Field Notes
Tempered-water mixing valve outlet logs before scald complaints
A useful scald complaint record ties the mixing valve, outlet temperature, fixture reading, flow condition, thermometer, limit device, check valves, witness, correction, and release boundary together before anyone changes setpoints.
Direct answer
Before reviewing a fixture scald complaint, the tempered-water record should identify the building, fixture, user area, complaint time, water heater or plant, mixing valve or limiting device, ASSE listing or device type, manufacturer, model, size, serial number if available, installation location, served fixtures, approved temperature target, code or owner limit, manufacturer instruction used, hot inlet temperature, cold inlet temperature, mixed outlet temperature at the valve, downstream fixture temperature, time to maximum temperature, flow condition, recirculation pump state, no-demand or active-demand condition, thermometer ID, thermometer verification status, measurement point, date and time, witness, failed readings, corrections, recheck readings, open exceptions, and release boundary.
Do not treat every high-temperature complaint as a master mixing-valve adjustment. A distribution valve, an ASSE 1070 point-of-use device, a shower valve, a faucet limiter, a water heater with integral controls, a failed check valve, a clogged strainer, a cross-flow path, or a recirculation condition can each change what the outlet reading means.
Use this as documentation guidance only. The plumbing code, local hot-water and anti-scald rules, owner water-management program, manufacturer instructions, engineer, AHJ, health or facility requirements, qualified plumbing contractor, and site safety plan control the actual device selection, target temperature, adjustment, repair, and release.
Device type controls what the reading means
The first field should be the device type. ASSE guidance separates temperature-actuated mixing valves used at or near the hot-water source for distribution from point-of-use devices that control or limit water delivered to fixtures. The same installed product may carry multiple listings, but the application still matters.
That distinction prevents a bad complaint review. A master distribution valve can set a tempered supply to the system, but ASSE guidance says a source-applied ASSE 1017 device should not be treated as the final point-of-use scald protection. Fixture-level devices, shower valves, ASSE 1070 devices, and other temperature-limiting devices may still control the water the user actually receives.
The log should say whether the complaint review is measuring a source valve, a recirculating tempered loop, a branch device, a single fixture, a group fixture valve, or a shower/tub valve. Without that identity, the outlet temperature can be read correctly and still lead to the wrong adjustment.
Measure outlet temperature under a known flow condition
A mixing valve outlet reading only means something if the flow condition is known. Record whether there was no demand, one fixture flowing, several fixtures flowing, a required minimum flow through the valve, recirculation pump on, recirculation pump off, balancing valve position, and whether the measured fixture was tagged open for the test.
Manufacturer literature commonly tells installers to use a thermometer at the faucet or outlet, let water flow until temperature is stable, and adjust according to instructions. Some recirculating-system instructions require a defined setup before the final adjustment, such as controlling unused fixtures, running enough flow, then restarting the pump and checking return behavior.
That does not mean every job follows one manufacturer's procedure. It means the log should preserve the operating state. A complaint reading taken during morning peak demand is different from a reading after a no-load recirculation period. A reading at the mixing valve outlet is different from a reading at the fixture after a long runout.
Pair valve outlet readings with fixture readings
The complaint happened at a fixture, so the packet needs both sides: what the valve delivered and what the fixture delivered. Record the valve outlet temperature, fixture outlet temperature, elapsed time to maximum temperature, fixture type, aerator or shower head condition if relevant, local limiter or cartridge setting where allowed, and whether the user has access to additional hot/cold mixing.
If the valve outlet is within the approved target but the fixture is hot, investigate the downstream device, cross-flow, recirculation condition, wrong connection, fixture cartridge, local limiter, or use condition before adjusting the source. If the valve outlet is hot, record whether the device is incorrectly set, unstable, outside flow range, fouled, missing checks, piped incorrectly, or seeing inlet temperatures outside its instructions.
A single fixture reading is not enough to change a building-wide setpoint. Take comparison readings at nearby fixtures, the same group, the branch, and the valve outlet as the complaint scope requires.
Use a log table that separates control points
Use the owner form, service ticket, water-management log, commissioning record, manufacturer startup sheet, or code inspection form first. Add this table where the required form does not make the scald complaint review clear.
