Powers 420U Series Under-the-Counter Thermostatic Tempering Valves - Manual (Page 5)

Recommended Used for
Problem Kit Type Repair Kit No. Model(s) Includes Items
• Variable or untempered Motor Replacement 420-519V (High temp) 1–9 Thermal Motor, Bonnet O-Ring,
discharge temperature 420-519 (Std. temp) 1–9 Motor Sleeve (6, 8, 12)
420-519W (Low temp) 1–9
• Water leaks at valve shut off, Combination Seat 420-559 (High capacity) 1–9 Combination Seat, Combination Seat O-
shut-off disk and/or hot Replacement 420-521 (Std. capacity) 1–8 Ring, Retaining Ring, Bonnet O-Ring
water seat have been 420-559 (Std. capacity) 9 (6, 9, 10, 11)
replaced 420-522 (Low capacity) 1–9
• Low flow, desired temp- Low Temperature 420-203 1-8 Bonnet O-Ring,Combination Seat O-Ring
erature cannot be reached Hot Water 420-557 9 (Mdls. 1-8 kit only), Combination Seat
Conversion Kit (Mdl. 9 kit only), Valve Assembly
(Mdl. 9 kit only)
• Water leaks at bonnet/body O-Ring Kit 420-524 1–9 Stem O-Ring, Bonnet O-Ring,
Combination Seat O-Ring (3, 6, 10)
• Variable or untempered dis- Valve Replacement 420-563 (High capacity) 1–9 Bonnet O-Ring, Valve Assembly
charge temperature continues 420-525 (Std. capacity) 1–8 (6, 13–19)
after motor replacement 420-560 (Std. capacity) 9
420-560 (Low capacity) 1–9
• Worn hot water seat Valve and Hot 227-340 (Std. capacity) 5-8 Bonnet O-Ring, Combination Seat O-Ring,
Water Seat 420-561 (Std. capacity) 9 Valve Assembly, Return Spring, Hot Water
Seat (6, 10, 13-19, 20, 21)
REPAIR KIT PART NUMBERS
Figure 2.
3. Flow is untempered hot or cold water…
• accumulation of lime deposits in hot water pipes,
restricting the flow of hot water
• thermostatic motor failure; replace with new ther-
mostatic motor
• hot and cold water supplies are connected to the
wrong ports
4. Maximum temperature specified for the 420
Hydroguard cannot be obtained…
• accumulation of lime deposits in hot water pipes,
restricting the flow of hot water
• hot water supply temperature is too low
5. Variable discharge temperature occurs…
• extreme pressure variations in supply lines
• valve operating below minimum capacity requirements
PREVENTIVE MAINTENANCE
Every Six Months: Check and adjust the maximum
temperature setting (see instructions below).
Every Twelve Months:
1. Shut off water supply.
2. Open up checkstops (if any).
3. Clean strainers (if any) and check for free move-
ment of checkstop poppet.
4. Remove the bonnet and check for freedom of
movement of internal components.
5. Test the thermostatic motor as described in
Thermostatic Motor Testing Section (page 5).
6. Replace seals if cracked, cut, or worn.
7. Reassemble.
8. Adjust screwdriver stem to desired temperature.
1. The flow of water is less than desired…
• valves upstream from supply not fully open
• low supply pressures
• accumulation of lime deposits in hot water pipes,
restricting the flow of hot water
• checkstops not fully open
• clogged strainer screens in the checkstops
• clogged hot water seat
2. Flow of water is completely shut off…
• valves upstream from supply completely closed
• failure of cold water supply pressure (the 420
Hydroguard is designed to shut off on a cold
water supply failure)
• checkstops completely closed
TROUBLESHOOTING
Screwdriver
adjustment
stem
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