Combining A/C or dehumidifier with ground heat storage
 

For almost five years now, I'm still working on my massive renovation project, which for monetary and personal reasons and for lack of the parts I need, have been dormant for a while.

Using seasonal heat storage (under the house), foundation heating circuit, and more than 1000 USG of extra water heat storage tanks - besides the underfloor heating. There is also rain water harvesting (2000 USG) and drain water heat recovery. Solar panels (hybrid PV-T) are not yet in place, as the ones I want aren't ready for sale yet, and most of the heat stores aren't connected yet (except the main water buffer heat tank and underfloor heating).

In this place (Scandinavia), cooling isn't normally necessary, as temperatures rarely get above 85F. But some days are a bit humid, and with neither dehumidification, nor A/C, it's not too comfortable at times.

So I was thinking of hacking an air condition unit (air/air with external evaporator/cooler), or even a dehumidifier, so that the cooling of the unit would be routed to one or more of the many heat storage facilities.

Imagine cooling off the air, while storing the excess heat for later use?

If I bought a simple dehumidifier (or a few), and managed to route the heat from the evaporator/cooler, into the heat storage, then I would have myself a little air con unit. The real simple ones, with a manual dial of humidity, could be controlled by my system so when demand is there, a relay opens the power to the unit, and it starts dehumidifying (and cooling) without any fancy digital control to stop the unit, while at the same time transferring heat into my system.

I am a bit wary of hacking into the cooling liquid of an air con / dehumidifier, so I was thinking of some kind of heat exchange. If I could route some kind of tube or pipe around the exit of the compressor to cool the liquid - even before it hits the "radiator"?

It must have been done before - any advise here?

A common window air conditioner is perfect for this type of conversion. You can do this without opening the refrigerant loop at all. Here's how:

Take the cover off of the unit. Figure out how to take the outdoor fan off the blower shaft. To do this, you will need to take the fan shroud and the heat exchanger coil loose from the frame.
http://img687.imageshack.us/img687/6212/sam1106y.jpg

These units are made so that the outdoor heat exchanger can be taken loose and moved a bit, so that the coil can be cleaned. The HX airflow is from inside the box to outside the box, so over the years, the coil clogs up with debris on the inside of the box. Also, if the fan blades ever break, usually the only way to change the fan is to make the unit give birth.

Different brands are assembled their own way, so you will have to look inside to figure it out. I have posted pics of different brands of units to illustrate: some are cheap plastic and foam, others are built out of more sturdy materials.

Once you get the fan blade and shroud off, you can fit a water container into that space. A beer cooler will fit nicely around the coil.
http://www.rubbermaid.com/Assets/ima...blue-large.jpg
For more info, search: RUBBERMAID 12 CAN SLIM COOLER

You may have to gently bend some tubing to make it come out towards the top (be careful) and/or notch the top of the cooler to fit your refrigerant piping.
http://forums.extremeoverclocking.co...3&d=1226824770
http://forums.extremeoverclocking.co...5&d=1226825606

The container doesn't have to be large or swallow the entire heat exchanger. As long as you can submerge some of the HX in water, it will do the job nicely.
http://forums.extremeoverclocking.co...1&d=1226825606

Drop a small submersible pump into the cooler, plumb hoses to/from your tank or heat exchanger, fill the cooler and prime the plumbing if necessary.In most cases, the pump can be run off the blower fan circuit. The a/c unit will work just as it did before the hack, except much quieter due to the missing noise of the outdoor fan.

Good luck! Take lots of pics and show and tell us please!

Thank you so much, jeff5may, for this post, it is very useful!

I am not sure I can get a window air conditioner in Scandinavia, they are not used very much. Looking at this unit:

Matsui Aircondition - Elgiganten

It's a 12,000 BTU air con / dehumidifier, which I hope to be able to hack in a similar way to how you showed it.

Are you not concerned there will be any problems of corrosion or other damage to the condenser, having it constantly submerged in water?

Copper and aluminum are both used as piping and pressure vessels. The water isn't going to hurt them. If the water is pure, or you add some corrosion inhibitor (auto parts store), the thing will live for decades. If the water is salty or not neutral in pH, your mileage may vary. In any case, the aluminum is going to sacrifice itself, so the copper tubing will survive.

