The Homemade Heat Pump Manifesto

[Spiv]

AC,
so nice of you to offer to help! Thank you!

The house will be built in Coogee (near Fremantle), in Western Australia, Zip code 6166 (if it can help).

The long term averages are Max 23c (72F), Min 12.5c (54F)
with highs of 42c (107F) and lows of 3c (37F).
Humidity is low and and average 125 days of clear skies
One of the best climates in the world....

However, we do need to warm the house in winter.
I the summer we tend to just open the windows and let the breeze in, but some days we get no wind and it gets hot.

The house has been designed with the best R rating in mind, double glazing and insulation in both walls and ceilings. As well as sun angles studies.
I might be wrong, but I think the ground temperature is close to 18c (64F) all year round.

I would also welcome any input from other people who might have experience with a similar climate and or are in Australia and have first hand suppliers info.
Lastly, since I have a low post count, I am not able to send/reply to PMs etc etc so bear with me if I seem to ignore people....

Keep smiling
Stefano

[AC_Hacker]

Originally Posted by Spiv

The house will be built in Coogee (near Fremantle), in Western Australia, Zip code 6166 (if it can help).

This is helpful information.

I did find a Google Map of your location.

I am trying to find more precise Degree Day information, as it will make design suggestions more accurate.

Can you tell me, in order of distance (closest first) where the nearest airports are?

Originally Posted by Spiv

The long term averages are Max 23c (72F), Min 12.5c (54F)
with highs of 42c (107F) and lows of 3c (37F).
Humidity is low and and average 125 days of clear skies
One of the best climates in the world....

This information is very useful, already.

Radiant floor heating is very comfortable, quiet, unobtrusive, and reliable. On a new-build, the cost of installing PEX is very low. The biggest problem with high-mass radiant floor (PEX in concrete) is that it responds very poorly to sudden fluctuations in temperature, since the slab can hold perhaps a three-day charge of heat. So high-mass radiant floors are the greatest for locations that get cold and stay that way through the winter.

Knowing as little as I do at this point, I would guess that your location has many short-term temperature fluctuations. Correct?

Originally Posted by Spiv

However, we do need to warm the house in winter.

If I can get more info on the extent of fluctuations and the frequency of the fluctuations, it might be possible to use high-mass radiant to supply a basic lower-temp thermal component to your winter heating needs and use secondary heating to fill in the gaps. This way, when an unexpected warm period comes your way, you can suspend the secondary source, and the high-mass contribution would still be there, for comfort.

Originally Posted by Spiv

I the summer we tend to just open the windows and let the breeze in, but some days we get no wind and it gets hot.

Here again, detailed degree-day info will be very helpful. So far, it sounds like you wouldn't need central air.

Originally Posted by Spiv

The house has been designed with the best R rating in mind, double glazing and insulation in both walls and ceilings.

OK, it's time to get down to the hard core facts. "...best R rating in mind..." is insufficiently precise to be useful in a careful analysis. You will have to do better than that. If we are going to calculate thermal loss and gain, "best" has no meaning.

The rest of your information looks useful, too. but we need specifics.

Best,

-AC_Hacker

[Spiv]

I did find a Google Map of your location.

This is the actual site.

Can you tell me, in order of distance (closest first) where the nearest airports are?

Jandackot airport about 10km E, Perth International 27km NE.

Radiant floor heating is very comfortable, quiet, unobtrusive, and reliable. On a new-build, the cost of installing PEX is very low. The biggest problem with high-mass radiant floor (PEX in concrete) is that it responds very poorly to sudden fluctuations in temperature, since the slab can hold perhaps a three-day charge of heat. So high-mass radiant floors are the greatest for locations that get cold and stay that way through the winter.

Knowing as little as I do at this point, I would guess that your location has many short-term temperature fluctuations. Correct?

If I can get more info on the extent of fluctuations and the frequency of the fluctuations, it might be possible to use high-mass radiant to supply a basic lower-temp thermal component to your winter heating needs and use secondary heating to fill in the gaps. This way, when an unexpected warm period comes your way, you can suspend the secondary source, and the high-mass contribution would still be there, for comfort.

There aren't really very large excursion, it get gradually cold, stays cold three months and gradually gets warmer, we normally plan heating the house three full months.
So I guess that if we start warming the slabs a few degrees at first than increase it gradually, we will be OK, we can open the windows or wear a jumper if something unexpected was to hit us....

