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  1. #1
    Join Date
    Nov 2004
    Location
    Atlanta, Ga. burbs
    Posts
    281

    Question

    Background: Many moons ago I had the pleasure of working with two licensed HVAC/electrical guys who maintained the plant. I owe them a huge debt of gratitude for teaching me, at a laymans level, how mechanical things work.

    This is just a curiousity question.

    I remember one of them telling me about someway he heated his water in the summer from his HVAC unit.

    Had not thought about this for many years. But how did he do it? Did this technology catch on? It is something you guys do in the field? He related it to "free hot water" since he had to cool his house anyway.

    Thanks-
    Wes

  2. #2
    Join Date
    Apr 2004
    Posts
    7,680
    It did for a while and in some cases it still is used. The problem you run into is that it is another variable in the exact charging of modern day high efficiency equipment. Granted it is free heat, but since condensers are more critical in capacities and efficiencies, it can cause some real headaches and equipment problems. Geothermal systems are more likely to use it now since their "Condenser" is more likly to operate with some consistant temperatures.

  3. #3
    Join Date
    Apr 2003
    Location
    Eugene, Oregon
    Posts
    1,209
    The de-superheater in a geo thermal system accomplishes this task. It is widely used and a big plus for energy conservation. You can check out the climatemaster website for more information. Michael
    Proud supporter of Springfield Millers and Oregon Ducks.

  4. #4
    Join Date
    Jul 2000
    Location
    Dallas,Texas
    Posts
    4,922
    A chain of cafeteria resterants used hot gas from the refrigeration equipment to preheat the hot water before it hit the water heaters. It was engineered and stamped.....
    and a pain. A few years down the road and all the extra piping started vibrating......They replaced a water heater and messed up the preheater.

    They were all disconnected after a few years to cut down on maintenance.

    In the early 80s someone got the bright idea to install a heat exchanger in the liquid line to preheat the water before it hit the water heater. Those things showed up on small commercial roofs all over Dallas. They didn't work very good and the first good cold winter the disconnected carcasses were laying on roofs all over Dallas.

  5. #5
    Join Date
    Mar 2004
    Location
    Grottoes VA
    Posts
    5,856
    I used do to work at a restuarant that had 4 evaps through out the kitchen. These were tied into a water tank as the condensor. This was used as a pre-heater for the water heater. This worked pretty good, it kept the kitchen cool and the water heater worked half as hard.

    I think it was a Therma-stor and they quit making the unit. They sold me one they had on the shelf for 200.00 bucks and it was full of R-500. The comp. went bad in the original unit, it was 16 years old.
    Karst means cave. So, I search for caves.

  6. #6
    Join Date
    Jan 2002
    Location
    Ft.Worth,Tx
    Posts
    4,581

    Hmm Bad Idea..

    Originally posted by wolfdog
    A chain of cafeteria resterants used hot gas from the refrigeration equipment to preheat the hot water before it hit the water heaters. It was engineered and stamped.....
    and a pain. A few years down the road and all the extra piping started vibrating......They replaced a water heater and messed up the preheater.

    They were all disconnected after a few years to cut down on maintenance.

    In the early 80s someone got the bright idea to install a heat exchanger in the liquid line to preheat the water before it hit the water heater. Those things showed up on small commercial roofs all over Dallas. They didn't work very good and the first good cold winter the disconnected carcasses were laying on roofs all over Dallas.
    I remember that well, Coleman was pushing the Heat Recover unit; we had to mount them on outside wall,pipe liquid line in-out and (2) 5/8" lines back to water heater. Custom builder jumped on them for about (2) years until the pumps froze up and they had to run electric heaters to keep lines from freezing in the attic.

    As far as Geo Thermal Heat Pumps w/de-superheaters, they work really well in Texas climate.

  7. #7
    Join Date
    Oct 2004
    Posts
    202
    We used to pipe them in series with the discharge line....Don't think they would work very well in series with the liquid line.
    They actually worked very well....I have had the same one in my home for 15 years now...It heats the
    water so well in the summer...that I leave the breaker to the water heater off all summer and turn it back on for 2 months of winter when we have the A/C off...
    Of course that would be South Florida climate

  8. #8
    Join Date
    Sep 2004
    Posts
    3,157
    on a much larger scale , I worked at a commercial laundry that heated their rinse water through heat exchangers that surrounded the thermal oil stacks

    so if a DIY kind of guy took a 55 gal drumn and wrapped it around -----ok ill stop before someone tries it

  9. #9
    Join Date
    Feb 2005
    Location
    small island in the Pacific Ocean
    Posts
    558
    I believe Lennox sells a desuperheater, to pre heat domestic hot water, that works with their residential heat pumps. Its in the hot gas line not liquid and would be great for summer but probably cause some aux. heat to come in winter. I guess it would take some number crunching to see if its benefits outweighed its costs

