Free Republic
Browse · Search
General/Chat
Topics · Post Article

Skip to comments.

Improving hot water heating efficiency ... with cold water
Gizmag ^ | April 4, 2013 | Darren Quick

Posted on 04/05/2013 10:30:55 AM PDT by Freeport

Apart from heating and cooling the house, water heating is one of the biggest energy drains in the average home. But what if you could literally use cold water to create hot water? That’s just what San Diego inventor Hal Slater claims to have done with the creation of a water heater system that promises to improve water heating efficiency by as much as 50 to 100 percent.

The system works on the basis that cold water supplied to households in temperate climates averages around 70° F (21° C), which the researchers say is 15° to 20° F (8° to 11° C) warmer than it needs to be. By using a small water-to-water heat pump, the system extracts this excess heat from water in a 20-gallon (76 liter) cold water tank and delivers it to a typical 50-gallon (189-liter) water heater.

With funding from a grant from the California Energy Commission, Slater teamed up with a research team from the University of California, San Diego (UCSD), led by Dr. Jan Kleissl of the Mechanical and Aerospace Engineering Department, to test the system. To test real-world performance and determine the effects of different incoming cold water temperatures, they installed three prototype systems in homes in coastal, mountain and desert climates. They also monitored each system for a year to compare performance over different seasons.

(Excerpt) Read more at gizmag.com ...


TOPICS: Business/Economy; Society
KEYWORDS: heating; heatingandcooling; heatingandcoolong; heatpump; hotwater; waterheater
Navigation: use the links below to view more comments.
first previous 1-2021-4041 next last
To: Freeport

Heat pump type water heaters fail miserably in real life use; it might be a function of the number of duty cycles but I think they’re just too complex for something that needs to be 100% reliable ,It shouldn’t matter if it’s a heat pump pulling heat from air like your A/C or it’s a water to water system as this guy wants to build.

I’ve had 2 tankless electric heaters fail over a 5 year period BIG 3*60 AMP ones ,, with 3 chambers theres a lot of possible failure points and don’t try to reason with the wife when she has to take a cold shower...

What works in any climate is/are GAS tankless water heaters ... my Aunts home in Brooklyn still has their original tankless water heater from 1926 ,, just updated to eliminate the pilot light... amazingly simple , just a copper coil about 6” in diameter and 2 feet in length(THICK COPPER) inside a tube that narrows to become the chimney/exhaust.

The 1970’s/1980’s solution was to capture waste heat from the A/C pressure/liquid side with a sealed heat exchanger box... WORKED GREAT and improved A/C efficiency also... don’t know why it has fallen out of favor.

Best solution now in warm climates is passive solar heat with electric backup.


21 posted on 04/05/2013 11:30:21 AM PDT by Neidermeyer (I used to be disgusted , now I try to be amused.)
[ Post Reply | Private Reply | To 1 | View Replies]

To: Freeport

I would think that the parts of the world which have 70 degree ground water would also have plenty of sunlight and ambient air temps.

A solar hot water heater, or even just heating the pipes to ambient air temp would probably be a far better primary solution in these places.

Perhaps the groundwater heat pump could be used in the “cold” season in those areas to some effect...


22 posted on 04/05/2013 11:31:18 AM PDT by chrisser (Senseless legislation does nothing to solve senseless violence.)
[ Post Reply | Private Reply | To 1 | View Replies]

To: redhead

Question! What kind of heat pumps are being used, air to air, or ground to air? Also do you have any data/idea on relative temperatures? We have an air to air heat pump for a home at 3600 ft. in northern CA and it holds house ,1500 sq. ft, temp at 69-70F down to about 32-35 degrees.


23 posted on 04/05/2013 11:32:27 AM PDT by noinfringers2
[ Post Reply | Private Reply | To 2 | View Replies]

To: noinfringers2

Don’t ask ME! I live in Alaska! But when I lived in St. George, all the homes had heat pumps on the roofs. Very common. Look them up online and you should be able to find out everything you are interested in.


24 posted on 04/05/2013 11:36:49 AM PDT by redhead (NO GROUND TO THE DEVIL! Use Weaponized Prayer)
[ Post Reply | Private Reply | To 23 | View Replies]

To: WinMod70
I had a similar idea years ago -- but the design I came up with was ridiculously (in retrospect) overcomplicated. More recently, I discovered that the devices are now available for purchase. The design is somewhat like what you envisioned -- except that a normal drain pipe is wrapped with copper tubing for the intake water. That avoids the clogging problem.


25 posted on 04/05/2013 11:50:03 AM PDT by USFRIENDINVICTORIA
[ Post Reply | Private Reply | To 13 | View Replies]

To: WinMod70

The way the one I referred to was described was that there was a central pipe (copper) 3” or 4” in diameter, through which the waste water flowed - spliced in to the existing drain line from the bathtub.

It, then, had another copper pipe - normal supply pipe, 1/2” or so, wound tightly on a mandrel so it was slightly deformed to increase the surface-area contact. The cold water flowed through that one on its way to the heater, and warmed significantly.

Worked well for showers, when the supply came in as the same time as the outflow; not so good for baths.


26 posted on 04/05/2013 11:53:37 AM PDT by DuncanWaring (The Lord uses the good ones; the bad ones use the Lord.)
[ Post Reply | Private Reply | To 13 | View Replies]

To: WinMod70

There ya go.

Effectively 7kw in free power while the shower is running.


