New DOE standards April 2015
Maintain your water heater
9 ways to save
New DOE standards April 2015 Maintain your water heater 9 ways to save |
 Take showers instead of bath. Energy
cost of 1 bath: assumes 60x30x14 insulated bathtub: Raise 20 gallons of
cold water from 60° to 120°
degrees
inside a water heater tank:
0.0024444 Kwh to raise 1 gallon of water 1°F = 2.9 Kwh at 100% efficiency Typical 50 gallon electric water heater 90% efficiency pre- April 2015= 3.22 Kwh per bath None of these costs factor maintenance, installation, purchase, repair, replacement of water heater... which can substantially add cost to final energy numbers. All costs and decisions are energy. |
Regular bath
uses 15 gallons hot water (20+ gal water total)
Princeton 60" x 30" x 14" insulated bathtub: Filled to overflow, the tub holds 42 gallons according to American Standard. Note: 60" x 30" x 14" is rough-in dimension of bathtub... and not interior space filled by water. Also note that many bathtubs are larger, such as 60" x 32' x 16" and these tubs hold proportionally more water. Body displaces water, so bathtub is not filled to overflow when taking bath. Moderately large person sitting in tub displaces about 20 gallons, so if tub holds 42 gallons, then amount of water used for bath is roughly 20+ gallons of water. Summary: 20 to fill tub + 20 for displacement = 40 gallons which rises almost to overflow when person sits in 60" x 30" x 14" bathtub. Water depth where person sits is 7-1/2" deep; measured next to hip of person sitting in tub at the point when water level starts to drain into overflow. Water depth at drain is minimum 1" deeper. Typical shower or bath is 104-110°F or less, but not more. Typical water heater thermostat is set at 120-125°F, giving a ratio of 85-90% hot and 10-15% cold if thermostat is not out of calibration, and single handle faucet cartridges are not leaking Read about crossover. For more accurate percentage, use cooking thermometer to measure your household temperature with full Hot water coming out of faucet, and then test again at bath or shower temperature. Repeat test after 4th person takes a shower. Repeat test in different seasons since cold water temperature varies. As the water inside tank cools, the greater the ration of hot-cold becomes. Each tank should have yellow label that shows first hour delivery: this is the amount of hot water that particular tank will provide before water turns cold. Buy: Cooking thermometer Bathtubs and shower stalls at Amazon Resources: Calculate water heater recovery Off peak water heater options 9 ways to save with water heater How to increase amount of hot water |
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| Prior to April 2015 energy standards: Set electric
water heater timer for 45-60 minutes for hot bath depending on
start-temperature of cold water inside tank. Electric water heater
rated 240 Volt 4500 watt will heat 21 gallons of water per hour based
on 60 degree rise in temperature/ 240 Volt 3500 watt will heat 16
gallons per hour. Gas water heater will typically heat 41 gallons per hour based on 60 degree rise in temperature. For example if water inside tank is 60 degrees F at start time, and you want 120 degree water, this would be a rise in temperature of 60 degrees. |
Details: Technique for estimating amount of total water in bath: After bath has been taken, dip the water out using a container to fill 1 gallon bucket or 5 gallon bucket. Tally the total buckets of water removed from tub. Temperature of incoming cold water is colder in winter and warmer in summer. Amount of cold water added to hot also varies winter-summer. Plus water heater energy-consumption varies winter-summer as more energy is needed to heat colder incoming water. To average the variables, we can estimate an 'average' year-round cold water temperature of 60°F in US, and colder in Canada, higher elevations etc. See groundwater temperature map If water is hotter than 120°-125°F, then less hot and more cold is used... but the energy and cost to heat water would be comparable when baths are same temperature, with slight energy savings per bath if thermostat is set lower. Also using mixing valve located at water heater can reduce energy consumption. |
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| A water heater holds 20/ 30 / 40 / 50 / 60 / 80 gallons of hot water depending on size of tank. Fully heated 40 gallon tank gives you 2 baths and a shower at one time. |  Use safety grab bar on bathtub Buy: Safety grab bar at Amazon Bathtub safety grab bars Shower rods Amazon |
