Emergency Shower Instantaneous Heaters
Emergency Shower Instantaneous Heaters
(OP)
Based on the new 20gpm at 80 deg F requirement for emergency eyewashes, our mechanical guys have specified an instantaneous heater for each emergency eye wash. We have about 6 of them. The size of this heater is 108kw, 480 Volts. Are there any special allowances for these heaters or do I have to run a minimum 130 amp rated cable from a 150 amp breaker for each shower.






RE: Emergency Shower Instantaneous Heaters
Your electrical utility may also prohibit instantaneous electric heaters or limit the size to far less than what you have.
20 gallons per minute seems to be quite excessive. I have to wash my eyes every day because when my eyelashes shed they fall into my eyes. I only use 1 gallon per minute of cold water and I do not see a need to warm up the water. The wind this time of year tends to blow outdoor debris into peoples' eyes.
An much cheaper alternative would be to install 30 gallon 120 volt 1500 watt electric heaters. You can install a tempering valve to limit water temperature to 85 degrees Fahrenheit. You can also add extra insulation to reduce heat loss woithout voiding the U.L. listing but I would only do so after rewiring the heater using 180 degree Celsius nickel plated copper wire.
If you need more tank capacity a 4500 watt 240 volt heater can also be used as an 1125 watt 120 volt heater. I do not remember if the thermostat setting goes as low as 80 F but a tempering valve would provide a backup for the thermostat.
Most residential water heaters around here are natural gas, sometimes with an add-on electric heater that serves strictly as extra storage capacity.
Mike Cole, mc5w at earthlink dot net
RE: Emergency Shower Instantaneous Heaters
However I agree with electrical comments made by mc5w.
RE: Emergency Shower Instantaneous Heaters
Perhaps you could use conventional heaters with the thermostats set at 100 Fahrenheit to supply the restrooms and then use 85 Fahrenheit tempering valves to supply the eyewashes. The heaters could then be gas, oil, electric, or steam driven.
RE: Emergency Shower Instantaneous Heaters
RE: Emergency Shower Instantaneous Heaters
Just for my information can you cite a source for the 80°F requirement? I work at a plant with outside safety showers and the water is not heated, other than to provide freeze protection for the supply piping and the shower. Thanks.
Don
RE: Emergency Shower Instantaneous Heaters
RE: Emergency Shower Instantaneous Heaters
Something has to be wrong with the cost calculation. An instantaneous heater that directly mixes medium pressure steam with cole water is very economical for this application because the boiler and piping provide energy storage. Electric instantaneous have to be about the most expensive method I could imagine.
Mike Cole
RE: Emergency Shower Instantaneous Heaters
However, I agree with you. I inputted the cost numbers for electrical, but I think the mechanical engineer who did his cost analysis did something wrong.
RE: Emergency Shower Instantaneous Heaters