Ask Me Help Desk - Repiping with Pex

Mark-

Yes, I noticed the instruction manual on soldering, I seriously can't thank you enough.

Bob- I agree with you. Plumbers suggested not getting a permit because the inspectors cause a lot of trouble on repiping older homes here. Also, DC won't allow homeowners to get permits for ANY plumbing work at all.

Stubits:

Many of the questions obou t PEX can be answered in the Radiant heat Instal book link I posted. Fastening, how far away etc.

Soldering - a couple of tidbits:

Damp rag.

Practice with a few fittings like an elbow with a short length of pipe with the pipe verticle and the elbow on top.

This will make it easier to get the feel, because the solder will run up hill based on capilary action. Always heat the more massive area first. e.g the fitting

By practicing, you'll get a better feel as to when to test.

The lines need to open so there is a place for gasses to go.

They must be free of water. There is a "bread trick" when things get tough and you can't seem to get the water out.

Finally:

There are heat shields. The hardware store variety isn't very good. www.smallparts.com has a really nice shield.

While the joint is cooling - DO NOT DISTURB.

There are two types of couplings. One had a dimple or a ridge and the other is straight through. The latter is a repair coupling. It allows you to but two pieces of pipe together when the ends are constrained.

Same in my area Stubits...

Nothing like encouraging people to do the right thing...huh??

Keep us posted as you go...

MARK

Wow guys, thanks! This is all so helpful. I won't be getting started on this for another couple of weeks, but this is just what I needed... and my wife is starting to resign herself to the fact that I'll be doing this, your confidence has helped.

One more quick questions... what brand of PEX do you recommend? I guess along those lines, what type of connection do you like best, compression? Crimp? Anything I should stay away from? I hear that Zurn has had some trouble.

I am a huge fan of the VIEGA system... only system I use so can't speak about other system.

Viega is a crimp with sleeve system... check it out at:

Viega | Plumbing, heating, gas, drinking water, drainage and bathroom design

Tools can be rented at local plumbing supply house... sometimes.

Which of the three, ViegaPEX & ViegaPEX Ultra or Viega FostaPEX would you suggest for this job?

I run viega fostapex for all my hot and cold water pipes. This type pipe is stiffer than ordinary pex... less difficult to handle and just looks less like spaghetti as it forms nice clean runs.

Bob has worked with zurn pex I think... wait till he pops back and see what he thinks of that...

Excellent... and what do you pay on average for 100 ft of 3/4"?

Hmmm.. don't know off the top of my head... but wayyyyyyyyy cheaper than copper... wayyyyyy cheaper!

My only price sheet for Zurn is a little old. http://www.zurn.com/images/pdf/PEXPriceGuide.pdf The big issue with Zurn was not the PEX but their brass connectors were failing premature. You can always use somebody else's fitting even though the issue was resolved in think in 2005.

Bob-

Do you use Zurn? If so, have you heard of any problems with it? I hear they have a class action lawsuit out against them.

We kind of bet each other to the punch, reread my post #31. I have no problem with their PEX but Mark does way more than me.

Bob-

Sorry to have jumped the gun, thanks for the clarification.

Stubits,

Click on the link below will give you a rough idea about the price and also there is a contact number for the pexsuply to call them for any question

FostaPEX - FostaPEX PEX-al-PEX - Viega FostaPEX - Buy FostaPEX

Quote:

Originally Posted by Stubits

T<snip>
1) What size PEX should I use? I am thinking 1" from the main, 3/4" branches and then 1/2" to the fixtures? Does that make sense?

Somebody above said use the same sizes as you would with CPVC. That's correct. If you can look at a code book you can figure out the minimum sizes required. Rule of thumb: Cold: 3/4" to the 2nd to last or last tee on the line. Hot: 3/4" to the first major use tee or use a manifold and run dedicated lines to each bathroom group, laundry, kitchen. Long runs of 3/4 waste a LOT of water until it gets hot. I've never used 1" PEX in residential domestic supplies. Usually when you have to flow that much water it is not heated. Just use PVC unless you are worried about freezing.

