The Homemade Heat Pump Manifesto

[j_abdeen]

Dear AC_Hacker,

I used the calculator on the link, consider total heating degree days 1069c ~= 1924f, and U values from Jordan Building code 2002 Uroof = 1 W/m2.k, Uwall = 1.8 W/m2.k. convert to R then to imperial by divide by 0.176 result in 91K BTU/hr (8 tons).

I prefer to enhance insulation first, the problem is walls, and ceiling are almost finished. do you have any recommendation? have you ever heard about supertherm from SPI coating, is it feasible and practical?

Regards

Jibreel

[AC_Hacker]

Originally Posted by j_abdeen

I used the calculator on the link, consider total heating degree days 1069c ~= 1924f, and U values from Jordan Building code 2002 Uroof = 1 W/m2.k, Uwall = 1.8 W/m2.k. convert to R then to imperial by divide by 0.176 result in 91K BTU/hr (8 tons).

I can’t see your calculations, but from your comments regarding unit conversion (Imperial, metric, etc) it sounds like you were mindful of the conversion problems.

However, when I look at your results, 8 Tons, it looks to be extraordinarily large, especially for a 1700 ft2 apartment.

Below is a yearly average temperature chart, with average daily highs in red (with statistical variations in various lighter shades), and average daily lows in blue (with statistical variations in various lighter shades). From this chart, it looks like the temperatures you would experience in Amman are fairly mild, never going to freezing, and rarely approaching 100 F. Does this seem like a fair description of the weather you experience?

You should go back over your calculations very carefully, because I suspect there is an error somewhere. I would very roughly estimate that you should require about 2-Tons to 3-Tons (or less).

If you know someone in Amman who has a house similar to yours, you should ask them about their heating/cooling requirements, to see if your calculations are close.

One of the reasons this is all so important is that if you want to do ground source heating and cooling, the amount of ground area will be much larger if your heating/cooling requirements are very large, and smaller if your demand is smaller. So less demand, less cost to you.

Originally Posted by j_abdeen

I prefer to enhance insulation first, the problem is walls, and ceiling are almost finished. do you have any recommendation? have you ever heard about supertherm from SPI coating, is it feasible and practical?

The idea of paint on-reflective coating have been discussed with great enthusiasm on our forums, with a few experiments actually being done by our readers, and to date there have been no significantly desirable results noticed.

I don't know if your house has a flat roof, and if you want to have access to it, for instance walk around on it at night. If you had some way to shade the roof, that would be very helpful.

Best regards,

-AC_Hacker

[rvCharlie]

I think the subject of roof coatings deserves a more detailed answer. The ceramic insulation product may or may not have merit, but in a sunny, hot environment, a WHITE roof coating can have a tremendous effect on heat gain in the structure. One of my neighbors covered the galvanized metal roof of his hangar with this stuff:
Black Jack- 5530-1-30

It has virtually no insulation ability; it's basically a roof sealant with a bonus of providing a radiant barrier for sunlight. After coating his roof (no insulation under the roofing metal), he measured the metal temp from inside the hangar on a hot sunny day with a laser thermometer, then went next door & did the same measurement in an uncoated hangar. I don't remember the exact number, but the temp spread was well above 10 degrees F. If you go from a dark roofing material to pure white, the spread would be even greater.

edit: Should have said that I'm in Mississippi, southern USA. A lot more humidity, & probably a little less solar gain than Riyadh.

[jeff5may]

Originally Posted by j_abdeen

Dear AC_Hacker,

I used the calculator on the link, consider total heating degree days 1069c ~= 1924f, and U values from Jordan Building code 2002 Uroof = 1 W/m2.k, Uwall = 1.8 W/m2.k. convert to R then to imperial by divide by 0.176 result in 91K BTU/hr (8 tons).

I prefer to enhance insulation first, the problem is walls, and ceiling are almost finished. do you have any recommendation? have you ever heard about supertherm from SPI coating, is it feasible and practical?

Regards

Jibreel

Something is not right here. The u-values you have reference to here are those typical for an unfinished steel building, such as a grain silo or hangar bay. Single pane glass windows have a u-value around 1.2, double pane windows are around the same value as bare drywall at 0.5-0.7 Watts per square meter per degree Kelvin...

IIRC, most urban buildings in Amman are sheathed in white sandstone or textured concrete. Even a solid stone or concrete shell of a house with no interior finishing would have a u-value below 1. For an armchair consideration, let's assume your lower level is white sandstone and you want the upper level walls to look the same from outside. A 25 mm veneer would have a u-value near 1. Add 100 mm of structural framing and your choice of insulation behind it, with drywall interior surface. The composite u-value for the assembled wall section would lie between 0.05 and 0.08, depending on construction details.

