22
3.8
CHECKING DIFFERENTIAL AIR AND GAS PRESSURES (AV800-AV4000)
Figure 11: Checking Differential Air and Gas Pressures (AV800
– AV4000)
The 1:1 air/gas ratio control actuator has embossed markings ident air, - air, + gas & - gas connections. Using a test hose
assembly fitted with tees, connections can be made from the manometer to the appropriate ports on the actuator.
Using tees connect a hose from the positive air and the negative air to each of the two sides of a monometer. This will allow the
two pressure points to be measured while at the same time the actuator still receives the proper operating signal.
If a second manometer is available, it can be connected to the appropriate gas ports. Typically, the gas signal will closely follow
the air signal on all models. If the incoming gas pressure reduces significantly as the VFD accelerates to maximum speed, the
gas signal may lag behind the air signal by up to 15%. This will occur once the actuator has driven downwards as far as it can
go. The amount that the actuator has opened is registered by an indicator arm which is visible through the view window.
As the appliance comes on and fires, record the maximum inches of water column which is achieved at maximum speed on the
VFD using startup report form (93-0332). To adjust this differential pressure when commissioning the appliance, use the
adjusting screw on the air shutter to the fan. In all cases, the final adjustment is to be made using a combustion analyzer.
Depending on field conditions differential pressures will have to be adjusted accordingly. Typically with long lateral runs, the
differential signal as read will be reduced from the value shown on the rating plate. The opposite will occur with tall stacks where
drafts exceed negative 0.15” W.C.
If the appliance will not light off it will be necessary to adjust the low fire as explained in the detailed startup procedure.
Pressure Measurement
Connections for Differential
Gas Pressure Measurement
Connections for Differential
Gas Pressure Measurement
Summary of Contents for ADVANTUS AVH 1000
Page 2: ......
Page 3: ......
Page 38: ...31 Figure 23 Recommended Piping with Reverse Return and Variable Primary Flow...
Page 88: ...81 PART 12 EXPLODED VIEW Figure A...
Page 89: ...82 Figure B FAN BURNER ASSEMBLY AV500 600 some items may not be as shown...
Page 90: ...83 Figure C FAN BURNER ASSEMBLY AV800 4000 some items may not be as shown...
Page 91: ...84 Figure D Figure E...
Page 92: ...85 Figure F Figure G...
Page 93: ...86 Figure H CONTROL BOARD ASSEMBLY...
Page 100: ...93 PART 13 ELECTRICAL DIAGRAMS...
Page 101: ...94...
Page 102: ...95...
