12-31-11, 11:40 AM | #1051 | |
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FYI, its nitrogen, both at Costco and Discount Tire they have nitrogen generators. Discount Tire has a policy that they cannot fill portable air tanks. However, they can fill spare tires. Costco was kind enough to fill the portable air tank for me. I will report back and let you know if clean and flake free brazing was successful. |
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12-31-11, 01:02 PM | #1052 |
Lurking Renovator
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the problem with brazing is that when you dont use nitrogen you have air in that pipe so you will have flakes the proces is called oxidation.
Nitrogen is an inert gas and will not burn so have a little flow in the pipe (nitrogen)and start brazing the circuit has to be open to do this otherwise your building pressure.... check youtube : |
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12-31-11, 01:03 PM | #1053 |
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Always install a NEW filter dryer in the liquid line to minimize problems....
Normaly every time you open the circuit you install a new filter dryer to "catch" your flakes or even better moisture the enemy of the cooling circuit... |
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12-31-11, 01:55 PM | #1054 | ||
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Thanks for your inquiry... My badly broken arm (April 5) has really set me back. I’m just getting to the point where I can move things around, like a compressor... I had a new heat pump on the bench awaiting final assembly when I broke the arm, it’s still right where I left it. I have learned a lot from this project. Some of it is very specific to my lifestyle and expectations, the size and thermal characteristics of my house, the particular weather characteristics where I live, etc. Some of the things I have learned are more general and might be applied anywhere. Last winter, I ran my little 400 watt unit 24/7 for a couple of months, without a thermostat... just wide open the whole time. I just wanted to see what would happen. I used the ground loop as my heat source, and I ran the heat output loop into a car radiator that had a box fan sitting behind it running on medium speed. I dumped all the output air into my small un-insulated basement. Most of the time the heat pump kept the basement pleasantly warm and some of the time it became too warm for comfort. When there was more ground heat available, there was higher air temp in the basement. I learned a huge amount form the experiment:
I also learned that rain brought heat with it. Every time it rained, there would be a delayed rise in basement temperature. I realized that in the same way that the refrigerant gives up its heat in the heat pump, the rain is doing exactly the same thing in nature. That insight is still ringing in my brain. I also no longer see the loop field as just a heat source, but also as heat storage. I plan to put up at least one hot water panel to use be used during the summer for storing heat in the ground. So the loop field shortfall has motivated me to keep improving my insulation. A lot of the heat pump action is now kitchen insulation action. But in reality, it's all the same project. Quote:
Then I hooked up all the wires and the beast sprang to life! Apparently some of the other wires were sense wires for the little Chinese computer brain module thingie. So I have a working 1 Ton ASHP unit! And I was able to preserve my virtue. I looked closely at the heat exchangers in the unit, and they're pretty small for a 1-Ton unit. I guess sacrifices were made for portability. For a limited-use shop warmer, it's not a bad deal, but for-full time service I think it will be disappointing. I also have my radar on full-power for a small 2 or 3 Ton split air conditioner condenser unit for free or cheap. Quite a few of them are being retired, and I could graft the 1 Ton compressor onto a 2 or 3 Ton condenser coil. That should make a pretty good ASHP to use in combination with my GSHP. I would also need to graft a lower-powered fan, too. I did find a perfect 1 Ton LG mini-split air conditioner, but it's in AZ and the seller is uber-flakey about returning phone calls or email... not a confidence builder at all. And, on a somewhat unrelated note, here are a couple of refrigerant to water HXs I picked up for $25 each, a couple of days ago. I'm starting to meet other HVAC hackers here in the area where I live. It would be a great idea to organize a local group who would be into swapping knowledge and parts. We'll see where that goes. The folks I have met so far are very enthusiastic about hacking HVAC stuff. This one HVAC hacking guy I talked to even tried to do a hydronic floor. He did a staple-up with one foot tube spacings, and tried to drive it with a heat pump. It just didn't pull the grade. If he had read the EcoRenovator thread on DIY hydronic floors, he would have done much better... he would NOT have done staple-up, he would have done some kind of top-of-floor sandwich, and he would have used MUCH closer spacing than 12", and he would have been warm & happy... ALSO, Xringer has been messing about with a PLC controller board, that looks to be exactly the ticket for controlling the heat pump(s). This has had me stuck for quite some time, but now I'm quite confidant that it will do the job. I bought one, and some sensors, and it's working right out of the box. I have yet to start getting the PLC logic to respond to set points, etc. But it's all there, and reasonably priced, too. There's nothing it will do that an Arduino will not do. There were some Arduino guys on the blog from time to time, but they faded like the morning dew. This PLC board is easier to get going but is more limited in it's capability. But it will do what I want, more than I want. I do wish it had included a data-logging capability... But for $35, I shouldn't complain. Well, now they know. -AC_Hacker
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12-31-11, 05:29 PM | #1055 |
Journeyman EcoRenovator
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12-31-11, 06:37 PM | #1056 |
Supreme EcoRenovator
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Physically, they're about 10" in diameter, and make about three turns. But as far as capacity, the guy I got them from said they were "...maybe 9,000 BTU, maybe a Ton...". I'm a little dubious about that. I tried briefly too look up the make & model number on the 'net, but the company seems to be out of business. I'll probably need to find another maker of tube-in-tube HXs to get a fix on the capacity of similar units.