OK, it's time to get down to the hard core facts. "...best R rating in mind..." is insufficiently precise to be useful in a careful analysis. You will have to do better than that. If we are going to calculate thermal loss and gain, "best" has no meaning.

In Au, The Nationwide House Energy Rating Scheme (NatHERS) is a star rating system (out of ten) that rates the energy efficiency of a home, based on its design.
New houses must have at least 6 star, 8 is expensive to achieve, our will have at least 7 stars.
See also Wikipedia.

Keep smiling
Stefano

[AC_Hacker]

If I understand you, your plan is to completely demolish the existing house in the photo, and build an entirely new structure.

Is that right?

Also, the star-rating system that is used in Australia is intended to be used as an evaluation tool by non-technical people. It gives a home buyer a way to decide that one house is better than another.

But for designing a heating or cooling system, a technical person (engineer, etc) needs to know the specific values, in units that are derived for the purpose of mathematical manipulation. Then these units can be used to mathematically calculate total heat loss and heat gain, etc.

Without this technical information, we can only give you vague, general advice about things that ought to work.

By the way, here is a day-by-day heating degree day graph of temperatures in the last 365 days, from the Jandackot Airport (10 km east of you):

The data for this graph comes from precision instruments that automatically measure and record temperatures at the airport that is near your building site.

This graph indicates very large temperature variations during the heating season. This is something to keep in mind as you design your house.

Best,

-AC_Hacker

[Spiv]

If I understand you, your plan is to completely demolish the existing house in the photo, and build an entirely new structure.

Is that right?

No, Google will not allow me to move that stupid marker, the lot is immediately north and empty, the drawings in the first post show the design that will fit on that empty lot.

Since I will start from scrap, I was thinking to install the slinkies below the ground floor slab.

But for designing a heating or cooling system, a technical person (engineer, etc) needs to know the specific values, in units that are derived for the purpose of mathematical manipulation. Then these units can be used to mathematically calculate total heat loss and heat gain, etc.

Without this technical information, we can only give you vague, general advice about things that ought to work.

Well, I cannot give you any more, so whatever help I can get here will definitely be better than nothing.

This graph indicates very large temperature variations during the heating season. This is something to keep in mind as you design your house.

We've lived here for the last 36y with no AC, just heating, we've learned to cope with what comes.....

[AC_Hacker]

Originally Posted by Spiv

Since I will start from scrap, I was thinking to install the slinkies below the ground floor slab.

OK...

The principle of Ground Source heating is that the heat ultimately comes from the sun, and that heat that is held in the ground, is harvested for use in our home.

There is a component of the overall ground heat that comes up from deep in the earth, and usually, the deep earth-thermal energy is small. In general, it is safe to estimate that 97% of the heat energy in the ground is directly from the sun, and 3% is from deep thermal.

Only in very rare situations, does the majority of the heat come up from the ground, due to thermal flow. If you are lucky enough to live in an area where hot water springs are very close to your build, then that source can certainly be harvested.

If you had a bore hole drilled straight down, and water circulated in pipes in the hole, this thermal well would pull in heat from the earth that is surrounding it. Heat moves very slowly in earth, but if you were able to visualize the heat movement, you would see the greatest movement closest to the bore hole, and progressively slower movement, farther away. For practical purposes, you could imagine this movement out to sixteen feet away from the bore hole. In truth it goes farther, but has tapered off so much that it would be considered to be not important. In some areas, such as very frigid areas, the useful diameter is considered to be even larger, as much as twenty-five or more feet. Where I live, a bore hole of 225 feet depth will yield a Ton (12,000 BTU/hr)

So for simplicity, you could imagine that your bore hole is a cylinder, with a radius of sixteen feet. If you place another bore hole sixteen feet away, both thermal wells will be competing for the same heat, but generally, sixteen foot bore hole placements are considered to be OK.

If you have a horizontal pipe, buried in the ground, you have the same situation, but the closer you are to the surface, the less remains of the cylinder.

Slinkys are highly redundant, but they are easy to put in, and overall, they have been proven to work. Where I live, to get a Ton of heat (12,000 BTU/hr) using a slinky configuration, will require an 80 foot long trench buried at least six feet deep. I know from my own measurement, that some of the heat come from rain.

