The Homemade Heat Pump Manifesto

[AC_Hacker]

My fusion heater is coming along also.

I used the following thrift-store, garage sale & junk bin items in making it:

* 300 watt heating element from mini-sandwich maker

* Teflon coated aluminum from heavy aluminum skillet

* Heat controller from unrelated skillet

Here are some pix:

This shows the plates milled out to accomodate the heater element. I also milled a plate on my drill-press using a quarter inch drill-bit. It looked like hell but worked. Howard has a NC shop and did a perfect job in just a few minutes (shown). Not shown in this pic is a channel I drilled out to recieve the temperature controller probe.

This shows the front of the unit. I still need to put a cover over the deadly voltage parts.

This shows the back of the unit.

This is a graph of the unit heating up when the dial is set to "400".

This shows the unit with the dial set to "367"... actually just a bit past 350.

So the skillet heat controller is working just great. The physical integrity leaves something to be desired, and the elecrtical safety is such that it is inviting an early death.

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I want to thank HJB for his knowledge, interest and suggestions, so I'm naming the unit the "HJB Junior".

EDIT (11/29/2011): There are two types of HDPE fusion welding being done, butt welding and socket welding.

The electric welding paddle, shown above, worked very well, for butt welding, and I am still using it.

The second type of HDPE welding, socket welding, requires Teflon coated parts of a precise size, that cannot be found on the second-hand market. Thanks to rhino 660, a reader and persistant EcoRenovator from Florida, a source for these parts has been found at a reasonable price, making DIY socket welding equipment also possible.

Source for socket Faces...

...the persistant EcoRenovator will still have to solve the heater and heater-controller problems, but therein lies the fun!

Best Regards,

-AC_Hacker

[Daox]

Woo, that actually looks pretty nice!

[Hugh Jim Bissel]

Originally Posted by AC_Hacker

I want to thank HJB for his knowledge, interest and suggestions, so I'm naming the unit the "HJB Junior".

I'm a father? This is the happiest moment of my life! I have a bouncing, baby.....heater?!?


Looking good! I haven't forgotten the class mp3's, but I've been out of town for the past couple weeks (still out of town right now), so I've putting that off.


Well, if it's going to live up to its name of Hugh Jim Bissel (say it out loud 5 times fast ), you might just have to leave the deadly voltage parts exposed!

[AC_Hacker]

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BEFORE YOU READ FURTHER:
If you are making your own tools, especially electrical tools that are not being used for the purpose for which they were originally intended, you must be aware that you are taking the responsibility for your own safety into your own hands. Be much more cautious than usual, think before you act and DO NOT work alone.
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Please Note:
What I learned applies to small pipe. As HJB has mentioned, larger diameter pipe ( 3 inch , 4 inch and larger...) could not be handled in this manner. But with the smaller pipe, we took advantage of the smaller scale and were able to use manual skill rather than precision tools.
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My son, William_Hackerson, came over the other day and together, we set to work making U-Turns for the bottom of the borehole pipes.

We made good use of the tools I had previously made for pipe fusing.

Here is the jig I made to hold the poly pipe in line while it was warmed by the heater and then joined together:

I did improve this jig from previous photos by using a wooden rest for the heater. this rest perfectly centered to heater on the pipe.

The base of the jig is angle iron so that it can be easily clamped to a stable surface. I had envisioned a saw-horse, but ended up using a wooden kitchen stool which worked out just fine. Angle pieces are also angle iron pieces, cut off of the base. The top is smaller angle iron, welded in place, with a space in the middle cut out (after the welds get completely cooled) to make room for the heater and then the fusion bead, when the two ends are pressed together. This jig was originally made for butt-fusion of straight pipe, which worked quite well. We also used it to make 30-degree angle joints as shown here:

After using the jig in this manner, I realized that for small pipe, like 3/4 to 1 inch, hand joining is quite feasible, but having a jig of some kind to steady the pieces is very helpful. I also realized that a welded steel jig is not at all needed, and that a wooden or plastic jig would work also. In fact, even a tin can with the edges bent in like this would work just fine:

I have come to the conclusion that the professional tools used by the industry actually put the skill of the job into the tool. This reduces training time and increases repeatability. It also costs $2000 for the tool, which is more than I intend to spend on my entire ground source heat pump installation.

We cut the 30 degree angles in the poly pipe with a power chop saw. I used a nice new blade with close-set carbide teeth and it did a fine job.

If there are very minor irregularities in the pipe ends, the heat of the fuser will melt then away. But it would be good to bear in mind that it would be a bad idea to rely on heat to make up for poor workmanship.

