ASHRAE Journal - November 2014 - 76

COLUMN REFRIGERATION APPLICATIONS
Andy Pearson

Heat Pumps: The Brutal Truth
BY ANDY PEARSON, PH.D., C.ENG., MEMBER ASHRAE

Last month we went back to basics: remembering that the suction and discharge pressures of any vapor compression refrigeration system are vital to efficient performance.
This month we start a closer look at the world of heat pumps, where some things are
not like refrigeration at all, but some other essential truths remain constant.
In the very first of these columns, back in March 2012, I save a bit on the running cost. The only debate is how
likened the thermodynamics of a refrigeration system to long anyone is prepared to wait until they have gotten
the removal of a piano from my basement to the lounge
their money back. If the cost of an upgrade is saved every
upstairs. The higher you have to lift the piano, the more
month, or even every six months, most people will welwork needs to be done. Running a refrigeration system
come it. If they have to wait five years for it to pay back
is like cleaning pianos out the basement; the importhey are not so sure. For a heat pump system the justifitant thing is that you are creating space by not having a
cation is more difficult. If my offering is too expensive or
piano there any longer. However, the folks upstairs want not efficient enough, or both, then the prospective buyer
music, but they don't really care what kind of music. If I
will not simply choose someone else's heat pump, he
can get my piano there quickly and easily then that will
might go for some alternative environmental technology
be welcome. However, if it is too difficult, or
such as a biofueled combined heat and power
Genghis had several ways to
too expensive, or too dangerous then they will heat his space.
system or he may even embrace his inner
settle for some other form of entertainment.
caveman and just burn some fossils. Either
Perhaps a banjo player will show up; his music
way, I lose.
is cheap, portable and easy to deploy, but it
As a refrigeration guy it has been hard to get
is perhaps not building the lasting cultural
used to the sensitivities and peculiarities of
heritage for my grandchildren that I had been
the heat pump market. I am used to people
planning.
who want pianos cleared out of basements.
The brutal truth about heat pump economThey don't care what I do with the piano - I
ics is that, unlike refrigeration, there are many ways of
can throw it away as far as they are concerned. Now I am
providing heat to a space. Burning stuff has been popudealing with the folks upstairs, the music lovers. They
lar since the caveman days. It is cheap and portable, but like my piano. It is valuable to them because they need
like banjo music we have learned to be concerned about music, but frankly they have no interest in the space in
the longer lasting effects.* There are many alternatives
my basement. It can remain empty for all they care. To
to traditional fossil fuel consumption, varying in popustretch the analogy just one more notch, the best of both
larity depending on the application. Direct electrical
worlds is when I can deliver piano music to the folks
heating is clean and easy. Combined heat and power
upstairs and rent my basement to a lodger who provides
systems seem to offer several advantages; gas-fired heat- a handy source of income. If it is proving to be too difing coupled with local electrical generation and giving
ficult to justify a heat pump system against other forms
the added bonus of some extra heat to run an absorption of heating and there is beneficial use for the cooling
chiller if necessary. Now we can use biomass as a renew- effect, then this might sway the decision. Government
able alternative to fossils and resolve that pesky environ- subsidy provides an alternative way of boosting the case
mental legacy issue.
for heat pumps. This is very welcome, but like all market
In a refrigeration system it is relatively easy to justify
interference it can have some unintended, illogical and
an energy efficiency benefit. Spend a little more and
unwelcome consequences. Watch this space.
*No offense intended; some of my best friends are banjo players.

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Andy Pearson, Ph.D., C.Eng., is group engineering director at Star Refrigeration in Glasgow, UK.

ASHRAE Journal - November 2014

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