Rheem Guardian Warm Water Owner's Manual And Installation Instructions page 29

MAINTENANCE
Performance: check blend stability against known datum (e.g. commissioning check) for an induced pressure or
flow change. Renew thermostatic cartridge when necessary.
Function: isolate warm water return, and check thermostatic mixing valve inlet pipe work temperature for correct
function of check valves, and maintain/renew as necessary. Check and clean strainers as appropriate.
Lubricate accessible seals when necessary using silicone-only based lubricant.
IN-SERVICE TEST
The principal means for determining the continuing satisfactory performance of the mixing valve is the In-service
test.
The In-service test procedure is shown on page 31. This should be carried out at both 6 to 8 weeks and 12 to 15
weeks after commissioning the valve. The results of these tests are used to determine when, after initial
commissioning, the In-service test is next repeated.
Whenever a cartridge is replaced, the In-service test should be repeated as if it was a new valve.
Note! In-service tests should be carried out with a frequency, which identifies a need for service work before an
unsafe water temperature can result. The general principal to be observed after the first 2 or 3 in-service tests, is
that intervals of future tests should be set to those which previous tests have shown can be achieved with no
more than a small change in mixed water temperature. But in no case longer than 12 months.
Maintenance personnel should also ensure that the user's staff is aware of the importance of reporting
temperature variations and that when detected, these should be recorded in the log.
It is recommended that the user maintains a log of the in-service tests described herein, together with a record of
any service work carried out and the replacement of cartridges. It is also recommended that any maintenance
personnel sign the user log in respect of the warm water system examined on each attendance at the user's
premises. Refer to 'Maintenance Check Log' on page 24.
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