4
Figure 3. Typical UL Gas Piping Train (Modulating Burner)
5.5
Install pressure regulator (not used with combination gas valve/pressure regulator) directly upstream of
main automatic gas valve(s) and fit drip leg and main gas cock upstream of regulator or automatic
valve(s).
5.6
The pilot line should be piped into the upstream tapped nipple to minimize pilot line piping length. An
optional location is in a tapping located on the main shut-off cock. Refer to Figure 3. For ease of
servicing the use of a union immediately upstream of the main gas pressure regulator or combination gas
valve/pressure regulator is recommended.
5.7
Install vent lines from main gas regulator (if used) and diaphragm gas valve where applicable. Vent lines
should be run to the outside of the building, terminating clear of windows or fresh air intakes. Outside
termination of vent should have a screen to prevent insects from building nests in vent pipe. The vent
should terminate in a manner, which will preclude the possibility of water, dirt or other foreign matter from
entering the line. Refer to state or local codes for proper venting requirements.
5.8
Test gas lines for leaks using a soap solution. Your local gas service company may wish to execute or
witness this test. CAUTION – gas pressure above 14” W.C. may damage the standard diaphragm gas
shut-off valve. Do not exceed this value when pressure testing lines without first capping off line
upstream of main gas cock and pilot take-off.
5.9
Check that side orifice size (if used) matches with the burner specification sheet See Figure 4 on page 5.
To gain access to orifice, remove orifice tee plug and withdraw spring and orifice. When reinserting or
replacing the orifice, ensure that it seats properly inside the tee and reinstall plug.