As always, the more details you provide about your real world conditions and methods will help us to get you the information you need before you make expensive mistakes. As with any real property project, having a properly detailed and scrutinized plan before labor is performed will save you big money and labor hours during construction. Having to tear down and rework something during the process can literally send your budget into the heavens.

As for the super-insulating super therm paint, I offer you a case study:

http://www.greenbuildingadvisor.com/...is-own-product

The short story: reflective paint does not count as insulation. Same story as the space blanket bubble wrap.

[j_abdeen]

Dear AC_Hacker,

Thanks for reply, as i mentioned i used values from the 2002 code - the following are the composites of the structure:
walls: 25cm white stone + 3 cm polystyrene + 10 cm concrete block.
expected U value is 1.8 W/m2.k
roof: 18 cm concrete hollow block + 3 cm polystyrene + reinforcement concrete. expected U value is 1 W/m2.k

a study i found from the internet by "Mohammed Ibrahim Daher, Jordan International Energy Conference 2011 – Amman" suggested 10 cm polystyrene to achieve 1.13 W/m2.k for walls and using foam concrete for roofing to achieve 0.2 W/m2.k.

Is there a practical and inexpensive way to measure R values for roof and walls?

I would start by enhancing the insulation, to achieve 3 tons only.

for my calculation it is below:
extreme temp is -5 c ( Oops forget to convert to f)
HDD 1924
ceiling area 1668 ft2, R = 5.6
Walls area 1372 ft2, R = 3.15
windows area 403 ft2, R = 1.6
floor area 1668 ft2, R = 20 assumed.
volume 16421 ft3, 0.5 air change per hour
occupants 5.

new design loss after rectify extreme temp is = 57174 btu/hr

[j_abdeen]

jeff5may
Something is not right here. The u-values you have reference to here are those typical for an unfinished steel building, such as a grain silo or hangar bay. Single pane glass windows have a u-value around 1.2, double pane windows are around the same value as bare drywall at 0.5-0.7 Watts per square meter per degree Kelvin...

Thanks for the clarification, the u values i used where mentioned in the paper I mentioned in the previous reply and it could be not precise.

I think it worth to find the materials specifications and calculate the R value for the structure.

Regards

[AC_Hacker]

j_abdeen,

Here is a conversion slider tool that does an excellent job of conversion.

CONVERSION_TOOL

This should make your job of conversion very much easier and more accurate.

Sincerely,

AC_Hacker

[AC_Hacker]

Originally Posted by superlen

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)...

Superlen,

Haven't heard from you on your project lately.

Last I heard from you, you had ordered the the IGSPHA manual..

Did it come in yet?

Do you have any updates on your thinking?

Any updates on your project?

Best,

-AC_Hacker

[DonT]

I’ve been reading this Manifesto for the past several weeks and I’m on page 58, (I’m a slow reader LOL). I’m thinking about putting in a GSHP this summer.
I’m a contractor doing new construction and remodels etc. so I know a couple of the HVAC, plumber, etc. I can do plumbing and electrical myself.
A bit about my current setup. I live on the MN-IA state line near I35, so my temperature are -30 in the winter to 100 in the summer. My home is build inside of a machine shed on an acreage. The machine shed is 64 x 42 with 16ft sidewalls. I built my loft in the back, 7ft off the ground. Its 18ft x 42ft with an entry 9ft x 12ft so total sq ft is about 864. I have ½ pex tubing hanging 3in down from the subfloor (that was a lot of holes to drill). I have a utility room on the ground floor that’s 12ft x 18ft cement slab with ½ pex tubing. I heat this entire area with a 6000w 10 gallon electric hot water heater, not a boiler. The water temp is set at about 175 deg. For the month of January it cost me $4.95 per day for my heat and hot water (potable). I do NOT have AC. I rig up a window AC that kind works.
So, 1st off would I save enough to make the GSHP pay off? It would add AC so that’s why I‘m thinking about doing it
I have a new 11350 btu R22 compressor a friend gave me, never used.
A friend has a mini-excavator I can rent for $100, so I can trenching in a ground loop about 8 to 10 feet deep.
My nephew works at a place that make stainless steel tanks and he can make my water tanks for me.
What I need to know is how much and what size copper tubing I need to make the Freon to water heat exchanger tanks.
For the ground loop, 1st HVAC guy said I need 300 ft per ton ground loop, the 2nd said 500 ft and the 3rd said 800 ft. So somewhere between 300 and 800 ft, big difference. I would like to narrow that down a bit.
So the big questions are the heat exchangers and the ground loop.
This is just the beginning of a lot of questions.
Don

[AC_Hacker]

DonT,

Welcome to the thread!

The Manifesto thread is long, and it has a lot of information that many people have found to be very useful.

Originally Posted by DonT

I’ve been reading this Manifesto for the past several weeks and I’m on page 58, (I’m a slow reader LOL). I’m thinking about putting in a GSHP this summer.

