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pro press and solar

Al Corelli_2
Al Corelli_2 Member Posts: 395
But it only has to overtemp and fail ONCE to cause a mess or worse.


Safety FIRST.

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Al Corelli, NY



914-804-2234

Comments

  • Mike Dunn
    Mike Dunn Member Posts: 189
    pro press and solar

    Has anyone used pro press fittings on solar DHW systems
  • Joe_122
    Joe_122 Member Posts: 3
    No...no...no....

    Mike,

    Don't do it, you'll hate yourself. Read the temperature ratings for the seal.

    Joe
  • hot_rod
    hot_rod Member Posts: 15,029
    and I say no, no, no

    like Amy Winehouse :)

    Ideally the fitting would be able to handle the highest expected temperature. For closed loop solar 300- 325F is possible.

    Glycol seems to slide by those rings, for some installers, also.

    hr
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Mike Dunn
    Mike Dunn Member Posts: 189
    thanks

    thanks for the info. Looks like I'll just have to do it the old fashioned way, with a push fit fitting....Kidding!
  • Paul Pollets
    Paul Pollets Member Posts: 3,428
    Once!

    I have one system using a 30 vaccuum tube array on 3/4" copper with propress fittings. I'll look at the system in late March to see if there's leakage issues. No antifreeze in this system.

    Looking forward to seeing you at Wetstock, HR!

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  • Derheatmeister
    Derheatmeister Member Posts: 1,140


    I say No.But if you want to save time,Use a system that is pre Insulated/ with the supply,return and the wire in one. It Is available! Heatmeister.
  • Ed_26
    Ed_26 Member Posts: 284
    not propress

    Caleffi.... but stainless 'corrugated' piping.. issues w/drainback? turbulence/high resistance to flow?
  • hot_rod
    hot_rod Member Posts: 15,029
    two more sizes

    will be added to the Caleffi offering.

    The pressure drop equates to one size smaller smooth tube size. the DN16mm flows about what a 15mm smooth tube would. The DN20 about the same as 18mm.

    I visited the the manufacturer of this product a few weeks back in Germany. Their shop has radiant floor heat powered by solar, pellet boiler back up and a Co-gen unit with a Kubota diesel engine. A 5000L buffer tank for storage.

    I would think with adequate pitch it should drain back well enough. But I will get some loops and try some experiments :)

    hot rod
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Derheatmeister
    Derheatmeister Member Posts: 1,140


    Hot rod, Is there a wire in between the insulation?
  • Ed_26
    Ed_26 Member Posts: 284
    Calleffi

    Dhm.. yes, has cable in insulation. See caleffi site - solar products. Haven't personally seen/touched :(, only available thru supplier in Alberta, Canada (to me, anyway)
  • John_162
    John_162 Member Posts: 35


    You can use ProPress as long as you change the O-Ring to a FKM that Viega also sells. Its even rated for Steam up to 15psi
  • Mike Dunn
    Mike Dunn Member Posts: 189
    Au contraire

    I received an email from Bill Burton with Viega about the issue and he said the FKM o-rings are good to 320 deg F. I believe Solar can get hotter than that. Please correct me if I am wrong. I would love to use propress on my first upcoming solar job but was told temps can get reach 350 deg F.
  • Derheatmeister
    Derheatmeister Member Posts: 1,140


    Mike,Why not use the pre made piping(Just pull it)?
  • Mike Dunn
    Mike Dunn Member Posts: 189
    caleffi pre made piping

    so your saying run the CSST from the panels to the pumping station then from the pumping station to the heat exchanger or coil in the solar tank.
  • Derheatmeister
    Derheatmeister Member Posts: 1,140


    Yes and it has the wire in between the Pre insulated jacket as well, I've never used it yet, But will try it on my next Install. Must be quicker than reg 1/2 cu and insulation and pulling a wire. We will see soon. HM
  • scott markle_2
    scott markle_2 Member Posts: 611
    350 deg

    These are not operating temperatures but worse case stagnation temperatures.

    Stagnation has serious consequences and there should be safeguards incorporated that make it an highly unlikely occurrence. My question would be in the event of a circulator failure or summer brownout, how long before these temperatures would be reached? Some of the evac. tube designs incorporate high limit valves within the heat-pipe that are supposed to mitigate this. How far from the collector would these 320 plus temperatures be experienced? Armacell HT insulation is only rated to 300. I'm thinking that the likelihood of sustained temperatures exceeding 320 much beyond the collector surface is fairly unlikely and would represent a serious problem beyond it's potential effect on the o-rings.

