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Weather parameters affect line ratings in decreasing order, as follows: wind is the most important factor [citation needed] ambient temperature [citation needed] solar radiation [citation needed] rain is generally not taken into account, as its physical load on the line is compensated by its cooling effect [citation needed]
[1] [2] It therefore has units of BTU/watt-hr. The higher the HSPF rating of a unit, the more energy efficient it is. An electrical resistance heater, which is not considered efficient, has an HSPF of 3.41. [3] Depending on the system, an HSPF ≥ 9 can be considered high efficiency and worthy of a US Energy Tax Credit. [4]
The energy factor metric only applies to residential water heaters, which are currently defined by fuel, type, and input capacity. [5] Generally, the EF number represents the thermal efficiency of the water heater as a percentage, since it is an average of the ratio of the theoretical heat required to raise the temperature of water drawn to the amount of energy actually consumed by the water ...
They typically use low power heating elements, about 1 kW to 1.5 kW, and can provide hot water long enough for hand washing, or, if plumbed into an existing hot water line, until hot water arrives from a remote high capacity water heater. They may be used when retrofitting a building with hot water plumbing is too costly or impractical.
The medication phentolamine can be given to try to decrease this risk. [4] It is unclear if dopamine is safe to use during pregnancy or breastfeeding. [4] At low doses dopamine mainly triggers dopamine receptors and β1-adrenergic receptors while at high doses it works via α-adrenergic receptors. [4]
Heat traps are valves or loops of pipe on the cold water inlet and hot water outlet of water heaters. The heat traps allow cold water to flow into the water heater tank, but prevent unwanted natural convection and heated water to flow out of the tank. [1] [2] Newer water heaters have built-in heat traps.
The BTU was originally defined so that the average specific heat capacity of water would be 1 BTU/lb⋅°F. [19] Note the value's similarity to that of the calorie - 4187 J/kg⋅°C ≈ 4184 J/kg⋅°C (~.07%) - as they are essentially measuring the same energy, using water as a basis reference, scaled to their systems' respective lbs and °F ...
It was first demonstrated, in 1978, by Conway et al. and possibly others that, while α-methyldopamine caused acute decreases in the levels of neuronal dopamine, in some areas of the brain in excess of 75%, levels returned to baseline within 12 hours, indicating that α-methyldopamine could not be responsible for the toxic effects observed. [4]