Reznor YDHA - Page 36

Form O-Y, PN 273647R5, Page 36
Depending on the heat section and gas control selected, all gas trains have one or
two single-stage and/or two-stage combination gas valves. These gas valves must
be checked annuallyWRHQVXUHWKDWWKH\DUHVKXWWLQJRIIJDVÀRZFRPSOHWHO\IROORZ
the instructions below.
Instructions:
1. /RFDWHWKH137SUHVVXUHWDSVRQWKHFRPELQDWLRQJDVYDOYH
2. Check the Manual Gas Valve - With the manual valve turned off to prevent
ÀRZWRWKHJDVYDOYHFRQQHFWDPDQRPHWHUWRWKH´LQOHWSUHVVXUHWDSLQWKH
combination valve. NOTE: A digital manometer is recommended.
:LWKWKH¿HOGLQVWDOOHGPDQXDOYDOYHUHPDLQLQJFORVHG¿UHWKHXQLWRQ7HVWPRGH
allow the unit to go through one trial for ignition. Turn off and observe the manom-
eter for two to three minutes for an indication of gas pressure. No pressure should
be indicated on the manometer.
If the manometer indicates a gas pressureWKH¿HOGLQVWDOOHGPDQXDOJDVYDOYH
must be replaced or repaired before the combination gas valve can be checked.
3. Check the Combination Valve - If the manometer does not indicate gas
pressureVORZO\RSHQWKHWHVWHG¿HOGLQVWDOOHGPDQXDOJDVYDOYH$IWHUWKH
manometer's indicated gas pressure has reached equilibrium, close the manual
shutoff valve. Observe the gas pressure. There should be no loss of gas pressure
on the manometer. If the manometer indicates a loss of pressure, replace the
combination gas valve before placing the heater in operation.
Operating Gas Valve -
Modulating Valve -
in Modulating Gas
Control Options
AG73 and AG74
Function:7KHPRGXODWLQJYDOYHUHVSRQGVWRWKHWR9'&VLJQDOIURPWKHFRQWURO-
ler to modulate the gas pressure to the burner.
Service:7KHPRGXODWLQJJDVYDOYHKDVQR¿HOGPDLQWHQDQFHUHTXLUHPHQWVH[FHSW
careful removal of external dirt accumulation and checking wiring connections.
FIGURE 26 - Top View of Two Types of Single-Stage Gas Valves and a Two-Stage Valve
1/8” Output
Pressure Tap
Inlet
Pressure Tap
Adjust Outlet
Pressure
1/8”
Output
Pressure
Tap
Inlet Pressure
Tap
Adjust Outlet
Pressure
1/8” Output
Pressure Tap
Inlet
Pressure
Tap
Two-Stage Valve
Single-Stage Valves
Modulating Valve in Options AG73 and AG74
Part No Size Single Heat Section Dual Heat Sections
273587 1/2" +++ +++++
271840 1/2"
*+
H300 (propane)
*++SURSDQH
H602 (propane)
273588 3/4"
G225 (natural),
G300 (natural),
+QDWXUDO+
G372 (natural), G452 (natural),
G525, G602, H502 (natural),
+QDWXUDO++
5.0 Maintenance/Service Procedures - Gas Heat Section (cont'd)
5.1 Gas Heat Controls (cont'd)