Univex 318258-000 ユーザーズマニュアル

5

Piping, fi ttings, and valves should be installed according to 

the installation drawing (Figure 4). If the indoor installation 

area is subject to freezing temperatures, the water piping 

must be properly insulated. 
Water supply pressure should be 50-60 PSIG and not 

exceed the maximum 80 PSIG. If the supply line pressure 

exceeds 80 PSIG, a pressure reducing valve (PRV) with 

a bypass should be installed in the cold water supply line. 

This should be placed on the supply to the entire house in 

order to maintain equal hot and cold water pressures.

 

• 

 

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Always use a good grade of joint compound and be 

certain that all fittings are tight. 
IMPORTANT:

 DO NOT over apply joint compound.

Install the water piping and fittings as shown in  Figure 

1. 

4. Connect the cold water supply (3/4” NPT)  to the 

fitting marked “Cold”. Connect the hot water supply 

(3/4” NPT)  to the fitting marked “Hot”. 
The installation of unions in both the hot and cold    

2. 

water supply lines are recommended for ease of    

removing the water heater for service or replacement.

Some local codes may require, and the manufacturer 

3. 

of this water heater recommends, installing a mixing 

valve or an anti-scald device in the domestic hot water 

line as shown in Figure 4. These valves reduce the 

point-of-use temperature of the hot water by mixing 

cold and hot water and are readily available. Contact 

a licensed plumber or the local plumbing authority for 

more information.
Some local codes may require, and the manufacturer 

4. 

of this water heater recommends, installing a pressure 

reducing valve (PRV) in the cold water inlet line where 

it enters the residence as shown in Figure 4. 
If installing the water heater in a closed water system,   

5. 

install an expansion tank in the cold water line as 

specified under “Closed System/Thermal Expansion.”
Install a shut off valve in the cold water inlet line. It   

6. 

should be located close to the water heater and be    

easily accessible. Know the location of this valve and  

how to shut off the water to the heater.
Install a discharge line from the temperature and 

7. 

pressure relief valve in the opening marked “T & P 

RELIEF VALVE”.  See Figure 5 and the “Temperature 

and  Pressure Relief Valve” section.) 

After piping has been properly connected to the water 

8. 

heater, open the nearest hot water faucet. Then open 

the cold water shut off valve and allow the tank to 

completely fill with water. To purge the lines of any 

excess air and sediment, keep the hot water faucet 

open for 3 minutes after a constant flow of water is 

obtained. Close the faucet and check all connections 
for leaks. 

Cold Water 
Inlet Valve

Cold Water 
Inlet

Whole House Pressure Reducing 
Valve (PRV) should be installed 
where the water supply enters 
the residence.

In a closed system, use a
thermal expansion tank.
See “Closed System/
Thermal Expansion”
section.

Cold Water Outlet

Shut-off Valve
(Cold)

Tempered Water to Fixtures

Untempered Water Outlet

Vacuum Relief Valve

Mixing Valve (Optional) - Follow the 
Mixing Valve’s Manufacturer’s Installation 
Instructions. (Set to 120° F)

6” Maximum 
Air Gap

Metal Drain Pan 2 1/2” 
Depth Maximum and
2 Inches wider than
the water heater.

Discharge Pipe
(Do Not Cap or Plug)

Temperature and 
Pressure Relief Valve

Union

Shut-off Valve (Hot)

Drain Line 3/4” 
ID Minimum

Drain

Condensate Drain Lines*

Massachusetts: Install a vacuum relief in cold 
water line per section 19 MGL 142.

Figure 4
Water Piping Installation 
with Mixing Valve

* If an adequate drain is not available for the condensate drain lines then a condensate pump should be used. DO NOT discharge the condensate drain   
   lines into the metal drain pan.

Union

Hot

(Outlet)

Cold

(Inlet)

Heat Trap - The top of the heat trap
must be higher than the storage tank
of the water heater.