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Old 03-07-16, 09:59 AM   #1881
AC_Hacker
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Default PEX spacing

DonT,

It is a good idea that you insulated below your slab with 2" of rigid foam.

How far apart did you space your rows of PEX and what diameter was it?

-AC

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Old 03-07-16, 10:18 AM   #1882
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Originally Posted by Mobile Master Tech View Post
Don, an 11kbtu R22 compressor will put out less and be less efficient at low source temps, high lift or both-Be careful running against minimum pressures or high pressure ratios. It will put out more with high temps or lower lift. Be careful running against the power or mechanical limits of the compressor. The difference can be as much as 50%, as I described HERE. You can probably find the chart describing this compressor's capabilities by searching it's model number on the nameplate. Running R290 will boost its capabilities a bit also.

If you combine numerous approaches such as annualized storage plus a buffer tank, you can size for average load, not peak load, which sounds doable based on your numbers.
Why don't you edit in relevant, appropriate graphs? They are much easier to understand, if your purpose in posting is for a new, unsophisticated reader to understand you and solve their problem. Graphs are much better than word count.

In your post I count at least 8 unexplained concepts and relationships.

Is your purpose to actually help someone or is it to put your concepts on display?

-AC
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Old 03-07-16, 12:08 PM   #1883
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Quote:
It is a good idea that you insulated below your slab with 2" of rigid foam.

How far apart did you space your rows of PEX and what diameter was it?
they about 24' apart. that's farther apart then they should be, but with the high water temp it's about 85f to 90f and I have the flow almost shutoff. I have a single zone system
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Old 03-07-16, 12:22 PM   #1884
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For what you have described, it would be very easy for me to justify a couple thousand dollars worth of sealing and insulating materials (plus effort), combined with a modest (1-ton) inverter mini-split-style ground source (or...ahem... air source) style of unit. A single zone unit could quite possibly keep the water heater from burning 3/4 of the time, and the envelope could be made 25% (or more) tighter
I should have said this earlier. I just built my
Quote:
barn-home
3 years ago. at the time I insulated it very well. The ceil is 2 inch of closed cell spray foam with R13 fiberglass covered with 3/4in knotty pine boards. That's about R25 to R30, (would have put in more but ran out of room). The walls are 1 1/2 in foam board with R21 fiberglass with 3/4in knotty pine boards, that's about R25 to R30. The floor has R13 fiberglass, cover with 2in foam board so that's about R25. Yes I have a few areas the could use a bit more insulation and I intend to do that a sometime.
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Old 03-07-16, 12:26 PM   #1885
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what is in a compressor that make it so I can't change the Freon. Example R22 to R410. My R22 compressor is new, never ran. Is there a seal or something in the compressor that the different Freon will destroy??
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Old 03-07-16, 12:45 PM   #1886
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they about 24' apart. that's farther apart then they should be, but with the high water temp it's about 85f to 90f and I have the flow almost shutoff. I have a single zone system
DonT,

That spacing does not look at all good for your GSHP.

The heat exchange from any GSHP heating system relies on temperature difference (AKA: delta-T) times the area of the transfer surface, PEX-to-concrete in your case.

Your delta-T will be very low compared to what would be assumed for fossil fuel. Maybe half the delta-T. As has been mentioned, a GSHP can heat water to 130F but that is the very top of its range. For real efficiency (and that is what you really want) from a GSHP system, you want to keep the water temperature much lower, like 110F or even lower. To do that, you need to drastically lower your heat loss, by insulating.

And your PEX-to-concrete area is very low even for fossil fuel temperatures, about half of what I have seen in most fossil fuel PEX layout designs. Are you ready to demolish your existing floor and put in another one with much closer PEX spacing?

{* Low temperature heating PEX spacing runs about 6 inches. *}

So if you want to do GSHP, you will need to insulate your place to a far higher level than it is now. Much higher than is common for fossil fuel heating, and much higher than for typical GSHP heating because your spacings are so wide.

Just a seat of the pants guess would be at least 4 times greater than it is now. That is based on how much heat you now require, using your present insulation level.

Quote:
Originally Posted by DonT View Post
I should have said this earlier. I just built my 3 years ago. at the time I insulated it very well. The ceil is 2 inch of closed cell spray foam with R13 fiberglass covered with 3/4in knotty pine boards. That's about R25 to R30, (would have put in more but ran out of room). The walls are 1 1/2 in foam board with R21 fiberglass with 3/4in knotty pine boards, that's about R25 to R30. The floor has R13 fiberglass, cover with 2in foam board so that's about R25. Yes I have a few areas the could use a bit more insulation and I intend to do that a sometime.


Thought I'd throw this in. It's the required insulation level in your state. Actually this is for Zone 7, the state just above you, but the numbers are all the same except for floor, which in your case will be heated. These are not extreme insulation levels, they are what all new builds are suppose to have.

In your case, if you want to do GSHP heating, with the concrete slab such as you have, you must go WELL BEYOND these levels.