Even with a slinky installation, the same 'cylinder of heat' model of extraction exists. And it is still true that the heat ultimately comes from the sun.

So, my questions for you are,

• If you build your thermal slab on the top of a slinky field, where will the heat ultimately come from?
• Will the slinky field suck heat from your thermal slab?

Best,

-AC_Hacker

[Spiv]

Thank you for the detailed explanation.

Originally Posted by AC_Hacker

So, my questions for you are,

• If you build your thermal slab on the top of a slinky field, where will the heat ultimately come from?
• Will the slinky field suck heat from your thermal slab?

The block is on a limestone hill, there used to be a limestone quarry there.
My brother lives nearby and he sunk a bore to irrigate his garden, but it was not cheap and only 6" in diameter....
I had a house under which I had a cellar, the temperature was around 18c all year round in that cellar, Not sure where the heat comes from, but I guessed that the whole crust stays at that temperature all year.
Alternatively, I could place the slinkies under the driveway, there the sun will heat the ground.

[AC_Hacker]

Originally Posted by Spiv

Thank you for the detailed explanation.


The block is on a limestone hill, there used to be a limestone quarry there.
My brother lives nearby and he sunk a bore to irrigate his garden, but it was not cheap and only 6" in diameter....
I had a house under which I had a cellar, the temperature was around 18c all year round in that cellar, Not sure where the heat comes from, but I guessed that the whole crust stays at that temperature all year.
Alternatively, I could place the slinkies under the driveway, there the sun will heat the ground.

There is an organization called the International Ground Source Heat Pump Association. They have collected technical information regarding the installation of heat pumps for the last 60 years or so. Their information will apply to your situation.

They sell excellent manuals, which can be purchased HERE.

You will see that they have a manual specifically about slinky installations on that page.

This will be exactly the information you will need.

However, the technical questions I was asking you previously, will be central to the successful completion of your project.

Any further questions?

Best,

-AC_Hacker

[Spiv]

Originally Posted by AC_Hacker

.... They sell excellent manuals, which can be purchased HERE.

Those books are expensive.... anyway, upon checking the shipping costs, I was told that they do not ship to Australia.

I am on this forum and more specifically on this thread because I was looking for DIY advice.
If I cannot do it myself, it will not happen as I cannot afford the 18,000~22,000 I was quoted.

So, I was thinking that I could place the collectors and the in-slab pipes and conduits myself, then wait to complete the system as money permits.

Any advice on:

• Type and size of pipes to use for both collectors and in-slab
• Laying, fixing the pipes in the slab
• Number of stations (max lenght of pipes)
• Conduits for thermostats
• Heat pumps: can I DIM or have to spend big money and buy?
• Any more I don't know yet....

[AC_Hacker]

Originally Posted by Spiv

Those books are expensive.... anyway, upon checking the shipping costs, I was told that they do not ship to Australia.

I am on this forum and more specifically on this thread because I was looking for DIY advice.
If I cannot do it myself, it will not happen as I cannot afford the 18,000~22,000 I was quoted.

So, I was thinking that I could place the collectors and the in-slab pipes and conduits myself, then wait to complete the system as money permits.

Any advice on:

• Type and size of pipes to use for both collectors and in-slab
• Laying, fixing the pipes in the slab
• Number of stations (max lenght of pipes)
• Conduits for thermostats
• Heat pumps: can I DIM or have to spend big money and buy?
• Any more I don't know yet....

Regarding the expense of the books, you probably have a rough idea how much you are going to spend on your house. If you divide the cost of the books (yes you can find a way to ship them to Australia) by the amount of money you will spend on your house, the percentage is really very tiny.

You sure can do all of it yourself and save big dollars.

I am an engineer, so that makes me very particular with regards to numbers, and how important it is to pay attention to things like precise heat gain and heat loss, in order to advise you how to spend your money in a way that does you the most good.

From our conversation so far, I suspect that you are the kind of guy who just wants to get on with it. Well, there are plenty of folks here on EcoRenovator who prefer to 'shoot from the hip', and I am quite sure that they will be willing to join in on your project.

Along that line I have just created a new thread dedicated to your project and I invite all of the talent that exists here in EcoRenovator to join in on this exciting project.

Design and Build Spiv's Solar and Geothermal House

Best of Luck!!

Sincerely,

-AC_Hacker