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 Energy cost of 1 bath using 45 gallon hot water: (10 gallons cold) Cost of filling 70 gallon walk-in tub: Raise 45 gallons of cold water from 60° to 120° degrees inside a water heater tank: 0.0024444 Kwh to raise 1 gallon of water 1°F = 6.6 Kwh at 100% efficiency Typical 50 gallon electric water heater 90% efficiency pre- April 2015= 7.33 Kwh per bath Typical 50 gallon electric water heater 95% efficiency post April 2015= 6.94 Kwh per bath Typical gas water heater post April 2015 None of these costs factor maintenance, installation, purchase, repair, replacement of water heater... which can substantially add cost to final energy numbers. All costs and decisions are energy. |
Typical walk in tub uses up to 55 gallon There are different size walk-in bathtubs Example American Standard: The final fill height of water inside tub is 4" lower than deck of tub Seat height from floor 17" From seat to fill height is 12.5" (you sit in 12.5" water vrs 7.5" in regular tub). From tub floor to fill height is 29" (your leg area of body is covered by 29" water). Tubs that take longer to fill will consume proportionally more hot water because water is cooling as tub fills. However the surface area of regular bathtub is larger and exposed to more air than walk-in tub, so regular bathtub and might cool faster. My estimate is 80+% Hot to Cold ratio for walk-in tub. Wlak-in tub filled to overflow: 60 L x 37 W = 80 gallons...25 displacement for person = 55 gal final fill/ 45 gal Hot 60 L x 32 W = 70 gallons...25 displacement for person = 45 gal final fill/ 35 gal Hot 50 L x 30 W = 60 gallons...25 displacement for person = 35 gal final fill/ 28 gal Hot 48 L x 28 W = 45 gallons...25 displacement for person = 20 gal final fill/ 16 gal Hot Displacement for regular bathtub is 20 gallon for moderately large person. My extimate for displacement of walk-in tub is 25 gallons, or 5 gallons more than regular tub, because about 5" more of person's torso sits inside the water. You might need larger water heater, or 2 water heaters to supply enough hot water for walk-in tub Resources: New DOE standards April 2015 Calculate first hour delivery 9 ways to save Two water heaters |
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| Typical faucet delivers 2
gallons per minute. Test your water flow using 1 gallon or 5 gallon bucket, and stop watch on cell phone. |
In
regular tub, person can lean back at 26 degree angle -or- displace
more water by sliding torso deeper into water by lifting knees, and the
water level can rise above overflow. Walk-in tub the person can lean back at 26 degree angle -or- displace more water by leaning forward to immerse torso into water which can raise water level above overflow. Bubbler will cool water more quickly. Energy cost of running 1 Hp blower motor, and heat loss when using blower are not calculated, nor energy cost of any blower heater. Floor loading 725 lbs for smallest size to 877 lbs for largest size. Subfloor reinforcement recommended and not included in energy calculations. All costs are energy. |
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Shower
uses 6 - 8 gallons of hot water (10 gal water total)
To check amount of hot water used during a shower taken in bathtub, stop the drain and then take shower. After shower, measure the amount of water in tub, or roughly compare with the 20 gallon depth of water needed to take bath. To check hot water usage when shower is taken in a shower stall, put stopper over drain, seal with duct tape. Tape will hold stopper in place when pouring water into shower. Add water to shower. Use measured amount of water to fill bottom of shower. Do not flood water over the top. This will give a baseline amount of water. Then remove taped stopper. Use stopper again during regular shower. No need to tape the stopper when taking a shower since water will be dropping from above and will not move the stopper. When water reaches same point as the measured test, remove stopper and release water. Estimate if you are half-way through shower, and then estimate how much water the total shower would use. If temperature of water heater is set at 120 degrees, you can probably estimate 75% how and 25% cold. But more accurate way is to look at position of shower valve and see what percentage of cold water is being added to hot to temper the shower. Set water heater timer for 20-30 minutes for hot shower Resource: Family chart for setting timer Buy: Shower stalls at Amazon Home energy savings books at Amazon |
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| Formula for heating water inside
tank: Gallon Per Hour (Electric) = (KW x 3413) divided by (temp. rise x 8.25) or (KW x 414) divided by (temp rise.) Let's say you have 5500 watt elements. let's say incoming water temperature is 65°F and you want to heat tank to 105°, or 40° rise in temperature. 5500 watt or 5.5Kw elements x 3413 = 18771.5 40 degree temperature rise x 8.25 = 330 So in this specific situation, the element would heat 56.88 gallons per hour If you have 4500 watt elements and incoming water temperature is 55°, and you want to heat to 120°, then the temperature rise is 65° 4.5 KW x 3413 = 15358.5 65 degree temperature rise x 8.25 = 536 So one element would heat 28 gallons per hour This number is for EACH element, but does NOT consider heat loss from tank, room temperature, or thickness of insulation etc. Remember, with residential simultaneous tank, only ONE element is ON at one time. Upper element is ON, or lower element is ON, or BOTH elements are off. At no time are both elements on. |
