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Old 05-13-12, 12:26 AM   #1231
AC_Hacker
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Read the whole manifesto including poring over linked info-wow! AC and others, thanks for your info and dedication.
Welcome aboard!

Your list of projects is pretty inspiring.

Have you got them all up and working, or are some in the design phase?

There are quite a few folks here that will be interested in your projects, as they have similar projects themselves.

In case you haven't found them yet, the radiant floor thread is HERE.

There are several threads in the Geothermal branch of our DIY tree.

There are many projects in the SOLAR branch.

You are in exactly the right spot for your hacked geothermal heat pump (I'm very interested in seeing photos of what you have done.

We have a heat storage project underway HERE... and also a very interesting exchange on HEAT ACCUMULATORS.

As far as underslab heat injection, you just might be at the cutting edge of this... maybe you should start a new thread on that!

"Supported extension ladder/winch/power auger drill rig"... I want to see the pix.

Homebuilt HRV/ERV's are HERE.

We really thrive on project details and photos... So let's see what's going on.

* * *

So, personally, I want to see what you did on your " Hacked homebuilt geothermal heat pump"!

I want to see some pictures and hear the whole story...

-AC_Hacker

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Old 05-13-12, 01:09 PM   #1232
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Thanks-will post details in appropriate threads, but here's a summary of what's done so far:

Radiant floors: All but 3 rooms upstairs and the unfinished basement are done. Let me tell you, it's easy to get spoiled padding around in your bare feet when it's below 20F outside. I didn't realize how much so until I walked across an area that wasn't done yet-BRRR! Staple up can be retrofitted into existing floor by cutting access strips out of the subfloor-easier than removing drywall from below since we are installing tigerwood throughout the entire house including kitchens/bathrooms as each area is completed. After experiencing warm floors, I would never be without it. Realtor surveys of homeowners that have experienced warm floors show that nearly all of them felt it was the best feature of their house by far. By the way, don't listen to naysaying that wood can't be used where humidity is an issue-if it's engineered rather than solid and you use urethane gluedown installation, you are good to go-2 years going and still looking great. The only exception is the first few inches by your shower door-standing water that dribbled out the corners several times every day has caused discoloration. I will cut out wood & install an accent tile strip in it's place to solve this. Staple up works great with 1/2" pex and 12" or less spacing and heat transfer plates, useless without. It can be used with setback strategies and is more responsive during shoulder seasons where a slab type wouldn't put out enough at night but too much during the day. Much easier than structural reinforcement and slab over frame!

Thermally reflective roof: Replaced with Energystar rated Certainteed Landmark in Silver Birch color. This is the only 25%+ solar reflective asphalt shingle roof that isn't white or rediculously expensive. Most roofs only reflect 2-6% of solar heat. On a 90F sunny summer day, the old roof surface tested at 159F, the underside of the decking was 136F, the top of the R30 insulation was 119F, and the interior surface of the drywall ceiling was around 89F. I put a test patch of the new shingles on the old roof before it was replaced. On a 70F mostly sunny day, the old roof was 148F while the test shingles were only 124F. We have had some 90F humid days already and the upstairs rooms without sun coming in are 3-8F cooler than the downstairs rooms that have sun coming in, and the ceiling was around ambient! Those rooms would have been roasting before due to the ceiling heat and how much wall exposure they have to the attic. Since the basement is ripped apart for finishing, we only have a "1.75 ton" upstairs airconditioner for the entire house. It ran for 20 hours a day, but kept the entire house between 74-79. That would have been impossible before-the house was equipped with 4.5 tons of ac.

A/C system/filtration: Found a Tappan (Nordyne) inverter central air system that can modulate down to 1.2 tons or up to 3.5 tons while being quiet enough for a low conversation nearby at surpluscityliquidators.com. These components normally would be over $6k, got them for just over $2k. These guys have tons of stuff and most of it silly cheap-expansion valves, compressors, delay timers, etc-great source for just about anything HVAC. This system is rated 14EER/22SEER. Need to get their proprietary (read $$$) controller stat before installation, unless anyone has insight into hacking their communication protocol and making something different-any takers? Using 20x24" 8 pocket 36" long MERV 14 bag filter with tackified prefilters in the return grilles. Installation happening as we speak, but need to find a good plate HX for the desuperheater. I am considering a Danfoss Micro Plate HX, since they have no internal gaskets to leak unlike regular plate exchangers. They are supposedly more efficient and can handle R410a pressures. Anyone have any good sources for these?