27 posted on 04/05/2013 11:57:41 AM PDT by DuncanWaring (The Lord uses the good ones; the bad ones use the Lord.)
[ Post Reply | Private Reply | To 25 | View Replies]

To: Last Dakotan

“No big deal.”

energy loss in both conversions, the guy is BS!


28 posted on 04/05/2013 12:02:42 PM PDT by dalereed
[ Post Reply | Private Reply | To 4 | View Replies]

To: Freeport

Improving hot water heating efficiency ... with cold water

Why is he heating hot water?


29 posted on 04/05/2013 12:09:44 PM PDT by csmusaret (America is more divided today , not because of the problems we face but because of Obama's solutions)
[ Post Reply | Private Reply | To 1 | View Replies]

To: Moonman62

I’m still waiting on that E-cat water heater.


30 posted on 04/05/2013 12:15:35 PM PDT by citizen (We get the government we choose. America either voted for Obama or handed it to him by not voting.)
[ Post Reply | Private Reply | To 15 | View Replies]

To: KarlInOhio
But if the now colder cold water must be mixed with more hot water to be usable for showering or clothes washing (the two biggest users of hot water) are you really gaining anything?

First thing I thought of. I was scrolling down looking to see if anyone brought it up. They might get some gains by capturing some of that ambient heat in the pipe water, but I highly doubt their efficacy numbers. A good amount of that ambient heat will be lost by warming the now too cold tap water. The dish washing machine is about the only thing that uses the fully heated hot water.

31 posted on 04/05/2013 12:20:03 PM PDT by douginthearmy
[ Post Reply | Private Reply | To 14 | View Replies]

To: redhead

I’m in Florida. I heat my house with a heat pump, as do 90% of Floridians. However, the efficiency of a heat pump is quite poor once the outside temps dip below about 25F.

I do like using the outside coils of the AC to heat water. But I think you would get a surplus of hot water.


32 posted on 04/05/2013 12:34:11 PM PDT by SampleMan (Feral Humans are the refuse of socialism.)
[ Post Reply | Private Reply | To 2 | View Replies]

To: Freeport

To preheat water, solar energy is the cheapest.

Best for non-freezing climbs, the pipes can be laid right below the roof. You’ll get 150F water.


33 posted on 04/05/2013 12:40:05 PM PDT by SampleMan (Feral Humans are the refuse of socialism.)
[ Post Reply | Private Reply | To 1 | View Replies]

To: FReepers
Look! It's Spam!!!


Click The Spam And Donate

Donate Anyway

34 posted on 04/05/2013 12:55:03 PM PDT by DJ MacWoW (My faith and politics cannot be separated)
[ Post Reply | Private Reply | To 1 | View Replies]

To: JRandomFreeper

just not around anyone’s necks, right. No mandela necklaces?


35 posted on 04/05/2013 12:57:08 PM PDT by Secret Agent Man (I can neither confirm or deny that; even if I could, I couldn't - it's classified.)
[ Post Reply | Private Reply | To 3 | View Replies]

To: Freeport
funding from a grant

Damn near any proposal containing the word "green" can get funding these days.

36 posted on 04/05/2013 1:24:20 PM PDT by MosesKnows
[ Post Reply | Private Reply | To 1 | View Replies]

To: DaxtonBrown
I can make money with just a cheap computer and an old color printer.

Ummm... did you say your name was Ben Bernanke>

37 posted on 04/05/2013 1:55:50 PM PDT by NoCmpromiz (John 14:6 is a non-pluralistic comment.)
[ Post Reply | Private Reply | To 20 | View Replies]

To: Jack of all Trades

Works the same way as a home heat pump, air conditioner or even the refrigerator. Compress a working fluid, radiate the created heat then take a pressure drop. It creates a cold point below ambient.


38 posted on 04/05/2013 1:58:16 PM PDT by thackney (life is fragile, handle with prayer)
[ Post Reply | Private Reply | To 6 | View Replies]

To: Neidermeyer

>> “Best solution now in warm climates is passive solar heat with electric backup.” <<

.
Warm climates, with soft water only!

Put it in a cold climate with hard water and the freeze valves will fail within a year. Warm climate with hard water, about two years.


39 posted on 04/05/2013 2:21:19 PM PDT by editor-surveyor (Freepers: Not as smart as I'd hoped they'd be)
[ Post Reply | Private Reply | To 21 | View Replies]

To: RegulatorCountry

For relatively low delta T, pumping heat requires relatively little energy. Going pumping from 70 degrees to 110 degrees wouldn’t require a huge amount of energy.

I haven’t done the math but going from 70 to 140 degrees might take twice as much energy. The lower the temperature delta, the closer you come to zero energy cost to pump heat. Now that I am rambling, the math is actually pretty cool as you approach 0 delta the amount of heat pumped per unit of energy expended approaches infinity. Ground source heat pumps are very efficient because they make delta T much smaller, both in the summer and the winter.


40 posted on 04/05/2013 2:42:55 PM PDT by dangerdoc (see post #6)
[ Post Reply | Private Reply | To 11 | View Replies]


Navigation: use the links below to view more comments.
first previous 1-2021-4041 next last

Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.

Free Republic
Browse · Search
General/Chat
Topics · Post Article

FreeRepublic, LLC, PO BOX 9771, FRESNO, CA 93794
FreeRepublic.com is powered by software copyright 2000-2008 John Robinson