Best,

-AC_Hacker
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Old 03-08-16, 03:03 PM   #1887
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what is in a compressor that make it so I can't change the Freon. Example R22 to R410. My R22 compressor is new, never ran. Is there a seal or something in the compressor that the different Freon will destroy??
DonT: This is a tentative reply. I'm hoping that Marx290 will join this conversation, because he has amazing expertise. Just regard my comment as a general overview.

Here are some factors:

There are High and Low working pressures for various refrigerants and the compressors are engineered to withstand those pressures. R22 has high working pressure some where around 250psi. R410a has a higher pressure, somewhere around twice that of R22. R290 (AKAropane) has a high pressure that is approximately half that of R22. So, if you had a compressor designed for r22, and you wanted to go to R410a, you could run into problems with over-stressing the compressor. There would also be the volume per rev issue (see below).

Compressors are also designed to compress a specific amount per rev for the refrigerant they are designed for.

Compressors are hermetically sealed, so no moving shafts or parts rotate outside of the hermetic envelope, therefore there aren't seals as you might find in a car engine. So no seals, no issues.

Compressors need lubricant that is compatible with the refrigerant that a compressor is designed for. So if you change refrigerant you will most likely need to change lubricant.

* * *

When I started the Manifesto thread, I realized that the working characteristics of R22 and R290 are very similar, even the lubricant was compatible. I also discovered that the metering devices (cap tube & TXV) for R22 were a nearly perfect match to R290. The unanticipated bonus was that compressors changed to R290 were more efficient. AND since R22 was being phased out, a raging river of R22 equipment was going to be flowing to the scrap yards for quite some time. Regarding working pressure, R290 was much less than R22.

So, some refrigerant changes are very easy and advantageous, while others may be more problematic and less advantage.

-AC
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Old 03-08-16, 09:37 PM   #1888
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Default

Quote:
Originally Posted by DonT View Post
what is in a compressor that make it so I can't change the Freon. Example R22 to R410. My R22 compressor is new, never ran. Is there a seal or something in the compressor that the different Freon will destroy??
Engineering, lots and lots of engineering. A compressor doesn't care what you put in it, or even if it is connected to any plumbing at all. If it can, it will run. In fact, it will run itself to death if allowed. The engineering keeps it alive.

Keeping that statement in mind, every different refrigerant used in refrigeration engineering has its own unique set of properties and parameters. When a compressor is designed, it is optimized to perform best within certain parameters of a certain refrigerant. It is tested and tortured mercilessly on a test rack for thousands of hours to make sure it will survive this unique set of conditions. Then the engineers start doing destructive testing, changing important parameters that they know will eventually kill something in the compressor. When it inevitably dies, they do an autopsy to find out how it died. If needed, the designers strengthen key components, then back on the rack the unit goes for more torture testing. The process continues forever, for every model, every refrigerant, and every range of operation...

Because of this massive amount of engineering, we as consumers are guaranteed that the equipment will have a long life if it is run as intended. From an experimenter or "hacker" standpoint, we know that if a compressor, heat exchanger, blower, pump, etc. strays very far from its design conditions that bad things can happen. In fact, the further we stray, the more risk we take with having unwanted side effects. Once something in the system gets far enough out of balance, this imbalance causes a "domino effect" and something bad usually happens. Every one of these systems has fail-safe components built into it, trying to prevent bad things from happening.

Again, from a consumer standpoint, the manufacturers of the compressors, heat exchangers, etc. do not approve or warranty anything we decide to do on our own. They have a huge support network of techs, installers, and engineers whose livelihood depends on normal failures in standardized systems. None of them will support anything you do without some kind of certification or license. In many parts of the world, it is illegal to do any of your own work on the system, besides changing filters and other minor maintenance tasks. Due to the various hazards in balance with each other (heat, high pressure liquids and gases, electricity, flammable / corrosive / poisonous materials, etc.), there are many reasons why unknowing consumers should leave well enough alone.

It is important to know your own level of expertise and skill when taking on a project like you are. It is perfectly OK to do what you know how to (at industry-standard quality levels), and bring in professionals to do the work you are sketchy about performing. Of course, the more you do yourself, the higher the potential of upfront cost savings. But new equipment is not cheap, and it really sucks to wake up in the morning to a cold house and find a frozen or burnt something you did yourself.
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Old 03-08-16, 10:32 PM   #1889
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Engineering, lots and lots of engineering. A compressor doesn't care what you put in it, or even if it is connected to any plumbing at all. If it can, it will run. In fact, it will run itself to death if allowed. The engineering keeps it alive.
Nice post Jeffmay.

Almost makes me want to start going to church again.

I think hacking is based on an intelligent and informed contempt for propriety.

To proceed down the path of the hacker requires keen knowledge of the process and a deep regard for your personal safety.

Quote:
Originally Posted by DonT View Post
what is in a compressor that make it so I can't change the Freon. Example R22 to R410. My R22 compressor is new, never ran. Is there a seal or something in the compressor that the different Freon will destroy??
Isn't DonT really asking the question, "Can I run R410a in my new R22 compressor?"

