Why dig??
 

http://www.mitsubishielectric.ca/en/...ything_img.jpg


Mitsubishi Electric Sales Canada Inc. - Air Conditioning & Heating

"Zuba-Central is capable of heating efficiently down to -30°C and beyond."


If you live in Canada that is.. :p

Can this thing extract heat from the surrounding area when buried in 4 and half feet of snow? Snowfall has been crazy this year!

It's the global warming..
 

I've heard there might be a few decades of cooling before the global warming really kicks in. :rolleyes:

I've been cleaning up the wall of snow around my Sanyo.
Luckily, we had a January Thaw and some rain to clean off the areas where we've
been cleaning off the walks, driveway & parts of the roofs we can reach.

I've got an old snow-rake, leftover from the days when we have solar hotwater panels.
It's coming in real handy for keeping the gutters from being ripped off by the ice ridge.

40F today and back to the 20s F tonight, more snow Friday and below zero F this weekend.

I think the Zuba system will work like most mini-splits, when the coil sucks in too much snow.
It will preform a defrost cycle (while your house cools a little) and then kick back into heating mode.

I find we can avoid some defrost cycles by shutting down the heat when the
wind is blowing the snow and it's is really coming down.
Once the worse is over, it can be turned back on. You just need some good backup heat in the meantime.

Interesting my heat pump just gives up and kicks on the back up at -4C it would be nice to go a little colder without needing that. Right now I just use the woodstove on real cold days though.

For global warming insulation and lots of it is your best friend. We can probably expect brutal hot summers and brutal cold winters with some wicked storms thrown in for the mix. Last year our town has set a new record high and a new record low...

The Sanyo is okay down to about -12C. It still puts out heat, but I'm not sure
how many BTUs I'm getting per watt. I don't think it's all that much.

When I see less than -10C in the forecast, I turn on the flow-through valve,
to allow oil+PV heated water to circulate in the baseboards.
If it's going to stay cold for a long time, I'll set the oil burner timer to kick
in an re-heat the water. 30 minutes on for each 90 to 120 minutes off.

If it going to be colder, (like below -15C) I just turn off the Sanyo and use a backup. :eek:

So these air heatpumps likely consume greater amounts of electricity the more the temperature drops? And puts out fewer BTUs as a result?

yes, they have to work harder to collect what is available as that amount decreases. Eventually they hit a point where they are using more energy then they are collecting so it's not worth running. Where that point is depend on the model plus a bunch of environmental factors.

Yeah
 

You can't use the heating mode on the Sanyo, if it gets too cold..

But, around here, the 'average' really cold day is about -5 C overall.
http://pics2.city-data.com/w1q/lhaq11355.png

As you can see from this chart, -5 C still puts you at about 22,000 BTUs.
If I leave it set for 21 C, it normally uses about 500w.


http://i46.photobucket.com/albums/f1...CL/heatcap.jpg

This table shows the power use from 290w to 2490w.
The specs are a general guide. Mostly your power use will depend on your
indoor set point temp, outdoor temp & dew-point and how tight your house is.
Do you have good insulation? Or high leakage?? Those things determine the monthly bill.

http://i46.photobucket.com/albums/f1...L/poweruse.jpg

I never use 290 watts.. The very minimum is about 440 watts.
At 21 cents per KWH, that's about 9 cents an hour.

If it was zero C and I was still getting 16,200 BTUs out, and the Sanyo was using max power of 2.49kW..
That's still not bad..

Considering that a resistive heating element needs 2.49kW to make 8,446 BTUs..


It's interesting how resistive heaters are such a bad investment.
But, if I had one using 24 kWh a day, (1kW = 3412.142 BTUh)
and it was able to keep us warm during mild weather, for a mere $5 a day..
That's not bad at all..
Compared to sitting in the cold or burning a few gallons of oil..

entirely true. I run about $80-$90/ month in the winter for heat pump heating, electric hotwater and everything else electric using the heat pump and wood stove. My buddy has a much newer better insulated walls and much tighter house but has electric baseboards and he runs $200-$300 per month. My woodstove helps a lot because it's effectively free since I pay about $30/cord when you include gas

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

I kinda like the nameplate..
http://www.mitsubishielectric.ca/en/...ations_img.gif

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

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


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). :D

Hey, that looks a little like my new thermostat!
 

http://www.mitsubishielectric.ca/en/..._2_diagram.jpg

http://i46.photobucket.com/albums/f1...CL/clipped.jpg

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

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

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.

