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Author Topic: Use of PEX for Basboard Heat Plumbing  (Read 24074 times)
WStayton
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« on: July 19, 2011, 03:08:28 PM »

Hi, Guys!

  I just bought some used baseboard heat radiators for my house and they were all, apparantly, connected with PEX, since they all have hose "bibs" on them and some of them still have a couple of inches of PEX.

  I was planning on using sweat soldered fittings originally, but if PEX works and is a viable approach to the problem, I am all for what is easy!

  So what;s the word here - is it okay to plumb baseboard heat radiators in with PEX, or was the last owner just lazy???

  I'm all for what is easy, and I THINK that PEX would be cheaper than copper, since I already have the fittings for PEX on all of the radiators.

  Oh, and these radiators were the financial windfall of all time - I got four each 8 ft units, four each 6 ft units and six each four ft units for the princly sum of $150.00, total!  I almost fell over when I asked how much and the ex-owner told me - I had to ask twice before I understood that it was $150 for the whole mess!!!  And, he even threw in an under-sink radiator with a blower in it, though it doesn't appear to be in the best shape - lots of green "fur", etc., but for free, I'll take it!  <grin>  Oh, and he also threw in couple of circulator pumps and a six channel pump control box, that uses lo voltage from the thermostat to control 120 volt ac, though the pumps are pretty cheesey looking compared to the legitimate ones I already bought

  So what do you guys think, is PEX okay for this use, or is it a good way to make a mess?

  All input is hereby solicited - don't be shy, say what you think! <smile>  As if you would do anything else, huh?

Regardz,

Wayne Stayton
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« Reply #1 on: July 19, 2011, 03:20:42 PM »

I can't think of any reason why not? Floor heating systems consist entirely of PEX. There is a certain type meant just for heating, you should probably use that. It would probably cost about half as much as copper.
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WGB
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« Reply #2 on: July 19, 2011, 04:25:10 PM »

I do it all the time.
As the pipe heats up it will expand like a can of worms, can be a esthetic issue, also makes noise if rubbing house framing.
Look at your specs, pressure rating goes down as temp goes up!
Most radiant pex heat systems run 140F or less, baseboard will run up to 180-190F.
And don't forget to use oxy barrier pex or you have to keep everything in the system non-ferrous.
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Tom
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« Reply #3 on: July 19, 2011, 05:10:53 PM »

I did our whole house with AquaPEX, including the radiant floors with it too. The fittings can be one of 2 kinds Wirsbo is an oversized fitting where an expander is used to stretch the pex tubing + a collar. The fitting is inserted and the assembly shrinks down onto the fitting. The others use copper bands that crimped over the tube to fasten it to the fitting. The expander tools are expensive $1k ish for the battery powered expander. I did the majority of the house with a expander tool borrowed from a friend. After the friend moved I purchased the band crimper version for around $125.00 which works well except in cramped locations.
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Tom
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« Reply #4 on: July 19, 2011, 05:45:16 PM »

PEX is what was used on "This Old House - Got Questions" or something like that.  It was last week or the one before.  They used the threaded compression fittings rather than the compression band fittings.  I think break even is at about 25 connectors.  The threaded ones can be taken dismantled.

Casey
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WStayton
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« Reply #5 on: July 19, 2011, 06:34:23 PM »

Hi, Guys!

  Thanx for the comments!

  A bit of explanation:  The hose "bibs" that have a short (2 inch'ish) piece of what I THINK is PEX on them, have something that looks like a multilayer "hose" that is black on the outside and inside and has a metal layer in the middle - maybe aluminum?  These are all held in place on the hose "bib" with a band that looks like a tool "crimped" it in place on the PEX.  I am looking at PEX, here, no?

  Also, my system is going to be at atmospheric pressure, so the only pressure on the connections would be from the depth of the water in the holding tank - maybe four feet above the baseboard, so something like 1.6 or 1.7 psi.

