Alternative Power sources - Re: Programable thermostats use / uselessness in continuous occupancy setting...

Author

Re: Programable thermostats use / uselessness in continuous occupancy setting...

GeoLegacy

2007-08-18, 8:25 pm

On Aug 18, 8:29 am, Paul M. Eldridge <paul.eldri...@ns.sympatico.ca>
wrote:
> On Fri, 17 Aug 2007 23:11:03 -0500, "Pete C." <aux3.DO...@snet.net>
> wrote:
>
>
>
> Hi Pete,
>
> If your home is moderately sized and reasonably well insulated, you
> may find a high efficiency air-source heat pump to be a more
> economical alternative. The installation costs in this case would be
> substantially lower and it wouldn't disturb your outside property.
>
> This fall, I'm adding a second mini-split heat pump to serve my lower
> level. It has a SEER rating of 21 (more than double the cooling
> efficiency of standard air-source units sold just a few years ago) and
> a HSPF of 11.0 -- a winter heating COP of just over 3.2. My cost
> (wholesale) is $1,846.00 CDN, and I expect to pay another $400.00 for
> installation.
>
> I haven't looked at the specs forgeoexchangeheat pumps recently, but
> I can't imagine their SEER ratings would exceed 21 or, if so, not by
> much. In terms of heating, if you pay 10 cents per kWh for electric
> heat, a heat pump with a HSPF of 11.0 would provide the same heat for
> as little as 3.1 cents (that's the equivalent of paying 70 to 75 cents
> per therm of natural gas, assuming your furnace or boiler has a AFUE
> rating in the range of 80 to 82 per cent). This particular heat pump
> continues to operate down to -15C (5F), albeit at reduced efficiency
> and capacity, so there may be a couple days each winter when it will
> switch over to backup heat (in my case, oil).
>
> Cheers,
> Paul

The BEST outdoor unit has an EER of just over 15 (check the ARI
Directory). The BEST geothermal unit has an EER of 30 and a COP of 5
- One btu of energy purchased from the electric company and 5 from
beneath your yard.

nicksanspam@ece.villanova.edu

2007-08-19, 9:25 am

GeoLegacy <geolegacy@hotmail.com> wrote:

>... The BEST geothermal unit has an EER of 30 and a COP of 5
>- One btu of energy purchased from the electric company and 5 from
>beneath your yard.

EER = 3.41xCOP, no?

Nick

Paul M. Eldridge

2007-08-19, 1:25 pm

On Sat, 18 Aug 2007 15:38:07 -0700, GeoLegacy <geolegacy@hotmail.com>
wrote:

[color=darkred]
>
>The BEST outdoor unit has an EER of just over 15 (check the ARI
>Directory). The BEST geothermal unit has an EER of 30 and a COP of 5
>- One btu of energy purchased from the electric company and 5 from
>beneath your yard.

I wouldn't discourage anyone from installing a geoexchange heat pump
if that's the way they want to go. I'm just not convinced they're the
only game in town, now that the efficiency of air source units has
improved so dramatically.

My previous home in Toronto had a twenty-plus year old, 2.5 ton CAC
that consumed something in the order of 4,500-watts (its EER was no
more than 6 or 7). I replaced it in 1997 with a 13.5 SEER,
multi-stage unit that uses roughly 2,200-watts. Today, if I were
faced with that same buying decision, I would likely opt for a 18 SEER
system, in which case, my electrical demand would fall to less than
1,700-watts, or about one-third my baseline (as mentioned, the SEER
rating of the ductless heat pump I'm putting in my current home is
21).

As you approach SEER 20, the law of diminishing returns takes firm
hold and any additional savings are likely to be achieved only at
extraordinarily high cost. If I currently pay $2,000.00 a year to air
condition my home with a SEER 10 CAC and replace it with a SEER 20
model, my annual savings are $1,000.00. Not bad. If we could bump
that up to SEER 25, say, (again, I'm not so sure even geoexchange
systems can attain such levels), I would save an additional 10 per
cent or $200.00. Could I recover the higher initial cost of this more
efficient system in what most consumers would consider a reasonable
timeframe (e.g., 5 to 7 years)? Most likely, not.

Cheers,
Paul

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