My intuition says they're probably about half of what he claimed, but even at that, I can find a use. I could maybe even run them in parallel. Good price. -AC_Hacker
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01-02-12, 02:09 AM | #1057 | |
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Quote:
Did you set it up so that you could read HS and LS pressure? I guess you installed at least one Schrader valve on the LS for charging with propane Most of the equipment I see does not have Schrader valves installed on the HS and LS, instead they have only one tube (LS), bent over and brazed, with no valve, OR they have two tubes (LS & HS) bent over and brazed, with no valves. The first thing I do is to install Schrader valves, HS & LS. Then I can put my manifold gauge set on and go by pressure readings instead of temp readings. The compressor will generate some amount of heat when it is running. It should be warm to the touch, but too hot to hold on to for more than 5 or ten seconds. The compressor also has an over-temperature switch located on the top, under the black plastic cap, close to the place where the power wires connect to the compressor. If it gets too hot, it will switch itself off, and then when it cools it will go back on again. If it cycles off & on due to over heating, it really is too hot. However, there is also a frost detector on the HX and it will shut the compressor off too, when there is too much frost build up... but then that is how the de-humidifier takes the water out of the air, so that is normal. So it might be just a bit tricky knowing if the cycling is due to over-heating or if it is normal operation... Tell me HS & LS pressures after 10 minute running. -AC_Hacker
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01-02-12, 02:31 AM | #1058 | |
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soil conductance....
ahhh ****.. that's so cool that you tested the conductance of your soil... I got some temporary data loggers that you can borrow if you need to do some more analysis...
I would have probably used an ice bath though in order to better simulate the conditions; that is, cold HX fluid... warm earth.. It would have also been interesting to test how quickly the earth temperature recovers during and after a 'long' run-time... and tested that against the theoretical recover times.. I believe the 'lumped capacitance' method is used... I recommend "The Fundamentals of Heat and Mass Transfer" by Incropera/Dewitt.. and I got a copy if you want to borrow it... the formulas are actually pretty easy to do... Quote:
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01-02-12, 02:32 AM | #1059 |
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AC, thanks for the update, very informative!