  Also, I know what you mean about the noise - my dad built a new house in about 1958 and installed sweat fitted baseboard heating and every time the circulator came on, the whole system made a chorus of cracks, snaps, pops, and groans.  After you got used to it, you hardly noticed it, but eveybody who visited commented about it!   <grin>

  So does what I have described sound like it is, in fact, PEX? 

  My brother installed some PEX (actually a LOT of PEX!) in his in the floor heating system and he told me that he used something that looked like a cross between a pair of pliers and a speculum which you inserted in the tube and then squeezed the handle and stretched it and, while it was still stretched, you put on a compression band and the pushed it on the fitting and that it would contract to the fitting diameter in fairly short order, at which time you crimped the compression band - or that is what I THINK he said!  <grin>  I was hoping that I could do the same thing with the baseboard fittings.

  So, if/when I go to get some PEX to do this installation what kind/type/variety should I be asking for?  I hear that there is also a type with aluminum on the outside for exposure to sunlight - but I don't think that is something that I need to sorry about!

  Thanx for the input, its good to know that everything I contemplate doing isn't impossible!  <smile>

Regardz,

Wayne Stayton
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Lloyd
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« Reply #6 on: July 19, 2011, 09:15:57 PM »

Hi Wayne,

Go ahead and use PEX,

I have always used the Wirsbo Brand...there are as many brands as there are Chinese manufactures of everything else plus there are quality brands, and everything in between just as everything in life...you get what you pay for.

You can use straight pex for domestic as long as it's EPA certified for domestic service(potable water) some are not.

Some are metric some are inch.

If it's for hydronic heat use only oxy-barrier/Alumi-Pex...anything else will bring air into the system, it cause corrosion in iron, electrolysis in combined sys, and vapor lock`s in an multi height sys.

I have only use the cold contraction method of joining pex, I'm not sure I would like to entertain a clamp method, I've be tempted to use Shark-Bites..but I just can't seem to get over the hump.

Almost every plumbing supply house that sells the Wirsbo  brand also will rent you the expander for the job for little money.

I put Wirsbo in my boat, in 2003 for both domestic and hydronic, todate I've never had a leak in either system, nor have I had an electrol/oxy issue in my system...which includes cast, and black iron, bronze, and brass/copper, even sum alum.

Go ahead and use it...........it's good.....just don't feed the alligators, even if it save you a nickle.

Lloyd
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Semantics is for sitting around the fire drinking stumpblaster, as long as noone is belligerent.
The Devil is in the details, ignore the details, and you create the Devil's playground.
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« Reply #7 on: July 20, 2011, 10:07:38 AM »

I did our whole house with AquaPEX, including the radiant floors with it too. The fittings can be one of 2 kinds Wirsbo is an oversized fitting where an expander is used to stretch the pex tubing + a collar. The fitting is inserted and the assembly shrinks down onto the fitting. The others use copper bands that crimped over the tube to fasten it to the fitting. The expander tools are expensive $1k ish for the battery powered expander. I did the majority of the house with a expander tool borrowed from a friend. After the friend moved I purchased the band crimper version for around $125.00 which works well except in cramped locations.

There are heck of a lot more than 2.
I have all the Wirsbo / Uponor tools including the electric over hydraulic. I started with this brand in the 70s.
Also I have four more crimp tools for other systems, make sure you know what you are getting.
The are many different fitting / crimp systems, and the warranty and code approvals are only for proper combinations.
I've been to numerous seminars on pex some as an inspector.
I think we are going to have failures and end up with a polybutylene type debacle.
There are some law suits already.
http://www.kitecsettlement.com/?gclid=COLMu-KzkKoCFcPs7QodjHRG0Q
Viega has 3 or 4 fitting, pipe, tool combination just in their line of products.
This use to be a simple easy to use excellent piping system, but like everything these days it has become a night mare.
http://www.viega.net/xchg/en-us/hs.xsl/780.htm
Sorry to get on the soap box!
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Tom
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« Reply #8 on: July 20, 2011, 10:49:38 AM »

Wayne you're going to need the crimper to install pex to the fittings on those baseboards. WGB is right there are many types of crimp systems and I have not personally done a mix 'n match, but it sounds like an inspector won't allow it. But I don't know how they can tell as the crimp type fittings I used had no distinguishing marks on them.

