COOK HMD Installation, Operation And Maintenance Manual - Page 5

Browse online or download pdf Installation, Operation And Maintenance Manual for Air Handlers COOK HMD. COOK HMD 17 pages. Heated makeup direct: a direct fire make-up air unit

Print Page

Gas

1. Check the supply gas pressure and compare it with

the unit's nameplate pressure requirements. Adjust

the supply regulator as needed until the supply gas

pressure is within the specified range (see below).

The nameplate is located on the outside of the unit

on the control panel side.

2. Check the settings on the optional high and low gas

pressure switches. The high pressure setting is typi-

cally 8 inches wc (2 kPa) and the low pressure is set-

ting is typically 3 inches wc (0.7 kPa). The switches

are set at the factory and should not need adjust-

ment. Adjust the setting only if needed. The pur-

pose of the high and low gas pressure switches is

to automatically shut down the burner if the inlet gas

pressure is too low for the burner to safely light, or

if the manifold pressure is too high for the burner to

operate properly. Proper air velocity over the burner

is critical on direct fired gas units. If the air velocity

is not within the unit specifications, the unit will not

operate efficiently, may have sporadic shutdowns,

and may produce excessive carbon monoxide (CO)

or other gases.

Control Panel Parts

1. Contactor

2. Overload

3. Three phase

transformer #A

4. 120 - 24v

transformer #B

5. Ignition control

6. High Temp Overload

Control Panel

HMD IO&M

7. Mild weather thermostat to

damper

8. Damper motor

9. Terminal blocks

10. Circuit breaker

11. Override switch

12. 120v spark ignitor

13. Pressure sensing probe (high)

14. Pressure sensing probe (low)

Testing Inspection

All components of this or any other gas-fired heating

unit must be leak tested prior to placing the unit into op-

eration. The factory piping has been checked for leaks

but should be rechecked due to shipping & installation

issues. The field-installed shutoff valve should also be

checked.

A soap & water solution should be used to perform this

test.

Never test for gas leaks with a flame.

When leak testing pressures that are less than or equal

to 14 in. wc (3.5 kPa), first close the field-installed shut-

off valve to isolate the unit from gas supply line.

When leak testing pressures that are more than 14 in.

wc (3.5 kPa), close the field-installed shutoff valve, dis-

connect the furnace & gas train from the gas supply line

& plug the supply line before testing.

All piping should be clean & free of any foreign matter,

which may damage the valves, regulators or burner.

15. Temperature controller

16. Thermostat to blower

17. Safety Shut off valve

18. Pressure gauge

19. Gas valve

20. Modulating gas valve

21. Pressure gauge

22. Safety Shut off valve

23. Optional V.F.D. here

B51242-002