Rinnai 37AHB User Manual

* In order to receive full warranty coverage on the Hyrdronic Furnace when connected to any other type or 
brand of product other than a Rinnai tankless water heater, the flow rate through the Hydronic Furnace 
must not exceed a maximum of 5 GPM.

Rinnai will repair or replace the covered product or any part or component that is defective in materials or 
workmanship as set forth.  

Rinnai will pay reasonable labor charges associated with the repair or replacement of any such part or 
component.  

All repair parts must be genuine Rinnai parts.  All repairs or replacements must be performed by an 
individual or servicing company that is properly trained, state qualified or licensed to do the type of repair.

20 gauge 
prepainted 
galvanized steel
fully insulated

copper tube
aluminum fin

high-head
low-flow
integrated check valve

multi-speed motor (ECM)

Connect an auxiliary 2.5 FLA, 2.5 LRA @ 115 VAC max Humidifier.  
Connections are made via the “HUM” quick connects. The humidifier 
output is on whenever a heating demand is being satisfied. The 
contacts of this output are isolated to allow application of 24 VAC or 
115 VAC to one terminal and the humidifier load to the other. 

Connect an auxiliary Electronic Air Cleaner; rating shall be max 1.0 
Amp @ 115 VAC. This output is energized whenever any of the four 
blower speeds are energized. Connections are made via 0.250 x 
0.032” male quick connect terminals labeled "EAC" and "N3".

Connect an auxiliary UV lamp (if required); rating shall be max 1.0 
Amp @ 115 VAC. This output is energized whenever any of the four 
blower speeds are energized. Connections are made via 0.250 x 
0.032” male quick connect terminals labeled "UV" and "N2".

Can accomodate most brands of evaporator A-coil for cooling 
applications.

FIELD-SUPPLIED ACCESSORIES capable of interfacing with the Rinnai Hydronic Furnace:

Programmable, 5-2 days; 
both A/C and heat pump 
versions

For domestic hot water priority

* Supplied with the unit

To maintain safe domestic 
hot water temperature

For modification to allow side-entry 
return airflow

Factory available from Rinnai

integrated 
microprocessor based

                                       37AH    B    045    08    K    A   5 

5 = Yes 

2 = No 

Denotes minor change 

K = 115 - 1 - 60 

L = 240 - 1 - 50 (export models) 

37AH - Multi-speed Hydronic Furnace

 

A - Unit with PSC Motor 
B - Unit with ECM Technology

 

045 = 45,000 

060 = 60,000 

075 = 75,000 

090 = 90,000 

08 = 800 (650-800) 

12 = 1200 (650-1200) 

14 = 1400 (1000-1600) 

16 = 1600 (1200-1750) 

6"

17 13/16"

1"

18 5/16"

1"

C

B

34"

A

22"

E

1 3/8"

D

17 13/16"

2 1/8"

TOP/PLENUM

zero

SIDE

zero

BACK

zero

SIDE

zero

FRONT

zero

BOTTOM

zero

SERVICING

24” (610 mm)

Nominal heating capacities as tested with Rinnai tankless water heaters. 
For final rated capacities refer to the Air Delivery and Performance 
Tables in the Operation and Installation Manual. 

27,700

36,400

43,700

54,900

33,300

45,100

52,900

63,900

40,100

50,800

61,600

76,200

47,700

59,700

70,400

86,600

51,200

68,100

78,900

96,300

37AHB04508KA5 (AHB45)

14

355.6

18

457.2

12

304.8

10 - 1/2

266.7

19

482.6

37AHB06012KA5 (AHB60)

17 -1/2

444.5

18

457.2

16

406.4

16 - 11/16

423.9

19 - 1/4

489

37AHB07514KA5 (AHB75)

21

533.4

18

457.2

20

508

18 - 11/16

474.7

19 - 1/2

495.3

37AHB09016KA5 (AHB90)

24 - 1/2

622.3

18

457.2

24

609.6

21 - 1/8

536.6

19

482.6

C

M

Y

CM

MY

CY

CMY

K

37AHB spec sheet inside (7-2010).ai   7/23/2010   11:58:33 AM

37AHB spec sheet inside (7-2010).ai   7/23/2010   11:58:33 AM