Quote:

2) What is the best and most trusted/secure way to make the connections? Crimping? Compression?

If you aren't going to crimp, you will get a WHOLE LOT of money in the fittings. Sharkbite tees are $9 and up each around here. Crimping probably is the biggest advantage of pex. I would use CPVC if I couldn't crimp. Really, a dual nest (1/2" and 3/4") crimp tool retails for about $150 to $170 locally. That's probably still cheaper than all the compression fittings you will use in a house. If you can afford to do the job yourself, you can afford to buy the tool. Sell it on Craig's list when you are done. :) Actually now that I think of it, donate it to me, I don't own one personally, my work supplies the crimpers, but I would love one! :D

Another thing, I try hard not to use joints in concealed spaces. (Remember why we don't use Qest anymore? :rolleyes: I'm still have a lingering concern about pex too even though I use it all the time.) I like bend supports whenever possible inside walls to eliminate joints. Tees are the biggest problem. Do them in the basement or behind access panels and run continuous tubes to the stub outs.

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3) I do not know how to sweat copper joints, but I will be connecting to copper in a number of places. What is the best way to connect PEX to copper without soldering? Most of these connections will be behind the walls.

Here you should learn to sweat copper. Practice on a piece of tube that you cut out. I can't quite trust even the brass 'Sharkbite' fittings for 30+ years. I hardly trust the plastic ones long term even when I can see them. I have installed a couple of sharkbites in walls when it wasn't avoidable, but I work very hard to only use them where I can get to them. Use the sweat/crimp adapters.

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4) Just a little nervous about running the PEX in the attic. I live in Washington, DC where it gets cold in the winter. The attic is of course unheated. Is it sufficient to insulate the pex with foam insulation? Currently the attic is uninsulated entirely, but I will be insulating it with fiberglass batting, would I want the pipes to run between two layers in the insulation? Under all the insulation? Above the insulation?

I'd be nervous too. Put your pipes in the warmest area of the attic. Which is BELOW the insulation. Slip on foam is a very good idea. It should be required for hot lines. Buy unsplit 6' lengths at a plumbing supply house, slip it on as you go and use the split stuff for what you have to do after the pipe is installed. The good split stuff has adhesive in the joint so it stays together.

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5) Finally, how often do I need to attach the Pex to a stud, etc. If I can manage to run the piping from my attic all the way to the basement utility room (two floors down) without having to open a wall, and therefore only attaching at the top and bottom of the run, is that OK?

It must be supported minimum every 32" horizontally. Hot lines work best supported every joist. I forget vertical, but it isn't a lot farther. I don't know off hand what is required for a fished run or even if that is allowed, but if you can put it in foam insulation (and DON'T stretch the stuff) so that it can't rub anything, I might try it if I knew it was supported correctly at the top. One of those 'chinese finger trap' things might work.

I mustn't have refreshed my browser enough, I missed half of the posts. I like the Wirsbo brand of pex. We use a lot of Zurn at work, it seems fine so far, just isn't as pretty. Some of the Zurn is in for 10 years and isn't giving us any trouble. Also I disagree on not insulating the hot line. The biggest problem is heat loss during use, not needing to gain heat while laying in the pipe. Also, I haven't read my code book lately, but I do think that pex must be supported much closer that what some have said. But maybe that's just the local inspectors here.

EPM

This is wonderful information. Many thanks to each of you.

I will be moving forward on this project in the next couple of weeks, after the summer heat breaks and hopefully before the cold sets in (will make working up in the attic much easier).

I think I have the sizing figured out now, I erred in my original post when I suggested using 1" from the main. I measured the current copper main today and it is only 3/4", so I will do 3/4" from the main and to each of the two major groups and then 1/2" to each fixture.