My short answer to DonT is that the new R22 compressor may not be up to the higher pressure of R410a. Additionally, it would require a lubricant change, etc.

However, your new R22 compressor would be a dandy candidate for R290. No lubricant change required.

Hack on, my brother.

-AC
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Old 03-11-16, 07:07 PM   #1890
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Originally Posted by AC_Hacker View Post
Why don't you edit in relevant, appropriate graphs? They are much easier to understand, if your purpose in posting is for a new, unsophisticated reader to understand you and solve their problem. Graphs are much better than word count.

In your post I count at least 8 unexplained concepts and relationships.

Is your purpose to actually help someone or is it to put your concepts on display?

-AC
Graphs and images are worthwhile but sometimes get lost, including some from the earliest pages of this manifesto and my "Don't Waste That Heat" thread. Text doesn't get deleted. I'm not a genius at creating new graphs, but where a graph or an image tells the story better, I will add them and include a brief text summary just in case.

As you asked, I am trying to not re-explain topics that I or others have already detailed. Please post which ones you would like me to document further.

My purpose is to help everyone, including myself, find the best way to economically have a comfortable, energy sustainable lifestyle. I hope good concepts from all contributors get "airtime" without bias and the best rise to the top, no matter whom they are from.

I hope my experiences and research help others. If anything I present turns out to be wrong or not a good practice, I want to know. I will be the first to acknowledge it and edit accordingly.

If someone wants to see the amount of BTU's a specific compressor can move at a specific set of temperatures with a specific refrigerant and how much power it will take to do it, I will help them find the chart. The general principles I described remain, though. I have seen charts of a Tecumseh compressor I was considering that showed it would move almost 50% more BTU's at my proposed conditions than the ASHRAE conditions used to establish it's nameplate capacity.



Don: AC and Jeff just gave some great discussion about equipment and refrigerant choices. I recently commented on why the flammability of a refrigerant isn't as big a concern as we thought.

There probably would never be a material compatibility problem with the kinds of refrigerants we might use. Ammonia can't be used with components containing copper, for instance, but I doubt anyone will be hacking an ammonia system together.

We can't greatly exceed the mechanical limits of the equipment. You can fudge a bit, but THIS LINK shows the pressure/temperature curves of many common refrigerants. R410a's pressure is too much higher than R22 equipment was designed for, so we need one that will work in our temperature ranges at similar pressures or less while cooling the compressor enough (or be helped along enough by blowing a fan on the compressor body, for instance). R134a's pressure is low and easy to work with, but you do need more flow to move a given amount of BTU's. R290 and several other "drop-in" refrigerants, such as R424a, have similar pressures and BTU moving capability as R22 equipment was designed for, so there are many good choices.

The refrigerant needs to be compatible with the oil in the system. However, this also isn't as big a deal as first thought, and compressors can also work fine if drained and changed to a different oil.

Originally, it was thought and recommended when retrofitting a car's R12 AC to R134a that in addition to changing the labeling, fittings, expansion valve (to meter the 134a properly), and the dryer/accumulator (because earlier desiccants weren't compatible with R134a) you had to do the following:

Replace all hoses/seals with newer "barrier" type (since R134a is a smaller molecule that can escape easier), flush all the mineral oil out of the remaining components, remove and drain the compressor (because R134a requires a PAG/PolyAlkyleneGlycol or POE/PolyOlEster oil), and add booster fans for the condenser (since R134a moves fewer BTUs for a given amount of gas flow and operates at a higher pressure).

Now we know that none of those things are required. A retrofit in practice is easy. R134a works fine with the existing mineral oil, you can mix mineral with POE oil as you top up, hoses/seals made since the late 80's had enough "barrier" properties anyway, and in practice the flow/pressure differences only meant that performance was slightly worse at idle speed and slightly better when the car is moving. Only one R12 compressor model, the FS10/FX10, ever got any reputation for failing more frequently because of the higher load(and it already failed very frequently on R12)-all the others did fine. I've personally retrofitted several cars without these extras and they are going strong.

Your refrigerant should be easy to obtain, inexpensive, easy on the environment and easy to comply with requirements.

The US since April 2015 is allowing flammable refrigerants in many types of equipment and removed the requirement for R290 and R600 to be recovered as described HERE. Other refrigerants would require recovery/recycling equipment, more stuff a hacker doesn't need if using R290.

The reason other refrigerants require recovery/recycling equipment is the potiential environmental damage. Most refrigerants have a Global Warming Potential of more than 3,000. This is the EPA's SNAP APPROVED REFRIGERANT LIST for HVAC. Notice the GWP. R424a's is 2,440. R134a's is 1,430. R290's is "3"!

Many refrigerants would work well with components designed for other refrigerants, but R290 can be had from your barbecue grill or a bottle from the grocery store, plus the flammability is less of an issue than previously thought. R134a is inexpensive and can be had without a license from any auto parts store. Other good possible refrigerants (such as R134a blends, R424a, etc etc) have extra requirements, require a license, are expensive, or harder to get. I'm going to be using R290, myself.

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