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Hot Water Temperature Maintenance

Hot Water Temperature Maintenance. HWAT Simply Keeps Hot Water Hot. Heat lost through the insulation. Water provided from Water Heater. Air at 70F. Pipe. Insulation. HWAT heating cable. Heat provided by HWAT heating cable. 70F Water moves through fixture. Hot water

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Hot Water Temperature Maintenance

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  1. Hot Water Temperature Maintenance

  2. HWAT Simply Keeps Hot Water Hot Heat lost through the insulation Water provided from Water Heater Air at 70F Pipe Insulation HWAT heating cable Heat provided by HWAT heating cable

  3. 70F Water moves through fixture. Hot water arrives at fixture. Heated water moves into pipes. Movement of Water in HWAT System Water heater is set to the desired maintain temperature Water in untraced section cools to ambient 70F HWAT-Y2 HWAT maintains the hot water by replacing the heat lost through the thermal insulation

  4. HWAT or Recirculation? Recirculation HWAT

  5. Typical Recirculation System Return Piping Balancing Valves Water Heater Recirculation Pump

  6. Typical HWAT System HWAT Heating Cable Water Heater

  7. HWAT History • System developed by Raychem in 1976 • Installed in more than 300,000 buildings • More than 2,500,000 feet of HWAT cable installed every year • More successful in Europe due to a greater focus on water and energy conservation which is only a recent trend in North America

  8. Advantages of HWAT • Easy to design • Low installed and operating costs • No flow-balancing issues • Compatible with low-flow fixtures • Easy to provide instant hot water to the point of use • Water conservation/Reduced time to tap

  9. Time to Tap – Water Conservation • Water in 10’ of ½” pipe = 0.1 gallons • Water in 40’ of ¾” pipe = 0.9 gallons • Water between fixture and recirculation loop = 1.0 gallons • If this fixture is used 5 times per day, the annual water waste would be 1,825 gallons per year!

  10. Disadvantages of HWAT • Perceived as new technology • May not be economical for certain building configurations • “Me-Too” competitive systems fail to perform as expected on an HWAT design

  11. Typical HWAT Building Why is this a good HWAT application?

  12. Typical HWAT Building • No horizontal return piping • No booster pumps or booster heaters • No balancing • Reduced supply piping

  13. Typical HWAT Building

  14. Ambient temperature Water moves through fixture. 115 HWAT maintained water arrives at fixture. Ambient temperature Slug Arrives at fixture. Uninsulated or unpowered section of HWAT HWAT replaces heat lost through the insulation and keeps the water at 115F. HWAT Performance Issues Sections without insulation or power Hot water heater continues to maintain the water at 115F. HWAT-G2 Heated water moves into pipes.

  15. Ambient temperature Water moves through fixture. 115 HWAT maintained water arrives at fixture. By-pass water Arrives at fixture. Cold water pulled into hot side through hot to cold connection HWAT replaces heat lost through the insulation and keeps the water at 115F. HWAT Performance Issues Cold to Hot water by-pass Cold to hot cross connection at fixture. Hot water heater continues to maintain the water at 115F. HWAT-G2 Heated water moves into pipes. Heated water mixes with by-pass water

  16. Mixing Valves Main Mixing Valves Main mixing valves are usually flow dependent. There should be a low flow and a high flow valve. If there’s only one, be sure it can function in a low/no flow situation.