Also this is an important note. PEX breaks down rapidly in sunlight. I left a small piece outside and after a year it crumbled in my hands. The Wirsbo PEX is the only one that will work with the expander and will work with the crimp fittings too. I got my crimper and supplies from pexsupply.com.
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« Reply #9 on: July 21, 2011, 04:31:14 AM »

WGB or anyone, what is the thermal conductivity of PEX compared to copper? If my suspicions are correct your going to need a LOT more linear feet of PEX to get the same heat output as copper.

Thanks, Geno
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WStayton
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« Reply #10 on: July 21, 2011, 09:15:11 AM »

Geno:

  You said " . . .  your going to need a LOT more linear feet of PEX to get the same heat output as copper."

  I wasn't expecting to get ANY heat out of the PEX - I'm simply using a short (maybe very short - like 4" to 6") to connect between adjacent baseboard heating units.  I am expecting that 99% of the heat released will come form the baseboard units, NOT the PEX between them!  I am thinking that the heat transfer from PEX is about half that from copper, but, in this case, that's not a factor.

 
  Okay, you have got me all concerned about different types of PEX and different connecting systems - I see on CraigsList full boxes of various sizes of PEX (1/2", 3/4", 1", etc., etc.)  that come in a multitude of colors - blue, red, orange, etc., is there any way to tell by the color, what type of PEX it is???

  Also, I checked with my brother (but forgot to ask him about the colors! A mind is a terrible thing to lose! <grin>) and he said that the PEX he used for his underfloor heating system was designed for use with just the stretcher and then putting it on the fitting and having it shrink, but being the type who likes his pants to have suspenders AND a belt, he put on the compression band in addition!

  So, to reiterate, if I try to cheap out and buy the stuff from CraigsList for 50% of retail, how can I tell what I am buying???  Is there a name for the material on the box which defines what type it is, or does each/every manufacturer use thier own system/name for different types?

  Thanx for holding my hand, so far - at least I'm asking more intelligent questions now!  <smile>

Regardz,

Wayne Stayton
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Tom
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« Reply #11 on: July 21, 2011, 09:42:42 AM »

You've got to have a crimper to connect to the fittings on the baseboard's. The streacher PEX is the Wirsbo AquaPEX and it is the only one PEX pipe that can be streached. It also works with the crimped bands too. I've done it here. The AquaPEX comes in white, blue and red which are all the same pipe, the red and blue are for color coding hot and and cold. Wirsbo also makes HePEX which has an aluminum barrier to keep O2 out of the system and is 2x the cost of AquaPEX. Go here http://www.pexsupply.com/PEX-Tubing-516000 and check out the comparison guide. It discusses all the tube/crimp types and what is compatible with what. I found good prices here too.
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Tom
WGB
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« Reply #12 on: July 21, 2011, 11:34:33 AM »

The web site Tom sent you has tons of good information.
Caveat is I know a guy that ordered from them, they sent him pipe, fittings, and rings from different systems. Or he BS'ed me and ordered the wrong parts!
Color doesn't tell you what kind of pex it is, the ASTM numbers on the pipe tell what fittings and crimp to use.
The fittings usually have different number of barb rings for different systems, you may get a hint what you need from that.
Also remember if you buy of line think about shipping, pex rolls cost, they are big.
You might be just as well off buying local.
Menards around the Midwest has great price on pipe as a come on, but break it off on the fittings, I've noticed that on line too.
You didn't say if you were going all non-ferrous?
If it's a non-pressure system, are you using water treatment?
Also some pumps won't last in non-pressure systems they will cavitate at the inlet of the volute, make sure you get pumps that can.
http://en.wikipedia.org/wiki/Cavitation

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Geno
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« Reply #13 on: July 21, 2011, 04:17:21 PM »

Geno:

  You said " . . .  your going to need a LOT more linear feet of PEX to get the same heat output as copper."

