[Greenbuilding] Sustainable Home Heating Systems (Bill Dorsett)

[Paul Eldridge]

Hi Bill,

Ductless heat pumps are "split" units that consist of an outside 
compressor and indoor air handler.  Room air circulated through this air 
handler is heated or cooled according to the mode selected.  In 
addition, there are "multi-zone" models that combine two or more 
independently operated air handlers with a single outside compressor.  
Ductless heat pumps work well for homes with hot water or electric 
baseboard heating and/or in-floor radiant heat (i.e., homes without a 
conventional forced air heating system).

My inside air handler is located in the main floor living room and air 
flow is directed outward towards the centre hall and adjoining dinning 
room.  Some of this air is circulated to other rooms by way of the heat 
recovery ventilation system, which I operate for the most part in 
"re-circ" mode.  This unit satisfies roughly 80 per cent of my home's 
total space heating needs and can keep things at a comfortable 
temperature all the way down to about -2C (28F); as outdoor temperatures 
fall below this point, my oil-fired boiler will fire up periodically to 
help out.

For more information on ductless heat pumps, see: 
http://www.friedrich.com/pdf/Ductless_Sales_Brochure.pdf

As for any particular brands I might recommend, I'm rather impressed 
with the Fujitsu line of ductless heat pumps.  Their 9RLQ model, for 
example, is rated at 21 SEER and has a HSPF of 11.0.  That's more than 
twice the cooling efficiency of many units sold as recently as two years 
ago and roughly 1.5 times the heating performance of some competitors.  
I don't know of any other product offerings that come close to matching 
these specs.

For more information, please see: 
http://www.fujitsugeneral.com/PDF_06/halcyon06_brochure.pdf

As mentioned here before, in the year prior to my purchase, the previous 
owners of my home consumed a mind-numbing 5,700 litres of fuel oil for 
space heating and domestic hot water purposes, plus an additional 14,000 
kWh of electricity (this is a forty year old, 230 m2 Cape Code exposed 
to high winds off Halifax Harbour).  Through various improvements to my 
home's thermal shell; the installation of a new boiler, indirect hot 
water tank and Tekmar control system; and, more recently, with the 
addition of a small ductless heat pump, I've managed to reduce this 
number to just 830 litres/year.  I'm guessing two-thirds of this amount 
is DHW related, a large portion of which can be attributed to standby 
and stack losses.  In the most recent twelve months, I've also consumed 
10,669 kWh of electricity, an amount that encompasses virtually all of 
my space heating and cooling needs.

For those who may be interested, a PDF record of my fuel oil consumption 
can be found here: http://www.datafilehost.com/download.php?file=34931a7d

A PDF summary of my ductless heat pump savings (simulated and actual) 
are available here: http://www.datafilehost.com/download.php?file=807d4076

This summary data is drawn from hourly temperature and operational 
records, a sample of which is accessible here: 
http://www.datafilehost.com/download.php?file=5efafed4

By way of explanation, the first column indicates if the heat pump is on 
or off (1=On, 0=Off); the second column is the outdoor air temperature; 
the following column is the estimated heat gain based on the heat pump's 
performance curve; the fourth column is my home's estimated heat loss at 
this temperature; the fifth column is the net heat gain (loss) and the 
adjoining column is a running total of this gain/loss.  Lastly, the far 
right column is a check flag that verifies the heat pump was, in fact, 
operational (although it may be switched on, this particular heat pump 
suspends operation at temperatures below -10C).

Best regards,
Paul

>Message: 4
>Date: Tue, 14 Aug 2007 22:07:17 -0500
>From: "wmdorsett at sbcglobal.net" <wmdorsett at sbcglobal.net>
>Subject: Re: [Greenbuilding] Sustainable Home Heating Systems (Ross
>	MacLeod)
>To: Paul Eldridge <paul.eldridge at ns.sympatico.ca>
>Cc: greenbuilding at listserv.repp.org
>Message-ID: <46C26DE5.80001 at sbcglobal.net>
>Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
>Paul, this is a system I'm not familiar with.  Heat through baseboard 
>radiators is fairly easy to understand but how does a ductless heat pump 
>distribute coolth? individual room fan coils? And are there particular 
>brands you recommend? Thanks for your thoughts.
>
>Bill Dorsett
>Sunwrights
>Manhattan, KS
>