Pex: To home run or not to home run


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Old 04-20-09, 09:14 AM
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Pex: To home run or not to home run

Hi everyone!

New construction home. 2 stories + full walkout basement. Water supply comes into the basement and is sent off from there to the kitchen and bath on the first floor, and 2 baths on the second floor. Basement will be finished off at a later date with a bathroom and bar.

I was talking to a friend of mine who does some GC work in his spare time and also works as a carpenter. We were chatting about wether to home run all the pex to a manifold system, or use the traditional way of trunking and teeing off?

Here's what I can identify as the pros and cons of home running with a manifold...
Pros:
- Can shutoff individual fixtures/runs
- Less branching off in the walls, less chance for a leaky "T" somewhere

Cons:
- More material (additional Pex)
- Additional cost of manifold(s)


I should also mention that I do plan on putting a hot-water circulator in the system as well. I'm not sure if there's any impact of that on a manifold system or not.

I've spoke to my builder who asked the plumber if he has done a home run manifold system. He says he's aware of it, and can do it, but personally has not done it in the past. His suggestion was that if I had a good reason to do it, he'd be happy to - but otherwise he didn't think it was worth the extra cost in materials.

Thoughts?

Thanks in advance!
 
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Old 04-20-09, 01:19 PM
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In my mind the only advantage to "home runs" is that it greatly reduces the number of fittings (and thereby joints) in the entire system. If you are going to have a hot water recirculation system it would require a supply and return line to each hot water faucet so, in effect, doubling the amount of tubing otherwise needed for your hot water. The return lines would need to go to a manifold and quite possibly also require flow regulating valves to allow all hot water faucets to get the recirculated hot water.

If it were my house I would not use home runs on the hot water but run a continuous line to all hot water faucets and then back to the recirculation pump. You will need to insulate all the hot water lines as well or the recirculation system will significantly increase your energy consumption for hot water.
 
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Old 04-20-09, 04:08 PM
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Originally Posted by furd
You will need to insulate all the hot water lines as well or the recirculation system will significantly increase your energy consumption for hot water.
Is it common to insultate PEX? Even if I don't use a manifold and home run, the plumber still plans to use PEX in the standard "run-and-branch" configuration method (tees and eles).
 
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Old 04-20-09, 06:55 PM
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I don't know if it is "common" to insulate PEX but I do know it is foolish to not insulate ALL hot water piping. This is especially true if you are going to have a hot water recirculation system.
 
 

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