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

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..

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

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!

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.

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

"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.

Hahaha! My idea of a "Solar Assisted Heat Pump", is to use PV to supplement the grid power..


I've been thinking it would be very easy to wire up my AC current sensor
to turn on an AC SSR which would connect a GTI to the AC line..
So, when the Sanyo was using over 400w, a GTI connected to my 400w PV array,
would come on and keep the grid draw to a minimum.. :rolleyes:
(I'm just joking!):D

Or if you don't own land you can dig up- say a condo or rental like my folks. Plus with this guy if you have to move just take the unit with you and put the old furnace back in.

Two complaints about the unit you've mentioned though:

1) If they don't list a MSRP, I can't afford it. :cool:

2) Why do they list F before C in the specifications? Is our backwardness leaking across the border?

Lastly to answer the thread title- because it's fun and a good workout! :thumbup:

I intend to eventually have a hybrid system by augmenting my ground loop with solar water heaters. This would allow me to reduce the size of my ground loop because I'd use it less often, so less long-term cooling of the ground. Also if there is a surplus from the water heaters during daytime it could be cycled through the ground to store energy for better efficiency of the ground loop during the night.

Hopefully I'll have those endeavors on my thread this summer ;)

http://i46.photobucket.com/albums/f1...CL/heatcap.jpg
Assuming these ratings are at the maximum power draw of 2.5kW, this is a table of CoP. 2.5kW = 8500BTU/hr of electricity input, and the table shows you the output. CoP = output over input.

So at -15°C, you have a CoP of 2. At 0°C, the CoP reaches 3 (and my furnace is barely required), and with a ground loop at 7°C, the CoP would be around 3.5 for the entire heating season. The ground loop will also double your heating capacity on the coldest days of the year in Buffalo.

A CoP of 3 is roughly equivalent to the performance of a good natural gas furnace, in terms of cost or CO2.

I never see 2.5kW during normal operations.
The spec says "290w to 2490w" & "4,400 to 29,000 BTU".

Of course, it's warmer here..

On Average:
* Woburn, MA is warmer than Buffalo, NY by 1°F.
* Woburn, MA is wetter than Buffalo, NY by 7.8 in.

Records:
* Woburn, MA recorded the highest temperature of 105°F in 1975.
* Woburn, MA recorded the lowest temperature of -21°F in 1961.

Due to all the heavy snow this winter, (like right now) we have not been able to use the Sanyo exclusively.
Last night, It shut off at 1AM (timer) because of the snow forecast.
(I'm trying to avoid doing a lot of defrost cycles).

But before these last few weeks, we've used very little oil.

Here's some approximate monthly power use.

kWh / Date
164 1-11
284 12-10
226 11-10
94 10-10
25 9-10
61 8-10
116 7-10
60 6-10
64 5-10
110 4-10

1204 kWh ($253)

~300 days is about 7,200 hours. On average, less than 170w per hour.

$25.30 a month for heating and cooling isn't too bad.

And, since we aren't using other (old tech) heating and cooling equipment
as much (no old window ACs at all), our monthly electrical use is actually
a bit lower than before the Sanyo.

Curious where you get this number?

There is an energy comparison tool over at Build It Solar that does the number crunching for you.


To really compare for your area, you'd need to plug in your own energy costs. But just as a test, I used the default values, which are pretty close for where I live and here are the results I found...

I get a minimum COP of 2.0 to break even in cost compared to low-efficiency Natural Gas (85%).

I get a minimum COP of 2.9 to break even in Carbon Dioxide emissions compared to low-efficiency Natural Gas (85%).

I get a minimum COP of 2.2 to break even in cost compared to high-efficiency Natural Gas (93%).

