What You Need to Know About Heat Pumps
The “air to air heat pump” (think of an air conditioner that can run backwards in the
winter) has the lowest installed cost, and renders the least acceptable heating
comfort, of any heating cooling system known to man.
Fred's been living with one for more than 14 years now and the older he becomes
the less he likes it; seems like he's becoming more sensitive to changes in air
temperature as he ages (younger viewers say “DUH” here), and that’s what
heating with an air to air heat pump is all about.
FACT: Air to air heat pump discharge temperature varies (more or less) as outdoor
temperature; the colder it becomes outside, the cooler the discharge becomes.
PARADOX: The more heat you need, the less you get.
FACT: Discharge is below body temperature much of the time (below around 45º F
outdoors – more than half the time in heating climates); this greatly increases the
risk of “draft” complaints.
FACT: Blower runs 24/7 and discharge fluctuates by 30º F or so below balance
point; some people (yours truly included) really notice that “blast of heat” when the
electric resistance “supplemental heat” is activated.
Just in case you didn’t understand what we think: Air to air heat pumps don’t
come close to providing acceptable heating comfort in heating climates; they’re
simply cheap systems in terms of installed cost, because you don’t need a
chimney or vent, and you don’t need fuel piping or fuel storage facilities.
Fossil Fuel Backup – Here’s an exception to the statement about comfort: With
fossil fuel backup, the compressor is deactivated below 40°F; the furnace
operates by itself cycling on and off as in a conventional warm air system. This
solves the main comfort issue (24/7 blower operation with widely fluctuating
temperatures), but greatly increases installed cost (and low installed cost is one
of the main reasons heat pumps finally succeeded, the other being a huge
marketing effort by utilities plagued by unused generating capacity in the winters),
and operating cost.
Geothermal – Here’s another exception: Geothermal heat pumps, especially
ground water types (AKA “Pump and Dump”), tend to have much more stable
discharge air temperatures; but they also cost a lot more to install, because of the
wells, pump and associated water piping.
We're all hearing the word "GREEN" a lot these days; it's used to refer to the
efficient use of energy. This website has been faulted for not promoting "green"
technologies, and this is to reply to the "Doubting Thomas" who said that (and
there might have been one or two others - Love You All - AND THANKS FOR YOUR
When you think about it, there is nothing "GREENER" than having the heating and
cooling energy you buy transmitted to the space in which you live (as opposed to
some portion of the energy you buy "heating and cooling Mother Nature"). The duct
systems documented herein are not "GREEN" because they waste energy; and by
describing how to do ductwork THE RIGHT WAY, this website is in fact promoting
the "GREEN" use of energy!
You can literally TAKE IT TO THE BANK!
BILL OF HVAC RIGHTS
The right of homeowners/renters to be comfortable and free from
adverse health effects in their homes and their right to heat and cool
their homes efficiently shall not be violated:
1. Their duct systems shall incorporate means to balance airflows so
that room temperatures are within 1°F or 2°F of each other:
a. Individual balancing dampers shall be provided at each branch
supply duct, and damper arms shall be accessible.
b. Separate zones shall be provided for each floor, and for rooms
with disproportionate glass areas.
2. They shall be given a clean duct system, so the air they breathe does
not contain construction or other debris.
3. They shall be given a quality air filter or air cleaner, so they do not
have to breathe impurities inadvertently drawn into their duct systems.
4. They shall not be subjected to objectionable air noise.
5. They shall be given the ability to balance airflows to suit individual
preferences (having the Master Bedroom cooler than the rest of the
house, for example), and their duct systems shall be designed and
constructed to allow that flexibility.
6. Their duct systems shall be well designed, well constructed and well
sealed, so that rated airflow is delivered, and they don’t pay to “Heat
and Cool Mother Nature”.
complained about the
HVAC from "Day One"
after moving into their
new home. The builder
(they're national, you've
heard the name)
pressured the sub and
he replaced the 3-1/2
ton AC with 5 tons and
put in a larger furnace
THE DUCTWORK. The
one thing they did do
was cut in two
additional return grilles
in the "drop" (that's the
vertical return duct
horizontal return main
to the furnace - in this
case, the filter).
We calculated heating
determined 3-1/2 tons
was plenty and
developed a Scope of
Work that dealt with the
and restored the 3-1/2
tons. It worked fine
after all was done.
FYI: The return grilles
at the furnace violate
Code, even with
as is seen here.