Engineered air DG series Bedienungsanleitung PDF herunterladen (Seite 10)

Page 6

LOW FIRE BUT NO MODULATION

The modulating valve should be able to be modulated to any position after the 109 contacts are

closed and the main flame is established. If the valve will modulate when a potentiometer is

connected to the 109 as described in point 2 above but it will not modulate from the normal

temperature controller, it is likely the normal temperature controller is at fault.

OTHER NOTES

A) If using a 0-10 VDC or a 4-20 ma signal to the 109, ensure the 24 VAC power to the 109

terminals “T and T” is from a separate underground transformer. The wires to the BMS

supply signal should be run in a separate shielded cable with the shield grounded at the unit

end only. This is to reduce interference.

B) With all wires except the “T and T” terminals disconnected and 24 volt power to those

terminals, the 109 should have about 15 VDC across the 109 terminals “4” and “W”.

C) With a 135 ohm pot connected as in point 3 above, the voltage across 109 terminals “4” and

“W” (-) should modulate between 1.75 and 4.5 VDC depending on the pot setting.

D) With a 135 ohm pot connected as in point 3 above, the voltage across 109 terminals “2” and

“w” (-) should modulate between 0 and the reading found in point ‘C’ above. (0 = low fire).

E) With a 135 ohm pot connected as in point 3 above, the voltage across 109 terminals “R” and

“W” (-) should modulate between 0 VDC and 2.5 volts at high fire, depending on the pot

setting.

F) Adjust the pot setting. When the voltage across the 109 terminals “R” and “W” is in excess of

about 1 VDC, the 109 relay contacts “8” and “9” should close. These contacts should remain

closed for about 1 ½ minutes after the voltage is reset to 0 and the internal timer completes

its cycle.

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Engineered air DG series Bedienungsanleitung Seite 10