# The cold hard numbers of my Heat Pump + part II



## Amaralluis

I got my december hydro bill and heres the cold hard numbers about my heat pump vs pellet stove since it was installed on November 1st.

My electric bill runs from around the 17th of every month. For Nov/Dec period in 2009 I've used 572KWH for a period of 28 days (I know it was awesome) with the pellet stove. In 2010 the total was 1298Kw for a period of 29 days with the heat pump.
For dec/jan then the usage was 786KWH for 2009 and 1739KWH for 2010.

The difference between 2009 and 2010 besides the pellet stove we had a teen that moved in August, which increased the electric usage for quite a bit. It was not a constant difference so what I did is that I took the difference between 2009 and 2010 for august, september and October and calculated the average of the difference for those months. With it Im assuming that approx 390Kwh over 30days are because of the extra person in the Household. I know that its not super accurate but Its the only way I thought to get an idea of how much the person costs. If someone has a better idea please let me know. 

This means that for nov/dec period the heat pump used approx 336Kwh and for dec/jan 563Kwh.
The hydro price is $0.11, 336*0.11=$36.96 and 563*0.11=$61.93.
Pellets used for the same period of time in 2010 = 0

Unfortunately I didnt record the bags usage in 2009 so I dont know exactly how many bags were used, but I can safely say that it  would averaged one bag per day so 29+33=62 bags. Cost of Bags $6.20 (with the taxes).
62*$6.20=$372.22

There you have it, $372.22-$98.89=$273.33 difference. 
Are this numbers accurate? 
No.
Do they tell me something?
Yes, the heat pump is saving me money from pellets, It might not be saving me $273 up until now, but it is undoubtedly saving me money.

PS - I know that the pellet stove also used electricity but I cant put a KWH value to it but from the readings in 2009 it was not considerable.


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## begreen

It doesn't surprise me, was the temperature of the house identical? One thing for sure, you are paying too much for pellets. At $6.20/bag they are much too pricey.


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## Amaralluis

I agree that the price of pellets is too high. I bought it at that price when they were on sale @ $5.49+tax (13%). Otherwise the price of pellets for the longest of time was $6.99+tax, but later last year it was $5.99-$5.49 + Tax of course.
As for the temperatures the answer is no. With the pellet stove I had a programmable thermostate to have the temp @ 20 when we were home and 17 at night or when we were at work. With the heat pump I leave at 21c all the time.


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## phatfarmerbob

Tax on pellets ?  are they not a fuel for home heating .... home heating fuel is tax exempt


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## Amaralluis

phatfarmerbob said:
			
		

> Tax on pellets ?  are they not a fuel for home heating .... home heating fuel is tax exempt


I wish....


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## phatfarmerbob

Really it seems to me there aught not to be tax on them


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## PastTense

There is another difference between the two years: the weather. You might try to find the heating degree days for those years and compensate.


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## midwestcoast

phatfarmerbob said:
			
		

> Really it seems to me there aught not to be tax on them


Since he used metric temps I assume he's in Canada. Different tax rules.


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## Amaralluis

Hello,

Yes I am in the Maritimes Canada.
I will have to look at the degree temps but I have a feeling that this year has been colder than last year.


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## henkmeuzelaar

Thanks very much for reporting your pellet stove and heat pump numbers. I am trying to figure out whether the cost of installing a heat pump makes any sense for our new loghome in the Idaho Rocky Mountains in view of the low electric rates (less than $ .05/kWh) here and the purported loss of COP in really cold weather. So I tried to rewrite your cost comparison numbers into energy budget data.

Your estimated 62 bags (40 lb each, I assume) of pellets should have generated roughly 20 million BTUs. Even at a low pellet stove efficiency of 75% (including the power cost of running the pellet stove auger) , this corresponds to no less than .75 x 20,000,000 / 3412 = 4396 kWh.

When running the heat pump in 2010 your electric power usage over the two months increased by a little over 1600 kWh. So even if you do not subtract the teenager's extra power usage, this would already correspond to a heat pump COP in the  2.5 to 3.0 range (4396/1600) which is very good for these cold winter months.

I know there are many other variables (weather differences, pellet stove operation, etc.) not fully accounted for, but the suggested heat pump performance got my full attention!!

Please tell us more about the type (ductless?), brand and model of heat pump and how it was installed. 

