Why dig??

[RobertSmalls]

Why dig? To tap in to a reservoir of 10°C year round, for a higher CoP and greater capacity.

It's kind of silly that this ASHP's nameplate capacity happens at an ambient temperature where people do not need to heat their houses. :-P

[Xringer]

I kinda like the nameplate..


If the dry bulb temp outdoors is 70 F, and I want to be 72 F indoors,
I'm gonna be happy.

Old folks are sometimes sensitive to the cold. That's why we wear
sweaters to the cinema in the summer time..


Anyways, my question "Why dig?" (applies mostly to Canadians)
is meant to get those folks up north thinking about all the heat
they can harvest right out of thin air..

Even in Canada, I'll bet a lot of folks don't live where it gets down to -70 F,
for very long. And a Zuba system will surely be quicker and easier to install.
Less installation labor cost is a big plus.
If the actual equipment cost is about the same as GSHP cost..?.
That could make the total installed costs less.
Of course the first adopters are going to charged extra (for R&D etc).

One other consideration is the land. Do you own a good sized piece of land?
Is the thin layer soil, sitting on top of a giant rock pile of granite boulders?

(I have some XXL granite boulders for sale. Cheap too. But buyer pays shipping).

[Xringer]

Which I actually got to use a few hours last week, when it got down under 5 deg F.

[AC_Hacker]

Originally Posted by Xringer

If the actual equipment cost is about the same as GSHP cost..?. That could make the total installed costs less.

I think you need to know and include the COP of both ASHP and GSHP systems to have a meaningful conversation here.

If you don't include the operating cost and the expected equipment life, your comments could be misleading.

-AC_Hacker

[Ryland]

Originally Posted by AC_Hacker

I think you need to know and include the COP of both ASHP and GSHP systems to have a meaningful conversation here.

If you don't include the operating cost and the expected equipment life, your comments could be misleading.

From what I've read about air source heat pumps, their operating cost ends up being about the same amount per BTU as I pay for natural gas to heat my house, Home Power magazine had an article 2 months back on the topic and they gave a charge comparing fuel use for different forms of heating, of course it has already been stated that if it's 70F outside and you want it 72F it will take very little energy to pull that heat inside, of course I don't even turn my furnace on until it's 45-50F outside for a few weeks straight as my house tends to stay pretty warm without the furnace just from the solar gain from south facing windows.
I also checked in to the ground source heat pumps and because my soil is sand I was informed that I would have to install a layer of clay and a drain field so I could flood the soil, adding a great deal of cost to the install and increase the operating costs.
I'd like to see someone combine a heat pump with solar hot water panels instead of a ground loop for people like me who have poor soil, allowing you to use the sky as a heat sink.

[AC_Hacker]

Originally Posted by Ryland

I also checked in to the ground source heat pumps and because my soil is sand I was informed that I would have to install a layer of clay and a drain field so I could flood the soil, adding a great deal of cost to the install and increase the operating costs.

Ryland,

There's a really good reason why Xringer should not dig. The soild where he lives if full of hard flinty stones, which is very tough to dig through.

But if you are in a different location, where the soil is mostly sand, things might look a little different...

I've looked over the charts that describe various types of soils.

For heat transfer, dry sand is the worst and wet sand is the best.

So I'd say that the advise you got is right, but it's not completely right.

Dry sand is really pretty rare, and it would be unusual, but not impossible, to have only dry sand as you drill deeper and deeper.

But, just assuming that you have dry sand, and it is the worst soil for thermal transfer, that would not mean that GSHP will not work for you. What it would mean us that you'd need more holes if you went down, or more trenches if you went that route.

On the bright side however, sand (dry or wet) is the easiest soil to dig through. It's quite possible that you could dig a loop field by had with a post hole auger and some extention pipes.

I did.

-AC_Hacker

[Xringer]

Originally Posted by AC_Hacker

I think you need to know and include the COP of both ASHP and GSHP systems to have a meaningful conversation here.

If you don't include the operating cost and the expected equipment life, your comments could be misleading.

-AC_Hacker

I did use the word 'If'... I have no clue of the cost of these new systems.
But, at first glance, they appear to be the hot-rod version of what's
keeping me at 75 *F right now, while it's 25 F outdoors. It's using 680 watts..
(*Why so toasty? It's movie night! "Salt" is playing).

IMHO, imported ASHP systems are getting better all the time. And should not be off the table,
just becasue a GSHP will still work when it's -107 C outside..

So, let me qualitfiy my statements, if any Canadians want to perform
some Due Diligents, these new ASHPs might be well worth looking into..

[Xringer]

Originally Posted by Ryland

From what I've read about air source heat pumps, their operating cost ends up being about the same amount per BTU as I pay for natural gas to heat my house, .

ASHP cost, might not be cheap as gas heat, but we don't have gas on my street..

And, I kinda like it like that.. When we go for a walk into Lexington,
we can smell the natural gas leaks. It comes up out of the streets.

Hank Investigates - Gas Leaks

Watch the video. About 22,000 leaks!

[AC_Hacker]

Originally Posted by Xringer

ASHP cost, might not be cheap as gas heat, but we don't have gas on my street..

Xringer,

Dont be so damn humble.

I ran the numbers and a really good mini-split out performs gas heating, both in terms of cost of opperating, and also in terms of Carbon Dioxide production.

Other than solar, the only thing that a really good mini-split won't out perform is a really good GSHP.

I suspect that Ryland's ASHP is an earlier model.

Originally Posted by Ryland

I'd like to see someone combine a heat pump with solar hot water panels instead of a ground loop for people like me who have poor soil, allowing you to use the sky as a heat sink.

Now, this would be a really great combo.

For one, if it was properly balanced, a heat pump working in combination with a hot-water solar panel would raise the efficiency of the solar panel (greater delta-T), and the solar panel would increase the efficiency of the heat pump (lower delta-T).

A real win-win.

I have seen a few papers on this by some Turkish scientists. The term is, "Solar Assisted Heat Pump".

Xringer, you've had solar HW panel experience, and you own all the tools to required to make a heat pump.

(we're waiting..........)

-AC_Hacker

[RobertSmalls]

"Still works" is one thing (and it sounds like a new and interesting development), but do you have any data on the CoP of these units when it gets cold out? As AC Hacker suggested, you can't have a meaningful discussion of cold-climate operation of an ASHP without this data.

I do most of my heating at -5°C to -10°C. Colder days aren't that common, and warmer days don't require much heating. Hence, in this climate (which is milder than the upper midwest), that's the temperature range in which I need to size a heat pump.

From what I gather, boreholes aren't cheap around here (and you have to watch out for natural gas if you drill deep enough!), so I'm inclined to dig a pit or a trench if I do a heat pump install, but I'll be sure to look for data on the ASHP option as well.