Heat Wise SU-3, Manual

Page: 9 / 20

9
Chimney Liner, Draft Regulator And Vent Pipe
Some utilities require new chimney liners for all gas installations. Use a corrosion resistant
chimney liner (approved for gas service) of the same size as the vent pipe. Use a double swing
draft regulator, listed by CSA or U.L. When the burner is used as a conversion burner, draft over
fire should be maintained between –0.02 and +0.01 “W.C. by adjusting the regulator when the
burner is fired. The installer should follow the barometric draft regulator manufacturer’s
instructions for complete details for installations and adjustments. The vent pipe should extend
only to (but not beyond) the inside wall of the chimney.
Adjusting the Firing Rate
See Fig. 6 below. Position D
1
represents the burner head all the way forward. By rotating the
burner head adjustment screw
clockwise
, the head can be moved back 0.5” (to position D
3
).
Similarly, if the head adjustment screw is turned counter-clockwise , the head is moved forward.
At head position D
3
, the SU-4 gas burner fires at 300,000 BTU when the gas manifold pressure
is 3.5” W.C. Adjust the air shutter and use a combustion analyzer to set the burner to between
8% and 9.5% CO
2
for natural gas or between 10.0% and 11.5% for LP gas. (See page 13 & 14 of this
manual for further details on burner operation).
By adjusting the manifold pressure, it is possible to adjust the firing rate. Refer to Tables 5 and 6.
Note: The pressure and head setting may vary for OEM packaged units.
When commissioning the burner, make sure the gas control knob is in the ”ON” position. Install monometers
at the inlet pressure tap and manifold pressure tap on the burner. Record the static incoming gas pressure.
When the burner lights off, record the running incoming gas pressure;
the running incoming gas pressure
should never be below 5”. Note: this pressure drop should not be greater than 1”. Check the manifold
pressure from the outlet pressure tap. Note: When checking manifold pressure, do not subtract burner
housing pressure during valve-on delay. Refer to Charts 5, 6, 7 and 8 on pages 10 and 11 to make sure the gas
pressure is set for the appropriate fuel and pressure. If adjustments need to be made, remove the cap screw and
adjust the pressure regulator. Screwing the regulator clockwise will increase the manifold pressure and
counter-clockwise will decrease the manifold pressure.
Fig. 6 Adjusting the Firing Rate
Manifold Pressure Tap