Rinnai 37AHB User Manual

Page of 6
37AHB Series Hydronic Furnace
The optimum in hydronic technology, the newly 
designed Rinnai® multi-position hydronic furnaces 
offer a unique solution for a wide variety of small- and 
medium-sized residential and light commercial 
applications. They are compact and ready to fit in tight 
spaces which may include, but not limited to, attics, 
basements, closets, crawlspaces, and utility rooms. 
Intelligent Microprocessor Controller
The 37AHB units are equipped with an intelligent 
microprocessor control that allows for domestic hot 
water priority and adapts to available hot water flow for 
space heating by automatically regulating the pump 
and fan sequence to maximize comfort.
Fine Tuned to Work with Rinnai Tankless 
Water Heaters
These unique hydronic furnaces are designed to work 
in combination with our line of Rinnai® tankless water 
heaters to deliver heating capacities that cover a wide 
spectrum of residential and light commercial heating 
applications. When combined, the units form the Rinnai 
Tankless Heating System, the first matched, tankless 
hydronic heating solution in the industry!
PATENT PENDING
FEATURES
Specifications
Air Delivery
● Four models covering a range of heating capacities
○ 27,100 to 96,300 BTU/hour
● Multi-position (upflow, downflow, horizontal left, 
horizontal right) without modifications *
○ Modifiable for side-entry return air
● Low-flow, high-head pump custom designed to work 
with Rinnai's tankless water heaters
● Integrated control board with learning algorithm 
● No combustion air infiltration losses when used with 
a Rinnai tankless water heater
● Four selectable heat blower off delay times
● Multi-speed motors (ECM)
● Strong 20-gauge steel cabinet
○ Galvanized, painted
○ Fully insulated cabinet
○ Low 34 inch profile
● Multi-position control box
● Designed for serviceability
● Schrader valves to purge air from the system
● Integral filter rack with filter
   Fan motor with ECM technology
*
 NOTE:   The unit is not designed to be installed on its back or 
face down.
37AHB Series Hydronic Furnace
†    Tested in accordance with ANSI/ASHRAE Standard 37-Latest edition.
‡    Airflows shown are nominal (blower speeds are factory set).  For air 
delivery other than stated, refer to the Air Delivery & Performance table.  
††  Required filter sizes shown are based on the larger of the AHRI (Air 
Conditioning & Refrigeration Institute) rated cooling airflow or the heating 
airflow velocity of 300 ft/min for throwaway type or 450 ft/min for 
high-capacity type.
Side intake filter to be (1) 20”x20”x1” typical for all models.
Air filter pressure drop for non-standard filters must not exceed 0.08 in. wg.
This product is manufactured in a facility registered by UL to ISO 9001.   
File No. A6887.
Part of the Rinnai Tankless Heating System
AHB90
AHB75
AHB60
AHB45
600000060 (7/2010)
 
UL recognized 
component 
This product is manufactured in a 
facility registered by UL to ISO 
9001.
37AHB Series Hydronic Furnace
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37AHB spec sheet cover (7-2010).ai   7/23/2010   10:16:37 AM
37AHB spec sheet cover (7-2010).ai   7/23/2010   10:16:37 AM