Hot water heater

They are designed to boost the temperature of already hot water to 180 degrees or so for sanitizing purposes for commercial dishwashers.

The Hatco heaters come in many sizes, and are often for sale cheap when a resturant kitchen is remodeled.

If you are subject to inspection, you probably couldn't use them, on a technicality, but the one I'm using is pressure test certified to 150 psi, has 4 built-in thermostats, and a low water cutoff.

MUCH more advanced, and more safety features than a typical "hot water heater", and CHEAP.

The top thermostat normally is on until the water at the top is hot enough then the top thermostat switches the top element off and sends the power to the bottom element. When the bottom of the tank is hot the bottom thermostat shuts the bottom element off.

When water is drawn from the tank the bottom thermostat will kick on first as new cold water comes into the bottom. As more hot water is used the cold water level will come up to the top. When the top thermostat senses cold water it switches the bottom element off and turns the top element on. The top element stays on until there is enough hot water at the top of the tank to turn it off and then the bottom comes on again as before.

The reason the top and bottom elements are swapped is so that a large amount of power is not required all at one time to heat the whole tank.

Heating the top of the tank first makes for a quicker recovery as only the upper part of the tanks water is heated. Less volume of water so it heats faster. The hot and cold water stay separated because the hot water always stays on top of the cold water.

If only small amounts of hot water are used at a time then the top element will not usually come on as the top thermostat will keep power sent to the bottom element and the bottom thermostat just turns the bottom element on and off. If the whole tank cools down too far then the top element comes into play for the fast heat up.

Also be sure your safety relief valve is working properly and your expansion tank is not waterlogged.

Regards
Gary

You can usually tell by looking at the tank wattage. It may say, "upper 4500 watts", "lower 4500 watts", "total 4500 watts. That tells you there are two 4500 watt elements that are getting switched as I described. If the "total" is the sum of the two then they have only one thermostat and are not switched. If there is only one element it will show only "lower wattage" and will be the same as total.

Regards
Gary

Thanks

• Water Heater

• Tankless heater