Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Hydro Separator

Thanks guys for all of your opinoins, you've help me out alot


  • Jeff Anderson
    Jeff Anderson Member Posts: 5
    HYDRO Separator

    I have a spec job that has a hydro separator (caleffi 548006A) on the supply and return is there a main reason for this? What is the benifit over a regular Spirotherm???
  • Brad White
    Brad White Member Posts: 2,398
    Not the same thing

    A hydraulic separator does several things: Provides a hydraulic separation between disparate circuits (well, duh..), allows a place to vent air and drop off any solids.

    A Spirotherm can, depending on what model, do either or both of the latter two.

    Neither product, despite my pleadings, will go for coffee.
    "If you do not know the answer, say, "I do not know the answer", and you will be correct!"

    -Ernie White, my Dad
  • ALH_4
    ALH_4 Member Posts: 1,790
    Hydo Separators

    The Caleffi Hydro Separator is essentially providing primary/secondary piping. However, both the primary and secondary loops have identical flow paths, as opposed to close tees. Their operation is particularly suited to condensing boilers that require p/s piping for hydraulic reasons.
  • Jeff Anderson
    Jeff Anderson Member Posts: 5

    I do agree, but if the boiler is not a condesing boiler then i don't see the advantage.
  • Bernie Riddle_2
    Bernie Riddle_2 Member Posts: 178

    Andrew How do you explain that? I would have thunk that flow would be the same in either one.

    From the discharge of the boiler to the emitters

    And from the emitters back to the inlet of the boiler
  • Brad White_2
    Brad White_2 Member Posts: 188
    There is an advantage

    P/S piping in a condensing or non-condensing system still requires a form of hydraulic separation and the Caleffi or others can do admirably.

    The key is that in condensing boilers your system flow has to be greater than your boiler flow. In this way, the boiler will always see only the coldest return water coming back to it and will not recirculate boiler water directly to it's return.

    In a non-condensing boiler, the reverse needs to happen. Boiler flow has to be higher and controlled in such a way that the boiler always sees return water higher than the flue gas dewpoint. Conversely, the system water can and will be much cooler for a more modulated heating effect.

    Of course there are other ways to achieve this (closely spaced tees and such). But the hydraulic separator can still play a role, plus vent and drain.
  • ALH_4
    ALH_4 Member Posts: 1,790
    cast iron

    With a cast iron boiler, I also question the value. The Hydro Separator provides a wide spot in the line for air and sediment, but a cast iron boiler is a wide spot in the line. If there is a bunch of sediment in the system, then a strainer might be a better option. Close tees are good for a cast iron boiler, though a Hydro Separator is fine and still performs its functions. It might help make the piping look a little cleaner.
  • ALH_4
    ALH_4 Member Posts: 1,790
    line vs branch

    You're right, they are basically the same depending on how the close tees are sized and arranged. Every boiler could be piped with close tees, and most of the mod/con manufacturers recommend this method.

    I look at the Hydro Separator as a big "point of no pressure change" and a nice wide spot in the line. It is an ideal location to provide primary/secondary piping, air elimination, expansion tank connection, drain fitting, and thermowell. It makes a nice addition to any boiler, but particularly low mass boilers.
  • Uni R_2
    Uni R_2 Member Posts: 589
    That would be me!

    I was the first documented "hydro separator".

  • Bernie Riddle_2
    Bernie Riddle_2 Member Posts: 178

    Andrew: Thanks for shareing your infinite wisdom...but i'm not sure it justifies the cost,I see some very large ones used today,Wouldn't one be better off using a small buffer tank with four full sized ports..just a thought
  • ALH_4
    ALH_4 Member Posts: 1,790

    If a buffer tank is needed, that is a good way to go. Wouldn't a buffer tank with the correct ports cost as much or more than a hydro separator?

  • I just looked at that for a job I quoted. I'm going to take a small stainless Superstor which IIRC was around $500 and have a local welder I talked to weld some 1 1/2" stainless nips on it for me, he said around $100. The Caleffi I looked at was more ($675 I think plus 6% tax )AND I was told I couldn't get an insulated Caleffi in 1 1/2". So that's that. THEN if you really want to go off the wall you could instead take a Megastor, for example, do the same thing with the nips and use it bass ackwards to heat domestic hot water in a holding tank or supplement your DHW heater. But naturally, that adds to the price. Im holding my breath on the job. It's another case of the guy is all enthusiastic about it until he gets the bottom line and then it's, "Oh, I didn't think it was THAT much!! ;)

    I'm thinking a TurboMax might fit the bill nicely as well but I haven't actually looked at it yet.
  • ALH_4
    ALH_4 Member Posts: 1,790
    Hydraulic Separators

    The Caleffi Hydro Separators, while very nice, are pretty high priced. Viessmann's Low Loss Headers are less and basically the same thing minus the auto air vent. Radiant Engineering's separator is (was) about the same price as the Viessmann, and is powder coated 304 stainless. I have some idea of the RE separator since I used to be the one who built them and originally set the price on them. 1-1/4" is the largest currently, but, since they are hand-built, any size is possible. No cool molded foam insulation available either.
  • The Wire Nut
    The Wire Nut Member Posts: 420
    Then I have a silly question...

