For me it wasn't even close, pay for someone else to do it in copper, or do it myself with pex. I saved $10k. I got around the 'long travel time' to the bathrooms on the far end of the house by putting in a tankless water heater with a recirculating pump built in. First thing in the morning and in the evenings it cycles every 15 minutes to put hot water at the sinks.

I wanted separate, simple manifolds with valves, not the dual hot and cold ones.

I have an account at a wholesale plumbing supply, but they didn't have them. They said nobody around here, MN, did home runs. And most of the PEX they sold was in 10' lengths. So it is assumed that they connect 10' lengths instead of seamless runs.

If someone is in the shower, no other water usage affects the flow or temp to the shower, or anything else. I also run at 60psi.

My water system is PEX, and it does not use manifolds. My well pump runs 40-60 psi (kicks on under 40 and off at 60). I do not have any pressure drops when using multiple faucets, so you can take a shower, flush a toilet, run the washer at the same time, and there are no noticeable problems. I have 3/4 inch PEX main lines with 1/2 inch running to the fixtures. I just cut the 3/4 line where I needed, inserted a 3/4 3/4 to 1/2 T fitting, crimped on the fittings, and ran the 1/2 inch to the fixture. I am using a Vertex 50 gal propane condensing hot water heater set at 105 on 125 off, and run the radiant floor through a heat exchanger on the same system. The HWH does a great job of keeping up with everything so far. I don't know how copper can possibly cost less or equal to PEX, and I definitely would not use 10 ft lengths when you can buy the stuff by the roll and get it shipped to you - often with shipping included in the price.

-Rosalinda

There are all kinds of sites that sell the pipe and manifolds, just do a search on PEX and manifold, you can get exactly what you specified. The dual hot and cold seem expensive to me, the simple manifolds are much more reasonable, and easier to find a place to mount. I've been doing a modified home run with a small manifold to distribute the trunk lines, then additional small manifolds for each fixture group, and not bothering with individual shut off valves.

Well, about 2k worth of Pex stuff is coming on Wednesday. I'm going to run two home run manifolds with two water heaters to shorten any long runs. After getting my HVAC roughed in this week, I'm glad I ordered the pex. Thanks everyone for your input. I'll let you all know how everything goes.

Sean

I checked how long it took the hot water to reach my longest run (actually the only long run in the house). From the hot water heater to the kitchen sink, about 40 feet, took 25 seconds from a cold start to full hot. The water lines are in conditioned space, and are insulated to approx R4.

Hope you have fun working with the PEX.  Do a few practice cuts and fitting installations so you get a good feel for the tools and pipe you are working with.

-Rosalinda

Rosalinda,

Do you consider 25 seconds too long to wait for hot water?  On one home, the homeowner and I rerouted a hot water PEX line because the wife felt like the wait was too long.  A local plumbing supply store loaned us the crimper tool.  PEX is very easy to work with.  I think Uponor is even easier - no crimping.

One other thing in favour of pex. It runs much quieter than copper and usually no hammering. In a multi storey home it is often most cost effective to run 3/4" runs than spilt to fixture groups. Remember many service lines are only 3/4" and even if you have a 1" service you would not see a drop in pressure or multi user problems unless you have very low service pressure.

Alton,
No, 25 seconds is fine. I keep a jug under the sink for watering my upstairs plants, and just add the cold water to the jug until it runs warm. Water is also something I have in great abundance on my farm, so it does not bother me to 'lose' that water. The overflow water from my spring flows into my pond and then eventually works its way down to the lake, this water just takes a slightly different route, but eventually filtrates down to the lake anyway. Since I have the bathrooms stacked close to the location of the hot water heater, and the clothes washer is also near the hot water system on the west side, there was no way to avoid the 40 ft run to the kitchen sink located on the east side.
-Rosalinda