I will definitely use crimp connections. I was just curious if there was a preference between the standard crimp connection and Wirsbo's expansion connection, but it seems like everyone favors crimping. The cost of the tool is negligible in comparison with what I am saving doing this myself.

There will only be a VERY small run of pipes in the attic. I will definitely run it under the insulation, but I am definitely confused about whether to insulate. I understand insulating as a means of reducing heat loss, but I don't want to do it if it would in anyway encourage freezing. Can anyone explain this topic a bit more? Any further suggestions?

As far as supporting the PEX, a couple of questions? Does something like this, Sioux Chief 555-23 - $9.95 - Sioux Chief - Tube Talon for 1/2" & 5/8" & 3/4" PEX Tubing (Bag of 100) - 555-23, allow for expansion? Would this be appropriate and acceptable for use? EPM, what is the "chinese finger trap" thing you are speaking of? Any links?

Ok, and a totally new topic, what about a gravity hot water recirculating loop? How complicated would it be to install one in this application? Does it work well with PEX? I was planning on using a "mini manifold" up in the attic to split the 3/4" supply line to 1/2" lines to each supply. They make one that has 3/4" in and 3/4" out, such as this http://www.pexsupply.com/categories....D=740&brandid=, can I just run a line back down to the hot water heater?

Thanks!

Gravity recirc.
I think all that's required is a check valve, ball valve and removal/reinsertion of the drain.

In the loop, you usually return the furthest fixture's hot water to the drain of the hot water heater, so a check valve is required probably at the fixture.

Then this needs to be plumbed into the drain. You need a valve and the ability todrain the recirc-loop.

You may have multiple loops. Not sure how that complicates things, but you would have to return the last fixture on every LOOP to the drain of the water heater.

Does this make sense?

You don't want the drain to supply the water, so that needs a check valve. Your return should handle the flows of all the connected fixtures in the loop.

Quote:

Originally Posted by KeepItSimpleStupid

Gravity recirc.
I think all that's required is a check valve, ball valve and removal/reinsertion of the drain.

In the loop, you usually return the furthest fixture's hot water to the drain of the hot water heater, so a check valve is required probably at the fixture.
<snip>

I really question a gravity recirc loop in this situation. If your lines are mostly vertical and straight, then yes, but unless you really chill the return line, if you have a convoluted install I don't think it will work well enough to be worth the cost of parts. Also, most garden variety check valves have enough resistance to opening that you will need a serious temperature differential to get any flow and even then it will be insufficient. And if it does work, you are creating a small in-wall and attic heating system that will continually take heat off your water heater. Think wear and tear on the elements and kWh $$.

If you want to save water (which I think is the reasonable thing to do), put a Grundfos or Taco recirculator system in and then time it to run only during the times you actually use hot water. Rather than a timer I personally prefer a momentary switch that is manually operated for 10 secs or however long it takes to bring the hot water to the end of the line, and not run the system otherwise and save both water and electricity.

If you do a recirc loop, just tee it into the cold supply above the water heater, but below the inlet shutoff valve and expansion tank. Some of the systems I maintain have sediment problems and returning the loop at the drain valve just stirs things up and makes draining the sediment out impossible. BTDT, repented and replumbed.

Those plastic pex supports that you link to are fine. Probably a bit more expensive than the individual size ones, but great otherwise.

PLEASE insulate your hot lines. It will pay for itself, especially if your hot water use is intermittent but mostly within the same hour or so block(s) of time. They will NOT freeze faster inside insulation. They will only thaw slower if they do freeze. Also the reason I recommend insulating both the hot and cold lines in the attic is because usually when run under insulation they don't get supported very well and so they can rub as they expand and contract. If against a nail or really rough surface you can imagine what will happen down the road. Also cold line sweating in unconditioned spaces can be a problem.

Hope that helps a bit. I could go into greater detail, but my wife says I spend too much time on the computer as it is. :D

EPM