Wirsbo PEX for hot water...?
john
brand PEX because of its superior ability to handle heat and pressure
compared to some of the other brands. The tools required to work it
seem a bit pricey and I was wondering if anyone here had anything to
offer in the way of experience, advice, and/or suggestions. The specs
on the product look good, but I'm a little confused on the tools
required to install it. Presumably the hand expander tool is adequate
for a homeowner. How does the tool work and how tight can the pipe bend
(probably 1/2" and 3/4".)
[Sorry if this is approaching "off topic" status, but I do plan to use
it in a solar thermal system, so it is kinda' sorta' related.]
Thanks
John
Rip
polybutylene tubing. Recently, I added radiant heat (under the existing
floor)using 1/2 inch Wirsbo PEX. In both cases I used standard brass
compression fittings with brass tube inserts, rather than the grossly
expensive fittings requiring special tools that are touted by Wirsbo.
I haven't had a leak in almost 20 years on the polybutylene, and I don't
expect to.
For the 1/2 inch PEX, if you work carefully you can expect to bend it
around an 8 inch curve (4 inch radius).
Just my $0.02 worth.
Rip
john
John
Robin Solar
wrote:
I have burst Wirsbo on a pumped evacuated tube system when the power
was off and the panel heated excessively. This caused the brass/pex
connection to overheat and the Pex softened, expanded and burst.
Selective coating systems ( flat plate or evac tube ) can overheat
these ratings, so only use them downstream of the storage tank and not
between the panel and tank.
Cheers
Robin
Rip
Robin, I'll second that. I added more radiant flooring to my house
because I've installed a pretty grossly over-engineered solar hot water
system (5 AET flat panels, 3 Steibel Eltron SB400+ storage tanks).
During Thanksgiving day, I finally filled the collectors with glycol and
turned the system on. It scared the hell out of me! Late November in
Connecticut, and the collectors stagnated at 205 degrees Fahrenheit!
Most definitely not a place for plastic pipes!
Rip
Steve Shantz
I agree with everybody else. In normal operations, PEX would probably
work just fine, but you system will not always operate normally.
Sooner or later you will almost certainly stagnate with a mid
afternoon 1/2 hour power failure on a sunny day. That first blast of
hot water will be nasty on your PEX. You might consider PEX for the
cold line from the tanks to the collectors but you need to make sure
the hot cannot get into this line.
Also, PEX has a much higher thermal expansion coefficient than
copper. PEX-Al-PEX is not as bad as plain PEX, but it is still higher
than copper. I'm not sure what the Wirsbo product is. A Google search
found a book "Modern Hydronic Heating for Residential and Light
Commercial Buildings" with a table of expansion coefficients (in/in/
°F):
Copper 0.0000094
PEX-Al-PEX 0.0000130
PEX 0.000094
So a 50' run of PEX with a 100°F delta T would expand:
0.000094 x 100 x 12 x 100 = 5.64"
PEX-AL-PEX would expand just under an inch, and copper would expand
1/2"
Steve
J. Clarke
> John,
>
> I agree with everybody else. In normal operations, PEX would
> probably
> work just fine, but you system will not always operate normally.
> Sooner or later you will almost certainly stagnate with a mid
> afternoon 1/2 hour power failure on a sunny day. That first blast
> of
> hot water will be nasty on your PEX. You might consider PEX for the
> cold line from the tanks to the collectors but you need to make sure
> the hot cannot get into this line.
If PEX can run 26 years continuously at 201F and 151 PSI I wouldn't
expect a single excursion to 212 to do much to it.
> Also, PEX has a much higher thermal expansion coefficient than
> copper. PEX-Al-PEX is not as bad as plain PEX, but it is still
> higher
> than copper. I'm not sure what the Wirsbo product is. A Google
> search
> found a book "Modern Hydronic Heating for Residential and Light
> Commercial Buildings" with a table of expansion coefficients (in/in/
> °F):
> Copper 0.0000094
> PEX-Al-PEX 0.0000130
> PEX 0.000094
>
> So a 50' run of PEX with a 100°F delta T would expand:
> 0.000094 x 100 x 12 x 100 = 5.64"
> PEX-AL-PEX would expand just under an inch, and copper would expand
> 1/2"
>
> Steve
--
--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net)
Rip
> Steve Shantz wrote:
>> John,
>>
>> I agree with everybody else. In normal operations, PEX would
>> probably
>> work just fine, but you system will not always operate normally.
>> Sooner or later you will almost certainly stagnate with a mid
>> afternoon 1/2 hour power failure on a sunny day. That first blast
>> of
>> hot water will be nasty on your PEX. You might consider PEX for the
>> cold line from the tanks to the collectors but you need to make sure
>> the hot cannot get into this line.
>
> If PEX can run 26 years continuously at 201F and 151 PSI I wouldn't
> expect a single excursion to 212 to do much to it.
Since I've just turned my system on, I don't know what it's going to do
next summer. However, with collector stagnation temps of 205 degrees in
New England midwinter, I expect to see stagnation temps at least
somewhere around the factory setting of the "Emergency" temperature
function on the Resol controller I'm using. That setting is 285 degrees
F. (adjustable from 230-400 F). Not a PEX environment.
Rip
J. Clarke
Uh, you are not talking about a hot water system at that temperature,
you are talking about 53 PSI steam. Is that your intention?
Rip
Hi J. Clarke. I can see that you are one of those jerks that just likes
to argue with no real informational input. FYI, the solar loop on my
system is filled with 50% volume Dowfrost HD, and pressurised to 50 PSI
gauge, yielding a boiling point just shy of 300 degrees Fahrenheit.
I'd suggest you go build your system entirely with plastic tubing, and
get back to us all when your collectors stagnate. The entire point of
this thread was "Is Wirsbo PEX good stuff, and has anyone had experience
with the tooling to install it?"
See you all. My installation is complete and working. I logged into this
newsgroup to see if I could glean, and supply, any useful info, but as
usual on USENET the signal to noise ratio isn't worth the effort.
UNSUBSCRIBING now.
Rip
J. Clarke
Geez, ask a guy if he means to be doing something that could get him
hurt and he flies off the handle. You can't win.
Steve Shantz
> If PEX can run 26 years continuously at 201F and 151 PSI I wouldn't
> expect a single excursion to 212 to do much to it.
>
John,
You need to be aware that your collector loop is pressurized and
likely contains glycol, and because of this, it can develop
temperatures much hotter than the boiling point of water. A 300°F
slug of hot pressurized glycol will be the death of your PEX. Also,
please be aware that in spite of the wonderful properties of PEX (I
think it is a wonderful material in the correct application), it is
plastic, and as such, it will rapidly loose strength when it gets too
hot.
Steve