I get a minimum COP of 3.18 to break even in Carbon Dioxide emissions compared to high-efficiency Natural Gas (93%).


The Fujitsu Halcyon 9RLS (9,000 BTU/hr) and the 12RLS (12,000BTU/hr) have a HSPF = 12. If you divide the HSPF by 3.412, you get COP = 3.52.

Pretty impressive, especially considering that with a COP of 3.42, they could beat a Natural Gas furnace running at 100% efficiency (none do).

I do believe that the Carbon Dioxide numbers in the BIS calculator even include electrical power transmission losses.

So, this all generally agrees with a Swedish study done not so long ago, that concluded that Ground Source Heat Pumps were the best source of heating that used manufactured energy. I believe that their study cited a COP of 3.5 as the efficiency level for GSHO in their area.

Those little mini-splits are pretty amazing.

But some GSHPs have hit a COP of 4.5 to 5.


Regards,

-AC_Hacker

P.S.: A house built to Passive House standards is so well insulated, and efficient, that a "heating system" as we know it is not required. In fact since the cost of the heating system can be eliminated, the cost of both types of construction is roughly equal.

I'm paying $1.06/CCF, which is roughly $1.04/therm. I was also comparing a high-efficiency natural gas furnace that I do not own, against heat pumps which I do not own. I find the break-even CoP to be around 3.3.

Make sure you're using marginal cost, i.e. the cost for one more therm. A large slice of my bill is monthly hookup fees, and if I (incorrectly) took them into account, I'd find a price per therm of $1.74.

And yes, if I do build a Passivhaus, or a low-budget approximation thereof, I'll be looking a heating system with a low up-front cost. Efficiency isn't so important when you hardly ever turn it on.

Why would it be incorrect to take them into account? I always include taxes and fees in my $ calculations. Those taxes and fees are rapidly moving towards 30% of the cost for each KWH on my electric bills. It makes a big difference when working out payback periods via savings.

Marginal cost - Wikipedia, the free encyclopedia

Unless you're contemplating getting rid of the gas dryer, stove, and hot water heater, the hookup fee is a sunk cost. You pay $149/yr for gas hookup, regardless of whether you install a furnace or a heat pump. Your first therm of the year costs $150, and each subsequent therm costs $1.

I accounted for taxes and fees that rise with my usage, and I excluded taxes and fees that don't.

I hate when they do that and it's a major reason why I don't have gas at my house even though it is on the street. $150 in an upfront fee would be my summers usage of electricity.

I have to say since this thread is comparing electric heat pumps to natural gas though that fee should be included. If everyone is just ignoring big upfront costs on either service you aren't getting the full picture of what that energy source is really costing you.

I've thought about that. My gas bill when the furnace is off is consistently 7CCF or 8CCF. My bill has a $2.50 city tax and a $8 'basic service' fee. My bill with 8CCF is about $15.

The problem is that we just hit -20F yesterday which is the design 1% temperature where I live and probably the coldest day of January, last years lowest temp was -18.6F in my city. I can't use an air source heat pump, except for the Zuba but the efficiency numbers on the Zuba seem much worse than other air source pumps and the Zuba is probably way out of a cost effective price range for natural gas.

$.746/therm for 30-110 therms
Yesterdays stats
High 2.6 °F Low -20.2 °F Average -7.6 °F
Peak sun was 550 but outside of the 15 minute window, it was about 200 from 9:30AM to 3PM
Furnace ran a total of 7 hours 0 minutes
Input rate is 75000 BTU so 5.25CCF and our therm conversion is pretty much flat here .99372.
$.746/therm for 30-110 therms -This month, the coldest won't use 110.
(5.25*.99372)*.746=$3.892 for the coldest day of the month with a 76% efficient furnace heating.
First 8 hours and 45 minutes used 3hr and 3 minutes which was the coldest part of the night ranging between -13f the first hour, hitting -20 at 7am and warming quickly with the sun to -15 at 8:45am. 57000 BTU output running .35% of the time. Oversized!

