Tankless water heaters

That's correct, this is the part of the propaganda that has my attention as high short period use followed by long periods of no use is pretty typical in my house:

The recovery time is a function of a number of different factors including the amount of hot water used, the temperature of the incoming water, the ambient air temperature, heating source, etc. The GeoSpring heat pump can recover 8 gallons per hour (at 68°F ambient air temp) while standard heating elements can recover about 22 gallons per hour. The difference is, the heat pump only draws about 550 watts of energy compared to 4,500 watts from standard heating elements. So if an average shower uses 16 gallons of hot water, the heat pump would run about 2 hours to reheat the water and use about 1.2 kilowatt hours of electricity. For the same 16 gallons of water, a standard electric water heater would take about 48 minutes at 4,500 watts of power which is about 3.2 kilowatt hours, almost three times the energy. Therefore, although the heat pump runs longer to reheat the water, it still ends up using approximately 62% less energy. Since most consumers use hot water in varying amounts followed by long periods of little or no usage, the heat pump has more than sufficient time to reheat the water and satisfy the consumer’s hot water demands. If more than the average amount of water is used, GeoSpring is uniquely designed to switch from heat pump to resistance heat and back again, to provide the same volume of hot water as a standard electric water heater. In the winter time when ambient air temperatures are likely to be lower, the heat pump will have to run longer to heat the water.

 

I was in the same boat as MasterMech a few years ago, oil fired furnace supplying DWH via a boilermate. As i started to burn more wood the $$ I was spending in oil for just hot water was getting stupid. I installed a Stiebel-Eltron accelera 300 heat pump hot water heater about two years ago and don't regret it for a moment. They are on the pricey side compared to the Geo, and others, but I think it is definitely a "get what you pay for" situation. The 80G tank helps a lot with the recovery time problem, and I have mine set for 160F and then have a mixer valve on the output so it is only supplying 110F water. I pay about $10-$15 a month more in electric since the install, not too bad for a house with two female teenagers, my wife and myself. Oh and the water heater is about four feet from the 30 in the basement, so it is living in a 90+F environment for a good part of the year, I'm sure the COP is maxed. Even in the summer, my basement stays at a constant 55F so still much better than resistance heating the water.

 

Noise is a little louder than a fridge for me, maybe not a big deal if it is in a closet. Clearance is a problem, the Stibel-eltron is a big unit. I need to check my anode rod, if I have to replace it, I will have to break/bend it to get the old one out and get a flexible/linked one as a replacement.

 

This subject is being revisited in our household as LP just jumped to over $5/gal closer to $6 from what I hear. Because of the shortage.

Now I'm thinking an electric tank type, I'm concerned about sizing the unit properly.

We have 2 teenagers and the wife all showering(long showers) in the morning and the current 50 gal LP tank type struggles.

I do know gas water heaters recover faster. I wonder if an 80 gal electric would suit my needs.

Thoughts?

 

Try the 80 gal but to give it extra punch run it at maximum temperature 16o f then run the hot water leaving the tank through an anti-scald valve and cut the temperature back to 120F. The higher temp gives you more BTUs stored.

 

we did this in a campground shower house
it works
We removed two 300 gallon heaters that ran at 105 degrees and I replaces them with two 80 gallon heaters and two thermostatic mixing valves and ran the heaters at 140-160 depending an how busy the campground was. There were 8 showers in the shower house and after the initial set up and a few days to get it adjusted there were no problems.
And it was cheaper to do all this than replace 3 elements, 3 temp sensors and 3 thermocouples each in the 2 old tanks

 

From what I've read, you don't want to install them in a confined space unless it had good airflow.. Since they work by removing the heat from the surrounding air and putting it in the water, with a closet installation, you could end up in a situation in which the air in the closet becomes too cold for the heat pump to function efficiently.

 

So in the summer time, the waste heat from your washer and dryer will be recycled to warm the new cool water in the heater.. Sounds like a mutually symbiotic relationship (a relic from biology class a hundred years ago!!).