03-24-13, 10:41 PM | #1421 | |
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What do you want to use your home made heat pump for?
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Thank you, and welcome to a very interesting world. There are a growing number of people here with experience to share. We all want to see you stay safe and to succeed. If there's anything you're not clear on, don't hesitate to ask. There are enough of us here that you'll be sure to get an answer in quick order. The Manifesto thrives on good photos and descriptions, so keep your camera close by while you're working. I'm familiar with that dehumidifier, too. What do you want to use your home made heat pump for? Do you want water-in-water-out? Do you want Air-in-Air-out? This could influence how you disassemble your dehumidifier. By the way, don't be too hasty about chucking out the controller and the sensor that goes with it. They might be usable later, either whole or for parts. When the refrigerant compressor runs it needs lubricant and it needs cooling. The compressor gets it's lubrication from the oil/refrigerant mix that is circulating. It gets it's cooling from the refrigerant & oil that is returning from the evaporator HX. If your refrigerant circuit is intact and still pressurized (no leaks), it will not harm your compressor to run it as you have described. But, the compressor depends on the circulation of lubricant which is mixed in with the refrigerant, to be able to continue safely running for longer than a few seconds. It need the cooling of the evaporator to be able to run more than several minutes. Best, -AC
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03-24-13, 11:08 PM | #1422 | |
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If you're going to try to reuse your cap tubes, you could choose to build two smaller HXs with a cap tube for each one. Or you might try to braze up some kind of two-into-one manifold. Most of the more experienced HVAC guys seem to prefer using a TXV metering device. I used a cap tube on my #1 proof of concept machine and it worked great and I learned a lot from the experience. I bought a TXV, for my first experience with TXV, to use in my next machine (ASHP air-in-water-out) that will be used for hydronic floors. -AC
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03-25-13, 07:01 AM | #1423 |
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I'm planning to use this unit for water-to-water, as you've described in your first machine. my plan is to hook one side into my hydronic floor and the other side into either solar panels or loops in ground. Both the solar panels and the loops in the ground I plan on building later on. Since I can't be on-site much during construction, and we've had a lot of rain lately, I'm working on this particular part of it for now.
I'm still looking around for other donors to use for this project, in case this one doesn't work out. I have a larger 230v 18000 btu unit that someone gave to me and doesn't work. I haven't dug into it as of yet. but from reading your previous posts on here, I was trying to use something smaller to learn/test this initially. the hydronic floor part of our house is about 1000 sq ft. it's a 2-story house, but I only have this in the first floor. I've calculated the heat load of my entire house to be in the area of around 18000-22000 btu, with the added insulation we'll be installing. |
03-25-13, 07:08 AM | #1424 |
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And thanks for the encouragement! I was wondering if the 2-cap tubes were for efficiency. def planning on using the cap tubes as it is in this system for now, at least until I learn more about how all of this works. I think your idea of the TXV is interesting, but I'm trying to take this one step at a time.
I have a small microcontroller called a Rasperry Pi, that I'll be using to monitor and control as much of my system as I can. For $35, it's pretty impressive what all it can do. So far, I can hook up as many 1820 temp sensors as I want into a network of temp sensors, accessed all from a single data line. This will all be translated into a web page that I can surf to on this same microcontroller box. I'll also be using this to control one of the relays from this old control board off the humidifier that will switch the compressor on and off. And I'll still have more i/o room on this to control my water pump for my hydronic floor, the water pump for my water storage heat tank, and the water pump for my solar panels. |
03-25-13, 10:54 AM | #1425 | ||||
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Quote:
The solar idea is good. At some point you'll need to do a site analysis to see how much solar energy you can realistically expect during the heating season. Also you might need to decide if you want your solar to play a primary part in meeting your heating requirements and have the GSHP fill in the rest, or the other way around. Keep in mind that solar temperatures can get very high, so high that it could have a disruptive effect on your heat pump if used directly, but if the temperatures were moderated by a very large heat storage system (using the earth or a very large tank of water or massive concrete slab), you could make it work. Quote:
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Well, let's look at the specs you posted on your de-humidifier: Cooling Capacity - 7250 BTU/hr (2125 Watts) Motor Input - 671 watts COP - 3.16 Looking just at the motor input of 671 watts. and the COP of 3.16, we can do a rough calculation of what the output might be: 671 * 3.16 = 2,120.36 watts Since 1 watt = 3.412 BTUs, 2120.36 * 3.412 = 7,235 BTU, which roughly corresponds to the output stated on the label. The heating requirements you supplied were 18000-22000 btu So your experimental project could supply... (7,235/18000) * 100 = 40% (7,235/22000) * 100 = 33% ...between 33% and 40% of your maximum heating needs. As you can see, your experiment could not only be a learning experience, but also a very significant contribution to your heating needs. You are on the right track. But don't make this whole thing too 'precious'. You are learning, you will make mistakes and might destroy your unit in the process (hopefully learning all the while). NOT A PROBLEM. I just wanted to do some calcs for you so that you had some idea of the potential you are working with. Quote:
But I think a more interesting way to go would be to build two smaller heat pumps that together would supply somewhat less than your total heat needs. So if you could locate a 1-Ton unit, it could supply about 12,000 BTU of your needs, and a unit like the one you have could supply 7,235 BTU... Total = (7,235 + 12,000) = 19,235 BTU You could run them as needed, first the smaller one in the beginning of the heating season, then switch to the larger one as weather got colder, then run them both in the coldest part of the season, and finally add some axillary heat on the days when the extreme weather days were upon you. Your micro-controller could switch the units in and out as required. But the success of this whole scheme will depend on the accuracy of your heat load analysis. I know that it is easy to get carried away with over-estimating the effects of future projects, so it is very important that you are realistic with your heating needs analysis, because the success of the heat pump(s) you build will be determined by by the load. And much more to the point, your earth work, the extent of your loop field which is a BIG DEAL will depend on your heating analysis. Best, -AC
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03-25-13, 12:15 PM | #1426 |
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That's an interesting analysis.
