The Homemade Heat Pump Manifesto

[superlen]

FYI,

Here's what led me to this.

The thermal conductivity of PE(X) is approximately 0.41-0.46 W/(m K), copper is a whopping 28. (no surprise)

And here is a table I found that is recommendations of trench length vs. the Thermal Conductivity of your dirt. As you might expect, if you have good dirt, you can have a shorter trench, but all we really care about for this discussion is that the range of thermal conductivity shown. I'm assuming that this covers 90% of the installations. Note that ever the worst soil is still almost exactly equal to the conductivity of our plastic pipe, and in most cases the dirt is twice as good or better at pulling the heat away from the pipe, once the heat gets *INTO* the pipe. Therefore anything we can do to more easily get the heat from the water to the pipe (turbulent for instance) can easily be absorbed by the ground and we can reap the benefits.

Now lets think about another scenario. We could *GREATLY* increase the heat xfer from the water to the pipe by making the pipe Copper instead of pex. (Let's totally ignore the potential pitfalls and massive cost of doing this for now). If we did this, then turbulent flow is not going to be as useful, as once you have the heat into the copper, it still flows slowly into the ground. A smaller loop field could be in order to reduce the under utilized surface area, but then you might need to bump back up turbulent....see how it all relates. The loop field of a geothermal has one simple task, transfer heat. But is an entire system with several variables, and they all need to work in sync for us to get the greatest efficiency out of them. Lots to think about. Luckily, others before us have done some thinking & established at least a rough outline of what has been shown to work. I think one can start there and then push the boundaries some to see what happens.

Len

[Zwerius]

Hello AC (and others),

I'm only up to page 55, so it might come up later on, but I thought just to give you a hint.
You're talking about very different (calculated) COP's in further identical conditions.
Since the temperature difference between heating water in/out of the condensor is realtively small, it's very important to have very accurate temperature measuring devices at those places.
In my air/water heatpump installation (Mitsubishi Zubadan) I have a proffesional thermal energy meter (Kamstrup). I know in the factory they pair the tempearture sensors (in/out), so that they have sensors with very similar deviations.
Suppose you have a sensor with an accuracy of +/- 5% + 1 digit and both temperature sensors measure tempeartures only differing 5°C.
If one sensor is measuring 1°C too much and the other one is measuring 1°C too low, you could read a temperature difference of 3°C where the real value is 5°C. In that case you have a misreading of 40% !!
And then you have the others inaccuracies, like waterflow etc.
The only thing I want to say is: don't just take the values you read for being true. Take care with interpretation of measuring data.
Maybe you know all this, I would just avoid you draw the wrong conclusions.

[j_abdeen]

Dear AC Hacker,

Your quote on the ground source technology prices are sadly true. I m building my own home which is a flat on top of my parents house. with prices sky high of fuel oil and electricity; boilers, electric heaters and DX units are not economically possible for 80% of population in my home country ( Jordan ).

I m crazy with geothermal idea, the first estimation i have got from the installers is about 40K USD. the majority here wont save this much during entire life.

further please share the study cost for the building and running such heat pump.

I highly appreciate if you can share guidance with me please. as I m planning to make a prototype.

Best Regards

Jibreel

[AC_Hacker]

Originally Posted by j_abdeen

Dear AC Hacker,

Your quote on the ground source technology prices are sadly true. I m building my own home which is a flat on top of my parents house. with prices sky high of fuel oil and electricity; boilers, electric heaters and DX units are not economically possible for 80% of population in my home country ( Jordan ).

I m crazy with geothermal idea, the first estimation i have got from the installers is about 40K USD. the majority here wont save this much during entire life.

further please share the study cost for the building and running such heat pump.

I highly appreciate if you can share guidance with me please. as I m planning to make a prototype.

Best Regards

Jibreel

Jibreel,

Assalam o alaikum!

It is not very easy to do such a comparison, because so much depends on local conditions.

However, I encourage you to proceed with your prototype, you will learn a lot, and you have the potential of saving much money.

We have had DIY builders who already had considerable machining and design experience, who have made very sophisticated machines, that are better in quality than commercial heat pumps. The amount of effort and money that they put in was high, but the final product is magnificent. The amount of money and time in this case was equal to or somewhat less than a commercial unit (of lesser quality).

We have had other builders who have tried to utilize as much as possible from discarded air conditioners, and their cost was extremely low... about the cost of taking your family out for dinner, or less.