The kids who built some of the units in the pictures I posted are now out of college. They have become homeowners and parents, and their hacked air conditioners remain. Most now live as relics in the museum (garage or attic), BUT SOME ARE STILL OPERATING AFTER 20 YEARS.

You can also get a heat pump outdoor unit (one that's easy to hack), connect it to a few feet of copper tubing, pull a vacuum and run the unit in *heating* mode. If it's not obvious why that would work, the heating mode of a heat pump is just an air conditioner in reverse, so that the outdoor unit is the evaporator.

If it's built like mine, it would be very easy to re-purpose.
http://i1326.photobucket.com/albums/...ps54628877.jpg
outside the box

http://i1326.photobucket.com/albums/...psaa424bee.jpg
inside the box

I have thought about making this one a combination unit. It would heat or cool the basement while heating domestic hot water. The only thing holding the top and bottom halves of the unit together are the silver rails. If I removed the rails, the unit would literally fall apart.

osolemio,

I have followed your efforts for a long time, ever since your first post to this forum.

Everything that Jeff said is true and it will work and is quite suitable if you are a college student living in a dorm. It could possibly even be a good idea if your use is fairly limited, living as you do.


You live in a house and you have gone to considerable expense and effort to improve your house. I am amazed at the work and accomplishments you have achieved.

I would ask you to reconsider your project a bit. Breaking into an air conditioner or a dehumidifier is not the Dark Art that many people believe. In fact, there are several people on this blog, Jeff is a good example, who have broken into more than one (he'll have to tell you how many).

You would need some tools or perhaps some friendly help but it could be a lot of fun for you, and would certainly be an improvement on the college student's styrofoam cooler unit.

I think that the weak part of that unit is the heat exchanger, the styrofoam cooler, and the open water bath and the aluminum & copper refrigerant-to-air heat exchanger used as a water to air heat exchanger.

I would start with trying to find out how much dehumidifying power you will need for a house like yours. Surely you have friends who live in houses similar to yours who also use dehumidifiers. Find out what size they use. There should be a label on the dehumidifier somewhere that will tell you how may watts a similar system actually uses. This would give you a good starting point, so even if you wanted to make a rig like Jeff suggested, it would be the right size.

But I would go farther and get or make a good refrigerant-to-water heat exchanger.



If the circuit you are going to store the heat into is closed (not a steady suppply of new water) then I'd suggest a brazed plate heat exchanger. (not so easy to make)



If the circuit is open (new water is constantly coming in from some outside source) I would suggest at tube-in-tube heat exchanger (HX) which you could buy or make. (not so difficult to make)

If you wanted to proceed down this road, there are other threads with useful photos that you can follow.

I don't know when the season will arrive in your area, for which you will need dehumidification... If it is soon you might want to try Jeff's idea. But I still think you should do a bit of research, to find out how many watts are required to get the dehumidification you need.

Then later, after the season is passed, you might want to do some serious improvements... and you would be starting with a compressor and evaporative (cold) heat exchanger of the proper size.

Best,

-AC

Wow, thank you for all the input!

I have had to defer it for now, at least until next month. I don't live in the house any more, though I still have control over it (100% ownership). In fact, I live quite far away, unfortunately, but things change, life isn't always as predictable as you like.

In this region, hardly anyone use air condition units in private homes, as the temperature rarely gets over 80F. But when it does, it is often with quite some humidity, and as there are usually no air conditions installed in private homes, you sweat it out, literally, or use simple fans, open windows and so on.

I am thinking that just removing some of the moisture would bring it a long way.

Yet when I got to the house last week, the RH was only around 30%, so not yet the time of year for dehumidification!

Thank you, AC_Hacker for the kind words. For sure, this is a big hack I am doing, and I cannot wait to get it working. I will have to focus to get it up and running, and when it does, there will be an interactive website to explain all the systems, as well as historical data to document it.

