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IS-TWH-UT_UTS

Tankless Water Heater 

3

4

" Service Valve Set

Installation Instructions 

ATTENTION INSTALLER: After installation, please leave this 
Instruction Sheet for occupant’s information.
IMPORTANT: Inquire with governing authorities for local 
installation requirements.

Fig.4

STOP!  
Before connecting any components, be sure to read all 
of the tankless water heater manufacturer’s installation 
instructions. Failure to follow instructions below can re-
sult in serious injury, death and/or property damage. 

1.  Identify all components and 

orientations before beginning 
installation

1. HOT WATER SERVICE VALVE (Fig.1) 

Identified by a RED ring on the upper 
union connection and by the red 
insulator handle. 

2. COLD WATER SERVICE VALVE (Fig.2) 

Identified by a blue ring on the upper 
union connection and by the blue 
insulator handle. 

3. CHECK MODULE

Check element is integral to cold 
water service valve in TWH-QC-HC, 
TWH-UT-HC-RV and TWH-QC-HC-
RV kits only. 

4. PRESSURE RELIEF VALVE (Fig.3) 

Identified by a silver test lever. 

Note:  ANSI Z21.22 and local 
codes govern the installation 
of pressure relief valves. 

2.  

Before attaching any components 
to the tankless water heater, 
attach PRESSURE RELIEF VALVE 
to HOT WATER ISOLATION 
VALVE (Figure 4)

CAUTION: Do not over tighten relief 
valve. Do not tighten more than 2 
turns past hand tight.

a.  

Apply thread sealant to the exposed 
threads of the pressure relief valve.  

b.  

Thread the pressure relief valve into 
the

3

4

" port on the side of the hot 

water valve and hand tighten. Using 
a wrench, tighten the pressure relief 
valve until the discharge on the pres-
sure relief valve is positioned down-
ward on the isolation valve, as shown 
in Figure 4.

Drain Line

Attach this end to 

tankless water heater

Attach this end to 

tankless water heater

3.  

Install COLD WATER SERVICE VALVE onto cold water 
inlet of tankless water heater

a.  

Locate the cold water threaded inlet on the tankless water 
heater and apply thread sealant to the threads. 

b.  

Slightly loosen the union nut on the top of the cold water 
valve (i.e. the end with the blue insulator ring) so that the 
union tailpiece rotates freely. 

c.  

Holding the cold water valve beneath the cold water inlet, 
thread the union tailpiece onto the inlet and hand tighten. 
Using a wrench, tighten the union tailpiece. Next, position 
the cold water valve with the purge port pointing forward, 
towards the front of the water heater, and hand tighten the 
union nut.

d.  

Verify that the blue insulator seats itself between the union 
tailpiece and the union nut. Tighten the union nut with a 
wrench, making sure that the valve does not rotate out of 
position.

4.  

Install HOT WATER SERVICE VALVE onto hot water 
outlet of tankless water heater

WARNING: There should not be a shutoff located between 
the tankless water heater and pressure relief valve. (see 
direction arrow in Fig. 5)

a.  

Locate the hot water threaded outlet on the tankless water 
heater and apply thread sealant to the threads.

b.  

Slightly loosen the union nut on the top of the hot water valve 
(i.e. the end with the red insulator ring) so that the union tail-
piece rotates freely. 

c.  

Holding the hot water valve beneath the hot water outlet, 
thread the union tailpiece onto the outlet and hand tighten. 
Using a wrench, tighten the union tailpiece. Next, position the 
hot valve with the purge port and pressure relief valve point-
ing forward, towards the front of the water heater, and hand 
tighten the union nut. Verify that the insulator seats itself 
between the union tailpiece and the union nut. Tighten the 
union nut with a wrench, making sure that the valve does not 
rotate out of position. 

Fig.1

Fig.2

Fig.3

Hot Service Valve Purge Port Flow Data

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