Some time back I was watching TOH, and Richard helped some guy hook up a heat exchanger between his pool circulation system and the AC condenser. http://goo.gl/jt3SW Free heat for the pool otherwise lost to the atmosphere! I read up on this and also found people experienced a substantial reduction in the cost to cool their house as well, because it’s a more efficient way to removed heat from the refrigerant lines.

I’m a home beer brewer and I use a simple heat exchanger to cool boiling wort to 70 quickly. I run a hose from my spigot through the exchanger with hot wort flowing in the other direction. http://goo.gl/lTlDs I’ve read where people have tied basement refrigerators to a water pre-heater prior to being sent to the conventional water heater. There are AC heat recovery systems to assist you water heater. It’s all about moving the heat where you need it.

I have well water that is typically 52 degrees. What if heated refrigerant lines went through some sort of heat exchanger cooled by household water? If I was watering the lawn when the AC was on wouldn’t I get an even bigger benefit than the guy with a pool? I understand the only time I would get the benefit would be if water was running in the house.

Did I just unnecessarily reinvent the open loop geothermal system? I envision problems using the whole house watering system when water isn’t running; would it overheat water in the heat exchanger and cause breakdown? Would it over-heat water meant for cold water pipes? Would it need a bunch of diversion valves for winter using an air source heat pump?

There are spray systems that attach to the top of your cooling unit and when the fan turns on it sprays a mist that helps cool your AC unit. It attaches to a garden fitting.

I wonder what happens after a few weeks when the coils get caked with hardness deposits. But rainwater might be available for this use. Or better yet, condensate from the indoor unit (if you can get enough of it).

Yep, minerals in the water will form deposits on the coils and eventually lower heat transfer...

Would the condensate (or possibly even the rain water) be too acidic to use in a heat exchanger?

-Rosalinda

Maybe not if you throw a couple of limestone stones in it. That's what I do for RO drinking water (which normally becomes acidic).

Hmmm, trading in acidity for lime deposits... sounds like a good trade-off! ;-)

The acidity of the coil condensate depends on the contaminants in the air. Down wind of a coal fired powerplant it could be pretty significant, otherwise not so much. But it's not as if there isn't other stuff that would come out of the indoor air that you wouldn't want caked onto your compressor coils.

Maybe if you tipped your head into the stack...

http://www.epa.gov/airmarkets/quarterlytracking.html

A far better solution would be to break the AC loop and add a gas to liquid heatex in line before the condenser coils, then evacuate and recharge the system with refrigerant. You would need a pressure rated heatex, but many brazed flat plate units are rated in the 400-600 PSI range. You could then pump your ground source water thru the heatex to remove most of the heat from the gas prior to it passing thru the normal condenser, with no fear of buildup on the condenser fins/coils... If circulating pool water, care in heatex selection would be needed as chlorine levels typically found in pool water and the copper used in brazed flat plate heat exchangers don't mix well...

Yes, but cooling with water and cooling with steam are completely different things (with the latter needing very little water).

We heat a lot of pools, both conventional and salt water but no longer use a common brazed plate opting for a rated 316L for common pools and a titanium SS HX for salt.

Posted By BadgerBoilerMN on 11 Apr 2013 04:56 PM
Maybe if you tipped your head into the stack...

http://www.epa.gov/airmarkets/quarterlytracking.html

Mmmmm TANGY!!!

Before they closed it down a couple of years ago a coal-fired power plant north of Boston would wash any boat that pulled in the boat-wash slip gratis, to get the acidic deposits off them!  It was cheaper than fighting damage claims in court, but wasn't exactly mitigating anything like 100% of the actual damage. Not to many people were sad to see it go, displaced on the regional grid by output from combined cycle gas at nearly 2x the thermal efficiency, and a lower source-BTU price to boot. The net effect lowered the per-kwh price somewhat, and the local emissions by a LOT.

There are still coal fired plants in MA, but the handwriting is on the wall. Even without the annoyed neighbor factor, cheap natural gas and already slated wind projects doom them financially (and that's without a carbon tax to put the final nail in the coffin.)  Nobody wants 'em, and nobody needs 'em.

And half the carbon foot print of coal, but still makes me sad to see people take for granted the lifestyle we enjoy, built by coal miners. Without coal we wouldn't have the smug leisure it takes to dismiss coal-fired power plants, without which, very few electric cars - wait that was redundant - could be plugged in.

http://www.wou.edu/las/physci/GS361/Fossil%20fuels/Coal.htm

Coal clearly powered the industrial revolution, often at great personal cost to the miners diggin' it up and shippin' it out, as well as a broader environmental cost to the population as a whole, even ignoring the longer term climate consequences.

At equivalent thermal efficiencies gas has about half the carbon footprint as coal, but at combined-cycle efficiencies it has between 1/4 & 1/3 the carbon footprint of coal. Gas peakers run at about the same thermal efficiency as can be had with coal.

Natural gas has it's own environmental "externality" costs beyond the mere carbon aspects, and where ignored it can be pretty devastating. Production brine dumping from coal-seam gas in the Wind River range hasn't been pretty (but is now under somewhat better control), and frack brine management from shale gas is an ongoing issue), but per tera BTU these dirtier sources of natural gas are still but a fraction of the impact of that of coal extraction as a whole. It's better than a sideways move for the environment for power production, but still nothing like a long-term solution. Improving efficiency at the load end is still #1 in the book of lowest first cost & ROI.

In MN/IA the surplus of off-peak wind power could support quite a fleet of electric commuter cars even without smart grids and smart batteries, even at the existing grid fraction. With a smarter grid and a larger electric car fleet the regional nukes currently slated for mothballing due to competition from wind & cc-gas could still be economically viable. The inflexibility of nukes makes them crummy responders to grid load, and the wasteful power-dumping required to avoid shutting down during off peak (incurring a week-long ramp-up time) would be much better used for charging an electric transportation fleet. I'm not anticipating the electrification of transportation with smart-charging to develop quickly enough to save them though.

Wind & gas are extremely flexible in comparison to nukes & coal, and play well together: For the cost of a small reduction in annualized capacity factor wind can be EXTREMELY flexible, with ramp up/down times measured in 10s of seconds, and quite valuable for maintaining grid stability, and can reduce the need for lower-efficiency low capacity-factor gas peakers. But without improved efficiency at the load end & smarter load management gas + wind isn't be an ideal 100 year solution either, but it sure buys a lot of time & benefit on climate and other environmental issues compared to the legacy coal dominated grid of the prior century.

Posted By smartwall on 05 Apr 2013 10:29 AM
There are spray systems that attach to the top of your cooling unit and when the fan turns on it sprays a mist that helps cool your AC unit. It attaches to a garden fitting.

I tried one, it leaked so bad it was inefficient. Gave up and threw it away