I have just found that the house is currently using more heating energy than average in this neighbourhood. There are around 100 similar houses, and the annual use varies from around 5.5 to 18.5 mWh - and mine is around 14.5, while the average is around 11.5. This is despite me changing all the glass in the windows, and insulating the foundation in a very efficient way, as you can see in the video at the bottom of this post.


The control of the radiant floor heating is not easy to manage, I haven't yet been able to make it work, so most of the winter it's running way too hot - and I guess that's why the house is using more than average.

By the time I get solar panels, insulated where it matters and all the heat storage is up and running, the house will only be using a few mWh of heating annually.

Speaking of hacking, the video below is made using a hack of a simple thermo camera (with a video output port), a bullet wide angle camera, and both go into a small digital video recorder. I wanted to make it PiP but the formats didn't work together, so instead it's side by side. Total price of this setup for making "Video Thermography" is around 4,000 USD. I have had this for several years now, and maybe there are cheaper options available today. Otherwise, thermography cameras that do video are 10,000 USD or more, for what I know of.

If anyone wants to see the setup of the video thermography hack, I'd be happy to show it.


Until 0:26 in the video, you are looking at a foundation of a similar house, but original, without the insulation modification. From 0:26 to 0:39, you see the foundation which I have insulated on the outside. There are two layers of non-compressive styrofoam arranged to minimize gaps. The top is sloping around 45 degrees so water and dirt will run off, and the bottom is extending quite far into the earth.

On the side of the house (as seen in the video), it extends about 4 foot down, while on the back of the house (see the other videos), it goes down, then out, then down again. The thickness it 2 x 100mm, which is about the same as 2 x 4 inch.

Finally, it's covered in a mesh and then finished off with some strong concrete to make it flush. The bricklayer was a bit sceptical of my hack, but after he saw the end result, he was quite pleased with the aesthetic looks.

https://www.youtube.com/watch?v=-FKLHN9swxs

Btw, "my" local plumber suggested to simply take the system off a discarded fridge or freezer, and hack it, instead of using an air condition or dehumidifier. I am not sure it would be enough cooling/dehumidifying capacity though.

Use what's available locally. If there are no comfort units and lots of freezers, hack some freezers!

There are both split air cons as in heat pumps, dehumidifiers and other air condition units, just not in the numbers seen elsewhere.

"My" plumbers uncle works in a company that does nothing but cooling applications, and he should be able to help me refill a system, if I open up to the coolant. For an older system, I am concerned that I would be releasing freon or other bad gases into the atmosphere though.

Unless you plan on heating with the unit also, a normal size heat pump unit would probably be too large in capacity. However, it would open up some heating options for you.

It's only going to be used for dehumidification and possible cooling. As I wrote earlier, since it rarely becomes hotter than 80F, it's not a lot of cooling which is required. At the moment, these houses don't have any cooling at all, so removing the moisture and lowering the temperature just a few degrees could be sufficient.

As for heating ... with that system I am doing, there won't be need for any heating! However, since I have a seasonal heat storage, why not heat that up in the process of cooling the house down? To me, it makes a lot of sense if I can split the air into cold and dry into the house, and the hot "exhaust" into the seasonal heat storage, and get that heat back 6 months later (or as needed).

There will eventually be plenty of other heat available from a whole summer of about 300 square feet of Solarus hybrid PV-T solar panels (electric and thermal), with a peak thermal effect of around 15kW (yet to be confirmed). Maybe even more, as the power you can extract depends on how cold your buffer is, and stays, and I will have plenty of capacity, as I have written about before.

So a little hacked dehumidifier or freezer won't make too much of a difference in the big picture, yet it saves me from making an exhaust AND I get the heat later - so why not?

One of my buddies made a "toilet lid" dehumidifier unit. He used one of the old brown units (GE, Kenmore, Whirlpool, they're all the same) that he found dumpster diving. He found the unit was short cycling because it was clogged up with dust. Once pressure washed, it worked fine. But that wasn't good enough for him.

http://www.naturalhandyman.com/iip/i/dehumid.jpg

The unit in question has a tube and fin evaporator, and a spiral tube condenser. The condenser was wound much like a cheap electric range element. He unwound a little of the condenser, so that it hung below the unit. I guess his toilet tank lid was broken already (or missing) and he had made a replacement out of aluminum. He took the catch basin out of the unit, so that the evaporator would drain into his toilet tank. He bolted the unit to his toilet tank lid, and hung the condenser into the toilet tank.