  17. Typical Maintain Temperatures TemperatureApplication 105°F Hospitals, Nursing Homes 115°F Schools, Prisons 125°F Hotels, Apartments, Offices 140°F Kitchens, Laundries 125°F Residential

  18. HWAT Heating Cables • B2 - 105°F • G2 - 115°F • Y2 - 125°F • R2 - 140°F • Y2 or R2 • R2

  19. HWAT Selling Tools

  20. HotCAP • Hot Water Cost Analysis Program • Introduced in March, 2004 • Integrates HWAT-ECO • Updated material costs • Updated labor, electricity and fuel rates • Download from web

  21. HWAT-ECO Electronic Controller • Flexible temperature control • Insulation schedule • Energy savings • 9 pre-defined programs • Heat-up cycle • Alarm events • Water heater sensor • BMS interface • Master/slave function • Power correction factor

  22. Flexible Temperature Control Maintain Temp HWAT-Y2 105°F – 125°F* HWAT-R2 105°F – 140°F *Depending on the ambient temperature and voltage

  23. Fiberglass Insulation Schedule Copper pipe size (in) IPS insulation size (in) Insulation thickness (in) ½ ¾ ½ ¾ 1 1 1 1¼ 1 1¼ 1½ 1½ 1½ 1½ 1½ 2 2 2 2½ 2½ 2½ 3 3 3 • Insulation thickness matches pipe diameter for equal heat loss • Pipes 1¼” and smaller require oversized insulation to allow room for the heating cable • For pipes 3” and larger, 1/3 the thickness of insulation can be used with 2 runs of heating cable

  24. 15% ON Economy Temperature 55% ON Maintain Temperature ON ON OFF OFF 0’’ 400’’ 800’’ 1200’’ 1600’’ sec. 0’’ 400’’ 800’’ 1200’’ 1600’’ sec. HWAT-ECO Limits the Power Output • 400 seconds duty cycle • “On” time depends on the desired maintain temperature • 4 Modes: Off, Economy, Maintain & Heat-Up Cycle

  25. 9 Pre-defined Programs

  26. Programming Options • (48) ½ hour time blocks • Additional energy savings during “Off” and “Economy”

  27. Heat-Up Cycle and Cool Down • Raise the water temperature of stagnant pipes • Determine the amount of time required to reach a desired maintain temperature • Program the number of hours required • Allow time to cool down before hot water usage

  28. Alarm Events • Water heater temperature too low (next slide) • Water heater temperature too high (Y2 > 150°F, R2 > 185°F) • Loss of power – relay closes • Loss of power for more than 8 hours – clock reset • Internal controller temperature too high (> 185°F) • Master/slave error

  29. Water Heater Sensor (Optional) • Ensures maintain temp does not exceed the water heater temp • Controller stores highest water temperature measured over last 24 hours • Delta between supplied water temperature and the maintain temperature setpoint selected between 9°F and 27°F • Connected to single or master controller only • Sensor cable can be extended up to 328 feet

  30. BMS Interface • BMS input is 0-10 Vdc • BMS controls the temperature setpoint • If water heater sensor is installed, it overrules the BMS temperature setting if necessary • Loss of power alarms BMS

  31. Master/Slave Function • Control up to eight additional controllers • Total maximum length of cable between all controllers is 328 ft • RS-485 connection • Water heater sensor connects only to master controller • Controllers on the same phase (max 3 controllers) have a delayed On and Off

  32. Multiple Circuits with Single Controller • For controlling multiple circuits with the same parameters (i.e. voltage, maintain temp, ambient temp, economy temp), connect the heating cable output relay to an external contactor coil

  33. Power Correction Factor • Fine tuning of system • Increase or decrease the actual pipe maintain temperature • 0.6 – 1.4 percent of duty cycle

  34. Legionella ~ What is it? • Received its name from a 1976 break out at an American Legion Convention in Philadelphia • Bacteria common to warm water environments • Cause of Legionellosis – any illness caused by the bacteria (Legionnaires’ disease and Pontiac Fever most common) • Attacks the respiratory system

  35. Legionella ~ www.awt.org • Legionella 2003: an Update and Statement by the Association of Water Technologies (AWT) • “raising water temperature to 122˚F = a 90% kill of legionella in 2 hours, 140˚F = a 90% kill of legionella in 2 minutes and 158˚F = a 100% rapid kill of legionella.”

  36. Hot Water Temperature Maintenance • Questions?

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