    As far as the effects of glycol on these seals I can attest to the fact that I have experienced some staining at fittings from "molecular" seepage.

    One thing I like about the possibility of Propress and solar is the lack of potential contamination from solder and flux. Viessmann instructs that their systems be filled directly with glycol, they don't want you to flush with water because this risks contaminating the solution. I can't imagine not flushing a system that had a significant amount of solder joints in it.
  • scott markle_2
    scott markle_2 Member Posts: 611
    Safety

    Assuming proper function of the pressure relief valve, I don't see a big safety issue here. The potential for dangerously high temperatures do make piping considerations especially important in solar work, but this is not the space shuttle. If a temperature over 320 was sustained outside of the collector for long enough to damage an o-ring yes this would be a mess in the sense of unfortunate and costly. However I don't believe that fluid would come screaming out of connections in a way that would pose a safety or even significant water damage issue. The pro-press connection is physically robust . I can't imagine an o-ring completely dissolving, and even if did, the metal to metal connections would remain intact.

    Pex is another story!

    Not that it's used in plumbing applications anymore but 60/40 tin lead solder has a 361 deg melting point This is getting pretty close to the 350 mentioned earlier. I can't see how a glycol solution could get this hot unless it was highly pressurized. Wouldn't the solution boil and blow the relief valve before getting this hot? The steam table I consulted shows 302f @ 69 psi, (not sure how glycol effects this) Perhaps 350 is more about potential collector temps as opposed to system (piping) temps. As I don't see how the transfer medium could get this hot. Of course the pipe work in contact with the collector could get this hot by direct conduction.

    I think this 350f number may be overkill as a limit. I noticed that the new Budarus flat panels are made with a fiberglass inclosure and have rubber hoses (that absorb expansion I assume) to interconnect panels.

    I'd love some more opinions/feedback on this.
  • scott markle_2
    scott markle_2 Member Posts: 611
    I reply to my self

    Hoping that there is some more input on this thread before it dies.

    Is there a consensus against pro-press and solar?

    Is 350deg possible beyond close proximity to the collector?

    Is it physically possible for the transfer medium to get this (350) hot at blow off pressures?
  • Ed_26
    Ed_26 Member Posts: 284
    high temps

    If the possibility exists, then it must be guarded against. I think a safety net is required.
  • scott markle_2
    scott markle_2 Member Posts: 611
    IF... the possibility exists

    Thats my question. does this this possibility exist? Where did this number come from? How can the transfer medium get this hot unless it was under high pressure? Since a failure of the relief valve would have dangerous consequences regardless of the piping system, is it reasonable to establish a maximum temperature that would require pressures in excess of the relief valve setting?

    Perhaps I'm missing something. What about those rubber connection hoses on the Budarus panels?

    Doesn't the heliodine panel have an o-ring union.?

    Doesn't the Vitosol 100 use an oring seal at the panel interconnection? (provides some movement for expansion on multi panel setups)

    I remember HR setting up an oventrop system with propress, why the change of opinion here ?

  • lund
    lund Member Posts: 25
    3 yrs

    I know a solar guy that has been using standard PP with glycol on systems for 3 years with no problems.

    Lund
  • Ron Huber_2
    Ron Huber_2 Member Posts: 127
    PP/Solar

    We have been using the Pro Press system for over 5 years, after not doing much with solar for a long time we got back into it about a year and a half ago and have been using Pro Press. 1) I have been doing solar DHW since 1977 and have never seen a quality collector or an array damaged from stagnation, degraded yes, but nothing serious. I am in New Hampshire and if I lived in New Mexico or Florida than maybe there would be an issue.
    2)We install the Veissmann evacuated tube system that has a high temp limiter that shuts down the heat transfer at about 260 degrees to protect the tube and keep the glycol from degrading.
    3) We used to use 95/5 around the collector for the potential of short bursts of stagnated fluid hitting the joints when the system came out of stagnation, and then switch over to 50/50 for the rest of the loop, that was before the advent of silver brite etc.
    4) We started using the stainless steel piping (gastite) last September, we insulate it on site and can run longer than the pre-assembled product without having to couple it. The flow rate is suprisingly better than I thought it would be. The pre-assembled tube set up is pretty slick and I am sure is a time saver, but it comes with a hefty price tag, maybe competition will make it more reasonable, there are other brands heading this way from Europe.
  • Metro Man
    Metro Man Member Posts: 220
    High temps... same pressure

    Scott,

    A closed loop solar system can see high temps at relatively low pressure.

