# Water Heat Circulator

Preliminary results testing a Haier HWR05XC5 5K Btu/h AC (\$98 from Wal-Mart, with a digital remote control), inside a room, measuring the cool output air temp with a Testo velocity stick, the central hot fin temp with a Raytek Mini-Temp IR thermometer, and the electrical power with a Kill-a-Watt meter:
hot cool power relative room time fin (F) air (F) (watts) COP temp RH notes
7:20 67.0 53.5 341 9.7/3.412 61.3 65% = 2.84 7:22 82.0 44.8 385 2.84x341/385 = 2.52 7:24 87.5 38.5 413 2.84x341/413 = 2.34 7:30 91.5 36.3 442 2.84x341/442 blocked some = 2.19 hot airflow 7:34 102.0 37.0 484 2.00 7:40 101.5 37.8 491 1.97 blocked more... 7:50 115.5 38.8 555 1.74 61.9 61%
Final hot fin temps:
116 118 123 111 115.5 118 113 121 118
The AC was sitting on top of a dry muck bucket, tipped backwards at 2 degrees, set to cool to 61 F at low speed. I didn't see any condensation during the test or at 10 AM. Page 9 of the AC manual says "Caution: the compressor of your air conditioner _will not_ work when the temperature goes below 65 F."
I didn't measure the cool airflow with the stick (altho it reads down to 1 lfm, digitally :-) The "relative COP" above is just a calc based on the nominal 9.7 SEER spec, derated with larger temp diffs and higher power consumption. It may be pessimistic, since the nameplate says 515 watts.
Preliminary conclusions:
It's hard to tell what the hot water temp might be from this test, since the fin temps vary a lot with position over the back face. The next step might be to make a bath for the hot fins and disconnect their fanblade.
It looks like a cool water bath might be helpful in wintertime to keep the COP up and avoid icing and allow disconnecting the fan motor. Steve Baer suggests cooling greywater this way, with normal summertime AC.
Nick
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As I mentioned to Nick in a private message, this use of the heat from the condenser coil is analagous to the use of a desuperheater on a large HVAC system. They are found often on geothermal (ie, ground/water loop, not air) heat pump systems. Probably because the clients buying those systems are interested in efficiency and energy savings. The desuperheater works by passing water over the refrigerant line (in a heat exchanger) right before it gets to the condenser. At this point, the refrigerant is a superheated vapor. The desuperheater is setup so that the refrigerant still remains a vapor, but is no longer superheated (its temperature drops to approximately the boiling temperature).
Nick's suggestion is basically the same idea, with a window-size AC, and a DIY standpoint. The condenser would basically be converted to a desuperheater by immersing it in water (or maybe glycol, depending on the setup).
Using ONLY the hot water loop to cool the refrigerant is equivalent to an HVAC system that doesn't even have a condenser, strictly speaking. The desuperheater would have to completely replace the condenser. That is really the basis of our previous arguement; whether it could dissipate enough heat without adding another cooling method. This depends on the usage of hot water. I think for a normal household, the answer is surely no; you would need to dissipate more heat. Maybe it would work for cooling 1 apartment where hot water is shared between 10 apartments. But even then, you'd need a very large hot water tank to "buffer" the periods of high and low water usage.
The "dumping hot water" method that was suggested is merely equivalent to cooling a condenser with tap water. The "long water hose in a pool" is equivalent to cooling a condenser with a closed loop of water. An obvious alternative is to seperate the desuperheater from the condenser (ie: braze on another condenser), and then air-cool the condenser. But this would require cutting the refrigerant lines, adds complication to a DIY project. Whether or not a second cooling method is used, the general idea of "cheap hot water" is good.
Like I said before, I'm now discussing this part of the thread only from a hypothetical standpoint.
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One more comment:
Even if the AC use of one apartment is equal to the hot water use of 10 apartments, and the water usage pattern is NOT a problem: this system would impose restrictions on either the type of refrigerant used, or the maximum temperature of the hot water. After all, the temperature of the condenser has to be LESS than the boiling point of the (pressurized) refrigerant.
In order to heat water AND run the AC at the same time, you're probably going to need 2 seperate condenser-type units. Either that or specialized refrigerants or optimized pressures. I don't have any tables of boiling points of various types of refrigerants at various pressures, so I can't comment any further.
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Maybe maybe, or rarely, vs "surely no." An average family might use 50K Btu/day of hot water, like a 5K Btu/h window AC running 10 hours per day, or less, on the hot side, but I'm hoping this thing can work all year in a damp basement, vs the mere 1-2 weeks per year of AC we need near Phila.
Nick
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Normally, I would not recommend the portable units, as they are usually much more expensive, less efficient, and bulky, when compared to standard window mount or through-the-wall mount AC units. Their sole redeeming feature is ease of setup. In this case, the ease of setup becomes an overriding factor.
Where I live, hurricanes are not a problem, so I use a window unit (and it's almost time to install it again).
CM
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Rarely, IMO, with only 1 out of N apartments using this scheme, with an automatic adaptive controller and (rare) hot water dumper.