Henk


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## henkmeuzelaar

PyMS said:
			
		

> >
> Please tell us more about the type (ductless?), brand and model of heat pump and how it was installed.
> 
> Henk




Sorry Amalluis, I just noticed the parallel thread where you described your heat pump as a Daikin 15,000 BTU unit.
I have found some US dealers but am still looking for any attractive discounts/sales by one of the large national a/c suppliers.

Henk


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## Amaralluis

Hey PyMs.
You are correct it is a Daikin FTXS15 model.
At -18 outside the unit was still able to maintain the temp, this is really impressive technology.

The idea of this thread was to give out real meaningful numbers that everybody can relate to.
Everybody understands KWH and 40lbs bags.
Everybody understands that my heat pump used 500kwh in one month against using 30 pellet bags instead of saying the it has COP of 3 or that the output of BTUS was X based on X degree Days.


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## henkmeuzelaar

Amaralluis said:
			
		

> Hey PyMs.
> You are correct it is a Daikin FTXS15 model.
> At -18 outside the unit was still able to maintain the temp, this is really impressive technology.
> 
> The idea of this thread was to give out real meaningful numbers that everybody can relate to.
> Everybody understands KWH and 40lbs bags.
> Everybody understands that my heat pump used 500kwh in one month against using 30 pellet bags instead of saying the it has COP of 3 or that the output of BTUS was X based on X degree Days.




Well, yes it is of course always better to provide easy-to-understand information if that will do the job.

In my particular case, however, it is not enough to know that electric heat sources can save money over wood pellet stoves. At our very low electric power rates even simple resistive heaters save quite a bit of money in fuel costs alone when compared to pellet stoves.   

Therefore, what people in my situation need to know is whether more complex and expensive electricity-driven systems such as heat pumps can save enough money -- compared to inexpensive resistive heating -- to pay for themselves in a limited number of years. 

Calculating the COP provides a relatively straightforward mechanism to make that decision.  In short, if the COP would be much closer to 1.0 in winter, an expensive heat pump install would be a waste of money (unless one lives in a warm climate where it could pay for itself in summer, of course).  

Henk


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## begreen

That is correct if the electricity is cheap enough. The decision needs to be based on what you have, what you need, and how reliable current rates will be into the foreseeable future.


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## woodsmaster

midwestcoast said:
			
		

> phatfarmerbob said:
> 
> 
> 
> 
> Really it seems to me there aught not to be tax on them
> 
> 
> 
> Since he used metric temps I assume he's in Canada. Different tax rules.
Click to expand...


Here in Ohio there is tax on kerosene. I think that it's wrong, but... Not sure about pellets.


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## woodgeek

PyMS said:
			
		

> Thanks very much for reporting your pellet stove and heat pump numbers. I am trying to figure out whether the cost of installing a heat pump makes any sense for our new loghome in the Idaho Rocky Mountains in view of the low electric rates (less than $ .05/kWh) here and the purported loss of COP in really cold weather. So I tried to rewrite your cost comparison numbers into energy budget data.
> 
> Your estimated 62 bags (40 lb each, I assume) of pellets should have generated roughly 20 million BTUs. Even at a low pellet stove efficiency of 75% (including the power cost of running the pellet stove auger) , this corresponds to no less than .75 x 20,000,000 / 3412 = 4396 kWh.
> 
> When running the heat pump in 2010 your electric power usage over the two months increased by a little over 1600 kWh. So even if you do not subtract the teenager's extra power usage, this would already correspond to a heat pump COP in the  2.5 to 3.0 range (4396/1600) which is very good for these cold winter months.
> 
> I know there are many other variables (weather differences, pellet stove operation, etc.) not fully accounted for, but the suggested heat pump performance got my full attention!!
> 
> Please tell us more about the type (ductless?), brand and model of heat pump and how it was installed.
> 
> Henk



At <$0.05/kWh, I would think that COP=1, electric heat might be cheaper than pellets!


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## Amaralluis

I wish it was that cheap too.