  I wasn't expecting to get ANY heat out of the PEX - I'm simply using a short (maybe very short - like 4" to 6") to connect between adjacent baseboard heating units.  I am expecting that 99% of the heat released will come form the baseboard units, NOT the PEX between them!  I am thinking that the heat transfer from PEX is about half that from copper, but, in this case, that's not a factor.


Wayne Stayton


Never mind, I misunderstood. I thought it was all pex.

Thanks, Geno
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WStayton
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« Reply #14 on: July 21, 2011, 08:24:59 PM »

WGB:

  About weight of PEX rolls for shipping:  This was another reason that I was looking at CraigsList - if it is local I can just throw it in my truck and shipping is incidental! <grin>

  About the "system":  I going to contain about 450 gallons in each of three "tanks" that are 23/32" plywood lined with EDPM roofin/pond membrane.  Plumbing will all be schedule 40 to the baseboard heaters.  The hot water in the tanks will also cool my 4 cylinder diesel generator - through a heat exchange on the engine, be heated by a 4' x 12" solar collector loop which will be exchanging heat with the tank through a closed loop and pieces of baseboard heating element immersed in the tanks (separate loop so I can have antifreeze in the solar collector and thus not worry about it freezing), and the tank water will also be used as a heat exchange medium in a wood fired boiler that I have purchased.  The boiler will  be the only steel/iron in the system, and I wrestled with how to keep it from rusting away - filling the system with antifreeze is prohibitively expensive since 50:50 would require something like 625 gallons of antifreeze!!!  Sorta out of my budget bracket!  I was thinking to use something like hot water heater zincs as sacrificail anodes to keep the boiler from rusting away before my very eyes!!!

Circulator pumps:  The circulator pumps which I have acquired for the system are Bell & Gossett 1/12 hp model MRP58JV.  These are 120 V AC, and I anticipate one on the baseboard loop, one on the solar collector, and one on the furnace.  I know that, ideally, they should be on the cold end of the loop, so that they are pulling the hot water through the whole loop and then dumping it back into the reservoir, but this also contributes to cavitation problems - is it acceptable to put them at the hot water tank and then use them to push the hot water through the system, rather than pull it through the system from the cold side?  This means that they will run very hot, since the hottest tank might get up to 190 to 200 F.  Is this accepatble?  Actually, this is only a problem with the baseboard pump, since the other two will be pulling out cooler water and running it through the furnace/solar-panel to heat and then back to the hot tank.

About Tom's PEX website:  I only performed cursory examination of this website, since it made my dial up connection choke with everything that it tried to download.  I did see where  they stocked three differnet manufacturer's of PEX, but I didn't see anything that showed what system was used with what manufacturer's version of PEX although Tom said that only AquaPex worked with the stretcher.  Also, there was nothing, that I could see, that specified how each different type was marked.  Is there a website somewhere that I can go to that says "AquaPex is marked with ASTM-XXX"?  Otherwise, how do you know, from looking at a coil of PEX if it is AquaPex,  Rifa Pex or Viega Pex or yet some other manufacturer???

  Knowing that you need type "A" PEX doesn't do you any good if you can't tell type "A" when you see it!  <grin>

  I'm still a little confused, as you can tell, as to how to tell what type a PEX a particular piece of it that I have in my hand is!  Is there some simple rule like "Only ASTM-YYYY pex can be stretched, everything else has to be crimped"?

  Also, if I succeed in figuring out how to buy the right type of PEX for the barbed" fittings that I already have, would it still be a good idea to add a compression band on each connection? Or, for that matter, would a stainless hose clamp work as a back up?  I know it is more trouble to screw in a screw in a clamp than to just crimp a ring, but I've got lots of time!  <smile>

  Thanx for the information, so far, guys - I am learning, albeit slowly!  <grin>

Regardz,

Wayne Stayton

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