It's difficult to "waste more heat than it saves," since 100% of the AC heat is normally wasted. In this scheme, most of the heat would go down the drains, ideally after showers, dishwashing, and so on.

"Simply not proper"? :-) You sound like George Ghio...
Nick
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The volume of water in the pipe is ((inner dia./2) x pi) x length, so assuming a large 1" inner dia. x 10' would equal (1/2 x 3.141592...) x 120 = 188.4955 cu. in., 1 US gallon is 231 cu. in., so that 10' pipe is about 0.816 gallons. I don't know how long or how big the water supply pipes are in the apartment, but I stand by my statement - after pumping just a few gallons, you'd be getting hot water out of the cold water taps. (That's assuming the apartment manager hasn't installed a heat trap that restricts backflow from the water heater - that would mean no circulation.)

But that heat is normally wasted *outdoors,* not circulated back into the house, where it defeats the whole purpose of an air conditioner. To make matters worse, the output from an AC desuperheater is normally near 110 degrees F, and water heaters are normally set 120 to 145 degrees F. And as that hotter water moves into the un-insulated cold water pipes, it radiates even more heat into the living space you are trying (and failing) to cool.
Then take into consideration the water wasted when tenants find their cold water taps now running hot, and the power needed to pump and purify said water...

You sound just like "nicksanspam".
CM
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The adaptive controller precools the thermal mass of one apartment during times of large hot water usage by all. The dumper dumps some hot water down the drain in the rare event that the incoming cold water temp rises to some predetermined threshold, eg 80 F. If somebody wants colder water during this rare event, they can wait a bit.

That pipe volume is likely minimal and irrelevant, IMO, compared to the amount of cold water in the bottom of a water heater tank. Hot water gets ever-so-gently pushed back into the water heater, not the cold water pipes.
Nick
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FWIW, the formula for the area of a circle is pi x (r x r). 1" copper holds about 0.045 gal/ft.

--
Be consistent - but don't do it all
the time.
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<sigh> I don't know why the OP wants to spend all his time and money on something that not only won't work, but will most likely get him evicted too. I was in Sams Club yesterday and they had a window shaker for *LESS* than the price of a service call.....even had an 18,000btu unit for less than \$275!! Seems that if there is no A/C in the guys apartment, and the management won't put it in, and won't approve window units, then he has 2 options... a mini-split, or MOVE. If I was the owner/landlord and some bonehead started screwing with the plumbing in my building, not only would he be out on his ass, but he would also be facing civil and criminal charges, not to mention paying to have everything put back to its original configuration.
--

Steve @ Noon-Air Heating & A/C
snipped-for-privacy@comcast.net
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Some one obviously condemmned spot coolers already I take it? Noon-Air wrote:

something
was in

price
management
options... a

the
would
have
so
3.141592...) x 120

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I simply ass-u-me d that being as how he's trying to rig something that he figures he can do for little to nothing, when in reality, its gonna cost a lot more than a window shaker for \$77, that he surely won't spend the \$\$\$ for a spot cooler. maybe I'm wrong, I would love to be proved wrong, but I don't believe that it going to happen.
wrote:

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What makes you think it won't heat water with half the usual energy, with free AC as a side benefit?

The best I've seen so far this year is a \$69 5340 Btu/h 10.2 SEER Daewoo at a local Shop-Rite supermarket. I wonder what Costco's selling.
Nick
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Noon-Air wrote:

something
Read any of the last few posts I've made, and you'll find that I've already settled on an alternative plan (read in one of the groups other than alt.HVAC, I stopped posting there). If I use something similar to what Nick is talking about, it will just be a regular desuperheater. That might happen in my OWN house, but not at this apartment.

price
management
options... a

What I'm going to be using is fairly similar to a mini-split. It's similar at least in the fact that most of the equipment goes outside, and the air handling unit goes inside. I was originally looking at those marine water-circulating ACs and portable water-cooled AC's. But recently, I found a nice 36,000 BTU swimming pool heat pump (reversible) for about a grand. It's really not that big, and I'm putting it outside. Small flexible water/glycol lines run inside, in a closed loop. Right now I'm working on making a semi-aesthetic enclosure to mount a fan-assisted radiator in.
The nice part about a water/glycol system like this is that it's easy to seperate into different zones, each with different flow rates of water/glycol. Also, I could install a large tank of water for additional thermal mass. Then, the compressor cycles are longer and farther in between. The indoor temperature can be maintained at a constant level by adjusting the flow rate of water, if that is even necessary.
If the tank of water was really large, I could even slow down the indoor air-handling units at night, but continue to cool the water tank all night. Electricity is cheaper at night, plus the AC would have an easier time cooling the water to a given temperature, since the outdoor temperature is lower at night long. I have a feeling I won't make a tank big enough to really take advantage of this benefit, though. It would require space that I just don't have.

the
would
have
And regarding the comment about spot cooling: as I said multiple times, I already have a 10,000 BTU portable unit. I doesn't work very well (probably because the exhaust air creates a vacuum inside, and sucks hot air in from cracks in the window/door gaskets).
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