...that's not my point though. Most of the December to February winter here has single digit nights which is when the furnace is really needed, no sun for a passive house either, even with tons of insulation a heater would likely still be needed to balance the temps. An ASHP is probably not ideal and November my gas bill was $25, December being a few cents short of $70. January probably $100. Equipment costs get me because I'm struggling with getting a good guess on the cost, installed, of a 95% or higher variable speed furnace, possibly 2 stage so I can go small(thinking 30k output), but have some room for a 2 hour setback recovery from 50 to 70(45k would be enough for a 8.4 degree recovery rate per hour at 0 degrees outside if I figure my 57k output gives me 12 degree heat rise over an hour at that temp).

What would a professional GSHP cost me though? Operating costs can be high with heating but equipment costs in comparison to the difference in the heating costs seem tough to work out. I can't imagine a DIY drill with a post-hole digger that I rent for $40 for a day and drill a bunch of holes will get close to the COP of a decent certified and test ground source heat pump system. If the coldest month is $100 for me($150 with the previous owners last year) with 8 inches of attic insulation, noticeable holes in wall insulation and 5/8" gaps around the windows under the trim. In a house that I will be insulating and air sealing as much as I can without ripping it down, I imagine I can have $100 for a more comfortable temperature next year or cheaper than $100 for say 65 degrees.

Either my natural gas is cheaper than everyone else and my winter electricity price at 11 cents including all of the fees and taxes that are based on kw usage directly. I'm trying to figure out if it could break even in my area even if I factored replacement cost of gas furnace with 95% versus GSHP over say 20 years. Maybe my situation is unique. It definitely would be better than heating oil anywhere, not sure how it compares with propane or other sources of heat. For whole house heat in a central air setup, I'm not sure anything would beat the cost of a GSHP for running costs compared to any other fuel, short of chopping down a fallen forest in the backyard to those who have such as resource available.

"High 2.6 °F Low -20.2 °F Average -7.6 °F"!!!

I've got the best solution.. Move to the sun belt!! Of course, that's just me.
I have to put on a parka to watch the movie "Fargo" or "The Day After Tomorrow"..

http://assets.huluim.com/shows/key_a...r_tomorrow.jpg


Yeppers, People born in South Texas should never be exposed to snow or cold weather.
It could cause irreversible harm!!

I remember when I was a kid.. "Momma, what's a snow shovel"?

Edit:
It's now 9:50PM..
6.3 °F, Clear, Windchill: 6 °F, Humidity: 82%

And, my meter shows the Sanyo is using 490watts (it's set to 21C).
It's not putting out a ton of heat, but it's not doing to bad. Output air coil is 85F.
~
Got bored and stepped it up to 22C. It moved up to 1400w for a few minutes and then
dropped down to 900w, now 880 and so on.. The fan is running faster now and the air warmer. Coil is now 100 degs F..
Have no clue about the BTUs, but it feels good!!

For BeanTown, this is a pretty cold night.. And the Sanyo seems to be holding it's own.. :D

Going back to the original post, I did a quick search and found this! Air Source Heat Pumps for Cold Weather If you look about half-way down the page the poster named biggarthomas installed one of the Zuba-Central units. And the price... :eek:


TomS

Wow! That was with 2.5 days of labor. How many installers?
But, 15,000 Canadian dollars is a pretty good sum.. Get you a real nice used Prius..

That guy also posted here: http://forums.redflagdeals.com/zuba-...ne-has-808426/

$15K could be a very good start toward a GSHP installation... It could also be used to buy a heck of lot of insulation/high quality windows.

-AC_Hacker

That would be a good down payment on the labor cost for a GSHP.. :eek:

Unless you were a DIYer.. :D

If I was a betting man, I would bet that 2.5 days of labor for a crew
of skilled guys, is likely the more than 1/2 the total installed cost.


Just wait, those Zuba-Central units or something similar will available in the USA someday..
And, in another 20 years, maybe we can buy them on-line and do a DIY install.. ;)

I think it would be a better bet to wait for climate change to keep you warm on those chilly nights.

-AC_Hacker