Brass/Copper vs Pex - water flow issues in 90 y.o. mansion

[macmedia]

I bought a 1929 mansion (16,000 sq. ft) at an auction and it is in need of TLC. I have some water pressure issues, leaky pipes and cracked junctions on a 4 floor house (basement + 3 floors). I have been fixing a lot of leaks/holes by replacing the brass piping with copper and getting close. Still, water flow has been spotty at times. Each time I open up the 2nd floor faucet, a bunch of black iron spits out before getting some water out. I haven't been able to see how the pressure is if I open up all the faucets as most have been capped off. 3rd floor shower is not giving great flow - maybe a gallon a minute. The well pump gives me in excess of 50 gallons per minute through 2" pipe. I have a relatively new 120gal pressure tank. Further upstream, the pipes are reduced to 1", 3/4 and then 1/2" to each bedroom. I personally don't think the current plumbing can handle 16 bathrooms of the house - but that is just an "uneducated" guess as I haven't been able to test all of the bathrooms at once

I'm somewhat savvy with construction but I'm kind of way over my head with this project. I was told that I should just start from scratch and pull out all of the plumbing and put in new. It originally scared me because of all of the plaster/mesh/steel ibeams that have to be dealt with but a crew of 6 came and gave me a reasonable quote - I just provide the parts. They work mainly with copper (as they are from NYC) but my friend who owns a big plumbing company told me it's all PEX up where I am (suburbs an hour from NYC). I'm trying to make better sense of this and wondering WHAT SHOULD I DO???? Naturally copper is far more expensive but PEX is easier to work with and easy to fix. Do they even have 2" pex?? I've never had to deal with a complex system as this.

The other alternative they mentioned is that just to fix what is broken, replace all of the valves and "hope" that I get good flow - at 1/10th of the replace price...

Thanks for your advice!!

 

[Matt30]

Yes there’s 2” pex. I highly reccomend Uponors expansion system in your situation where you’re dealing with flow issues.

 

[Jamesplumbing06]

16 bathrooms? O my lord. No a standard residential plan of 1” to 3/4 to 1/2. You can do that but your best option would be a manifold with expansion pex. This way you can build a 2” manifold with 1/2” take offs using brass. 1 -1/2” take off will feed a faucet and a toilet but don’t include the shower. Always tap each shower. But this way you buy a butt load of pipe but build your manifold with room to grow and run the baths you can afford now. And then just tap into one of your future take offs as you add bathrooms. But 16 baths will have a whole lot of fittings hidden by expensive handy work. I would highly recommend a manifold for you tapping into 2” manifold. Then on hot side you need 3 heaters in the end al plumbed in parallel so you can physically feed 2” pipe with hot water thru 3/4” fittings on heater tanks. Then build hot manifold and tap into that. It’s the only way you will have a chance at having all faucets on at once as in a maximum usage scinario. Also believe you should bite the $500 for a sit down with an engineer on this project. I am not one to just blow money. But 16 baths to a plumber would be kicking the doors of $75k. And trying to this as a standard house will be wasting that money. Regardless right now you should be good. But you need to get every leak fixed so it can charge the whole system to give an accurate test.

 

[Diehard]

I would highly recommend that you, at a minimum, have the entire water system engineered and/or designed based on the detailed requirements of the plumbing code. Or as a minimum, as @Jamesplumbing06 suggests, discuss with a plumbing designer/engineer. As mentioned, consideration must be given to a design approach that would lend to a relative uniform flow and pressure distribution.

Codes if properly followed would dictate requirements, which should be incorporated early in the design stage.
Examples:
Domestic hot water systems are required to have a recirculation system or heat tracing when the distance between the source and the demand exceeds 50 feet. Without double checking, I'm pretty sure this is a requirement of the model plumbing codes.

Pipe sizes will be based on WSFU's(Water Supply Fixture Units), which take into consideration diversity factors such as probability of use, duration of flow, volume of flow, average flow rate(gpm), available pressures as well as a consideration of velocity. This would be difficult to achieve if a piece meal approach is considered.

An advantage of using WSFU's is , for example, the water demand for a bathroom group would not be multiplied by 16 for 16 bathrooms.