Drill Rig: I bought a 52cc gas auger ($180 @ Harbor Freight) that has more displacement and lower auger RPM than others. It came with a 4" auger that is seriously reinforced on the business end. I am planning to clamp this to the upper half of an extension ladder where the lower half is firmly anchored to the ground with cable stays and screw-in earth anchors ($20 for 4 30" anchors at Home Depot online) and another ladder lashed to it at an angle for support (plus you can climb to the top of the rig if necessary). With the rung latches disabled, I plan to use a hand boat winch to raise/lower the upper section after drilling the starter holes with the auger by hand. This will make it easy to bring cuttings to the surface then relower without having to remove drill stems and will also prevent the auger from screwing itself into mud since it will be "on a leash". I can add weights to the moving section or connect another winch to an earth anchor to pull down on the moving section if necessary, but I doubt it.

GSHP: I have an 8000btu R22 portable air conditioner ready for hacking. A similar Tecumseh compressor is rated 8100 btu at ASHRAE conditions, but 12100 btu at 90F condensing and 55F evaporating temps while drawing 521w. Thanks to the stratification in the tank and 62F natural ground temp before summer heat injection raises the ground temp, I think these will be realistic operating conditions. Adding the compressor energy, that should be just shy of 14,000 BTU/hr into the storage tank, this should be able to provide all space/DHW heating not provided by the solar, since it can run 24hrs/day while using the tank to even out the load.

Solar: got a SR728C controller from aliexpress.com for $130 shipped. It has 5 temp inputs, 2 collector array controls (one for solar and one for the desuperheater on the A/C in my case), plus it can control 1500W of aux heat which I will be using to turn on the GSHP when the top of the tank drops below 135F.

Tank: Using 4x8 sheets of 3/4" plywood, I could build a tank 8' wide by 6' high inner dimensions using 2x4 horizontal ribbing supported by chainlink fence posts at the midpoint to prevent bowing. Since the top and bottom can be secured to the sides, they will act as a diapragm in tension to support the fenceposts clamped to them. This gives a volume of around 2400 gallons, but mine won't be quite as wide for space constraints and to have the tank closer to a cube. I am planning for 2000 gal. The tank surface area per gallon of storage is 0.12 square ft. Although the tank and water will weigh over 17000 lbs, the bottom loading is around 2lb/sqin, well within the compressive limits of polyiscocyanurate foamboard. Interior will be lined with the Sanitred/Permaflex system. Having a 5'10" depth allows the top of the tank to be around 145F while the bottom is around 110F, demonstrated by research I found. Keeping it that way involves a low velocity return to the tank with multiple outlets so the water goes in at its own density. 3" pvc with sanitary tees every 1.5 ft is my plan.

Gotta go-it's Mothers Day. More info and pics to come!
Craig
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Old 05-13-12, 02:39 PM   #1233
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Need to get their proprietary (read $$$) controller stat before installation, unless anyone has insight into hacking their communication protocol and making something different-any takers?
Take a look at what I'm up to..
http://ecorenovator.org/forum/geothe...r-machine.html

An impressive list of projects!

Nigel
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Old 05-15-12, 08:32 AM   #1234
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Thanks-these projects all work together and will keep me busy for a while.

Nigel, you are on the ball! Of all the things I have ever learned, the most important lesson is realizing how much I do not yet know. Your work falls in that category!!!
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Old 05-15-12, 09:55 AM   #1235
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Radiant floors: All but 3 rooms upstairs and the unfinished basement are done...
Mobile Master Tech,

I have posted some questions regarding your radiant floor in the DIY Radiant Floor thread located HERE.

I realize that radiant floors driven by homemade heat pumps become one whole system, but to keep things tidy I shifted floor considerations there.

Best,

-AC
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Old 05-15-12, 10:23 AM   #1236
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I am considering a Danfoss Micro Plate HX, since they have no internal gaskets to leak unlike regular plate exchangers. They are supposedly more efficient and can handle R410a pressures. Anyone have any good sources for these?
The kind of plate HXs I have been interested in are called brazed plate, and they are all one hermetically sealed unit... no gaskets used in their construction. If they are brazed into your system, you shouldn't have any leakage problem.