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## henkmeuzelaar

woodgeek said:
			
		

> PyMS said:
> 
> 
> 
> 
> Thanks very much for reporting your pellet stove and heat pump numbers. I am trying to figure out whether the cost of installing a heat pump makes any sense for our new loghome in the Idaho Rocky Mountains in view of the low electric rates (less than $ .05/kWh) here and the purported loss of COP in really cold weather. So I tried to rewrite your cost comparison numbers into energy budget data.
> 
> Your estimated 62 bags (40 lb each, I assume) of pellets should have generated roughly 20 million BTUs. Even at a low pellet stove efficiency of 75% (including the power cost of running the pellet stove auger) , this corresponds to no less than .75 x 20,000,000 / 3412 = 4396 kWh.
> 
> When running the heat pump in 2010 your electric power usage over the two months increased by a little over 1600 kWh. So even if you do not subtract the teenager's extra power usage, this would already correspond to a heat pump COP in the  2.5 to 3.0 range (4396/1600) which is very good for these cold winter months.
> 
> I know there are many other variables (weather differences, pellet stove operation, etc.) not fully accounted for, but the suggested heat pump performance got my full attention!!
> 
> Please tell us more about the type (ductless?), brand and model of heat pump and how it was installed.
> 
> Henk
> 
> 
> 
> 
> At <$0.05/kWh, I would think that COP=1, electric heat might be cheaper than pellets!
Click to expand...




Yep, at $0.05/kWh it should only cost a little over $200 to generate a similar amount of usable heat with electrical resistance heaters as generated from 60 bags of wood pellets. Even at 4 dollars per bag that would still be a losing game, let alone at the 6 dollars the OP was paying.

At the same time, however, the calculated heat pump COP of 2.5 or better suggests that I might be able to save approx. $ 600 to 750 per heating season in my own home by a DIY install of a $3,000 or so ductless, minisplit heat pump system. If so, the system would pay for itself in 4-5 years.

Just in case the OP's numbers might have been jinxed by weather differences, etc., I plan to keep an eye out for more heat pump cold climate performance data on this site before definitively committing to such an install. 

Henk


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## woodgeek

PyMS-- It is amazing how much everyone's situation differs.  At your low electric rate, the savings from a HP (relative to elec resistance) is so low, I can see how it might be hard to justify the cost of the unit.  Now I am a big fan of ASHPs, and they make a lot of sense in mild climates like Maritime Canada (Amaralluis), the PNW (Begreen) or the MidAtlantic (Me), not to mention points south, BUT it seems that your climate is a bit more, well, extreme.   Between the cheap elec and the climate it isn't clear what your ROI would look like.  

I would assume that it would shut down at some reasonable temp like 15-20Â°F, and estimate how many BTUs it would deliver seasonally when temps were above that.  That is, if you know your demand you can figure at what outdoor temp the unit can carry you to without backup (say 25F), and what fraction of your seasonal heating demand are above that temp. Add to this the number of hours you spend below that point down to some set shutdown temp (say 15F) times the average BTU output running full cycle.  I would then assume a worst case SCOP for those BTUs of ~2.0, and compute your savings and ROI on that basis.

If you get like 10 feet of snow on a regular basis, I guess you know to mount it on the side of your house.


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## henkmeuzelaar

Thanks for the valuable input, WoodGeek.

One option that I have been thinking about is to try a ductless heat pump with outside (or garage-based) air intake and see what the COP turns out to be for 1 or 2 winters. If the results are disappointing we could then perhaps use our well water plus a suitable water/air heat exchanger (e.g. a big old car radiator?) to preheat the intake air a bit. I have noticed that water-to-air systems tend to have much better COPs.

I know one can directly buy water-to-air HPs but am assuming that one cannot simply have an air-to-air heat pump modified to water-to-air operation at reasonable cost unless one is willing to do it oneself.

Either way, this would require that we have a shallow re-injection well drilled and I am not sure how difficult it might be to get a permit for that since we do live in a pretty fussy county, alas. 

Henk


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## begreen

PyMS said:
			
		

> Thanks for the valuable input, WoodGeek.
> 
> One option that I have been thinking about is to try a ductless heat pump with outside (or garage-based) air intake and see what the COP turns out to be for 1 or 2 winters. If the results are disappointing we could then perhaps use our well water plus a suitable water/air heat exchanger (e.g. a big old car radiator?) to preheat the intake air a bit. I have noticed that water-to-air systems tend to have much better COPs.
> 
> I know one can directly buy water-to-air HPs but am assuming that one cannot simply have an air-to-air heat pump modified to water-to-air operation at reasonable cost unless one is willing to do it oneself.
> 
> Either way, this would require that we have a shallow re-injection well drilled and I am not sure how difficult it might be to get a permit for that since we do live in a pretty fussy county, alas.
> 
> Henk



A ductless system recycles interior heat, it doesn't have an outside air intake. Just the compressor sits outside. The heat transfer is done with the freon coolant.


