Which is More Energy Efficient? Gas vs. Electric Water Heaters

not sure but i wonder which one is cheaper 

Surely Google would know!

i just went back and reread my dumb comment.  lol

Flow activated, electric, instant water heater. 

Posted by: STTsailor

Flow activated, electric, instant water heater. 

We had one of those that could handle a small house. It was a complete hog. It used TWO 50A Dual breakers. Yes, 100 AMPs / 220V. I imagine the smaller point of use ones are better. 

Tankless water heaters heat on demand.  They must heat the water from cold to 120F or whatever you set it at instantly before the water exits the heater.  Your microwave doesn't even heat that fast.  Takes a lot of power to do that, hence the 100A service.  The tankless is the hare.  The old tank heater is the tortoise.  Both may use the same energy to heat the same amount of water but over a different time period.  The big different other than size is the tank water heater must keep the entire tank hot indefinitely.

Posted by: MichelleAna

Which is More Energy Efficient? Gas vs. Electric Water Heaters

The standard electric tank heater is 100% efficient as all the energy goes into the water until you consider the heat lost while water sits in the tank.  The standard gas tank heater is less than 100% efficient as some of the heat from the flame goes up the flue.  Both will lose the same amount of heat  while water sits in the tank for the same tank size and amount of insulation. 

Typically gas is cheaper than electric to operate even with gas being less efficient.

We have an electric 20 gallon tank that we have on a switch.  I turn it on in the morning for about 20 minutes and it's enough to last my family of 4 all day.  The water is 'hot' at the end of the day but it's warm enough to take a shower.  We save a lot of money/electric by not having it run all day/night long.  We looked into a tankless awhile back but just didn't make sense for us to do the breaker upgrade and have that major draw on power every time we needed some hot water.  

Yes, we have a 20 gallon under the counter type electric and we intend to put a timer switch on it. Switch on, wait 10 minutes, take a shower. It's not like we will want steaming hot showers like we take in NY anyway. 

Posted by: Scubadoo

Tankless water heaters heat on demand.  They must heat the water from cold to 120F or whatever you set it at instantly before the water exits the heater.  Your microwave doesn't even heat that fast.  Takes a lot of power to do that, hence the 100A service.  The tankless is the hare.  The old tank heater is the tortoise.  Both may use the same energy to heat the same amount of water but over a different time period.  The big different other than size is the tank water heater must keep the entire tank hot indefinitely.

Yes I know they draw 0 Amps while water is not flowing, but our 4 breaker 100A / 220V "whole house" model actually made our lights pulse dimmer & brighter rapidly as it's coils cycled on & off during use.  I imagine if you buy smaller 110V "point of use" models for an individual shower or kitchen sink they won't draw nearly as much power and will provide instant hot water to the tap. Of course, you'd need a dedicated 110V, 15 or 20A, GFI protected circuit nearby. 

I use a small electric tankless water heater I got at Home Depot for under $300. Works fine off the old 30amp breaker I used for a standard 40 gallon electric water heater.

Thing to remember here is your not using much hot water. Water sitting in your cistern really isn’t “cold” maybe cool at best.