Bosch GWH 425 PN Specifications download pdf (Page 12)

8 716 473 148

Installation instructions

3.6 Measuring gas pressure

Connecting manometer

B Shut off gas.

B Remove front cover and locate inlet gas pressure

measuring point on the right side of the gas valve.

B Loosen screw from test point on the left side of gas

valve and connect manometer tube on test point.

Static pressure test

B Turn gas supply back on.

B Operate all other gas appliances on same gas piping

system at maximum output.

B Record static gas pressure reading on back page of

manual.

Operating pressure test

B Run high hot water flow rate.

B Set flow control knob fully clockwise.

B Set slide control to the right.

B Record operating gas pressure reading on back

page of manual.

Gas pressures lower than 5.7" W.C. for Natural Gas or

10.5" W.C. for LP Gas will result in insufficient degree

rise to the hot water being used, and must be corrected.

See Gas Line Sizing under chapter 3.5.

3.7 Water connections

When facing the heater, the ½” cold water inlet is on the

bottom right and the hot water outlet is on the bottom

left.

B INSTALL A UNION WHEN CONNECTING

WATER PIPE TO FACILITATE ANY

NECESSARY CLEANING AND SERVICING.

Although water piping throughout your structure may be

other than copper, we recommend that copper piping

or suitably rated stainless steel flex line piping be used

for at least three feet before and after the heater (follow

local codes if more stringent). Never sweat any rigid

piping directly to or beneath the water connections,

damage can occur to the internal water valve from

heating of the pipe. Plastics or other PEX type plumbing

line materials are not recommended for connecting

directly to the water heater. Keep water inlet and outlet

pipes to no less than ½" (12.7mm) diameter to allow the

full flow capacity.

It is recommended that all water piping below the

heater be properly insulated to avoid heat loss. If

below freezing temperatures are ever anticipated where

the heater is located, insulation material is required and

must be capable of protecting the piping from freezing.

The freeze protection that is equipped within the heater

will not prevent any freeze damage to the exterior water

piping.

If the cold and hot connections to the heater are

reversed, the heater will not function. Be certain there

are no loose particles or dirt in the piping. Blow out or

flush the lines before connecting to the water heater.

Full port valves should be installed on both the cold

water supply and hot water outlet lines to facilitate

servicing the heater (see Fig. 9). For installation on a

private well system with the use of a pressure tank, the

lowest pressure range setting recommended is 30-50

psi (2.07 and 3.45bar).

Connecting the pressure relief valve (PRV)

A listed pressure relief valve supplied with the heater

must be installed at the time of installation. No valve is

to be placed between the PRV and the heater. No

reducing coupling or other restriction may be installed

in the discharge line. The discharge line must be a

minimum of 4” above a drain and installed such that it

allows complete drainage of both the PRV and the line.

The location of the PRV must be readily accessible for

servicing or replacement, and be mounted as close to

the water heater as possible. See Fig. 9. To install the

PRV, a suitable fitting connected to an extension on a

“T” fitting can be sweated to the hot water line.

Support all piping.

Fig. 9 Plumbing Connections and Pressure Relief

Valve

1 2 ... 7 8 9 10 11 12 13 14 15 16 17 ... 24 25

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Bosch GWH 425 PN Specifications Page 12

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