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## henkmeuzelaar

Sorry for my confusing terminology. What I referred to as the "air intake" is the forced airflow past the compressor's freon-to-air heat exchanger. I understand that this is normally a wide open fan box, but know that it is usually fairly easy to attach some ducting to the intake (suction) side of the fan in order to move the actual "air intake" (sorry for using that term again) to a more advantageous nearby location.

So, in my simple-mindedness, I assume that it must also be possible to cap off that inlet air flow with a water-to-air heat exchanger that would slightly preheat the intake air using well water.

Looking forward to any further corrections or suggestions;

Henk   






			
				BeGreen said:
			
		

> PyMS said:
> 
> 
> 
> 
> Thanks for the valuable input, WoodGeek.
> 
> One option that I have been thinking about is to try a ductless heat pump with outside (or garage-based) air intake and see what the COP turns out to be for 1 or 2 winters. If the results are disappointing we could then perhaps use our well water plus a suitable water/air heat exchanger (e.g. a big old car radiator?) to preheat the intake air a bit. I have noticed that water-to-air systems tend to have much better COPs.
> 
> I know one can directly buy water-to-air HPs but am assuming that one cannot simply have an air-to-air heat pump modified to water-to-air operation at reasonable cost unless one is willing to do it oneself.
> 
> Either way, this would require that we have a shallow re-injection well drilled and I am not sure how difficult it might be to get a permit for that since we do live in a pretty fussy county, alas.
> 
> Henk
> 
> 
> 
> 
> A ductless system recycles interior heat, it doesn't have an outside air intake. Just the compressor sits outside. The heat transfer is done with the freon coolant.
Click to expand...


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## begreen

I would suspect that the net gain of this type of mod would be short lived. These units move a fair amount of air which should not be restricted. To assure free flow I would think that would require a lot of air exchange from the garage which would very quickly cool it down to ambient. Maybe it would work if you had a barn full of animals to draw the heat from? 

The issue I would have with using water is how do you stop it from freezing? Above freezing these units are already amazingly efficient. My thought is for all the work, it's not worth it. The really good units are quite well fine tuned for performance already. If there was an easy way to make it better they would do it.


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## henkmeuzelaar

Yeah, you are right. After reading up on heat pump compressor fans a bit more I realize that they are much too finely balanced to mess around with.

I think our well water has a high enough temperature, though, to yield up to 7 degF without freezing. If so, I might be able to produce ~1 kW at a flow rate of 1 gal/min. Of course, a single stage water-to-freon heat exchanger (such as available in geothermal heat pumps, if I understand well) would be preferable by far.  

The only reason I briefly played with the idea of a DIY mod is that I am not ready for the cost of a complete ground-based (geothermal) HP system -- even with the big tax rebates-- and therefore was looking for a way to start first with a standard air-based HP.

All in all, I think I'm gonna stick with resistive heating, plus passive energy conservation measures, for now and see where the power and technology markets are headed.

Henk    




			
				BeGreen said:
			
		

> I would suspect that the net gain of this type of mod would be short lived. These units move a fair amount of air which should not be restricted. To assure free flow I would think that would require a lot of air exchange from the garage which would very quickly cool it down to ambient. Maybe it would work if you had a barn full of animals to draw the heat from?
> 
> The issue I would have with using water is how do you stop it from freezing? Above freezing these units are already amazingly efficient. My thought is for all the work, it's not worth it. The really good units are quite well fine tuned for performance already. If there was an easy way to make it better they would do it.


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## Mr. Heat Miser

Amaralluis said:
			
		

> PS - I know that the pellet stove also used electricity but I cant put a KWH value to it but from the readings in 2009 it was not considerable.



I have measured the electricity consumption of several pellet stoves with a P3 Kill A Watt meter and they average between about 125 Watts to 150 Watts instantaneous power draw depending on the auger and blower settings.

Here's some actual numbers from a 20+ year old Whitfield Advantage II T Insert. During the monitoring period of approximately 2 weeks the stove was running 24 hours a day, only being shutdown for routine cleanings, with the auger and blower speeds being adjusted as usual by the user.