As you can see, the cost range is very large, and it depends on your local conditions, and the availability of potentially-usable, discarded air conditioner or heat pump units, your skill and your resourcefulness.

Can you give me a clearer idea of what you are trying to accomplish?

• Cool?
• Heat?
• Both?
• Location? (so I can get weather data)
• Size of building?
• Photos?
• etc.

I look forward to hearing about your project, especially because we have never had anyone from your part of the world take part in our discussions.

I personally welcome you to our discussion, and I hope that working together, we can give you the information you need to succeed.

Sincerely,

-AC_Hacker

[j_abdeen]

AC_HACKER ,

Wa Alaikom Assalam (peace back to you and sincere wishes of ultimate happiness and god mercy).

Thanks for your reply, I m planning to have both heating and cooling using 2 pipe fan coil system. the location is in Amman, Jordan.
The flat size is 1700 ft2, divided into 5 zones. the land mainly 2~4 meters soil and calcium stone underneath.

Regards.

Jibreel

[AC_Hacker]

Originally Posted by j_abdeen

I m planning to have both heating and cooling using 2 pipe fan coil system. the location is in Amman, Jordan.
The flat size is 1700 ft2, divided into 5 zones. the land mainly 2~4 meters soil and calcium stone underneath.

OK...

The next step is to get some accurate weather data for your area.

Below are some weather information data collection stations in Amman. Which one is closest to your home?

1. Amman Airport, JO
2. Queen Alia Airport, JO
3. Amman, MARIKH, JORDAN
4. Demashk, Al Bunayyat Ash Shamaliyah, JD
5. Queen Zein Al Sharaf, Al Bunayyat Ash Shamaliyah, JD
6. Mohammad Ali Janah, Wadi As Sir, JD
7. Zahran, Wadi As Sir, JD
8. Amman, MRJ AL-HAMAM, JORDAN

The next step after this will be to get some idea of the heat loss, or gain for your house, but for now, weather data is most important.

Best,

-AC

[j_abdeen]

AC HACKER,

Number 4 is the closest. And number 1 , 4 and 8 are adjacent.

Regards

Jibreel

[AC_Hacker]

Originally Posted by j_abdeen

Number 4 is the closest. And number 1 , 4 and 8 are adjacent.

Jibreel,

I use Heating & Cooling Degree Days - Free Worldwide Data Calculation to get data, and apparently many of the data collection stations in the Amman urban area don't seem to have a full set of data accessible at this time. I did find that the Amman Airport weather data collection system is fully functional.

From the look of the aerial photo, I would guess that the weather at the airport would be similar to the weather at your house.

From the weather data, I made a chart for the Daily Cooling Degree Days in Amman, over the period of the last year:

The higher up the chart, the more heat removal your system will have to do.


And here is a chart for the Daily Heating Degree Days in Amman, over the period of the last year:

The higher up the chart, the more heat addition your system will have to do.

In essence, these charts give a clue as to how much work your system must do. They don't tell the whole story, because there are some details about how much Heat Loss and Heat Gain your house has.

The next step will be for you to do a Heat Load Analysis, or to hire someone to do it for you. If you want to do it yourself, it may require at least a modest technical background.

Here is a free calculator, all in US units (Imperial units), but you could do all the measurements in Imperial units and convert the final answer. If you have questions, let me know. There are also other calculating tools available. This one is free, and fairly simple to use.

If you want to do a Ground Source Heat Pump, we need to know how much ground space you have for a Loop Field, and if you are going to drill boreholes, we will need to know more details about the soil structure. But these details will come later.

By the way, do you have any idea if heating and air conditioning measurements in your country are done in metric or in imperial units? There was a time, long after the world (at least the rational world) converted to metric, thst all HVAC work was still conducted in Imperial units. I ask because we should continue our discussion using the measurement system commonly used in your country.

Sincerely,

-AC_Hacker

[SDMCF]

That heating and cooling degree days link is really useful. What base temperatures are typically used with that data? (For both heating and cooling).

[AC_Hacker]

Originally Posted by SDMCF

That heating and cooling degree days link is really useful. What base temperatures are typically used with that data? (For both heating and cooling).

Yes, it really is useful. If you find other clever uses, please share with us.

It comes up with an average 'best guess' base temp.

If you read the fine print on the site, it goes into good detail.

Best,

-AC_Hacker