  10. #10
    Join Date
    Mar 2004
    Location
    NJ
    Posts
    1,214
    Originally posted by qssfl
    We used to pipe them in series with the discharge line....Don't think they would work very well in series with the liquid line.
    They actually worked very well....I have had the same one in my home for 15 years now...It heats the
    water so well in the summer...that I leave the breaker to the water heater off all summer and turn it back on for 2 months of winter when we have the A/C off...
    Of course that would be South Florida climate

    LMAO I SAW THIS THREAD AND WAS GONNA SAY THE SAME THING I STARTED OUT IN PB COUNTY AND I NEVER INSTALLED ONE BUT I CAME ACROSS THEM AND JUST LIKE U SAID CUSTOMERS THAT HAD THEM SWORE BY THEM AND ...

    OF COURSE "SUMMER" IN SOUTH FLORIDA LASTS A LONG TIME.

    I AM IN NJ NOW AND IN MY OPINION EFFICIENCY A/C'S AND HEAT RECOVERY SYSTEMS LIKE THAT WONT PAY FOR THEMSELVES. SOMEONE MENTIONED A G-SOURCE H-PUMP...

    IMHO IN A NORTHERN CLIMATE BEST OVERALL VALUE.

    OF COURSE HIGH $$$ TO INSTALL AND FEW KTR'S DO IT.

    BUT HERE THEY HAVE REBATES FOR THE HO

    LIKE 400 A TON TO INSTALL ONE HERE.

    BUT GSOURCE H PUMPS(WHICH IMHO DONT WORK AS WELL AS A STANDARD SYSTEM) AND SOLAR ELECTRIC FUEL CELLS ARE THE ONLY EFFICIENCY STUFF I HAVE THE SEEN IN THE NORTH WHERE INSTALLATION COST,EQUIPMENT PRICE DIFFERENCE,AND LIFESPAN OF THE EQUIPMENT ENDS UP EXCEEDING THE INITIAL INVESTMENTS.

    SEER IS A JOKE ...WHAT SEER DO U GET WITH AN 18 SEER SYSTEM?

    WHEN INSTALLED WITH EXISTING DUCTWORK
    THAT IS IMPROPERLY SIZED?

    OR AN UN MAINTAINED 18 SEER SYSTEM WITH AN EVAP COIL CLOGGED WITH DOG HAIR AND AN OUTSIDE CONDENSOR CLOGGED WITH DIRT AND DUST?

    OF COURSE THE ENERGY "SAVINGS"

    WHEN THEY ARE CALCULATED

    DO NOT REFER TO THIS BUT AS IF...

    THE SYSTEM WAS CONSTANTLY

    PERFORMING AT 18 SEER.

    tHAT DOES NOT EVEN HAPPEN IN ebaum's world.
    thehumid1-------I live in NJ, a state where it's free to come in but you have to pay to leave!

  11. #11
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,061
    Originally posted by karsthuntr
    I used do to work at a restuarant that had 4 evaps through out the kitchen. These were tied into a water tank as the condensor. This was used as a pre-heater for the water heater. This worked pretty good, it kept the kitchen cool and the water heater worked half as hard.

    I think it was a Therma-stor and they quit making the unit. They sold me one they had on the shelf for 200.00 bucks and it was full of R-500. The comp. went bad in the original unit, it was 16 years old.
    Most supermarkets use these unit to heat their water. Also dairy farms and resturants on coolers. A/c is operate enough hours to make it pay. Check out http://thermastor.com/heat_recovery.htm

  12. #12
    The capturing of waste heat through the utilization of water source heat pumps is very much alive in my businesses. I currently run a swimming pool business (20 years) and a HVAC business (5 years). The HVAC was an outcropping of the swimming pool business as the demand for dedicated swimming pool heat pumps has increased substantially in recent years.
    Recently though, (to answer your question), our specialty has become "Geo-Synergy." The ability to transfer heat normally wasted to atmosphere and supplement, if not entirely provide, waste heat for residential swimming pools.
    My website http://www.longislandgeothermalenergy.com (still under construction) will provide you with some cursory insight to a somewhat unique application of waste heat.
    Conventional geothermal systems, whether they be ground source, water source, etc. never caught on in popularity due to the cost of the loop side. While conventional geo does operate 30% more efficiently than a ASHP, ask yourself what possible benefit is there to rejecting heat back to the earth if you are trying to truly optimize a system?
    We have many installs of this system and have addressed all issues from automation, hyporchlorous acid, cu nickel heat exchangers, salt generators, entering water temps, pool temp control, evaporative cooling, etc, etc,etc.
    One of the biggest customer benefits to this system is it costs less to install and run than our competitors air source condensers. Go figure..........thanks for listening.

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