Instantaneous Measurements: 
Stove Settings:   Auger = 2, Blower = 3

Auger Off                    Auger Feeding

76 Watts                     100 Watts
1.33 Amps                  1.71 Amps
159 Volt Amps             197 Volt Amps
.48 Power Factor         .48 Power Factor              

Electric Rate:   19.1 cents/kWh   (Townsend, MA)

Elapsed Time  353 hours   (14 days, 17 hours)
kWh's used:     29.81
Total Cost:     $ 5.69        (29.81 kWh x .191 = $5.69) 

Projected Costs to run stove

6 Months   $70.00
1 Month     $11.55
1 Week     $ 2.69
1 Day       $ 0.38

Based on the measurements above I could estimate that this stove uses approximately 2 kWh per day or 60 kWh per month the way the user runs it. Many articles I have read estimate about 100 kWh per month for pellet stoves, which is an acceptible number, but probably a little high.

Surprisingly, my 2010 Harman P35i uses slightly more electricity than the Whitfield (125 Watts - Auger Off, 150 Watts Auger On), and most notably consumes a significantly higher amount (395 Watts) when using the electric heating element for the auto igniter, but only for about 6.5 minutes when starting the fire. This does not really add a significant cost to the electricity consumption however. Here's an example:

395 W x 1 hr = 395 Watt Hours     (That's about .4 kWh for roughly 10 fires - 1 hr / 6.5 minutes)

So for every 20 fires, (about 20 days at 1 fire a day) the stove uses about 1kWh if you added up the consumption for the first 6.5 minutes of operation while the igniter is on, which for me costs 19.1 cents - fairly insignificant.


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## henkmeuzelaar

Thanks for the real-world energy budget data Mr. Heat Miser. I have noticed that most pellet stove manufacturers talk about 100 Watts, or so, electric power consumption. 

This might, of course, reflect advances in blower and/or auger technology since you bought your stoves or it might mean that blower and/or auger might have started to use a bit more power as they aged and friction losses in bearings increased...

Either way, it is very useful to have these type of data when planning a new home heating system.

Henk


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## Amaralluis

Mr. Heat Miser said:
			
		

> Amaralluis said:
> 
> 
> 
> 
> PS - I know that the pellet stove also used electricity but I cant put a KWH value to it but from the readings in 2009 it was not considerable.
> 
> 
> 
> 
> So for every 20 fires, (about 20 days at 1 fire a day) it uses about 1kWh which for me costs 19.1 cents - fairly insignificant.
Click to expand...

Thanks for the numbers. They do confirm my suspicions.


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## Mr. Heat Miser

PyMS said:
			
		

> Thanks for the real-world energy budget data Mr. Heat Miser. I have noticed that most pellet stove manufacturers talk about 100 Watts, or so, electric power consumption.
> 
> This might, of course, reflect advances in blower and/or auger technology since you bought your stoves or it might mean that blower and/or auger might have started to use a bit more power as they aged and friction losses in bearings increased...
> 
> Either way, it is very useful to have these type of data when planning a new home heating system.
> 
> Henk



Actually, the 20 year old Whitfield uses less power than my brand new 2010 Harman P35i, which was surprising to me.


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## Mr. Heat Miser

Amaralluis said:
			
		

> Mr. Heat Miser said:
> 
> 
> 
> 
> 
> 
> 
> Amaralluis said:
> 
> 
> 
> 
> PS - I know that the pellet stove also used electricity but I cant put a KWH value to it but from the readings in 2009 it was not considerable.
> 
> 
> 
> 
> So for every 20 fires, (about 20 days at 1 fire a day) it uses about 1kWh which for me costs 19.1 cents - fairly insignificant.
> 
> Click to expand...
> 
> Thanks for the numbers. They do confirm my suspicions.
Click to expand...


This 1 kWh for every 20 fires is only counting the total juice the stove consumes while the igniter is on. For a more accurate overall consumption for the Whitfield (which does not have the auto igniter) the numbers are about 2 kWh per day, or 60 kWh per month.


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## Amaralluis

Got my february hydro bill.

Heres the numbers.

2010 697Kwh for a period of 31 days. 
2011 1587kwh for a period of 28 days.

This results for 2010 in a daily consumption of 22.48Kwh and in 2011 56.68Kwh which makes a difference of 34.19kwh more in 2011 compared to 2010.
From this amount I take out 13.10kwh for the extra person in the household (read my first post) and Im left with 21.10Kwh daily usage for the heat pump.

21.10*28days for a total of 590Kwh for the period of 28 days.
At 11cents/kwh, the cost of the heat pump was approx $65.00.

I had to shut down the heat pump for one evening. The temps dropped below -20C and the heat was still blowing warm air but the defrost mode kicked too often and it couldnt keep the temp in the house. Used one pellet bag for the night. ($6.20)

The hard numbers? Assuming It would only burn one bag a day, the pellet stove would cost 28*$6.20=$173.
$173-$65-$6.20=$102 savings. Not bad.


