Click here to Find a Contractor in your area.
Welcome! Here are the website rules, as well as some tips for using this forum.

If you've found help here, check back in to let us know how everything worked out.
It's a great way to thank those who helped you.
Need to contact us? Visit

I think I'm in love

Steve MinnichSteve Minnich Posts: 2,465Member
I was able to put my hands and eyes on a Viessmann CU3A today. Wow! Easy to service, 13.5 gallons of water in the smallest model, and what looks like a bullet-proof HX and burner. It's in my shop now and will be installing my first one before long. I'd love to hear what others think of it.

Steve Minnich
Tell me I can't, and I'll show you I can.


  • Robert O'BrienRobert O'Brien Posts: 3,136Member
    Have only installed one, very nice! Takes up some space though
    To learn more about this professional, click here to visit their ad in Find A Contractor.
  • Steve MinnichSteve Minnich Posts: 2,465Member
    edited April 2018
    Yeah its a big one but still takes up less room than a boiler AND a buffer tank : )
    Steve Minnich
    Tell me I can't, and I'll show you I can.
  • Danny ScullyDanny Scully Posts: 1,193Member
    Tank...enough said :wink:
  • SuperJSuperJ Posts: 478Member
    Variable primary is so simple and elegant.
    High mass, high efficiency makes so much sense. I've got the poor mans version with a Polaris and hacked controls. I live 5 minutes from the Viessmann factory in Waterloo, only got to inside once though.
  • Solid_Fuel_ManSolid_Fuel_Man Posts: 1,602Member
    Pretty sure the HX has been used in Europe for many years, just made it over here 3 years ago AFAIK.
    Master electrician specialising in boiler and burner controls, multiple fuel systems, radiant system controls, building controls, and universal refrigeration tech.
  • hot_rodhot_rod Posts: 11,684Member
    13 gallons is nice. It takes a large cast boiler to get that type of water content these days, most are under 5 gallon capacity

    maybe fixed output cast boilers are the application need for buffer tanks
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • We just placed our first CU3A in the boiler room yesterday and attended the Viessmann classes in Warwick, RI last month to go over installation and servicing.
    I love it that we are returning to high volume boilers, this time with condensing technology.
    Often wrong, never in doubt.

    Click here to learn more about this contractor.
  • Steve MinnichSteve Minnich Posts: 2,465Member
    I have not taken the classes yet but I will. Meanwhile, I'll read every manual as if it were a textbook with highlighter in hand.
    Steve Minnich
    Tell me I can't, and I'll show you I can.
Sign In or Register to comment.


It looks like you're new here. If you want to get involved, click one of these buttons!