Need hot water heater to recover faster.

[yeto]

Need hot water heater to recover faster.

I have a 40 gal hot water heater tank with (2) 4500 watt elements.

It is my understanding that the following is how a hot water heater works:

*only one element is on/active at the time
*the bottom element does not turn on until the top element has satisfied the set water temp at the top of the tank
*the intake and output water openings are at the bottom of the tank.

My question is if I set the upper element thermostat at a lower temperature than the bottom element this should cause the lower element to be on longer than the upper element therefore keeping the water in the bottom of the tank warmer which is also where the output tube opening is located. This should help to keep the water at a temperature that would be tolerable for someone to take a shower.

Is my thought process correct?

Thank you in advance for any help,
yeto

 

[yeto]

I now see that the output tube is shorter and near the top of the tank so would it benefit me to keep the top element a little hotter versus the bottom element?

 

[Sponsor]

 

[Mliu]

Cold water is introduced near the bottom of the tank via the dip tube. Hot water is drawn off near the top of the tank.

If you want to increase the amount of hot water available, you have two choices:

1. Install a water heater with a greater volume, or a higher heat input rating, or both.

2. Install a thermostatic mixing valve on your heater's hot water outlet. This will allow you to set your heater's thermostat higher which will effectively increase the volume of hot water available.

 

[Storm rider]

I had my water heater wired to run both elements simultaneously. It does improve recovery time. You do need to make sure the wiring can handle the electrical load.

 

[Mliu]

You would need at least a 50A circuit to run both elements simultaneously. That means upgrading your electrical circuit to a 50A dual-pole breaker and 8ga wire from your breaker panel to the heater. It would probably be cheaper to replace the heater with a larger one or install a thermostatic mixing valve.

 

[Reach4]

I now see that the output tube is shorter and near the top of the tank so would it benefit me to keep the top element a little hotter versus the bottom element?

I think that as the unit is sitting there, if the lower element does most of the work, the hot water will rise, and the cooler water will fall. That circulation seems desirable.

 

[Dana]

What are the hot water use cases/loads that are depleting the tank?

If it's bathtub filling there isn't any way around either bigger tank, higher storage temp, or more watts.

If it's showering, a drainwater heat exchanger downstream of the shower pre-heating the water going to both the tank and the cold side of the shower will increase the "apparent capacity" since it takes less hot water to serve up shower temperatures when mixing with tepid rather than truly cold water, and the water entering the tank is already at a higher temperature, needing less total heat to reach it's final temperature.

It has to be a decent sized version rated 40% heat recovery or higher @ 2.5 gpm to really see the difference, and they're not cheap. But from a raw economics point of view the tallest and fattest one that fits has a faster "payoff" in reduced electricity use, the higher performance of the bigger unit generating more savings value than the difference in proportional up-front cost. (If it saves you from buying a bigger tank a big chunk of it is paid off up front.)

The current best-in class units are EcoDrain's VT-1000 series, though the prior industry leader, Renewability's PowerPipe series aren't bad. There are others. In the US it's often cheaper to buy direct from the (mostly cold-water Canadian) manufacturers, though sometimes there are deals elsewhere.

While these are a great solution for extending showering capacity, they don't do a thing for tub fills, since the drain has to flow at the same time as the water is coming in.