Sorry to hear about your arm, but glad to hear it sounds like its well on it's way to being healed. Side note, I never realized just how heavy a compressor was, even a small one from a window unit! That's a significant portion of the weight of one of those units. Sounds like the test of your GSHP has been pretty successful, especially when one considers it was backyard engineered and on the budget it was done. I commend you on that! If your loop doesn't have the extra predicted capacity, will you be able to run a bigger compressor without issues? Or is it still showing signs it's large enough to handle that. What size is your current system, tonnage-wise? I know you're using a fairly small compressor. Did making the ground loop two parallel runs have any impact on its feed and return temps? I think your plan to use solar or ASHP heat when it's more efficient and relying on the ground loop more as backup or additional capacity is the ideal way to set up a system like this, a lot less taxing on the ground loop for sure. Your note on ground loop temp difference in tenths of a degree resulting in full degree swings in basement temperature is very interesting to me. What sort of temp difference did you notice in heat loop temp when the ground loop temp changes occured? Very excited to hear you got the portable unit up and running! Is this the unit you're considering using for the final version of your heatpump? It seems this would be ideal considering it's already got controls and a reversing valve integrated, all you'd have to do is switch it's exchangers no? Even comes in a nice housing that I'm sure would fit both brazed plate exchangers, resulting in a professional looking final product. That HVAC group you found sounds like a really cool idea, how'd you go about finding these people near you? This guy has a very interesting blog, he has a(what I believe to be) standard York Heatpump condensing unit hooked up to a coaxial HX for hydronic house heating. Oikos Blog Update on my little project,the woman I am buying the window unit from stopped answering calls or texts after agreeing to meet the other day before giving me her address. Today she finally texted back with her address so I'm picking it up tomorrow and the fun can begin. Currently I'm trying to think of ways to impove the efficiency beside using two blowers. I need to see how much heat my 4'x10' unglazed pool heat collector will pick up on a sunny day. Then I'll decide if it's worth filling with antifreeze solution to set up a system to preheat the incoming evap air for the HP. Also considering using my shed as a greenhouse of sorts as it will get a few degrees above outdoor air temp on a sunny day. Adam |
01-04-12, 03:22 PM | #1060 | |||||||||||
Supreme EcoRenovator
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So right now it looks like my loop field is small for my entire heat needs, so overall, I am proceeding along three fronts:
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I did the best I knew to determine the thermal performance before I put in the field, but my assumption, regarding several small holes being equal to one big hole was wrong. Truth is, I don't know exactly what the thermal capacity is of my loop. I should test the loop as a whole, using the previous method, and I would be much more sure. I could also move ahead with the new heat pump and see how it goes... By all rights, testing the entire loop field should be my Plan A. Plan B might be to try a different heat pump setup and monitor the difference. So my current thinking is that by splitting the one loop into two loops, and running them in parallel, I can reduce the loop pump power to 25% of its previous level. so instead of 250 watts, it would need to be about 60 watts... much better... So I should have that part of the problem solved. Also, instead of running a small pump continuously, I will be running a larger pump intermittently, and using a buffer tank as a heat reservoir. So the heat pump will run until the buffer tank reaches its set-point, and I will draw heat from the buffer tank, as required... This tank can also be used as a reserve for some modest solar contribution, and additionally as a store for an ASHP. Because I am trying to make a system that will have the lowest possible feed temperatures (best heat pump performance and also lowest rate of heat extraction from the loop field), my previous plans have included a high efficiency radiant floor for my final heat exchanger... that looked to be the very best route for me to take. High efficiency floors are not a given... There are lots of configurations of radiant floors, though fairly easily built, are not such good performers. An example would be widely-space staple-up, even with spreader plates is not such a good performer and will require higher feed temperatures. I have seen top of floor systems that use thick aluminum plate and have grooves for the PEX. These look really good... the downside is very high cost, and the fact that they lock you into 12" spacings. WarmBoard Thermal Image I have even seen thermal images of this system (see above) and it is clear that closer spacing would bring great improvement. This system (warmBoard) looks to me to be the best there is. If there was ever a place for some awesome DIY development, this is it. I have recently become very intrigued by fine wire heat exchangers. If their performance is as good as their sales literature suggests, it would make a huge difference for me. I wouldn't have to massively re-design my floors, I might even be able to get by with lower feed temps, and it could be cheaper. Quote:
The ends are coming out into the basement, but I don't have them plumbed together yet, but I see no reason to suggest that there will be any difference. Quote:
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The discussion I read before on this topic pretty much veered off the road. People are getting hung up on the idea of a space full of warm air... What is needed is extra BTUs coming in, it makes no difference if the space feels cold, if there are extra BTUs, it will be of benefit.
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I'm not an HVAC technician. In fact, I'm barely even a hacker... Last edited by AC_Hacker; 01-04-12 at 04:06 PM.. |
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Tags |
air conditioner, diy, gshp, heat pump, homemade |
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