The Homemade Heat Pump Manifesto

[AC_Hacker]

Originally Posted by launboy

I wish I had the resources some of the people on this board/thread do. It seems everyone knows someone in the HVAC/R trade, but scouring my brain I don't believe I do, unfortunately.

Don't forget car freaks. That was my first equipment loan, I have a friend who got good at fixing the family car A/C's. Might be worth asking around. And even though I make a huge deal of having a micron gauge (I absolutely love mine, wouldn't be without it), you can hack without one. You can even build your own vacuum pump out of a couple of refrigeration compressors in series.

Originally Posted by launboy

...I am wondering if it'd be of any advantage to me to use two of them either run in series or parallel? I think series would be better if I did this, and the coil is free, from a window unit with a leak, but would there be any advantage to it in my application? This would effectively double my evap size.

Yes, the force is definitely with you.

Originally Posted by launboy

Could I just cut the fins off the tubing? It would be an annoying process I'd imagine, but since I already have the coils, it's copper I wouldn't have to buy.

The fins aren't as useful in water as in air, since water is so much better at heat transfer. If you're going to use this for a hot tub, you will have dissimilar metals together and the boron stuff that gets put in hot tub water will probably accelerate galvanic deterioration.

Originally Posted by launboy

Just thought about the controls aspect, I have a dehumidifier control that senses when ice forms on the coil and shuts the unit off so it can melt, maybe this could act as a sort of defrost board so I could let it run when I'm not out there to check on it. If that doesn't work I can always fall back on the old put it on a timer that shuts it off for 5-10 minutes every half hour or however long it seems to take on average. As far as temp controls go, having the Spa Pack makes that easy. It has a temp sensor, thermostat, and contacts for the heating element already installed. I'm just going to disconnect the terminals from the heating element and reconnect them to an outlet. It's designed to handle the element so it should have no problem with an A/c drawing half that. I'm so impatient to get back home and try this out!

You might be on to something here.

Originally Posted by launboy

This summer I fully intend on becoming a full fledged hacker and learning to braze and charge my home made heat pumps.

Give, 'em hell Adam!

BTW, seek out the forums where people have built refrigeration devices to chill computer CPUs... Gobs of great hardcore DIY info there.

I think you are standing at the door to insanity, we're here to help pull you through.

-AC_Hacker

[ThomSjay]

launboy, you most likely know someone who knows someone else. Just ask around.

[launboy]

I just remembered there's a guy who live a fe houses down from me that doe HVAC for a living. I know he'd have the tools and knowledge. Never really talked to him though. This could be a valuable resource in my projects, especially if he happens to find what I'm doing interesting.

"I think series would be better if I did this..." I wrote that wrong, I was thinking parallel would actually be better, but maybe I'm wrong. What do you all think, and what's the reasoning behind it?

Originally Posted by AC_Hacker

The fins aren't as useful in water as in air, since water is so much better at heat transfer. If you're going to use this for a hot tub, you will have dissimilar metals together and the boron stuff that gets put in hot tub water will probably accelerate galvanic deterioration.

Water is definitely better at transfering heat, but enough so that the same amount of coil pipe without fins in water equals the coil with fins in air? Also what are you refering to with the boron stuff? Some people use Bromine in their tubs for sanitation as an alternative to Chlorine, or Borax for PH adjustment. Those are the only two similar sounding things I can think of to boron. Personally I use chlorine(unscented bleach) for sanitation, some CYA(cyanuric acid that makes chlorine last longer) and very rarely Muriatic acid to bring the PH down if it goes above 7.8.

Originally Posted by AC_Hacker

You might be on to something here.

I think so! Although the Dehu frost sensor probably goes by temp and the air temps ill be running in may be below its frost threshold(around 32* I'd guess).

Originally Posted by AC_Hacker

BTW, seek out the forums where people have built refrigeration devices to chill computer CPUs... Gobs of great hardcore DIY info there.

Great idea! I'm sure many of them have run into the same problems as me with equipment and lack of knowledge. It'll be interesting to see how they overcame them.

Adam

[randen]

Launboy what a great hack. A perfect use for an old unit. The cost of heating a hot tub ouch. If I may suggest, what about installing a length of stainless tube in the return line for the circ. pump for the hot tub. I would think a piece of 0.375 to 0.5 inch dia about 4 to 6 feet of tube would work well for the condensor side. Don.t forget the counter flow very inportant. To just drop a fined evaporator into the water would be combersome. Take your time, line up some borrowed tools and hack with a little finness.

The shop GSHP is indeed providing all it can for heat. The heat exchangers are picking up all the heat produced by the compressor. In fact they are likely oversized by alot. I have mixed feelings about installing the larger compressor. I have some room for more insulation in the roof. But best of all I have some very good results with solar hot water. The rear of the shop has about 300 sq ft. for solar hot water panels. During a sunny day a huge amount of heat is avalible and its FREE FOREVER. Have a look at the other post about solar heating. There is a photo there of my friends helping to install the last panel on my home. You may want to consider a panel for your hot tub. The heat is free for the collecting.

