Hot Water Temperature Maintenance

HWAT Simply Keeps Hot Water Hot Heat lost through the insulation Water provided from Water Heater Air at 70F Pipe It is important to remind ourselves when talking about the HWAT-Plus system that HWAT-Plus is a temperature maintenance system, not a hot water heating system. It is common to lose sight of the fact that HWAT-Plus is designed to maintain water at an elevated temperature, not heat it up to that temperature. The system starts with hot water entering the traced pipe. Let’s look at 115F water which sits in an insulated pipe in 75F air. If this system is allowed to move toward equilibrium the water temperature would move toward 75F. There are two practical ways to keep this from happening. The first, less efficient, way to do it is to push the 115F water out and replace it with more 115F water. Unfortunately no matter how fast you push and how much insulation you put on the pipe, you will still lose heat to the 75F air. Second way? You find a way to deliver just as much heat to the water as the water losses to the air. This way you stay at 115F you didn’t have to waste energy reheating recirculated water. Insulation HWAT heating cable Heat provided by HWAT heating cable

Movement of Water in HWAT System 70F Water moves through fixture. Hot water arrives at fixture. Water heater is set to the desired maintain temperature Water in untraced section cools to ambient 70F Heated water moves into pipes. HWAT-Y2 If no more water is removed from the system, the water will return to it’s equilibrium state again. The hot water heater will maintain its water at 120F. HWAT will maintain it’s water at 120F. And the water left in the unmaintained pipe will cool towards 75F. HWAT maintains the hot water by replacing the heat lost through the thermal insulation

HWAT or Recirculation? HWAT Recirculation The HWAT system consists of a sef-regulating heating cable attached directly to the supply pipe. The cable produces enough heat to maintain the water temperature directly in the supply pipe. The cable can be placed only on the mains, or it can be run to each fixture to eliminate waiting time and water waste. HWAT Recirculation

Typical Recirculation System Return Piping Balancing Valves Water Heater Recirculation Pump

Typical HWAT System HWAT Heating Cable Water Heater The HWAT system consists of a sef-regulating heating cable attached directly to the supply pipe. The cable produces enough heat to maintain the water temperature directly in the supply pipe. The cable can be placed only on the mains, or it can be run to each fixture to eliminate waiting time and water waste. Water Heater

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

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

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!

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 Despite the fact that the HWAT system is installed in over 250,000 buildings, many engineers, contractors, and owners are unaware of the system.

Typical HWAT Building Why is this a good HWAT application?

Typical HWAT Building No horizontal return piping No booster pumps or booster heaters No balancing Reduced supply piping Eliminating horizontal pipe and booster heaters greatly simplifies the high rise plumbing system.

Typical HWAT Building

HWAT Performance Issues Sections without insulation or power Ambient temperature Slug Arrives at fixture. Ambient temperature Water moves through fixture. 115 HWAT maintained water arrives at fixture. Hot water heater continues to maintain the water at 115F. HWAT replaces heat lost through the insulation and keeps the water at 115F. Uninsulated or unpowered section of HWAT HWAT-G2 Heated water moves into pipes. If no more water is removed from the system, the water will return to it’s equilibrium state again. The hot water heater will maintain its water at 115F. The HWAT-Plus will maintain it’s water at 115F. And the water left in the unmaintained pipe will cool towards 75F.

HWAT Performance Issues Cold to Hot water by-pass Cold to hot cross connection at fixture. 115 HWAT maintained water arrives at fixture. By-pass water Arrives at fixture. Ambient temperature Water moves through fixture. Cold water pulled into hot side through hot to cold connection Hot water heater continues to maintain the water at 115F. HWAT replaces heat lost through the insulation and keeps the water at 115F. HWAT-G2 Heated water moves into pipes. If no more water is removed from the system, the water will return to it’s equilibrium state again. The hot water heater will maintain its water at 115F. The HWAT-Plus will maintain it’s water at 115F. And the water left in the unmaintained pipe will cool towards 75F. Heated water mixes with by-pass water

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.

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

HWAT Heating Cables B2 - 105°F Y2 or R2 G2 - 115°F Y2 - 125°F R2 R2 - 140°F Y2 or R2 R2 There are two major misconception that people have about IceStop. IceStop does not keep snow from sliding off roofs. IceStop is not intended to melt all the snow off roofs. IceStop is designed to provide drainage paths to remove melted snow from roof and subsequently eliminate ice dams. In many cases the best design uses both heating cable and snow fences. The snow fence keeps the large sheets of snow from sliding of the roof while the heating cable prevents ice dams and icicles. The photo above shows how heating cable can be doing its job even though it is covered with snow.

HWAT Selling Tools

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

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

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

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

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

9 Pre-defined Programs

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

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

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

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

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

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

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

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

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 There are two major misconception that people have about IceStop. IceStop does not keep snow from sliding off roofs. IceStop is not intended to melt all the snow off roofs. IceStop is designed to provide drainage paths to remove melted snow from roof and subsequently eliminate ice dams. In many cases the best design uses both heating cable and snow fences. The snow fence keeps the large sheets of snow from sliding of the roof while the heating cable prevents ice dams and icicles. The photo above shows how heating cable can be doing its job even though it is covered with snow.

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.” There are two major misconception that people have about IceStop. IceStop does not keep snow from sliding off roofs. IceStop is not intended to melt all the snow off roofs. IceStop is designed to provide drainage paths to remove melted snow from roof and subsequently eliminate ice dams. In many cases the best design uses both heating cable and snow fences. The snow fence keeps the large sheets of snow from sliding of the roof while the heating cable prevents ice dams and icicles. The photo above shows how heating cable can be doing its job even though it is covered with snow.

Hot Water Temperature Maintenance Questions?