A heat pump, or hybrid, water heater is a more efficient way to generate hot water than the usual electric water heater. Instead of only relying on electric resistance heating elements a hybrid water heater also uses a heat pump to take heat from the surrounding air and transfer it to the water in the tank. They cost more upfront, cost less to operate, have rebates and tax credits available... are they worth it?
The most likely situation for a hybrid water heater is the replacement of an existing electric tank style water heater. That's what I'll consider in this post.
Assumptions
Household of 4 people
Hot water useage per day per person is about 17 gallons. 68 gallons per day total.
Incoming water temperature of 60 degrees, outgoing 120. 60 degree temp rise.
68 gal X 60 deg X 8.33btu/gal/deg = 33,986.4 btu needed per day to heat water... let's call it 35,000 for easier calculations
Water heater is in a conditioned basement
Heating season is 180 days.
Electric rates are $.16/kWh (including all delivery charges)
Natural gas is about $1.00/therm (including all delivery charges)
Oil is about $3.50/gallon
Propane is about $2.50/gallon
Cost of Traditional Electric Water Heater
Traditional water heaters use heating elements... electric resistance heating. All electric resistance heating is 100% efficient... all of the electricity that it consumes gets turned into heat. To deliver 35,000 btu we would need:
35,000 btu/3,412btu/kWh = 10.25 kWh
10.25 kWh x $.16/kWh = $1.64 per day
Cost of Hybrid Electric Water Heater (using only the heat pump)
I'm going to assume no usage of the backup heating elements in the hybrid water heater. The heat pump should deliver around 8 gallons per hour. Many customers can get by without ever using the heating elements.
A hybrid water heater moves or pumps heat from the air into the water in the tank. It is significantly more efficient than resistance heating. A typical heat pump water may be 375% efficient. For every 1 kWh of electricity that it consumes, it pumps/moves 3.75 kWh of heat.
So, this household needs 35,000 btu per day. To get that from the hybrid water heater will require:
35,000 btu/3,412but/kWh/3.75 = 2.73 kWh
2.73 kWh x $.16/kWh = $0.44 per day
What about the heat?
We can't ignore where that heat came from. A heat pump water heater is taking heat from your house in order to heat your water. During the heating season, you will need to replace that heat.
Below is the cost per day to replace 35,000 btu of heat from common varieties of hvac equipment at the above listed fuel prices:
Electric resistance heat(baseboard/miracle heaters, etc) - $1.64/day $295 annually
Oil furnace/boiler 85% AFUE - $1.03/day $185 annually
Propane boiler/furnace 80% - $1.19/ day $214 annually
Propane boiler/furnace 95% - $1.01/day $181 annually
Natural gas boiler/furnace 80% - $.44/day $79 annually
Natural gas boiler/furnace 95% - $.37/day $66 annually
Heat pump 8.0 HSPF2 - $.70/day $126 annually
I did all of that math behind the scenes to keep it reasonably short. All of those numbers depend on fuel pricing pretty dramatically.
Compared to an electric water heater a hybrid water heater in this scenario will save $1.20 per day, or $438 dollars per year. Accounting for re-heating the air, the actual savings would be:
Savings per year by heating source:
Electric: $143 per year
Oil: $253 per year
Propane 80%: $224 per year
Propane 95%: $257 per year
Natural Gas 80%: $359 per year
Natural Gas 95%: $372 per year
Heat Pump: $312 per year
Upfront cost
I'm going to use the pricing from our website. We charge $1050 total (as of now) to provide and install a traditional 50 gallon electric water heater.
We typically charge $2,990 total to provide and install a 50 gallon hybrid water heater. There is a 30% Federal Tax Credit and $400 PP&L rebate available, bringing the total cost down to around $1,700. Roughly a $700 premium to switch to a hybrid water heater.
In the worst case, it would take about 5 years to recoup your money. In the best case it would take a little less than 2 years. That is a good payback period even if we assume that the water heater will only last through its 10 year warranty period. Pretty, pretty good.
Lots of variables at play, but this one example should be pretty accurate for most households in our area. If you use less hot water, savings will be reduced. If you use more hot water, you may see additional savings. If incentives disappear, the payback periods will be significantly worse.
What else to consider
Hybrid water heaters generate condensate. If there is no nearby drain, a condensate pump may need to be installed which can increase cost.
Hybrid water heaters are bigger. If space is limited, it might make installation difficult.
Hybrid water heaters will cool and dehumidify the space they are in. Usually a benefit.
Hybrid water heaters run for extended periods of time and make some noise. Louder than a fridge, less than a dehumidifier (usually)
To operate effectively hybrid water heaters need a certain volume of air. If they are in a confined space they may not perform adequately.
Give us a call if your considering a new water heater and we can help you determine if a hybrid might be right for you.
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