A GSHP is pretty much the most economical form of heating you can have. But it is not like running you are going to run GSHP right into your ordinary house heating system and expecting everything to work just like it did before, only cheaper.

Most forms of heating, such as: wood, coal, gas, electric-resistance, oil, etc. are all High Temperature Heating. Ground Source Heat Pumps are Low Temperature Heating. It may take a while for this idea to sink in, but it is very important to your success.

EcoRenovator 'randen' already had a GSHP system that he had installed heating his home, and he really loved it. So, after he read into the Manifesto, he though he could build one to heat his shop. It was not quite as easy as falling off a log, but he persisted and his GSHP has reduced his shop winter heating cost from about $2400 (oil) to about $600-ish for the winter (GSHP). (randen, if I got the numbers wrong, please weigh in here with corrections)

One of the most important things to bear in mind is that a GSHP will produce hot water at a temperature of 120F max. And you also need to know that if your heating needs can be met with water running less than 120F, your saving will be much greater, the lower the water temperature you require.

There are three big things that can lower the required water temperature:

1. Minimize the heat loss in your heated space by reducing the infiltration (air leakage) to the very minimum.
2. Increase the quality and quantity of insulation significantly above the required code level.
3. Insure that your heat input method, forced-air or water heated radiating panels, are as efficient as possible.

You can't use the methods that worked for heating with wood, coal, gas, oil, etc. because these methods produce much hotter temperatures than a GSHP is capable of... things need to be done in a different way.

Originally Posted by DonT

I have ½ pex tubing hanging 3in down from the subfloor (that was a lot of holes to drill).

What you have is called "suspended tube" and I'm afraid that I have to tell you that it is the very least efficient setup. It will work if you have very high water temps, but it will not work well for GSHP (low temperature heating).

On this EcoRenovator site there is an extensive discussion on building your own radiant floor that can be successfully heated with a GSHP. That discussion starts right HERE.

Originally Posted by DonT

I have a utility room on the ground floor that’s 12ft x 18ft cement slab with ½ pex tubing.

Out of curiosity, did you insulate your 12ft x 18ft slab and it's edges from the ground with about 2 inches of high density blue or pink insulation board?

Originally Posted by DonT

I heat this entire area with a 6000w 10 gallon electric hot water heater, not a boiler. The water temp is set at about 175 deg. For the month of January it cost me $4.95 per day for my heat and hot water (potable).

There is a big difference between 175F and 120F, so you need to realize the differences when working with GSHP systems.

However, this is a pretty interesting setup.

Some questions for you:

• Where is it that you live? what's the nearest town?
• How much do you pay for a kW-h of electricity where you live?
• What is your ZIP CODE?
• Your $4.96 per day was only for the electricity to the heater only and not to anything else like lighting or anything?
• did you have a circulation pump going all the time?

Originally Posted by DonT

I do NOT have AC. I rig up a window AC that kind works.
So, 1st off would I save enough to make the GSHP pay off? It would add AC so that’s why I‘m thinking about doing it

The EcoRenovator named 'randen' did a setup like you are describing and he has loads of hands-on experience. I have a hunch that you'll be hearing from him pretty soon.

I have a new 11350 btu R22 compressor a friend gave me, never used.
A friend has a mini-excavator I can rent for $100, so I can trenching in a ground loop about 8 to 10 feet deep.
My nephew works at a place that make stainless steel tanks and he can make my water tanks for me.

Originally Posted by DonT

What I need to know is how much and what size copper tubing I need to make the Freon to water heat exchanger tanks.

We have had several people here build Heat Pump water heaters from scratch, and they all worked really great. However, none off them were built using a 11350 BTU heat pump. I think that most of them were using compressors about half that size, and they were using copper loops in the tanks that were about 30 feet in length, so you should be able to scale them up pretty easily, like about twice the length, and you would want to increase the diameter a bit. There have been several very clever designs, each with unique features that proved advantageous.

Originally Posted by DonT

For the ground loop, 1st HVAC guy said I need 300 ft per ton ground loop, the 2nd said 500 ft and the 3rd said 800 ft. So somewhere between 300 and 800 ft, big difference. I would like to narrow that down a bit.
So the big questions are the heat exchangers and the ground loop.
This is just the beginning of a lot of questions.
Don

I think that the 300 ft and 500 ft are too short, and I think that the 800 ft might be short also. A lot of it has to do with the year round ground temperature where you live. It also matters what the soil conditions are where you live, sand? clay? wet? dry? a lot of variables.

It will be helpful to know from professional GSHP installers in your area what will work.

But the most important thing you need to know is how much heat does your house require in the worst months? In other words, how much is it losing?

I can calculate it for you if you tell me your price per kW-h, and zip code.

That will tell you how much loop field you will need and how many BTU/h your compressor needs to put out.

Talk you soon,

-AC