| Record item | Field detail | Why it matters |
|---|---|---|
| Complaint fixture | Room, fixture ID, use, complaint time, reported condition, vulnerable-user area if applicable | Ties the record to the actual scald complaint |
| Device identity | Mixing valve, limiting device, shower valve, manufacturer, model, size, ASSE listing, location | Shows which control point is being reviewed |
| Control basis | Code section, owner limit, water-management plan, manufacturer instructions, engineer direction | Prevents field guesses about target temperature |
| Inlet readings | Hot inlet, cold inlet, pressure where relevant, supply condition, strainer/check status | Shows whether the valve has the input conditions it needs |
| Valve outlet | Mixed outlet temperature, setpoint or limit stop status, thermometer ID, reading time | Documents what the valve delivered at the test condition |
| Fixture outlet | Start temperature, maximum temperature, time to maximum, flow condition, aerator/head condition | Shows what the user actually received |
| Operating state | Recirculation pump, demand condition, no-load period, tagged fixtures, balancing valve status | Explains why the reading may change over time |
| Cross-flow check | Check valves, warm cold line, cold-to-hot crossover, fixture cartridge, hose station, equipment tie-in | Prevents a valve adjustment from masking a piping problem |
| Correction | Cleaned strainer, restored check, reset limit stop, replaced cartridge, adjusted valve, held for engineer | Shows what changed before recheck |
| Release | Held, safe to use, temporary restriction, recheck required, owner/AHJ review, final closeout | Separates measurement from permission to return the fixture to service |
Watch for cross-flow and minimum-flow problems
A scald complaint can be caused by a mixing valve, but it can also be caused by a failed check valve, wrong piping connection, fixture cartridge, hose station, recirculation bridge, equipment connection, or local limiter. The record should show what was checked before the adjustment was blamed on the main valve.
Minimum flow matters too. Thermostatic mixing valves have operating ranges. If the complaint fixture draws below the minimum flow needed for stable operation, or if a group valve is oversized for the active demand, the outlet temperature may hunt. Record flow condition, fixtures opened, and whether the manufacturer instructions require a minimum flow for adjustment.
Strainers and check valves belong in the same packet. Debris can affect valve control, and missing or failed checks can allow unwanted hot/cold movement through the valve body. Record cleaned strainers, restored checks, replacement parts, and recheck readings.
Do not erase the first bad reading
The initial complaint reading is evidence. Keep it even if the final recheck is acceptable. Record who took it, where it was taken, the thermometer used, the flow condition, the elapsed time, and whether the reading was repeated.
If the temperature is high enough to create a user hazard under the site rules, record the immediate hold or restriction before documenting repairs. Do not let a later adjustment make it look as if the fixture was never unsafe.
The recheck should repeat the same measurement points where practical: valve outlet, complaint fixture, nearby comparison fixture, and any return or branch point used in the review. If the recheck uses a different flow condition, say so.
Before scald complaint checklist
Run this check before closing a fixture scald complaint or changing a temperature-control device.
- Identify the complaint fixture, served area, user group, complaint time, and whether the fixture must be held out of service.
- Identify the exact temperature-control device: ASSE 1017 source valve, ASSE 1070 point-of-use limiter, ASSE 1016 shower valve, group valve, water heater control, or other device.
- Attach the control basis: plumbing code, owner standard, water-management plan, manufacturer instruction, engineer direction, AHJ note, or facility policy.
- Record hot inlet, cold inlet, mixed outlet, and complaint-fixture temperatures with thermometer ID and verification status.
- Record flow condition, fixtures opened, time to maximum temperature, recirculation pump status, no-demand period, and whether the reading stabilized.
- Check whether the device is within its application, flow range, inlet temperature range, and manufacturer adjustment procedure.
- Check strainers, integral or supplementary check valves, cross-flow symptoms, local cartridges, limit stops, hose stations, and connected equipment.
- Preserve the first failed reading, immediate hold, correction, approving person, and recheck reading.
- Do not change a master distribution setpoint to solve a local fixture complaint unless the approved procedure and responsible authority allow it.
- Write the final release boundary: fixture returned to service, temporary restriction, recheck required, owner/AHJ review, or broader system investigation.
Weak and strong scald complaint notes
Weak note: Lavatory was too hot. Adjusted mixing valve.
That note does not identify the fixture, device type, approved limit, thermometer, inlet readings, outlet reading, flow condition, point-of-use device, cross-flow check, correction, recheck, or release boundary.
Stronger note: Fixture scald complaint reviewed at Level 2 public lavatory L2-14 served by tempered branch TB-2 and point-of-use mixing valve MV-L2-14. Complaint reported hot discharge at 9:10 a.m. Control basis is owner plumbing standard P-7, local code maximum for this fixture type, and Leonard valve manual G-170370 for the installed model. Fixture held out of service at 9:22 a.m. Field thermometer T-04 verified against shop reference cup before use. Initial reading at the faucet reached 123 degrees F after 42 seconds at normal handwash flow. Hot inlet at the point-of-use device was 132 degrees F, cold inlet was 68 degrees F, and mixed outlet at the device was 122 degrees F. Nearby fixture L2-13 reached 108 degrees F after 35 seconds. Integral check valves were present; cold inlet warmed during flow stop, so cartridge and check condition were reviewed. Strainer had debris, cartridge was replaced by qualified plumber, and limit stop was reset per manufacturer instructions. Recheck at 10:35 a.m. under the same fixture flow reached 106 degrees F after 45 seconds. Fixture returned to service for handwash use only. Master mixing valve, water-heater storage setpoint, and recirculation controls were not changed. Owner to recheck L2 fixtures during afternoon peak use.
The stronger note works because it preserves the unsafe reading, names the device and authority, records the measured points, explains the correction, and limits the release.
