Tankless Technical Bulletin
Vertical Venting - Zero Clearance - Demand Pumps
Vertical Venting
In the past, we required to have a horizontal offset and a form of condensation collector (in-line
or condensate tee) for any of our Tankless water heater installations terminated with vertical vent
configuration. Effective with this notice Rheem will allow a straight vertical vent run off the top of
the water heater provided that a vertical condensate collector, as designed by the appropriate vent
manufacturer, is installed as close to the tankless water heater as possible. All other considerations,
clearances, and installation requirements as outlined in the Use and Care Manual must be met.
See our Tankless Application Drawing RTG11171 and RTG11172 for information and suggested
components.
Zero Clearance DV Venting
Previously, Rheem has required a one (1) inch clearance around concentric vent piping to
combustible surfaces for our tankless water heaters. Through testing we have certified that a clearance
of zero (0) inches is acceptable to combustible and non-combustible surfaces. Effective with this notice
a clearance of zero (0) inches to combustible and non-combustible surfaces for our Direct Vent (DV)
concentric venting for our RTG-66 and RTG-53 Series Direct Vent water heaters is acceptable.
Demand Pump Systems
While we have allowed return circulation with our tankless products, we have in turn reduced the
warranty of those products in installations where water is re-circulated through the tankless unit. These
types of applications typically include hot water on demand plumbing system composed of a return
circulation loop and a high flow pump. These types of systems can put undo stress on a tankless water
heater and dramatically shorten the life expectancy of the unit, thus we reduce the applicable warranty
Vertical Installation under those conditions.
In consideration of these types of applications, and seeing more and more tankless water heaters
Typical 66DV
being installed under these circumstances, it is our recommendation that only a Demand Pump System
be used. This is a pump system that works via a push button or motion detector that will activate a
small high flow pump for a short duration to bring hot water from the tankless unit to the desired fixture
location. These pumps typically include some circuitry to limit the amount of operation time, not a timer,
and have an integrated thermostat that will shut off the pump when the hot water reaches the fixture.
There are several different brands and manufactures of such systems, the use of these systems with
a Rheem Tankless Water Heater will not impact or affect the warranty. A system that uses a timer to
control the operation is NOT considered a demand pump. Any other recirculation system, continuous,
timer, thermostatic, domestic heat, or any application where the water is re-circulated through the
tankless water heater, will reduce the warranty of the Rheem Tankless Water Heater to 3-Years on the
heat exchanger and parts.
See our Tankless Application Drawing RTG11154 for information.
In keeping with its policy of continuous progress
and product improvement, Rheem reserves the
right to make changes without notice.
Tankless water heaters
Endless hot water
Rheem Water Heating
101 Bell Road
Montgomery, AL 36117-4305
07/08
TKTB-104
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