    ... I have seen a Vitola, gas-fired, in the field, with a big Caleffi hydraulic separator... considering the neglible flow resistance through the Vitola, the lack of return water temp restrictions, and a plain vanilla house heating system (some RFH, some radiators, etc.) on the receiving end, what could be the net benefit? I'm still scratching my head on that one but if anyone knows, it would be you.

    It was an engineered system, BTW.
    "Let me control you"

    Lost in SOHO NYC and Balmy Whites Valley PA
  • john_83
    john_83 Member Posts: 76

    I still think its easier to just pipe out the primary secondary loop plus its custom. Just my opinion

  • In my case my system wants a buffer tank and a separator. That's the reason I'm doing it the way I described.
  • Nron_13
    Nron_13 Member Posts: 164

    Give Ziggy a shout I just heard the discussion on hydrolic seperators and why and what size You can build and paint one for about 100 bucks from steel and that includes labour , a low loss header is designed to allow the lowest possible temp to return to the boiler and seperate the boiler pump from your system pump . there great for mod/con boilers with larger or smaller flow rates than what the boiler is designed to flow at
  • hot_rod
    hot_rod Member Posts: 22,105
    Other options

    I see that Caleffi separator in many colors these days. I believe they are private labeling it to B&G and several others. Sometimes you can get better pricing by shopping.

    Also the insulation is a nice feature and worth some bucks on the Caleffi. Insulation is code required in many countries and certainly a good idea to prevent those separators into becoming boiler room radiators:)

    Here is another clever design I spotted at the Foothills Conference in Canada this week.

    hot rod
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Brad White
    Brad White Member Posts: 2,398
    Just saw this, Constantin

    With the system you describe, I see the same benefits as with any low-temperature system. You still need a form of hydraulic decoupling given the presumably two separate temperatures (RFH and radiators).

    But if a single temperature? Not So Much. A single temperature I would run directly off the boiler.

    Your comment about the low internal PD's of the devices- does that go to an assertion that the single common circulator should handle all duty and negate the need for a secondary circulator? I see the LLH principle being necessary for P/S without diluting the boiler return with hotter water. But direct coupled and with one temperature? No, I do not see a need for P/S let alone the LLH approach.

    For my Susan's Vitodens, I elected to use the LLH because of future RFH. Right now it runs CI radiators on one (variable) temperature. There was a distinct possibility that the Vito could have been direct-connected to the new looped copper pipe mains, but the numbers were too close to call, only 2 feet of residual head to a system that has a measured DP of 3.5 feet. Besides, the RFH hook-up is ready with taps for future mixing valves and circulators.
    "If you do not know the answer, say, "I do not know the answer", and you will be correct!"

    -Ernie White, my Dad
  • Kal Row
    Kal Row Member Posts: 1,520
    me and moses of eny have installed many...

    one of the pictures is in the new idronics magazine –
    the reason? Simple: freedom and economics:

    1)i needed an air separator

    2)i needed a dirt separator

    3)i needed to guarantee the flow through the boiler

    4)i didn’t want the system flow to be restricted by the boiler

    5)i don’t want a high flow load pump to erode my copper boiler tubes

    6)i wanted a large convenient point of zero pressure change so that
    I could “pump away” in many directions – so that I could pump
    away and yet at the same time “into” the return of my low mass
    boiler to keep some serious head on it’s hx, whilst at the same
    time letting my load pump, “pump away” to it’s load

    7)i wanted a high and convenient place to tee in my low water cut-off so
    that I can protect my pumps also

    8)a 4” Spirovent and dirt separator costs me apx 2000, add to that,
    the cost and labor of close tee’s + insulation
    - and suddenly, the 2200 cost of the Caleffi looks real attractive,
    so far, i have checked the economics down to two inch and it holds

    com’on people, Like duh! This isn’t rocket science!!,
    we’v all read siggi’s and dan’s books,
    - and if you havent you should stop whatever you are doing and read them now!!!

    The only drawback, is that the boiler room looks like a submarine – “did someone say fire ONE?…”

    Here is our latest – another job with no single point of failure it’s our trademark redundant systems designed by redundant engineers

  • Nice work!

    I hope the neighborhood winos don't hear about all that copper. ;)
  • Brad White_9
    Brad White_9 Member Posts: 2,440
    One thing you can say about a Hydraulic Separator

    is that it indeed is by defintion a PONPC. Great place to connect the expansion tank.
  • hot_rod
    hot_rod Member Posts: 22,105
    I like that piping better, Kal

    than the one you showed in the below "mod-con" thread. Better then those bull headed connections.

    Nice install.

    hot rod
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Kal Row
    Kal Row Member Posts: 1,520

    there only is orders of manitude more space here, necessity is a mother...
This discussion has been closed.