Common mistakes
The first mistake is adjusting the source mixing valve before identifying the fixture-level device. That can create new complaints elsewhere and may not fix the fixture.
The second mistake is using an unverified thermometer or a vague hand-feel note for a scald complaint. The record needs measured temperatures and a measurement point.
The third mistake is ignoring flow condition. A valve outlet reading at no flow, minimum flow, full fixture flow, or no-load recirculation can mean different things.
The fourth mistake is losing the first failed reading. The failed reading explains why the fixture was held, why a repair was made, and whether the recheck actually solved the complaint.
The fifth mistake is treating ASSE 1017 distribution control as final scald protection. ASSE guidance distinguishes source/distribution control from point-of-use protection.
The sixth mistake is changing temperature controls without documenting code, owner, water-management, manufacturer, and qualified-person authority.
Questions that come up
Is the mixing valve outlet temperature enough to close a scald complaint? No. The fixture reading matters because the user is exposed at the fixture. Record both the valve outlet and the fixture outlet where the complaint occurred.
Can a master mixing valve be the only scald-control record? Not usually. ASSE guidance treats source/distribution valves differently from point-of-use and shower/tub protection. The log should identify the device application and the fixture-level protection required by the project and code.
Should the record include water-management temperatures? Yes, when they control the work. CDC hot-water guidance also says anti-scald regulations still matter, so the record should show which limit controlled the complaint review.
What if the reading is high but the device is not accessible? Hold the fixture or area under the site procedure and escalate to the responsible plumber, owner, engineer, manufacturer, or AHJ as required. Do not close the complaint from a remote guess.
Can a manufacturer preset be trusted without field measurement? No. Manufacturer documents commonly require field temperature checks or adjustment to the desired safe setting. Record the actual outlet temperature.
Compliance and safety limits
This field note is not a plumbing design, scald-prevention plan, water-management program, Legionella control plan, code interpretation, medical guidance, manufacturer instruction, warranty approval, or permission to adjust water heaters, mixing valves, point-of-use devices, shower valves, limit stops, check valves, pumps, recirculation controls, BAS points, or fixture cartridges. The plumbing code, local anti-scald rules, water-management program, owner standard, manufacturer instructions, engineer, AHJ, qualified plumbing contractor, and site safety plan control the work.
Do not use this checklist to bypass hot-water burn protection, fixture maximum-temperature limits, anti-scald devices, water-management controls, lockout/tagout, electrical safety, public protection, infection-control requirements, ceiling access controls, ladder safety, PPE, chemical treatment limits, or site-specific procedures. Do not raise temperatures, defeat limit stops, disable checks, remove cartridges, or change recirculation controls without the required authorization and qualified review.
Sources checked
- U.S. Consumer Product Safety Commission, Avoiding Tap Water ScaldsUsed for tap-water scald risk, 120 degrees F public-safety guidance, and the need not to take hot-water temperature for granted.
- ASSE International, Guidelines for Temperature Control Devices in Domestic Hot Water SystemsUsed for ASSE 1016, 1017, 1069, and 1070 device distinctions, source versus point-of-use application, scald and thermal-shock limits, cross-flow cautions, and multiple-listing caveats.
- ICC Digital Codes, 2021 IPC Chapter 5 Water HeatersUsed for code-context source material around water heaters and temperature limiting. Adopted local code and AHJ control the job.
- International Code Council, Hot Water SafetyUsed for 2021 code-change context around temperature limiting means, ASSE 1070, ASSE 1017, circulation controls, and fixture hot-water delivery.
- CDC, Monitoring Building WaterUsed for hot-water monitoring, anti-scald caution, point-of-use mixing context, time-to-maximum-temperature observation, and water-management limits.
- ASPE, Smarter Safer Hot WaterUsed for mixing-valve system context, safe water temperature, source versus point-of-use balancing, digital mixing valve monitoring points, and outlet/return temperature data.
- Caleffi, idronics 21: Recirculating Domestic Hot Water SystemsUsed for recirculating domestic hot-water context, point-of-distribution mixing valve examples, and operating-condition documentation.
- Watts, Thermostatic Mixing ValvesUsed for product-category context, ASSE 1017 and 1070 application distinctions, check valves, cross-flow detection, and point-of-use versus source control.
- Leonard Valve, Eco-Mix Installation, Operation and Maintenance ManualUsed for manufacturer warning and field requirement to check outlet water temperature and adjust to safe delivery temperature according to instructions.
- Resideo, AM-1 1070 Series Mixing Valve InstructionsUsed for ASSE 1070/1017 dual certification context, point-of-use application, thermometer-at-faucet instruction, check-valve context, and licensed-contractor/local-code limitation.
- Symmons, MaxLine Tempering ValveUsed for product context around ASSE 1070/1017 dual certification, tempering-valve temperature-control range, and point-of-use valve category.
- Aalberts Integrated Piping Systems, MVB Thermostatic Mixing Valve InstructionsUsed for manufacturer procedure context around stable outlet temperature, minimum flow, recirculation pump state, tagged fixtures, check valves, and unsafe discharge warnings.