Rheem TKTB-104 产品宣传页

Tankless Technical Bulletin

Tankless 

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.

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 

under those conditions. 

In consideration of these types of applications, and seeing more and more tankless water heaters 

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.

Demand Pump Systems

07/08      TKTB-104

Typical 66DV

Vertical Installation