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kbsparky 09-10-2008 09:21 PM

Replacing plumbing system
My house was built 19 years ago, and has polybutylene pipes for the water pressure lines. At that time, it was the cat's meow. One of the things I really liked about using it was all the connections were crimped, and there was no glue involved. I really did not want any "glue" taste or smell in my water, and using Poly-B pipes prevented that, even from day one.
Now, I have to tell you that I don't have municipal water here, so there is no chlorine, or other toxic chemicals added to my water. We have a private well, and the water is quite good. The Poly-B pipes have held up considerably well over the years, without the chemical breakdown associated with it.

My problem has been the failure of fittings, mainly on the hot water lines. Although the last leaky fitting was in a cold line. The fittings employed a copper crimp ring, and used a special compression tool for installation. All the leaks have apparently been from failed crimp rings, as that is where the water has been coming from. I have used either compression fittings, or them new-fangled "jaws" type fittings for interim replacements.

The other issue I have here is the length of time and water wasted when trying to use faucets on the far end of the system. In the master bathroom, it takes quite a while waiting for the hot water to arrive when using the shower or sink.

The problem is a 3/4" main line (to maintain pressure as I was told by my plumber), tee'd off with a 1/2" line for each fixture. So, when starting out with the lines "cold" one has to waste a lot of time and water down the drain in purging that 3/4" line waiting for the water to "warm up".

I was considering installing a new PEX system, with individual lines originating from a manifold located next to my water heater. There would be no more fittings to loosen or leak under my house.

I figure that by using a much smaller supply line to each fixture, there will be much less water needed to purge before the hot water will be present. Most installations seem to prefer using a 1/2" line from the manifold to the faucet. I was thinking of using 3/8" lines to reduce the wait time/water wasted even further. The supply tubes to each fixture is already a 3/8" size above the cutoffs.

I suppose that proper flow and pressure could be a factor in using the smaller lines. My system pressure varies between 40-60 PSI depending on the pump cycle. So my underlying question might be: Will I have sufficient flow in using the 3/8" lines to supply the fixtures? Taking that thinking one step further --- what good is it to have a larger line (for increased water flow) only to have a nasty flow-restrictor installed at the faucet?

What are your thoughts and experience on all this?

brownie 09-10-2008 09:49 PM

I had the same problem. Remove the flow restrictor on your faucet. What you want to do sounds like it will work. You will have water to waste, just not as much. I solved my problem by using 3/4 all the way to the fixture,Alot of waste but hot water faster. If you do as you are planning run 3/4 to your shower.

Termite 09-10-2008 11:15 PM

I'm a huge fan of PEX, but I'd advise against using 3/8" PEX. Since the fittings slip into the PEX tubing, the pipe diameter is essentially necked down at each fitting to 1/4". That will reduce flow, and won't do much of anything to solve your issue of getting the hot water to the faucet faster. 1/2" PEX necks down to 3/8" at the fittings. I installed 1/2" in place of copper in my home and there was no noticeable reduction in pressure.

Most DIYer level PEX crimping tools use that type of fitting (Zurn, QuestPEX, etc). There are PEX tools that expand the tubing to utilize a full-diameter fitting, but they are much, much more expensive.

As for the hot water issue...

Have you considered a hot water on demand system or a hot water recirculation system? You might also consider a small water heater at or near the kitchen as part of the instant hot water system. Linked in series with the main hot water tank, you'd have a couple gallons of hot water instantly, which would allow time for the big tank's hot water to get there.

wcb7962 09-16-2008 02:26 PM

I'm in the process of buying a 108 yr old house. I intend to replace the plumbing and have just recently heard of PEX and it sounds like the way to go. My question is where shoud I put the manifold. I watched a This Old House video and they showed a new home under construction in which they were using PEX. In their video it looked to me like the manifold was mounted under the house between floor joices. I was thinking about mounting it in a wall with an access door, or at least somewhere easily accessible. Maybe even in the bathroom itself since the other bathroom is directly above it, and the kitchen is closeby. Does this make any sense?

kbsparky 09-16-2008 03:20 PM

I would think that the manifold should be somewhere near the water heater. You have access to both hot and cold supplies at that point.

DVLCHLD 09-16-2008 09:41 PM

I AM NOT GIVING ADVICE HERE! I just want to share what's in my house. I live in a 100 year old house too. All the plumbing has been replaced with PEX pipe and QEST fittings that just screw together. It works great. It's all 1/2" but I think the shower supply line is 3/4". I just moved my washer and dryer to a different wall and I had to extend the hot and cold supply lines for the washer and using the PEX pipe and QEST fittings was a snap. The manifolds for both the hot and cold water are both under the house near the water heater. I think they put the cold water manifold near the hot water manifold just for simplicity's sake. This plumbing is about 10 years old and doesn't leak anywhere.

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