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Waterman
12-01-2014, 06:28 PM
What would the advantages and disadvantages be of using a heat pump hot water heater in Eastern Washington, which typically has very hot dry summers (requiring almost continuous air conditioning from May through September) and, of late, moderate winters with lows in the 20's and highs in the 30's-40's from December through February?

Our household used 14,609 kwh of electricity for the past 12 months with monthly high of 1940 (July) and low of 908 (March). Our electricity costs \$0.062/kwh (a mix of nuclear and hydro).

bob++
12-01-2014, 06:37 PM
That's a lot of electricity - I just looked at my history and we used 3,700 kwh over the last four quarters. However that cost me £461 (\$725) as opposed to your \$900. Energy is a lot more expensive here so we try hard to use as little as possible.

Waterman
12-01-2014, 11:28 PM
Anyone out there that can answer the OP?

Snnipe 70E
12-02-2014, 01:07 AM
The advantage some heat recovery. But very expensive to control and use.

With a hot water temp in the 115 degree range the heat pump would have slightly higher head pressure meaning it would consume more energy.

If you are using a lot of hot water while the AC is running then it might be possible to balance system. But when all the water in the tank was heated to 120* and you were not using hot water you would either need a second condenser or dump some of the water to the drain.

Now for some math
Supply water 60 degrees
Max water temp 120 Degrees
Temperature delta 60 degrees.
To heat 1 pound of water from 60 to 120 degrees 60 BTUs.
1 Gallon = 8.33 pounds One gallon.
To heat one gallon of water 8.33X60= 499.8 BTU per gallon
Assume a 3 ton heat pump, or 36000 BTU/hour
Water required 36000/499.8= 72 gallons per hour. That is a lot of water.

Snnipe 70E
12-02-2014, 01:12 AM
What would the advantages and disadvantages be of using a heat pump hot water heater in Eastern Washington, which typically has very hot dry summers (requiring almost continuous air conditioning from May through September) and, of late, moderate winters with lows in the 20's and highs in the 30's-40's from December through February?

Our household used 14,609 kwh of electricity for the past 12 months with monthly high of 1940 (July) and low of 908 (March). Our electricity costs \$0.062/kwh (a mix of nuclear and hydro).

\$0.062/KWH REALLY.
Tier 1 rate is over \$0.11/ kwh. and as usage goes up the tier rates increase. Tier 5 is in the range of \$0.56/kwh. And I would bet a lot of your power usage would be in tier 5 if you were in California.

And that is the reason I had solar put on my house.

Waterman
12-02-2014, 04:07 AM
\$0.062/KWH REALLY.
Tier 1 rate is over \$0.11/ kwh. and as usage goes up the tier rates increase. Tier 5 is in the range of \$0.56/kwh. And I would bet a lot of your power usage would be in tier 5 if you were in California.

And that is the reason I had solar put on my house.

Love hydro power!:D We have a single flat rate for all residential usage.

Thanks for the info in your previous post and if you don't mind another quick question for clarification. What is the best course of action for making hot water in the non-AC months?

Snnipe 70E
12-02-2014, 11:21 AM
Tank less water heater. Original cost is more. Normally I would recommend gas but at \$0.06/kwh not sure gas would be cheaper.

Also a water source heat pump is going to be a lot more expensive than a standard heat pump.

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