A.O. Smith 101 Series, Instruction Manual

40

t&p ValVe discharge pipe

Explosion Hazard

Temperature-Pressure Relief Valve

must comply with ANSI Z21.22-

CSA 4.4 and ASME code.

Properly sized temperature-

pressure relief valve must be

installed in opening provided.

Can result in overheating and

excessive tank pressure.

Can cause serious injury or death.

This  water  heater  is  provided  with  a  properly  rated/sized  and 

certified combination temperature - pressure (T&P) relief valve 

by the manufacturer. See Temperature-Pressure relief Valve on 

page 15 for information on replacement and other requirements.

Water Damage Hazard

Temperature-Pressure Relief Valve discharge

pipe must terminate at adequate drain.

•

CAUTION

install a discharge pipe between the T&P valve discharge opening 

and  a  suitable  floor  drain.  Do  not  connect  discharge  piping 

directly to the drain unless a 6” (15.2 cm) air gap is provided. 

To prevent bodily injury, hazard to life, or property damage, the 

relief  valve  must  be  allowed  to  discharge  water  in  adequate 

quantities should circumstances demand. if the discharge pipe is 

not connected to a drain or other suitable means, the water flow 

may cause property damage.

t&p Valve discharge pipe requirements:

• 

Shall not be smaller in size than the outlet pipe size of the 

valve, or have any reducing couplings or other restrictions.

•  Shall not be plugged or blocked.
•  Shall not be exposed to freezing temperatures.
•  Shall be of material listed for hot water distribution.
•  Shall be installed so as to allow complete drainage of both 

the Temperature-Pressure relief Valve and the discharge 

pipe.

•  must terminate a maximum of six inches above a floor 

drain or external to the building. in cold climates, it is 

recommended that the discharge pipe be terminated at an 

adequate drain inside the building.

•  Shall not have any valve or other obstruction between the 

relief valve and the drain.

water line connections

The water piping installation must conform to these instructions 

and to all local and national code authority having jurisdiction. 

Good practice requires that all heavy piping be supported.
read  and  observe  all  requirements  in  the  following  sections 

before installation of the water piping begins:

1.  mixing Valves on page 14.
2. 

Dishwashing machines on page 14.

3.  Temperature-Pressure Relief Valve on page 15.
4. 

Closed Systems and Thermal Expansion on page 14.

5. 

For  multiple  water  heater  installations  see  Water  Piping 

Diagrams beginning on page 67.

water piping diagrams

This manual provides detailed water piping diagrams for typical 

methods of application for the water heaters, see Water Piping 

Diagrams beginning 67.

The water heater may be installed by itself, or with a separate 

storage  tank.  When  used  with  a  separate  storage  tank,  the 

circulation may be either by gravity or by means of circulating 

pump. When a circulating pump is used, it is important to note 

that the flow rate should be slow so that there will be a minimum 

of turbulence inside the water heater storage tank.
Adjust  flow  by  throttling  a  full  port  ball  valve  installed  in  the 

circulating line on the outlet side of the pump. Never throttle flow 

on the suction side of a pump. See the Water Piping Diagrams 

beginning on page 67.

note:

 in addition to the factory installed Temperature-Pressure 

relief  Valve  (T&P  valve)  on  the  water  heater,  each  remote 

storage tank that may be installed and piped to a water heating 

appliance  must  also  have  its  own  properly  sized,  rated  and 

approved Temperature-Pressure relief Valve installed. 
Call the toll free technical support phone number listed on the 

back cover of this manual for further assistance in sizing a T&P 

valve for remote storage tanks.

thermometers (not supplied)

Thermometers  are  installed  in  the  water  piping  system  as  a 

means of detecting the temperature of the hot water supply at 

critical points in the system. Field supplied thermometers should 

be obtained and installed. See Water Piping Diagrams on page 67.

water (potaBle) heating and space heating

1. 

All water piping components connected to the water heater 

that are for space heating applications shall be suitable for 

use with potable water.

2. 

Toxic  chemicals,  such  as  those  used  for  boiler  treatment, 

must NEVEr be introduced into this system.

3. 

The  water  heaters  covered  in  this  manual  may  never  be 

connected to any existing heating system or component(s) 

previously used with non-potable water heating appliance.

4. 

When  the  system  requires  water  for  space  heating  that 

exceed  safe  temperatures  at  domestic  water  fixtures  a 

mixing valve must be installed, see mixing Valves on page 14.