The pipe heater (AKA: HJB_Junior) worked quite well. I did learn that even though`the tool will reach sufficient heat for the controller to start cycling in about three minutes, the fusion proceedure shouldn't begin until the tool has been powered up for at least ten minutes. This will allow the heat to spread fully to all of the tool, creating a reservoir of heat that will sustain contact with pipe and not drop below a minimum temperature threshold (around 425 degrees).

One handy tool I have used in this project is an Infra-Red thermometer. I used one on the heater that had a range of at least 800 degrees F, figuring that the target temperature range (425 to 550) would be well within it's scale. I bought mine for $40, but you could borrow or rent one to calibrate your tool and carefully immobilize the adjustment knob (I used electricians tape). Using the IR Thermometer, I noticed that the heater would reach a rather high heat, then it would start temperature-cycling with the overall temperature dropping somewhat until it stabilized (aprox. 10 minutes). Arnie observed that "the first waffles just don't taste as good as the last batch". Looks like the same can be said for poly pipe heaters...

Also please note that I made a cover for the exposed high voltage parts... William_Hackerson told me that he didn't want to die fusing pipe. Can't say as I blame him.

So here is a photo of our efforts:

EDIT (11/29/2011): at the time I made these U-turns, I only had a butt-welding tool that I could use, subsequently, thanks to rhino 660, a reader and persistant EcoRenovator from Florida, a source for the parts to make a socket fusion tool has been found at a reasonable price, making DIY socket welding equipment also possible.

Source for socket Faces...

Having such a tool, and using two fusion elbows to make a U-turn will result in a U-turn that has less friction to flowing water.

As can be seen in the photo below...

...butt fusion will leave a "roll" on the inside of the pipe, which will result in increased internal friction. In my case, I was unaware of the cumulative effect, and all the butt welds in my loop field (almost 100) resulted in friction that was equivalent to a 30% increase in loop field length, not so good in the long run.

Again, thanks to rhino 660, a source for the fusion elbows...

...has also been found.

ADDED NOTE:

I discovered the additional friction problem by doing a calculation of friction loss (AKA: head loss) for the loop-field and then physically measuring the resulting head loss, and comparing the two figures.

Butt welding is plenty strong and the equipment is very simple and cheap to make. From my calculations and measurements, I can estimate that added friction due to butt welding would be .003 times the number of butt welds.

The formula would be:

Equivalent-length-of-loop-field = length * (1+(number-of-butt-welds * .003))

I didn't realize the cumulative effect, and went overboard, trying to avoid wasted pipe scraps, etc. So if kept to a minimum, butt welding should not be such a big problem...

NEXT POST: "Planting Plastic"

Regards,
-AC_Hacker

[Daox]

Thats a lot of joints. How long did that take you? How happy are you with your tooling and jig?

[AC_Hacker]

The time it took to do all 20 U-Turns was about six hours, because we were figuring it out as we went along. We could do the same job again and it would take maybe two hours or less.

The fusion process had about four steps:

1. Aligning the pieces in the jig and checking for good surface contact. Then while holding them at that angle, pulling them apart to allow space for the heater.

2. Applying the heat to the pipes. The pipe surfaces should be in full contact with the hot teflon surface. If there is a paper-thin gap, the heater will take care of it. If it's much more than paper-thin, you'll likely have trouble. Apply constant pressure, but let the heater do most of the work. After the correct time (25 seconds worked for us), QUICKLY remove the heater and...

3. Fuse the molten polyethylene surfaces together. You have about a second to correct for any minor mis-alignment. Apply steady pressure all the while, hold in position 30 to 60 seconds.

4. Set the fused pieces aside to rest...

William_Hackerson and I both spent about an hour practicing on pipe, making dozens of welds and cutting them apart to check to see how they worked. You will see a double roll (see pic) that indicates that both surfaces were sufficiently melted and had sufficient pressure.

But the double roll also happens INSIDE the pipe. The trick is to make a good, strong joint, without excessive inside roll, which would restrict the flow of water.

We also tried to break the welds we practiced on. The strength is truly impressive.

The Heater (AKA: HJB_Junior) worked just great. We found that the good working temp range was between 425 and 460 degrees F. The handle stayed cool, too. The teflon surface was from a used skillet. On hindsight, I would have done better to get a new skillet and cut it up to make the faces. The teflon surface still releases, but there were some tiny scraped-thru places in the teflon, and the pipe sticks to those a bit. Although it's working fine, I could fix it with a cut up new skillet, just screw the new pieces on top of the old ones.

The commercial tool is about twice as thick, and I was worried that there might not be enough thermal mass in my heater, and that it would cool down when it was in contact with the pipe, but it doesn't seem to be a problem at all. Letting the tool pre-heat for ten minutes provides for an adequate reservoir of heat.

The jig worked fine. the limitation being that the smaller pipe like I'm using comes in a coil and you have to work with the arch of the curve down. the tomato can jig as pictured would actually have an advantage that you could work with the curve at any angle, you'd just need steady hands an a bit more skill.