    For example; if there is a lot of exterior plumbing on a closed loop glycol solar system, power goes out to house or solar circ fails, middle of the day and sun is baking on collectors. Expansion tank was sized correctly for entire system and doing it's job taking up the added pressure from the stagnating solar collectors. Pressure gauge in basement is inching up but not drastically. Just to add another variable this is on a flat roof. Little Johnny hits his ball on the roof and scampers up to retrieve. Being the little boy that he is, he doesn't step over all the insulated piping secured to the roof but stands, jumps, bounces off piping. Collectors and fluid are now 375*. I wouldn't rely on a propress system to hold. In fact on systems like these we would braze all of our connections. If you have ever witnessed a system like this blow....... it is something to behold.

    Just another good reason for a drain-back water system.

    When it comes to plumbing w/pro-press manufacture's limits are just that. Also, what happens to the fluid years down the road. If left unchecked and system stagnates frequently the glycol could go south on you. What effect would this fluid then have on the pro-press o-rings?

    As far as O-rings in other solar manufactures equipment I believe they are using Viton seals but off top of my head can't remember temp limits.

    Haven't used the Buderus panels but would think the "rubber" is probably silicone or other to handle temps/press.

    Plumbing is only as good as the weakest link.

    Metro Man
  • scott markle_2
    scott markle_2 Member Posts: 611
    375

    M.M,

    Thanks for the input the little Johnny story is effective I support the design for worst case perspective. However If we can trust our children to retrieve balls from roofs then is it to much to ask them not to dance on the solar pipe work.

    We get in cars everyday with little thought of the dangers and tens of thousand perish on our roads every year. How many solar collector fatalities ? I agree that if the possibility exists for abusive contact this pipe work should be extra robust.

    What I don't understand is how a transfer medium can get this hot at low pressures. Seems physically impossible to me. Also how is it that the pressure at the roof could be significantly different than in the mechanical room? if anything wouldn't pressures be slightly higher at the lowest elevation in the system. If a 30 psi solution begins to boil in the collector are not pressures going to rise throughout the system and blow the relief valve? How could pressures in connected areas be significantly different? The weakest link should be the relief valve, I don't see how it's proximity to the collector is so significant.

    So lets say the valve is constricted or can't relieve the full output of this collector, how high do pressures need to be to raise a glycol solution to 375deg. I'm thinking pretty high, maybe my information is flawed but as I mentioned the table I consulted showed 302f @ 65 psi for steam, seems to me to indicate that even higher pressures would be required for temperatures to reach 375. I believe this is why the concentrating systems use silicon or liquid salt as a medium.
  • Ron Huber_2
    Ron Huber_2 Member Posts: 127
    look out Johnny

    Johnny goes down to the basement, the door was unlocked, he pokes around the boiler because it looks very interesting and the parts look so mysterious, he lifts up the arm on the pressure relief valve and is scolded by the piping hot water, even though the drip leg was properly piped to 12" from the floor, it splashes on to his bare legs (he is wearing shorts)then he stumbles over the gas piping and ruptures a joint that is ignited when his mum turns on the cellar light when she comes to his rescue.
    Give me a break, you can always find SOMETHING that can go wrong, some times you have to push the envelope, stop living in fear, if the system is at low pressure, how the *#@&amp; is it going to blow apart, I have seen solar systems steam at stagnation when there is air in the system, like when some Bozo puts an auto air vent at the top of a system and leaves the cap loose on a permanent basis, when the air vent fails at high temp (and it will) it starts sucking in more air then it bleeds out, and you end up creating steam in the system that will seep out of a bad joint, but it will not blow up, never has, never will.
  • Metro Man
    Metro Man Member Posts: 220
    Dancing Little Johnny

    Little Johnny was just an example but... if you (a contractor) installed pro-press (I think this was the topic) on a solar system and that system could reach temps higher than what connector was rated for, somehow it failed..... you better have good insurance.

    Also I haven't looked at your tables but what I think you are missing is the fact that the temps (not pressure which should be constant through entire system) at the immediate collector array area could significantly be different than the temps in the mech. room that could be 100' feet of plumbing or more away. So if the entire system volume was 20 gallons but only 4 or 5 of those gallons where actually collector volumes and the expansion tank was properly or oversized the pressure relief valve (located in mech. room) would never blow during a stagnating condition. 375* may be a little high but would burn just as bad as 350*.