Randen
Happy Holidays Everyone

[launboy]

Randen, any reason for using stainless instead of copper for the condensor HX? Putting the coil in the tub directly is definitely a very ugly way of doing it, but for my initial proof of concept to see if I can pull enough heat from the atmosphere in this cold air to make moving forward worth it, it'll work. I'm putting it in front of the main suction grate as it's a place no one sits in front of and it'll help pull water through.

I actually do have solar water heat, 120 sq ft on my south facing garage roof.

They heat our pool and hottub in the summer with no problem. I've gotten the hottub over 120*F in the summer on accident once or twice. They're rated at 120,000 BTU but I think they rarely achieve that full output. Unfortunately being unglazed the efficiency drops wayyy off with any wind or low outside temp. I did consider using it to create low grade heat for the HP instead of the air when the water temp is warmer then the air. That adds complexity though. Maybe next this summer when I can make a Ref. - Water HX.

The solar has appeal in your application too! You said it works really well when it's sunny and provides hot enough water on its own, but on the days where the water isn't hot enough to use directly you could run it through the heatpump.

Adam

[randen]

Launboy Good job with the solar. Did you know there are polycarbinate sheets for roofing avalible to cover your solar hot water collectors. The home Depot and other suppliers carry them. They are clear corrigated roofing sheets treated for ultra violet exposiure and quiet reasonably priced. Just to cover them to prevent the wind and exposure from removing heat would improve their efficency.

Launboy wrote The solar has appeal in your application too! You said it works really well when it's sunny and provides hot enough water on its own, but on the days where the water isn't hot enough to use directly you could run it through the heatpump.

The short answer yes but no. Don.t forget if there is no heat the heat pump is not going to help. You will only gather the small amount of heat that is there and start to freeze the panel. Remember the solar hot water panel is insulated all around and if there is no sun there is no heat and you will form frost on the interior of the panel.

On the days with no sun the Geothermal heat pump starts and warms the concrete floor from the huge source 6ft down in the ground. When its 20 deg F outside the ground temp is 50 deg F a great source of heat.

Randen

[launboy]

Originally Posted by randen

Launboy Good job with the solar. Did you know there are polycarbinate sheets for roofing avalible to cover your solar hot water collectors. The home Depot and other suppliers carry them. They are clear corrigated roofing sheets treated for ultra violet exposiure and quiet reasonably priced. Just to cover them to prevent the wind and exposure from removing heat would improve their efficency.

I never thought to use the polycarbinate sheets. I've tried to think of things that would be cheap and work but that never occured as one. I like it and will definitely look into prices. I also have a 4'x10' panel thats not mounted up anywhere that might work better for hot tub heat, it'd be 40,000 btu and I could mount it on a stand at a higher angle close to the tub so I'd have less piping outside. This also has the benefit of acting as a wind break somewhat.

Originally Posted by randen

The short answer yes but no. Don.t forget if there is no heat the heat pump is not going to help. You will only gather the small amount of heat that is there and start to freeze the panel. Remember the solar hot water panel is insulated all around and if there is no sun there is no heat and you will form frost on the interior of the panel.

I realize it wouldn't work well on days with no sun, but on days where there's only enough sun to get the water to say 70*. Not hot enough to heat with directly but there's still plenty of energy available to be withdrawn from that water. This could be used in conjunction with the ground loop to lessen the draw of heat from the ground.

Adam

[Geo NR Gee]

Ordered the R22a (R290) today and will be replacing the R22 refrigerant when it gets here. How would I go about checking the known benefits of the conversion, before and after? Take temperature readings at the vents? Its a 220v unit, figuring a kill-a-watt meter won't hook up to it. How about taking a meter reading with all of the power off but the ASHP? Any ideas?


The ASHP is an outdoor unit by the way, with the ducts (conditioned return and heated/cooled air) go into the side of the bulding. If a leak so happened to occur, it would be outside.

[Geo NR Gee]

Did I read somewhere that there is also someone making gauges that have the R290 refrigerant on them? In Australia?

[AC_Hacker]

Originally Posted by Geo NR Gee

Did I read somewhere that there is also someone making gauges that have the R290 refrigerant on them? In Australia?

I have seen R290 Manifold Gauge sets on ebay, some for pretty cheap.

The ones I see there right now are pretty expensive.

A R22 set will be good for reading the pressures, but the pressures of R290 will be lower than for R22.

To do super heat and sub cool optimization, you will need a R290 PT chart, there's one on the manifesto thread, search for it.

I put a super heat and sub cool explanation in the thread too.

You might search the Internet for other explanations of the procedure. Sometimes reading how to do it from several sources makes it easier to understand.

-AC_Hacker