Design and Build Spiv's Solar and Geothermal House - Page 3

Spiv · 07-08-16, 04:21 AM

Quote:

Originally Posted by jeff5may

If you are looking at installing a solar thermal collector array, take a good hard look at "steam back" system design.

We don't seem to have any problems with the systems available in Oz, in previous houses, we often went on holidays and left the house empty in the middle of OUR summer and the solar panels didn't boil or were otherwise affected by excessive heat.

mejunkhound · 07-08-16, 11:32 PM

Had to look up what a WA AUS unit was for gas, elec unit is the kw-hr.

Gas unit is 3.6 megajoules = 1 kw-hr (0.034 therms) 1$ US = 1.3 $ AUS

3.6 megajoule number comes from,
.278*3.6 MJ = 1kw-hr

Rates are gargantuan compared to USA WA state: About 3X higher!

Elec power runs about 30 cents kw-hr including supply charge (AUS$) < 10 cents in WA state USA
Gas is $3.50 a therm ($1.50 or less in USA depending on area)

SPIV: IT IS TIME FOR GSHP! with your high rates.

Really surprised you nat gas rates are so high - of course, prior to fracking, many USA gas prices were over $2 a therm (7 cents a 'unit')

My DIY GSHP (60,000 BTU, 5 ton) cost under $600 and has a COP of 5.7 with 52 deg ground temp below water table.

With the WA high rates, solar is a definite option to consider!

Spiv · 07-09-16, 01:16 PM

Quote:

Originally Posted by mejunkhound

Rates are gargantuan compared to USA WA state: About 3X higher!
......SPIV: IT IS TIME FOR GSHP! with your high rates.

Really surprised you nat gas rates are so high - of course, prior to fracking, many USA gas prices were over $2 a therm (7 cents a 'unit').

And I thought our gas was cheap!!!

Quote:

My DIY GSHP (60,000 BTU, 5 ton) cost under $600 and has a COP of 5.7 with 52 deg ground temp below water table

That sounds good, pity I don't understand it.....

.
Can you help me out with those figures and tell me where to find info on DIY GSPH?

mejunkhound · 07-09-16, 04:48 PM

......help me out with those figures and tell me where to find info on DIY GSPH

If you have not already done so, read ALL 1,910 discussion in AC_Hacker's 'heat pump manifesto' thread !

99% of your technical questions will be answered there.

For the solar questions, look at those threads.
You really should look at solar first given you high energy rates in Perth area.
To assess your solar potential, research 'solar insolation' NOT installation or insulation, inSOLation - e.g.
Australian Climate Averages - Solar exposure

mejunkhound · 07-09-16, 05:07 PM

Just for curiosity I looked at the link on the prev post.

You are pretty much under clouds in July there, eh? Only about 3 kW-hr per day available for a 2 by 3 meter array of solar cells, $1 at your rates, right when you need heat!

so maybe solar is not a good deal in Perth due to overcast skies when you need the power for gshp ?

In January, you will get about $5 worth of power a day from a 2x3 meter array.

Yearly average solar power of maybe close to $1000 though.
A 2x3 meter array PEAK power rating would be about 1.2 kW, Maybe $1500 DIY installed - pretty good payback due to high rates there!

Kinda like parts of Germany, where power rates are close to 40 cent kw-hr, and nearly everybody has some solar or wind.

Does AU have solar subsidies or tax credits? Look into it !

jeff5may · 07-09-16, 11:09 PM

COP: coefficient of performance. A measurement of heat moved divided by power consumed. Watts / watts. Higher is better. Most manufacturers use weighed (seasonally adjusted) measurements for performance figures. All refrigeration units are more effective and efficient when the outdoor air or ground water is close to the target indoor temperature. As the difference widens, it takes more energy to move the same amount of heat. The weighted figures make it easier for the common buyer to choose between units.

Spiv · 07-19-16, 07:24 PM

So,

from the advice received and what I learned from it, it seems that the most appropriate course of action is:

Insulate as much as economically viable.
Ensure good airtightness of the house
Use mini splits
Use Solar PV to assist minisplits in summer
Use gas to to assist minisplits in winter.

Did I get it right?

Minisplits are definitely the easier and cheaper option up front.
I had them installed in previous houses and it only takes an afternoon to get them retrofit, in a new install it might even be easier as the electrical and plumbing can be worked out in advance.

What I have against them in the noise they make and the seem to waste a lot of energy (a lot of heat is produced by the external unit).

I was sort of sold to the idea of hydronic floor heating as a sort of quite and ecological way to get warm in winter, but I might have to give up that idea.....

AC_Hacker · 07-20-16, 10:52 AM

Quote:

Originally Posted by Spiv

[*]Insulate as much as economically viable.