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## semipro

PyMS said:
			
		

> Sorry for my confusing terminology. What I referred to as the "air intake" is the forced airflow past the compressor's freon-to-air heat exchanger. I understand that this is normally a wide open fan box, but know that it is usually fairly easy to attach some ducting to the intake (suction) side of the fan in order to move the actual "air intake" (sorry for using that term again) to a more advantageous nearby location.
> 
> So, in my simple-mindedness, I assume that it must also be possible to cap off that inlet air flow with a water-to-air heat exchanger that would slightly preheat the intake air using well water.
> 
> Looking forward to any further corrections or suggestions;
> 
> Henk



Interesting idea and one similar to something I've considered.  My thought: take a flowing source of water such as a spring, pipe that to a tank so that there's a constant flow of water, and then immerse your Heat pump unit's external coil in this tank (just the coil of course not the compressor or fan).  

Of course a freon to water heat exchanger would work better but I was just thinking...


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## henkmeuzelaar

Semipro said:
			
		

> PyMS said:
> 
> 
> 
> 
> Sorry for my confusing terminology. What I referred to as the "air intake" is the forced airflow past the compressor's freon-to-air heat exchanger. I understand that this is normally a wide open fan box, but know that it is usually fairly easy to attach some ducting to the intake (suction) side of the fan in order to move the actual "air intake" (sorry for using that term again) to a more advantageous nearby location.
> 
> So, in my simple-mindedness, I assume that it must also be possible to cap off that inlet air flow with a water-to-air heat exchanger that would slightly preheat the intake air using well water.
> 
> Looking forward to any further corrections or suggestions;
> 
> Henk
> 
> 
> 
> 
> Interesting idea and one similar to something I've considered.  My thought: take a flowing source of water such as a spring, pipe that to a tank so that there's a constant flow of water, and then immerse your Heat pump unit's external coil in this tank (just the coil of course not the compressor or fan).
> 
> Of course a freon to water heat exchanger would work better but I was just thinking...
Click to expand...


That's a bold mod, especially since it would not be easy to ever revert back to the original freon-to-air configuration without buying a new HP.

However, I do like the fact that it does not mess with the intricacies of trying to re-balance a delicate air intake fan. Perhaps this is something I might be willing to try in a situation where the air intake fan was already toast (e.g. after being buried under snow and ice for a long time). 

Did you already think through how this setup might (or might not) work if you needed to cool the house in summer??

Henk


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## woodgeek

PyMS said:
			
		

> Semipro said:
> 
> 
> 
> 
> 
> 
> 
> PyMS said:
> 
> 
> 
> 
> Sorry for my confusing terminology. What I referred to as the "air intake" is the forced airflow past the compressor's freon-to-air heat exchanger. I understand that this is normally a wide open fan box, but know that it is usually fairly easy to attach some ducting to the intake (suction) side of the fan in order to move the actual "air intake" (sorry for using that term again) to a more advantageous nearby location.
> 
> So, in my simple-mindedness, I assume that it must also be possible to cap off that inlet air flow with a water-to-air heat exchanger that would slightly preheat the intake air using well water.
> 
> Looking forward to any further corrections or suggestions;
> 
> Henk
> 
> 
> 
> 
> Interesting idea and one similar to something I've considered.  My thought: take a flowing source of water such as a spring, pipe that to a tank so that there's a constant flow of water, and then immerse your Heat pump unit's external coil in this tank (just the coil of course not the compressor or fan).
> 
> Of course a freon to water heat exchanger would work better but I was just thinking...
> 
> Click to expand...
> 
> 
> That's a bold mod, especially since it would not be easy to ever revert back to the original freon-to-air configuration without buying a new HP.
> 
> However, I do like the fact that it does not mess with the intricacies of trying to re-balance a delicate air intake fan. Perhaps this is something I might be willing to try in a situation where the air intake fan was already toast (e.g. after being buried under snow and ice for a long time).
> 
> Did you already think through how this setup might (or might not) work if you needed to cool the house in summer??
> 
> Henk
Click to expand...


Um, why not buy a small geo system and feed it water from the spring rather than hack an ASHP?  The unit costs are not the problem--its the drilling.


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## henkmeuzelaar

woodgeek said:
			
		

> Um, why not buy a small geo system and feed it water from the spring rather than hack an ASHP?  The unit costs are not the problem--its the drilling.



