Patterson-Kelley TBIG-03 - Manual (Page 12)

Gemini™ Twin-Fuel Gas-Fired Boiler
4.4.5 Gas Pressure Adjustment
Increase Decrease
Figure 4-7 Regulator
The gas pressure is set initially during a factory fire-
test. A final adjustment must be made after the boiler
has been installed, as follows:
See rating plate for the minimum and maximum gas
pressure of the boiler.
Each boiler is furnished with three plugged taps in the
gas train for test gauge connections. Two taps are lo-
cated at the natural gas and propane manual shutoff
valves and are for measuring the gas supply pressure
(1/4" I.P.S.). The supply pressure during main burner
operation must be greater than the minimum indicated
on the rating plate (6 inches W.C. for natural gas, 6
inches W.C. for propane). The remaining tap is lo-
cated downstream from the secondary manual shutoff
valve at the elbow where the gas line enters the back
of the cabinet and is for measuring the manifold gas
pressure (1/8" I.P.S.).
If a replacement Lo-Hi-Lo actuator is required, follow
manufacturer's instructions and pre-set the "Lo" fire
setting of the actuator the same as the original actua-
tor. This must be performed by qualified service per-
sonnel.
To adjust gas pressure, first connect an appropriate
pressure-sensing device at the manifold tap, then re-
move seal cap from regulator. Turn adjusting screw
clock-wise to increase pressure, counter-clockwise to
decrease pressure. The manifold gas pressure on the
"Rating Plate," affixed to the back of the cabinet, is
provided only as a guide to the proper setting. The
manifold gas pressure indicated on the "Factory Fire-
test" label (affixed to the back of the cabinet) should
be used to achieve the proper firing rate of the
individual boiler as installed. Replace seal cap after
adjustment.
4
.4.6 Leak Testing of Valves
Annually test for by-pass leaks on all motorized gas
valves. If gas flows when the motorized gas valve is
closed it is defective.
downstream
leak test
valve
upstream
leak test
valve
motorized gas
valve (natural
gas)
motorized gas
valve (propane)
secondary
shutoff
to burner
secondary
motorized
gas valve
Figure 4-8 Leak Testing of Valves
Each branch of the gas train must be tested separately,
s follows: a
1. Open the natural gas connection manual shutoff.
Close the propane connection manual shutoff.
(Refer to Figure 4-1.)
2. Close the secondary shutoff (downstream of all
motorized valves).
3. Attach a short piece of hose to the downstream
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