The more you are able to slow heat loss, through rigorous control of infiltration (will require a very high efficiency HRV), and heat loss through walls (insulate > 2X the required insulation in you area)...

...And also use construction that will prevent thermal bridging (which will eat away 18% of your insulation value), the less you will need to heat and cool your house.

Just imagine, silent comfort with no moving parts, due to proper design of your structure.

-AC

07-08-16, 11:32 PM	#22
mejunkhound Apprentice EcoRenovator Join Date: Apr 2011 Location: PNW Posts: 197 Thanks: 0 Thanked 47 Times in 31 Posts	Had to look up what a WA AUS unit was for gas, elec unit is the kw-hr. Gas unit is 3.6 megajoules = 1 kw-hr (0.034 therms) 1$ US = 1.3 $ AUS 3.6 megajoule number comes from, .2783.6 MJ = 1kw-hr Rates are gargantuan compared to USA WA state: About 3X higher! Elec power runs about 30 cents kw-hr including supply charge (AUS$) < 10 cents in WA state USA Gas is $3.50 a therm ($1.50 or less in USA depending on area) SPIV: IT IS TIME FOR GSHP! with your high rates. Really surprised you nat gas rates are so high - of course, prior to fracking, many USA gas prices were over $2 a therm (7 cents a 'unit') My DIY GSHP (60,000 BTU, 5 ton) cost under $600 and has a COP of 5.7 with 52 deg ground temp below water table. With the WA high rates, solar is a definite option to consider! Last edited by mejunkhound; 07-09-16 at 05:23 AM..*

07-19-16, 07:24 PM	#27
Spiv Lurking Renovator Join Date: Apr 2015 Location: On a Catamaran sailing the Oceans Posts: 23 Thanks: 8 Thanked 0 Times in 0 Posts	So, from the advice received and what I learned from it, it seems that the most appropriate course of action is: Insulate as much as economically viable. Ensure good airtightness of the house Use mini splits Use Solar PV to assist minisplits in summer Use gas to to assist minisplits in winter. Did I get it right? Minisplits are definitely the easier and cheaper option up front. I had them installed in previous houses and it only takes an afternoon to get them retrofit, in a new install it might even be easier as the electrical and plumbing can be worked out in advance. What I have against them in the noise they make and the seem to waste a lot of energy (a lot of heat is produced by the external unit). I was sort of sold to the idea of hydronic floor heating as a sort of quite and ecological way to get warm in winter, but I might have to give up that idea..... __________________ Keep smiling Stefano To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

07-09-16, 04:48 PM	#24
mejunkhound Apprentice EcoRenovator Join Date: Apr 2011 Location: PNW Posts: 197 Thanks: 0 Thanked 47 Times in 31 Posts	......help me out with those figures and tell me where to find info on DIY GSPH If you have not already done so, read ALL 1,910 discussion in AC_Hacker's 'heat pump manifesto' thread ! 99% of your technical questions will be answered there. For the solar questions, look at those threads. You really should look at solar first given you high energy rates in Perth area. To assess your solar potential, research 'solar insolation' NOT installation or insulation, inSOLation - e.g. Australian Climate Averages - Solar exposure

07-09-16, 05:07 PM	#25
mejunkhound Apprentice EcoRenovator Join Date: Apr 2011 Location: PNW Posts: 197 Thanks: 0 Thanked 47 Times in 31 Posts	Just for curiosity I looked at the link on the prev post. You are pretty much under clouds in July there, eh? Only about 3 kW-hr per day available for a 2 by 3 meter array of solar cells, $1 at your rates, right when you need heat! so maybe solar is not a good deal in Perth due to overcast skies when you need the power for gshp ? In January, you will get about $5 worth of power a day from a 2x3 meter array. Yearly average solar power of maybe close to $1000 though. A 2x3 meter array PEAK power rating would be about 1.2 kW, Maybe $1500 DIY installed - pretty good payback due to high rates there! Kinda like parts of Germany, where power rates are close to 40 cent kw-hr, and nearly everybody has some solar or wind. Does AU have solar subsidies or tax credits? Look into it !

07-09-16, 11:09 PM	#26
jeff5may Supreme EcoRenovator Join Date: Jan 2010 Location: elizabethtown, ky, USA Posts: 2,431 Thanks: 431 Thanked 619 Times in 517 Posts	COP: coefficient of performance. A measurement of heat moved divided by power consumed. Watts / watts. Higher is better. Most manufacturers use weighed (seasonally adjusted) measurements for performance figures. All refrigeration units are more effective and efficient when the outdoor air or ground water is close to the target indoor temperature. As the difference widens, it takes more energy to move the same amount of heat. The weighted figures make it easier for the common buyer to choose between units.