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Clean
shower and doors with White
vinegar or CLR calcium and rust remover Buy: CLR shower cleaner Amazon Shower stalls at Amazon |
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Pour
bath water into rain barrel Use 5 gallon bucket to empty tub and pour into rain barrel Cut off top of 55 gallon drum and leave lip around edge for screen Cover top with hardware cloth and then window screen to keep out mosquitoes Add 2 pints Hydrogen peroxide occasionally to disinfect/ deodorize Buy: Order 1" bulkhead fitting, and drill 2" hole, uses 1" IP Bulkhead fitting at Amazon 55 gallon barrel Amazon Rain barrels Amazon |
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What
is water worth? If you had to carry each gallon from the river up to your 2nd floor bathtub, when would you start to conserve? Average home uses 1/2 acre-foot water per year. 135,000 gallons = 27,000 5-gallon buckets Read about growth and electric consumption |
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Set rain barrel
higher than 550 gallon tank Use bulkhead fitting to tap into rain barrel Use 1-1/4" PVC water line to connect rain barrel to tank Tank must be on flat concrete pad. Cover top of rain barrel with hardware cloth to protect animals from falling into tank. Use gutter to channel water to rain barrel. Pour bath water into 55 gallon barrel using 5-gallon buckets Low pressure water timer |
 For large bathtub, use 80 gallon first hour |
What size
water heater? Size chart shows First Hour delivery rating First hour is capacity of tank at peak-usage times. For example at night when everybody is taking a shower or bath Increase amount of hot water with changes and maintenance How to adjust temperature How to increase amount of hot water How to maintain water heater Homes with garden tub, whirlpool bath, or oversized tub = first hour 80 gallon |
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Old
sizing chart Post 2015 heaters require high tech for sizes over 50 gallon Take showers instead of bath. Save 10 gallons hot water each time. To achieve same hot water consumption as previous heater withut buying more expensive heater install 2 water heaters, cut consumption, maintain heater, turn up thermostat temperature Two water heaters 9 ways to save with water heater Maintain water heater How to adjust themostat Ways to increase hot water Calculate first hour delivery |
 How to install gas water heater |
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How to adjust temperature on water heaters |
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What size
water heater for oversize bathtub? Large bathtub / whirlpool tub Recommend 80 gallon first hour delivery Electric: minimum 60-to-80 gallon size just for that one tub Gas: minimum 50 gallon size just for that one tub Electric heat pump water heaters generally cannot produce enough hot water. Tankless promise unlimited hot water, but temperature of water is 120 F and water in tub may be cool by time tub fills. Cost of maintenance and repairs never pay back. All costs are energy. Troubleshoot Rheem tankless |
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Fix
drips and leaks When hot side faucet drips, then cold water is entering tank at same rate water is dripping out of faucet. Water-loss-with-one-drip Government drip calculator Save 1/2 gallon per day: Save $1-8 per month. 9-ways to save with water heater |
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No water = No
Electricity Much of today's electricity is made using steam turbine. Coal-fired power plants use steam to rotate turbine. Steam comes from boiling water. Oil and gas fired power plants can also use steam to rotate turbine. Hydroelectric dams use water to rotate turbine Solar and wind powered electricity use fewer water resources. What is 3-phase electricity |
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Resource: Compare box timers DPDT timers Intermatic Control water heater w/ Z-wave |
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Resource: Intermatic control centers: and parts Digital control centers and parts Tork control centers and parts Subpanels All control centers and parts Enclosures |
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Resource: Programmable timers Countdown timers Off delay timers On delay timers Timer modules Din rail Twin & one-shot Woods Intermatic Tork |
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Recirculation systems |
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