The pressure part is another story. Maximum pressure and working pressure are two of the characteristics that you should be able to find in the Specifications Sheet for each exchanger.

The pressure will be highest in the condenser side of the circuit:


...which is the part coming from the compressor to the expansion valve (the part of the circuit shown in red-to-pink).

As you already know, R410a is higher pressure than R22, etc. and care needs to be taken that the HX can stand the stress, so make sure that the 'working pressure' rating is higher than the high-side pressure of your system.

You might try looking on ebay for BRAZED PLATE you are sure to turn up something.

Good luck with the project.

-AC
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Old 05-16-12, 12:49 PM   #1237
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I have heard that around here, a 5 foot deep by 3 foot wide trench with 300 feet of slinky loops would get you about 12,000 BTU/hr...
I think that there needs to be a trench length specification also.

Randen used this trench & slinky approach on his successful homemade heat pump project, too. It is saving him lots of money.

How far along on your project are you?

-AC
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Old 05-16-12, 06:25 PM   #1238
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Posted tons of info in the radiant section here detailing the staple-up retrofit at AC's sugggestion. Check it out!

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Old 05-16-12, 06:56 PM   #1239
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Although a hydrocarbon refrigerant system should be safe when designed and serviced properly, I will recall an incident that gives me pause. I was managing a Goodyear store during the phaseout of R12 in mobile air conditioners. A Thunderbird was brought in because the A/C didn't work, no service history was given. My tech pulled the car into the bay and was holding the engine at 2k and checking to see if the system was cooling at all when we heard a big boom and flames started licking out around the edge of the hood. We opened the hood and saw flames spurting out of a rupture in the side of the accumulator (an aluminum cylinder around 2 qts in volume that holds the desiccant and any excess refrigerant on a CCOT system). The split had acted like a blowtorch and melted nearby wiring, hoses etc. before we could put it out with an extinguisher. The customer, of course, said nothing was wrong with the car before we touched it, and it took her a while to understand we hadn't even touched it yet.

Our theory of what happened? There was lots of evidence a hack mechanic(the bad kind!) had worked on the car. We suspect the system was discharged and left open so if was completely full of air, reassembled, then charged with a hydrocarbon R12 replacement. When running, a hot spot in the compressor ignited the mixture in the system, which overwhelmed the pressure safety valve an ruptured the accumulator, allowing the accumulator to become said blowtorch.

Evidence shows that mishaps such as this do happen, although rare. I second AC's recommendation that any system using more than a small amount of refrigerant (150 grams?) be outdoors or run a refrigerant that is mostly nonflammable.

Right now I am doing some research on R134a blends that incorporate R290 (propane) and R600a (isobutane). R134a has low volumetric efficiency (lots of refrigerant CFM for a given amount of cooling, only 67% of R22's cooling capacity for a given flow) but is a superb refrigerant. It also has very forgiving properties for the system hardware. Tecumseh says the max compression ratio for most of their compressors is 7 when running R22, but 15.8 running on R134a. Adding 4-20% of other refrigerants apparently lowers the compression ratio while increasing capacity to within 85% of R22. Due to the headroom that R134a offers, I plan to solder the sides of the liquid line before the expansion valve and the vapor line after the evaporator to each other to allow heat transfer. This LLSLHX (liquid line/suction line heat exchanger) should give efficiency and capacity boosts, since the liquid will be better subcooled to prevent gas flashing in the expansion valve, increasing capacity, while also allowing almost zero superheat coming out of the evaporator, reducing throttling losses from the expansion device (which costs COP), getting the most heat transfer possible in the evaporator, and still warming the refrigerant headed to the compressor enough to get the 10-20F superheat required to protect the compressor from liquid ingestion.

I also discovered that R290 and R134a are by far the most efficient single component refrigerants to replace R22 at high temperature lifts. Anyone want to chime in with thoughts?

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Old 05-18-12, 09:55 AM   #1240
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The old roof was 144F while the new one was 124F, (not 148F). A 20F temp reduction ain't shabby!

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