External Auxiliary Bypass Valve

INTERNAL AUTOMATIC BYPASS VALVE

PRESSURE RELIEF VALVE INSTALLATION

In addition to the Unitherm Governor, a built-in auto- matic bypass valve is provided in the in/out header. While the Unitherm Governor responds to the changes in water temperature in the heater, the internal bypass valve automatically responds to changes in water pressure in the piping system. Proper amount of water flow is maintained through the heater under varying pressures dictated by the conditions of the pump and filter.

Bypass Disc

Spring

Bypass Body

Fig.# 2003

(Where Required)

An auxiliary bypass valve should be used when flow rates exceed 125 GPM. Usually a high-performance pump size larger than two horsepower will exceed this flow rate. This valve is required to complement the function of the automatic bypass valve, particularly when starting the heater in winter or early spring when the spa or pool temperature is below 50°F. It also serves to eliminate needless pressure drop through the heater and accompanying reduction in the flow rate to the spa jets, etc.

From Heater To Heater

To Pool/	From Pool/
Spa	Spa
	AUXILIARY BYPASS VALVE
	(DO NOT USE GATE VALVE) Fig.# 81.50.0

AUXILIARY BYPASS VALVE ADJUSTMENT

To set bypass: With clean filter, adjustment is made by feeling the inlet and outlet pipes at the heater. Outlet pipes should be slightly warmer than inlet and comfort- able to the touch. If pipe is hot, close bypass; if cold, open bypass.

To conform to local building codes, it may be neces- sary to install a pressure relief valve. A 3/4" pressure relief valve, having a capacity equal to the BTUH out- put of the model to be installed, is recommended for this heater. The maximum acceptable pressure relief valve setting is 125 psi.

A 3/4" NPT connection is provided in the Polymer header for installation of a pressure relief valve. The valve shall be installed in a vertical position. Do not overtighten. Install pressure relief valve hand tight plus 1/2 turn.

POLYMER HEADER

(STANDARD MODELS)

Pressure Relief Valve

PRV Discharge

Connection

In/Out Header

Fig. #2004

A 3/4" NPT connection is provided in the header for installation of a pressure relief valve. The valve shall be installed in a vertical position.

CAST IRON HEADER	PRV
(ASME MODELS)

NOTE: To avoid water damage or scalding due to valve operation, drain pipe must be connected to valve outlet and run to a safe place of discharge. Drain pipe must be the same size as the valve discharge connec- tion throughout its entire length and must pitch down- ward from the valve. No shut-off valve shall be installed between the relief valve and the drain line. Valve lever should be tripped at least once a year to ensure that waterways are clear.