My watt meter only measured 330-430 watts when the compressor was running for a few minutes. I noticed that it gradually increased the watts reading the longer I had it on. Granted, I only kept it on for maybe 4-5 minutes. Also, the heat load figures I had for my house were for the entire house, both floors. My hydronic flooring is only going to be on the first floor, roughly 1000 sq ft of space. I know that whatever heat is generated from the floor will slowly rise to the ceiling and possibly up to the 2nd floor. And I'm not sure yet what kind of insulation (if any) will be in-between our two floors. I think they are planning on installing the duct-work for our normal air heat-pumps. (everything I'm building is completely separate and aside from the normal heating/cooling they are building on my house. I'm simply trying my best to augment or replace some of that usage with energy to/from the ground and/or to/from the sun.) That being said, wouldn't my heating load need to be done on just the 1st floor only? Or am I making too many assumptions about how the heat will travel/act on the 1st floor and how long it will stay there? I reran the heatload calc online using just my 1st floor, but changing my ceiling insulation from R38 to R10. This is a rough estimation, I know, but I needed to put something in there. I started with about 22000 before I made these changes. I'm getting about 15000 Btu/hr. with just one floor. And if I take away ceiling loses since it's not exposed to outside temps, I get about 11000 Bu/hr. Comments? Anyone throwing tomatoes or eggs at me over this?? haha. |
03-25-13, 12:42 PM | #1427 | |
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Quote:
There's something called Exergy Analysis, where the path of heat is examined as it makes it's way to the great heatsink in the sky. The intent of the analysis is to attempt to find ways to use the lower temperature heat, also. So my bedroom is on the second floor, and I don't heat it unless I'm doing some extended work there. At night, I warm the bed with an electric blanket before I get in, then I turn it off. But the heat from down stairs will warm the upper rooms to some extent. -AC
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03-25-13, 03:22 PM | #1428 |
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Heating second floor with Hydronic first floor
CBearden
Your going in the right direction. I know from experience that it can be difficult to get good information. Alot have read about it. "It should work" Yes indeed the heat will radiate to the second floor. Our first floor heated concrete slab warms the second floor no problem. BUT for air-conditioning you will need ducts in the second floor to allow the cold dense air to fall to the lower. If at all you will need a little blast of heat to the second floor you can get a little blast up there with the air-conditioning ducts. But I doubt you will ever require heat to be forced up to the second floor by what we experience here. For sure air con. Insulation between the first & second floor totally not nessisary. Put that insulation in the second floor ceiling/roof. Min. code maybe R38 but R50-60 would really be the best investment. The greatest heat loss is through the roof. If you have good sun fraction for your location the solar hot water can be a large portion of you heating load. But you require close to 30% of panel vs. floor area. And you can DIY. It will work. Yes you can hack your own heat-pump it will work and work well but:: numerous units with seperate HX or to add up to the total load for each zone could get expensive. Brazed plate heat-exchangers are not cheap. One unit sized correctly or just slightly smaller as AC Hacker had mentioned for your total load would be the ticket. Randen |
03-25-13, 03:30 PM | #1429 | |
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Solar Insolation Lookup
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Annual Insolation (U.S.) This value is very accurate, using factual data all the way back to 1961. It measures insolation per square meter assuming zero shade. For hobby purposes, a 4 x 8 sheet of plywood has very close to 3 square meters of surface area. another page has a chart of monthly insolation, but with fewer lookup points: Solar Insolation Levels - Apricus Solar Water Heater Happy hunting! |
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03-25-13, 03:55 PM | #1430 |
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Heating second floor with Hydronic first floor
CBearden
Your going in the right direction. I know from experience that it can be difficult to get good information. Alot have read about it. "It should work" Yes indeed the heat will radiate to the second floor. Our first floor heated concrete slab warms the second floor no problem. BUT for air-conditioning you will need ducts in the second floor to allow the cold dense air to fall to the lower. If at all, you should need a little blast of heat to the second floor you can get a little blast up there with the air-conditioning ducts. But I doubt you will ever require heat to be forced up to the second floor by what we experience here. But for sure air con. Insulation between the first & second floor totally not nessisary. Put that additional insulation in the second floor ceiling/roof. Min. code maybe R38 but R50-60 would really be the best investment. The greatest heat loss is through the roof. If you have good sun fraction for your location the solar hot water can be a large portion of you heating load. But as mentioned earlier you require close to 30% of panel vs. floor area. And you can DIY. It will work. This season for us so far for solar fraction has been very poor as we ve had no sun but in the past its been an amazing asset. Yes you can hack your own heat-pump it will work and work well but:: numerous units with seperate HX or to add up to the total load for each zone could get expensive. Brazed plate heat-exchangers are not cheap. One unit sized correctly or just slightly smaller as AC Hacker had mentioned for your total load would be the ticket. For our installation I was a control freak, each zone is on its own control. (temperature sense of slab) {1700 sq ft of slab}Un-nessisary with the exception of the attached garage. All the zones are set the same so one t-stat could have been fine. The slab heating is sooo uniform seperate controls are over kill. But since you have it better more control than not enough. The outside temp. sense is a good idea for the slow response for the slab but it will still take about 2 hrs for a 1 deg C change in slab temp. We have had so many compliments on our heated floors from visitors we are very pleased. My appologies guys, should have been in In-floor heating thread. Randen |
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air conditioner, diy, gshp, heat pump, homemade |
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