According to him, the thing does an awesome job. I do know it's quiet, unlike the newer dehumidifiers. It sounds something like a dorm refrigerator when it runs.

If I can remember, I'll take pics of it next time I visit him. His stuff looks like Randen's when he finishes it. Neat and sanitary.

Oh, don't you just love hacks like this! Brilliant :)

But is he then heating up the poo?

I would also imagine that the warmed water in the tank would counterproductively increase humidity, but maybe the tank is sealed up well enough to prevent that.

Now if the original problem was the toilet tank "sweating", dehumidifying the air while heating the water would fix the problem two ways.

So whenever someone flushes, the system gets a boost in efficiency with colder water against the condenser coil.

It is interesting to hear of someone else attempting to use seasonal heat storage. It should be the main way to heat buildings in winter and would be relatively easy to do on a big scale for groups of houses with a large combined store. The difficulty in a small scale system is that there has to be a lot of insulation in a store to retain heat for half of a year.

I have a fairly large store, about 180 cubic metres, insulated with straw bales. The main cost was the straw at €800, a JCB for a day and the plumbing parts. It would have been about €1500 total but I now have a large mound and two ponds which would only fit in a big garden.

One thing I have found is that the store works best when the heating temperature range is not too much above ambient but it is not yet working long enough to measure heat losses at different temperature differentials. It means that the temperature is not high enough to use directly for underfloor heating but is good for heat pump input. I have about 85 sq' of solar panels dedicated to heating and a small VAWT currently being added , also for heating only. Increasing the panel area would have allowed the option of not using the heat pump but I was concerned that the heat losses could be excessive and the heat would not last over winter. It will be interesting to compare with a 300 sq' collector system.

I hope to (finally) be online during this fall (of 2014).

For my project, I have been waiting for 4+ years now, to get some special hybrid thermal-electric solar panels from solarus.se - and it seems I will get them within a few months, so at the moment, installation is scheduled for September.

There are massive unused potential in solar energy, especially thermal, one "just" has to solve the supply and demand time offset, ie transfer the heat over time with proper solutions.

One of the most critical areas is obviously storage, but also the area (and mass) of heating in a building. The larger the area, the lower temperature you need to heat to, and the larger the mass, the longer it will last (along with a good insulation). For that reason, I would like to experiment with extending underfloor heating to walls, ceilings and any other significant area and thermal mass of a house. The lower the temperature of the receiving heat storage, the more you can extract from a solar panel (without using a heat pump). Imagine an extreme situation of one single radiator heating an entire building, versus all surfaces being heated. And if you can control the dew point of incoming air, it would even work in the summer (be sure the surfaces in the house don't fall to get too close to the dew point - ideally by keeping the dew point low).

Low dew point / relative humidity is another overlooked and very important parameter, both for comfort as well as building preservation.

I also find it vital to look at air quality for ventilation (ie temperature and humidity), rather than just volume pr hour. What is the point of requiring a certain amount of air shifted pr hour, if the humidity of that air is quite high? I'd rather have a slow air change, and then control the temperature and humidity of that air is very precise. I am sitting in a hotel room right now, where the air con has an "auto" setting only, so I'm sitting in a constant draught unless I turn the entire A/C off.

To me, the seasonal heat storage is a bit like when you are hot or cold (your body). Some times you work hard physically, it's hot and humid, and you need to get rid of heat to maintain your body temperature. Other times, it's colder, and you have the opposite problem. It's not a question of heating and cooling as much as it is of maintaining a constant temperature. A bit of a mindset thing - but yes, we are not heating or cooling our homes, ideally, we are keeping the temperature constant by offsetting heat loss or gain.

Hence, it is so obvious that if we can keep heat when it's warm, and get it back when it's cold - then we can have both "cooling" and "heating" by using the heat storage as a "savings account"

More of all of that later - it will make a lot more sense when I can actually document with data that it works.