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Calculate standby loss for
electric water heater E-mail: geno03245w@gmail.com |
Because there are so many variables
when considering water heater efficency and costs, a meter is only
reliable measure... and then because incoming water temperaturtes and
ambient air temperatures both affect standby costs, and both vary with
seasonal and regional differences,the meter readings must be tracked
over a full year ... or extrapolated from samples taken with each
season. Resource for improving water heater loss: 9 ways to save with a heater |
Standby loss is the amount of eneegy consumed by a tank-type water heater to maintain temperature of water when no Hot is being drawn from tank. Standby includes the loss of energy when burner or element are not ON. Just like a cup of coffee gets cold the longer it sits, the same with tank-type water heaters. Thermal efficiency. TE is the ratio between energy contained in delivered water and energy consumed to heat it. It’s derived by measuring the flow of water the heater can heat to a 70°F temperature rise with the burner at full fire, calculating the amount of energy that was added to the water, and dividing it by the energy used to heat it. The result is expressed as a percentage and does not account for standby loss. Condensing storage models are between 90 and 96 per cent thermally efficient. Standby efficiency is the water heater’s ability to contain heat in the tank. A minimum of heat loss per hour is desired. Basic formula: temperature change per hour = [BTU/H loss per square foot of tank surface] divided by [“R” value], shows that more insulation is better. EF or energy factor is an indicator (approximations) of the combined thermal efficiency and standby efficiency of a water heater. The higher the energy factor, the more efficient the water heater will be. Energy factor test is intended to rate efficiency of heater over the course of a day. The test assumes that the homeowner uses 64.3 gallons of hot water at a temperature rise of 77°F and that the water is consumed in six equal draws. The EF is derived by calculating the amount of thermal energy added to the water and dividing it by the energy needed to heat it. Also, if a fuel-burning water heater uses electricity (to power a controller or fan), the electrical consumption is measured, converted to BTUs and added to amount. Test is performed over 24-hour period, so standby loss is automatically accounted for. EF is used to compute the projected annual operating cost. |
1st source: ''If a heater costs $200 a year to operate according to the Energy Guide And it has an Energy Factor of .93 That implies 7% of the $200 (or $14) was lost. A more accurate and difficult way would be to meter the energy used by the heater over a 24 or 48 hour period with no hot water usage.'' |
Another source: ''Assume indoor tank with 72 degree ambient room temp, no flows in or out .93 Energy factor = 236K WH per year @ $0.10 = $24 per year .94 Energy factor = 189 KWH per year @ $0.10 = $19 per year'' |
Enery factor for common size tank
heaters. Energy factor is not efficiency. Energy factor is a formula for calculating efficiency, where a small percentage of tank volume is subtracted from EF. Standby loss is directly correlated with efficiency of heater, and efficency is directly correlated with amount of surface space and thickness of insulation. Manufacturers added more insulation to meet the April 2015 energy standard. Result is higher efficiency, larger tanks, more space needed to install, store, more cardboard for packaging and shipping ... and generally more cost than the savings generated by the increased efficiency. Note that generally larger tanks with more surface space have lower efficiency |
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Install meter on Gas water heater Record exact usage of BTU of gas appliances. 3/4" pipe thread connections. Use yellow teflon tape or gas-approved sealant. No excess tape or sealant inside pipe. Use black pipe or yellow flex line. Keep pipes clean during assembly. Install in vertical position with inlets pointing up as illustrated. 12.2" Tall x 8.5" Wide x 11.2" Deep No power source required Digital readout in cubic feet Remote Readable option (pulse output) using EKM-25IDS Buy: EKM gas meter Approved gas pipe sealant Yellow gas line Resources Gas meter spec sheet with optional remote monitor specs |
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Meter on water heater The Kwh meter is din rail mounted inside enclosure. Records billable power usage in Kwh. Multiply by rate you pay per Kwh to get monthly/ yearly cost of running electric water heater. Buy Bomain power meter Ketotek power meter 240 volt pass through Kwh meter 2T2502GA beige plastic enclosure 2T2500GA grey plastic enclosure din rails Resource: Enclosures Figure volts amp watts for water heater |
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