    As far as kids listening to what we tell them...... good luck. It would only take once for little Johnny to dare little Jimmy!

    But if you feel confident using pro-press on an install..... go for it!

    Metro Man

  • Metro Man
    Metro Man Member Posts: 220
    Johnny's having a heck of a day

    Ron, I was talking about temps not pressure ratings for pro-press.

    We are going to have to keep an eye out for Johnny though! He seems to be getting into all kind of trouble today.

    Metro Man
  • jeff_110
    jeff_110 Member Posts: 4
    viega needs to get on the train

    sounds like there are some bucks waiting around out there for a certain company should they develop a seal that could take the heat.
  • ScottMP
    ScottMP Member Posts: 5,884
    My Understanding

    is that Viega does Not Approve thier fittings for solar.

    No warranty. No install. Thats my policy.

    Scott

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  • You Guy's Know How I Feel About Pro Press

    You can take my torch away when you pry it from my cold dead hands. And that goes double for high temp steam or solar. I lost electricity at my house a few years ago and my system overheated and blew off a compression joint up at the collectors and turned the anti freeze to steam, I thought my tubes were protected against overheating too. I don't know why it blew off up there instead of at the relief valve, maybe because it was so hot up there? But I think we have to do our best to make these systems foolproof.

    Thanks, Bob Gagnon

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  • Kevin_in_Denver_2
    Kevin_in_Denver_2 Member Posts: 588
    don't forget dry stagnation

    That's when the tin-lead solder drips out.

    They used to say 95-5 (tin-antimony) was OK, and I never saw it melt out in the field, and no solar is hotter than Colorado solar.

    Metro Man is the man, brazing is the way to go within 6 inches of the collector panel.

    Unglazed PV/thermal hybrid panels is the direction I'm heading, I'll keep you posted.
    Superinsulated Passive solar house, Buderus in floor backup heat by Mark Eatherton, 3KW grid-tied PV system, various solar thermal experiments
  • Dave Larsen_11
    Dave Larsen_11 Member Posts: 39
    propress with solar

    Some Propress Facts;
    FKM sealing element is rated to 320 degrees and 200 psi, test pressure 600psi
    The sealing element "o- ring" is never in contact with the fluid so degradation of the fluid is more of a hazard to the system than the fitting. (Hate to see failing glycol in WI!)
    As far as the strength, the copper is also pressed on each side of the element so the joint is extremely rigid. Still, I wouldn't recommend any one let johnny play around any of my mech equipment, would you?
    As long as you stay within the ratings Viega put out,there's no reason to avoid pro press with solar.
  • Ron Huber_2
    Ron Huber_2 Member Posts: 127
    PP & Solar

    We now use the high temp rings on our solar systems. But before this spring we used the regular rings. Never had a problem with the regular rings on solar loops (with glycol) and started using the press fittings on them 2 years ago, using the press system for 5.5 years with no leaks (tried Nibco for a while but had several leaks with them). If they can take 320 at 200 psi, I think we are pretty safe at 30 to 40 psi on a solar loop at anything we are going to see here in New England.
  • hot_rod
    hot_rod Member Posts: 15,029
    I did see ProPress solar

    or some brand of press fittings in Germany. Actually the Resol test lab has press fittings on all the solar piping as well as some silver soldered connections on a few joints.

    I think the solar flex products are the way to go. A couple gasketed mechanical joints, panel to pump station, pump station to solar tank 4 connections! No soldering needed.

    Pic 72 picture is an inprogress shot with SolarFlex from the roof solar panel to the pump. From the pump station to the solar tank, and from the second coil to the hydronix radiant module.

    The evac tube header had compression to SolarFlex fittings from Caleffi. No torch or soldering in the entire solar loop.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • hot_rod
    hot_rod Member Posts: 15,029
    I did see press fittings

    on solar installs in Germany. If I remember the Resol control factory had press on their piping in the lab. Some silver solder joints, also.

    Really the flex solar products make sense. Just a few gasketed mechanical joints, no torch or special tools required.

    On this one job pic 72 I piped (in progress picture) from the collector to the pump station, station to the solar tank, and from the upper coil to the radiant Hydronix panel with SolarFlex.

    The evac tube header even used Caleffi high temperature compression fittings from copper to Solarflex.

    hr
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
This discussion has been closed.