Well, so far the discussion has been about what to do if you already do have an ASHP and don't want to buy additional geo HP.

However,  your suggestion might even be worth pursuing for a new installation.   

All three ideas (i.e. yours, Semipro's and mine) , however,  are only worth pursuing if the ground water flow used can be disposed off in an economical manner. In my county, that means reinjection at 18+ ft depth (potentially deeper, dpending upon a hydrogeological survey). So, at least some drilling costs will always be incurred. 

Henk


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## Amaralluis

I got my december hydro bill and heres the cold hard numbers about my heat pump vs pellet stove since it was installed on November 1st.

My electric bill runs from around the 17th of every month. For Nov/Dec period in 2009 Iâ€™ve used 572KWH for a period of 28 days (I know it was awesome) with the pellet stove. In 2010 the total was 1298Kw for a period of 29 days with the heat pump.
 For dec/jan then the usage was 786KWH for 2009 and 1739KWH for 2010.

The difference between 2009 and 2010 besides the pellet stove we had a teen that moved in August, which increased the electric usage for quite a bit. It was not a constant difference so what I did is that I took the difference between 2009 and 2010 for august, september and October and calculated the average of the difference for those months. With it Im assuming that approx 390Kwh over 30days are because of the extra person in the Household. I know that its not super accurate but Its the only way I thought to get an idea of how much the person costs. If someone has a better idea please let me know. 

This means that for nov/dec period the heat pump used approx 336Kwh and for dec/jan 563Kwh.
 The hydro price is $0.11, 336*0.11=$36.96 and 563*0.11=$61.93.
 Pellets used for the same period of time in 2010 = 0

Unfortunately I didnt record the bags usage in 2009 so I dont know exactly how many bags were used, but I can safely say that it would averaged one bag per day so 29+33=62 bags. Cost of Bags $6.20 (with the taxes).
 62*$6.20=$372.22

There you have it, $372.22-$98.89=$273.33 difference. 
 Are this numbers accurate? 
 No.
 Do they tell me something?
 Yes, the heat pump is saving me money from pellets, It might not be saving me $273 up until now, but it is undoubtedly saving me money.

PS - I know that the pellet stove also used electricity but I cant put a KWH value to it but from the readings in 2009 it was not considerable.


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## Amaralluis

Got my february hydro bill.

Heres the numbers.

2010 697Kwh for a period of 31 days. 
 2011 1587kwh for a period of 28 days.

This results for 2010 in a daily consumption of 22.48Kwh and in 2011 56.68Kwh which makes a difference of 34.19kwh more in 2011 compared to 2010.
 From this amount I take out 13.10kwh for the extra person in the household (read my first post) and Im left with 21.10Kwh daily usage for the heat pump.

21.10*28days for a total of 590Kwh for the period of 28 days.
 At 11cents/kwh, the cost of the heat pump was approx $65.00.

I had to shut down the heat pump for one evening. The temps dropped below -20C and the heat was still blowing warm air but the defrost mode kicked too often and it couldnt keep the temp in the house. Used one pellet bag for the night. ($6.20)

The hard numbers? Assuming It would only burn one bag a day, the pellet stove would cost 28*$6.20=$173.
 $173-$65-$6.20=$102 savings. Not bad.


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## semipro

My question is basically academic.  We have a geothermal heat pump.  I was just wondering if someone already had an air-to-freon heat pump and a ready source of flowing water.


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## semipro

PyMS said:
			
		

> Semipro said:
> 
> 
> 
> 
> 
> 
> 
> PyMS said:
> 
> 
> 
> 
> Sorry for my confusing terminology. What I referred to as the "air intake" is the forced airflow past the compressor's freon-to-air heat exchanger. I understand that this is normally a wide open fan box, but know that it is usually fairly easy to attach some ducting to the intake (suction) side of the fan in order to move the actual "air intake" (sorry for using that term again) to a more advantageous nearby location.
> 
> So, in my simple-mindedness, I assume that it must also be possible to cap off that inlet air flow with a water-to-air heat exchanger that would slightly preheat the intake air using well water.
> 
> Looking forward to any further corrections or suggestions;
> 
> Henk
> 
> 
> 
> 
> Interesting idea and one similar to something I've considered.  My thought: take a flowing source of water such as a spring, pipe that to a tank so that there's a constant flow of water, and then immerse your Heat pump unit's external coil in this tank (just the coil of course not the compressor or fan).
> 
> Of course a freon to water heat exchanger would work better but I was just thinking...
> 
> Click to expand...
> 
> 
> That's a bold mod, especially since it would not be easy to ever revert back to the original freon-to-air configuration without buying a new HP.
> 
> However, I do like the fact that it does not mess with the intricacies of trying to re-balance a delicate air intake fan. Perhaps this is something I might be willing to try in a situation where the air intake fan was already toast (e.g. after being buried under snow and ice for a long time).
> 
> Did you already think through how this setup might (or might not) work if you needed to cool the house in summer??
> 
> 
> I would think the cooling cycle would work also, maybe better.
> Henk
Click to expand...


