Measuring gas pressure
▶ Shut off gas.
▶ Remove front cover and locate inlet gas pressure
measuring point on the right side, see Fig. 13.
▶ Loosen screw from test point on the right side and connect
manometer tube on test point.
Gas pressure measuring point
[A] Inlet tap
Static pressure test
▶ Turn gas supply back on.
▶ Record static gas pressure reading on back page of manual.
Operating pressure test
▶ Turn on all hot water taps served by the water heater.
▶ Run high hot water flow rate.
▶ Set flow control knob fully clockwise.
▶ Set slide control to the right.
▶ Record operating gas pressure reading on back page of
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 4.7.
When facing the heater, the ½ " cold water inlet is on the bottom
right and the hot water outlet is on the bottom left.
▶ Install unions or the Webstone service valves when
connecting plumbing to the water heater. This will
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 or 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
It is recommended that all water piping below the heater be
properly insulated to avoid heat loss.
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. 14). 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 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. 14. 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.
Installation instructions | 19
6 720 644 951 (2014/11)