12-02-12, 06:49 PM | #51 |
Less usage=Cheaper bills
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Just shy of 11 cents including fees that are based on kwh and sales tax based on the usage. This excludes the monthly service/connection/city fees that are the same every month which have managed to about double the bill over the actual kwh usage costs the last two months and probably the upcoming bill too.
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12-09-12, 02:16 AM | #52 |
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Very cool project. Just like AC made Heat pump from junk......
Just few things to add: 1 You can distill propane like I did. It is very easy just like making vodka. Old Russian tradition. a. I put propane tank in freezer overnight. Low temperature will keep many additives frozen or liquid. b. I connected refrigerant recovery unit and started pulling vapor propane from tank. Evaporating propane will keep tank even colder. c. I used filter drier before recovery unit. There are some filters driers with male/female flares. d. Condense propane to second tank. After this I got odorless propane. I checked it's pressure/temperature looks just like R290. 2 You can connect condenser and evaporator in series to make bigger evaporator. This will help to get better COP but this won't change system capacity. System capacity is a compressor size. I do understand that better COP= more BTU output and kinda more capacity but this doesn't affect much. 3 For defrost you only need off-cycle defrost which is compressor off and fan on. Warm air will melt the ice. You need to figure out timing. Just experiment. 4 To get better COP you need to keep water temperature as close as possible to air temperature. Sounds stupid but this is reality. The best way is to have 2 water tanks one is preheater with heat pump and the other is electric or gas to heat and store hot water at safe temperature 140F (Legionella ). Last edited by Vlad; 12-09-12 at 02:20 AM.. |
12-09-12, 05:47 AM | #53 |
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I like the popsicle propane idea so i will try it when I finish my system.
About Legionella......the tank only has to go above 55C for an hour or two every few days as Legionella doesn't grow above 50C. It is also only transferred as an aerosol so showers or humidifiers need to be watched. That said, it is a rare issue with most cases in institutional settings where something went wrong with the AC system. Most European solar controllers have a Legionaires setting that brings the tank temp up to 60C+ once a day or every 2 days. |
12-09-12, 12:59 PM | #54 | |
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Quote:
The condenser and evaporator are looped together. I've actually never heard of Legionella. The government here recommends keeping your water heater under 125deg f to prevent scaulding and to save energy. My geospring heater makes me confirm I want to go over 120deg and warns me of scaulding before allowing me to do it. I've always kept it set at 120deg for the energy savings. Hv23t |
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12-10-12, 07:11 PM | #55 |
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Well it's been just a couple hours short of 10 days since I reset the kill a watts meter. It read 39.67 kwh, so right at 4 kwh ave a day. Or 1460 kwh a year, which at .12 kwh that's $175. That's not bad, on the EPA sticker it estimated 4800 kwh a year which is $576, almost a $400 savings. And compared to the $700-850 a year of propane they had been using its incredible. I'll keep everyone updated as time goes by. I still need to install the defrost circuit and insulate the lines going to the tank individually.
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12-12-12, 12:02 AM | #56 | |
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Quote:
Way to go!! Best, -AC
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12-12-12, 05:33 AM | #57 |
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There are a few tanks out there with an electric element on the top for backup and a HX for solar on the bottom. I was wondering if the HP HX could be put in the bottom hole and the element in the top. It depends on the load but you would only need one tank to to run the system and the HX would see lower temps more of the time so it would be more efficient.
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12-12-12, 10:05 AM | #58 | |
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Quote:
I've seen these, too. The idea with these tanks is to encourage the natural temperature stratification (hotter at the top, cooler at the bottom), while at the same time maximizing the temperature differential for the lower temperature heat input (at the bottom). The hot water output from the tank is at the top, where temperature is highest. I think it could improve an already efficiently functioning design. Best, -AC
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12-12-12, 10:26 AM | #59 | |
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Quote:
Hv23t |
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12-12-12, 03:07 PM | #60 |
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Some heat exchanger designs
Now we can compare 2 projects. One is professionally manufactured HWT with Heat Pump:
http://ecorenovator.org/forum/geothe...er-heater.html The other is made from scrap dehumidifier. I think there are many features missing on AirTap from DIY point. Heat exchange part is probably one of complicated in DIY project. There are many ways to make heat exchange part of Heat Pump water heater. Let's see some and their pros and cons: 1. Just like AirTap and Hv23t's Heat Pump copper coil made from soft copper line coiled and inserted in water. Pros: easy, cheap, efficient (depend on tubing location the lower the better). Cons: sharp bend at the end , hard to position copper tubing in right place (the lower in the tank the cooler water. The cooler water the more efficient your Heat Pump will run.), position of Heat Pump is limited to as close to water tank as possible (otherwise you have to heavily insulate copper tube), copper tube length and diameter must be chosen right or Heat pump won't function properly. 2. Coaxial heat exchanger- water circulator combination can be used instead of copper tubing. Pros: Heat Pump unit is self-contained and can be installed away from water tank(you do need to insulate water lines), Heat pump can be installed in better "heat source" location like attic or...., you can take colder water from bottom of the tank (just add T at the drain valve) and return water can be put back at the top of the tank where it is needed (this will make Heat Pump more efficient) Cons: more expensive. You need coax heat exchanger (which can be found at scrap yard) and stainless circulator. 3. Copper tube wrapped around the bottom part of your water tank. You need to strip insulation from bottom part of your tank and wrap it with copper tube. You can add some heat transfer compound for better heat exchange. Also you need to heavily insulate copper tubing back (Styrofoam with polyurethane foam will work the best) Pros: easy, no sharp bends, located in the coolest part of water heater, you don't deal with water connections and circulators. This can be added to almost any already installed water tank. Cons: need more copper tubing, Heat pump must be as close to water tank as possible. This are just few ideas. I am sure there are more different ways to make it work. Last edited by Vlad; 12-12-12 at 03:14 PM.. |
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