Service - Honeywell R7795A Manual

GENERAL
1. Only qualified personnel should attempt to service
heating equipment or controls.
2. Check all the items required in the Checkout section
when replacing or servicing the R7795 or when restoring
power or relightlng the system after shutdown.
3. On each service call, check the controller for ap-
proximate calibration and differential. Make sure that it is
mounted securely.
4. Never use oil on any part of the R7795.
5. DO NOT PUSH IN THE R7795 RELAYS MAN-
UALLY. Damage may result or important safety features of
the device may be overridden. Clean contacts only as
instructed below.
PERIODIC MAINTENANCE
The specific maintenance schedule depends on a num-
ber of factors, including the types of equipment controlled,
operating conditions, and the cost of nuisance shutdowns.
The following must be included in any program:
Perform flame failure and pilot turndown tests when-
ever the burner is serviced and at least annually.
Inspect and clean the detector and any viewing windows
as often as required by soot accumulation and heat condi-
tions at the detector.
Check flame current at least monthly and more often
when a shutdown may be costly.
Clean contacts only when required by a failure to operate.
CONTACT CLEANING
!
CAUTION
Open the master switch before removing the cover
or cleaning contacts. Line voltage is present on
most contacts when the power is on.
IMPORTANT:
1. Do not clean contacts unless absolutely necessary.
2. Use only Honeywell contact cleaner part no. 132569.
DO NOT use any other type of contact cleaner.
3. Use the utmost care to avoid bending the contacts or
changing the configuration in any way.
4. Do not use abrasive materials to clean contacts.
5. Do not use hard paper such as a business card to
clean contacts.
If relay contacts must be cleaned, use only Honeywell
pressurized contact cleaner part no. 132569. The Honeywell
chemical analysis laboratory finds this cleaner to be ac-
ceptable for this task. Follow the directions listed on the can.
Do not use other types of contact cleaners. Analysis
shows that other pressurized contact cleaners are undesir-
able for these reasons:
1. Some have solvents that deteriorate plastic parts or
wire insulation.
2. Some leave oily residues that collect dust or dirt. The
residue further breaks down to form various carbonaceous
products. Either results in early contact failure.
Do not use abrasives (burnishing tools, sand paper stick,
file, etc.) to clean contacts. Use of abrasives can cause early
contact failure for these reasons:
1. Some relay contacts are plated with gold for in-
creased reliability. Burnishing removes the plating.
2. The radii or points of the contacts are designed with
specific shapes to best serve the intention of the contacts.
Burnishing can alter these contact configurations.
3. Use of abrasives loosens fine particles of the contact
materials that adhere to the surface of the contact, increas-
ing its resistance.
4. Contact specifications (pressures, pressbacks, and
gaps) are carefully controlled during manufacturing to
assure maximum contact life. Burnishing can easily change
these specifications.
19
R7795A,B,C,D

SERVICE

Service
66-2001—2