When we got the process under way, I set my watch next to the jig and William_Hackerson would count the seconds for melting (25 seconds) and also
count the seconds for cooling (30 seconds). We found from prior testing that it's important to let the newly-fused joint rest for at least several minutes before subjecting it to stress, else a permanently weak joint will result.

Another point is that since the jig does not embody the skill of the job, lots of light is required, so you can see what's going on. An important addition to the jig would be a small mirror so that the person holding the pipe together can see exactly how it is positioned, ninety degrees from his line of sight.

William_Hackerson does production sewing for a living and he has good manual skill, I've been playing guitar for a long time so ditto on the hand-eye coordination.

Hope this has addressed your questions.

Regards,

-AC_Hacker

[AC_Hacker]

William_Hackerson came by this afternoon and we planted plastic.

I decided to do the first hole entirely by hand, to show that it can be done. I used a post-hole auger that uses 3/4 inch water-pipe for a handle. This makes it easy to add extentions so that deep holes can be dug. The cost of this auger new is about $40. You might be able to pick one up for $5 or $10.

Your success will very much depend on the soil characteristics where you dig. You may be able to learn something by talking to the local state or city or county geologist. I talked to one locally and he was only marginally useful. He did refer me to a map that made the call worthwhile. I also went through the yellow pages and called some water well drillers (who often to geo-thermal drilling). They were very helpful, much more so than the geologist. Through all of this I gathered a picture of events that have taken place in this area over the last 15,000 years (yes, fifteen thousand years). I learned that my site was once the river bank of a mighty, raging river. The remanent of that river is now called the Columbia River, large by modern standards, but tiny by comparison to the old one. So my site has been at various times (and depths) right in te river, and later located a mile or so from the river. The Big River was actually many pre-historic flood events, each leaving it's mark on the layers far beneith my feet. If I were to dig a few city blocks from my site I would only be able to go down maybe three feet with the tools at my disposal. If I were to go in another direction, I might be able to go 40 feet easily. If I were 35 miles from here, in an ideal area, I could easily go down 75 feet.

But I've drill some test holes, and in my site I can get down easily 14 to 17 feet, then I hit 'hard pan', which is a clay and basalt gravel layer that is turning to stone.

So I'm betting that because my climate is pretty mild, and because my house is small, and because I'm doing a much better job of insulating my house than average, I can get sufficcient ground-source heat from 18 holes, each 14 to 17 feet deep.

We began by digging a small hole through the surface roots.

We were hitting roots near the surface so we used a root-hacker tool I had made from a 4 inch cold chisel welded to a piece of 3/4 inch water pipe.

...this tool would have been improved by grinding the chisel at an angle indicated by the yellow line. The root-hacker tool was also useful to loosen the dirt at the bottom of the hole as we went deeper.

The auger went fast:

... and we were ready for a three foot long extention:

...to be continued...

-AC_Hacker

[AC_Hacker]

...soon we were down to the end of the extention. We also determined that a bit of water helped the mostly sand adhere better, and made it stay on the auger head while we lifted it to the surface"

...and then the 3-foot extention came off and a 6-foot extention went on:

...then the three foot extention went on top of the 6-foot extention:

...soon we were hitting the hard pan (This made William_Hackerson happy):

So we warmed up the heater (AKA: HJB_Junior), fused some pipe lengths onto the U-Turn, waited a bit for things to cool off, then down the hole with the poly pipe:

The time code on the last photo is off, but it took less than 5 minutes to fill the hole back up. I have determined not to use grout on my holes because:

1. In the winter time here, the ground is drenched sand, which has thermal conductivity about as good as thermally enhanced grout.
2. Because I'm not going to punch through the hard pan, I will not be causing any cross-aquifer contamination.
3. Easier, cheaper.

So it took about 4 hours to do one hole...

One down, seventeen more to go.

Best Regards,

-AC_Hacker

[Hugh Jim Bissel]

Sweet, Looking good! When you backfilled were you able to pack the dirt in any? Hopefully if you water the hole every so often it'll settle around the pipes tightly (besides, thats what you do when you plant something; you water it, right?).

Originally Posted by AC_Hacker

Also please note that I made a cover for the exposed high voltage parts... William_Hackerson told me that he didn't want to die fusing pipe. Can't say as I blame him.

Youth these days; they have no sense of adventure! Why when I was a young kid I had to walk to school 100 miles through the burning snow and freezing sun..... .....uphill both ways.... ....mumble.... ...grumble..... ....durn kids, get off my lawn!


(The first 3 pictures in the U-turn fusing post (pics of the jig) aren't showing up for me) (maybe they're still walking through the burning snow?)

[Daox]

Awesome progress. That sure looks like a lot of work digging the holes though!