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## begreen

Amaralluis said:
			
		

> Hey PyMs.
> You are correct it is a Daikin FTXS15 model.
> At -18 outside the unit was still able to maintain the temp, this is really impressive technology.
> 
> The idea of this thread was to give out real meaningful numbers that everybody can relate to.
> Everybody understands KWH and 40lbs bags.
> Everybody understands that my heat pump used 500kwh in one month against using 30 pellet bags instead of saying the it has COP of 3 or that the output of BTUS was X based on X degree Days.



I have friends that are looking at installing this unit. How large a home is this unit heating? It sounds exceptionally well insulated.  Based on Daikin's specs, it would be putting out less than 8000 btu at around -9ÂºC (15F). It's amazing to hear that it would be putting out enough heat at temps far below zero (-18ÂºC -4ÂºF) considering the sharp drop off in heat output at lower temps. Was there supplemental heat in the building at this temperature?


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## Amaralluis

why was my part ii thread merged with this one??
This one has gone offtopic and I wanted to start it over to discuss other people experiences.


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## begreen

Yes, trying to bring it back on topic by understanding the numbers. Had friends over yesterday and I showed them the thread as they are looking into your unit. They currently have a pellet stove, but pellets are half your price. The questions that arose were the size of the house and temps in 2010 vs 2011.

Did you get the degree day comparison between the 2 years?


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## Amaralluis

My house is a approx 1300sqft bungalow style with an unfinished basement.
Heres the degree days comparaison between 2009/2010 and 2010/2011. 

2009.....oct/nov.......427.1.............2010.....oct/nov.....383.1
............nov/dec......534.4.........................nov/dec.....541.4
............dec/jan.......708.8.........................dec/jan......670
2010.....jan/fev.......764.9..............2011.....jan/fev......879
............fev/mar......523.1..........................fev/mar    

The date range is from the 17th to the 16th of the following month to match my electricity bill cycle.
I used the Heating degree days from the chart found here : http://www.climate.weatheroffice.gc...ationID=6207&Day=1&Month=2&Year=2009&cmdB1=Go


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## begreen

Excellent, thanks. This is what I wanted to see. It looks like jan/feb this year was a lot colder, so the savings are actually better for the heat pump than initially calculated. The unit appears to be performing very well. This is impressive performance.  Is the Daikin unit carrying the full load all this winter?

Our friends move in tomorrow. They will have about the same electric rates, but they get better pellet pricing. Their house is about 1500 sq ft, in milder temps, so this looks pretty good for them.


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## Amaralluis

The heat pump has been the sole heating source this winter except on one occasion when the temps dropped below -20 during the night.


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## begreen

Very impressive! That is quite awesome.


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## Amaralluis

Finally got my bill for the Fev/Mar period. The results are very surprising, it makes me wonder if the reading last month was a real reading or just an estimate from the electric company.

Heres my results:

Fev 17 to Mar 16 in 2010 - 632Kwh 29 days - 523 Degree days
Fev 17 to Mar 16 in 2011 - 1223Kwh 29 days - 640 Degree days

Difference between 2010 and 2009 - 591kwh or 21.79kwh daily.
Take the average usage from the new person in the household 13kwh/daily, the heat pump used approx 20.80Kwh/day or 211.21Kwy for 29days.
At 11cents/kwh the total for the heat pump was $23.5.

Theres a few points that skew these numbers. on the last week of february because of a sensor problem that had to be replaced the heat pump was off and I used the pellet stove instead. In total I used 7 bags, one per day.
At $6.20/bag it cost me in pellets $43.40. Obviously had I not have the problem with the heat pump, its cost would be higher. That week was probably the coldest period too.

Regardless, the hard numbers? Assuming It would only burn one bag a day, the pellet stove would cost 29*$6.20=$179.80
 $179-$23.5-$43.40=$112.90 savings. Still not bad.


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