I think I'm in love

Stephen Minnich

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.

Robert O'Brien

Have only installed one, very nice! Takes up some space though

Stephen Minnich

Yeah its a big one but still takes up less room than a boiler AND a buffer tank : )

Danny Scully

Tank...enough said

SuperJ

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_Man

Pretty sure the HX has been used in Europe for many years, just made it over here 3 years ago AFAIK.

hot rod

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

Alan (California Radiant) Forbes

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.

Stephen Minnich

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.