain shower head) and still get full volume for best shower experience... ;)

What size is your water heater (or water heating appliance)? Let me know, OK?

Mark

I agree with Mark. You will not be happy with the finished product if you reduce to 1/2". The valve wants 3/4 and the valve needs what it wants. Don't ask me how I found this out the hard way

I also agree with previous posts. Since you have walls open, run new pipes. It is worth the money - and lot cheaper to do it now. Once you cover up - and notice, you don't have adequate water flow - it will be too late - and too costly - to deal with it.

Thanks for your sound suggestions.The problem is the hot water tank is very far from the master bath... that's a lot of feet of copper pipe plus the labor... you really don't think the shower system would work with 1/2" pipes coming from a 3/4" valve? I wouldn't run everything at once... for instance I would use the 3 jets and the shower only... and then the rainshower probably by itself, and the handshower by itself.You still think the pressure results would be disappointing?
Another question: Would PVC pipe be just as reliable as the copper?

HI Remodgal...

It's not about the pressure... it's about the VOLUME of water available... pressure won't really change with 1/2" vs 3/4" tubing.

In other words, you can use 1/2" tubing and end up with a low volume of water coming out the shower head and 3 jets or spend the money now to increase to 3/4" (hot & cold) and get a full flow shower experience where the shower head and 3 jets all provide a full volume of water out each head... the difference in your shower experience can be dramatic!

With that being said, I don't want you to think that things won't work with the 1/2" tubing...just that you asked us our opinions and if you were our customer we would recommend as we have is all. The fact remains, however, that using the 1/2" will still provide a fine shower experience... just not a WOW FACTOR type of shower experience! :)

In most areas, PVC can be used for cold water but CPVC is used for hot water. In most cases, people will just use the CPVC for hot and cold piping. I have recently heard of a newer PVC pipe that is approved for hot water use, but have not worked with it so can't comment on it, but if your plumber knows about it and wants to work with it then go for it if he is confident in it, OK?

PVC, CPVC and copper are all considered to be reliable. I would NOT recommend PEX thermoplastic tubing for this particular job.

Finally, I asked you a really important question you didn't answer? I asked you to tell me what size (how many gallons) water heater or what type of water heating device do you have? Is the water heater (or water heating device) gas or electric? These questions are important because if you don't have a water heating system capable of providing the higher volumes of water needed your showers with multiple shower heads/jets won't last very long, OK? Let me know the answers...

Mark

PS: PVC or CPVC cannot be connected to within 24" of your water heating appliance.

Thank you for your reply and advice
My water heater is electric/I think like 60 gallons or more.. I think I will change the plumbing to 3/4"
Thank you so much for your feedback
Be well