On 2/10/09 12:20 AM, Bill Loesch wrote:
What I can offer is that there are five (5) major _manufacturers_ of
tankless water heaters that market to North America. Alphabetically: Bosch,
Noritz, Paloma, Rinnai, and Takagi. A multitude of other companies market
gas tankless. Even more market electric tankless. Sometimes these other
companies simply change the decal on the machine to their own name. Not
unlike buying a Mercury instead of a Ford (or vice versa). For example. A.O.
Smith, a premier manufacturer of tank water heaters, also markets a tankless
under the A. O. Smith label. Today A. O. Smith are marketing the Rinnai,
earlier they were using a competitor tankless manufacturer.
You could add to that a number of hydronic boiler manufacturers whose
products work quite well for DHW.
There are two classifications of gas water heater both tank and tankless -
natural draft and power vented. The only commonality between the two are the
fact they both use gas. If you have properly installed a natural draft tank
or tankless you have zero experience (and carryover skills) with a power
vented tank or tankless. Read the manual _before_ installation and save
callbacks and frustration.
I would add condensing and noncondensing variations.
Heat exchanger design is a critical area that has a complex relationship
to service conditions (water chemistry, set points, usage patterns,
venting, feed gas quality, etc.)
At a minimum, be aware that hard water and tankless generally do not
play well together. We are testing a new scale prevention system that
shows great promise (a German technology marketed in the US by Watts.)
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