Ok Trader. I got real bored and thought Id use one of the calculators
Quite honestly, at first glance it looks a little cheasy and too easy.
But I thought Id humor you.
Gas Price 1.24 from my last months bill
Electric Price 0.084 also from my last month bill
Gas Furnace Eff 92 because that is its eff.
Inside temp 67 where I tend to keep it set
Heat pump make Any Make although mine is a Tempstar
Heat pump model HSPF 8.0 from the info in the
performance specs booklet of my heat pump
Would you care to guess what my "Transition Temp" is?
Here is a clue: It isnt close to 35 or 30 or 25 or 20 or 15.
It comes up at 8.8 degrees.
Now you do realize that this is the economic balance point and not
a thermal balance point? You do know the difference in the two, dont
you? If you had your own HVAC business and used YOUR calculator to
install and set heat pumps I would hate to be the person answering the
phone at your place of business. You would have nothing but nasty cold
I hate to repeat this again but, You seem to do things with a book and
a pencil in your little labratory world. Thats all nice and well but
seldom do things work that way in the real world that I live in.
Especially when you show me calculators that come from people that
dont specialize in heat pumps or HVAC. And when you show me anything
like a calculator from the govt (DOE) it just makes me laugh. Tell me
the last time the govt did ANYTHING for your or my benefit?
Let me point you to a little bit more involved calculator. This one
has all kinds of options including a "comfort balance point"...that of
which requires doing a load calculation on the home.
Click on "Product Information." Go down to "hvac equipment cost of
operation calculator". Now click on "open" (or save it if you wish)
when that menu pops up.
You can read whats on that page for some insight and then go to the
tabs at the bottom of the page.
You are looking for the "dual fuel" tab. It may be hidden over to the
right on the page so use the arrows to uncover it.
This is close to the calculator you are familiar with from the
Now go back to the tabs at the bottom and use the "Thermal Balance
Notice here that you need the "Design Heat Loss Btu's" and your
outside design temperature.
This would be info found needed from a heat loss calculation for your
specific home. THIS is the proper way to figure out what temperature
you need to set your heat pump temperature changeover at. Done this
way, you get a relatively decent cost of operation efficiency and most
importantly a thermal balance point that heats the home relatively
well and doesnt have the customer calling you back telling you that
the airfrom the register is freezing and it never shuts off. Again,
this magical 35 degrees is NOT the way to just willy nilly set your
heat pump to shut off at.
If that doesnt help explain it to you any better trader, then "Heaven
Help You" because I cant
Are you sure that's the total cost per KWH? Meaning it's the total
bill divided by the KWH? For example, my bill is broken down into a
generating component, plus a delivery component. If it is the total,
it's among the lowest rates in the country. Where are you?
Yes, in fact I was the one that explained that difference in my last
post in the other discussion thread. Which should have been obvious
all along, because the other thread was about efficiency.
We know. You totally reject science, engineering, the laws of
You seem very conflicted. Above you used the calculator to make a
point and now you say it makes you laugh.
So silly it doesn't even merit a response, but I'll give you one
anyway. I just drove my car down the street. That street was paid
for by govt.
Where do you think that calculator came from? I doubt someone found
it under a tree in the forest. It comes from straightforward science
And again, the discussion was centerd on the temp point regarding
economic efficiency. Not one centered on the point where you need gas
to kick in to be able to supply ENOUGH heat.
If you look at what I have been posting in the other thread, it's all
consistent with the above. And once again, I never stated that 35 is
the number to set your heat pump to shut off at. Below is
requoted exactly what I've said. Notice the part where I clearly said
it depends on the actual cost of the electricity and gas:
"1 - With a heat pump, as the efficiency declines with outside temp,
there is a temp point at which other fuels like nat gas become MORE
COST EFFECTIVE. This doesn't depend on the heat loss of the house,
the number of windows or anything else. It depends on the
of the heat pump at a particular temp, the efficiency of the
alternative gas furnace, the cost of electricity, and the cost of
gas. You could have the windows wide open and all the heat going
out. The only question here is to generate X BTU's with a given
outside temp, which is more cost effective, running the heat pump or
running a gas furnace.
2 - With a heat pump, as the efficiency declines with outside temp
the total heat output drops too, there is a temp point at which the
heat pump can no longer supply enough heat to keep the house at the
desired temp. It then requires additonal heat from some other
again it could be gas, per this example. The temp at which this
occurs, does depend on the heat loss of the house.
#1 Above involves efficiency, ie which fuel will heat the house most
economically. You want to switch at that temp to save money.
#2 just involves getting enough heat, withour regard to efficiency.
You have to switch at that point to keep the house at the desired
temp. In fact, if the alternate fuel is resistance electric heat, #2
Which is why, at some point below about 30 deg, it become more
economical to use another fuel, like natural gas to supply the heat.
The exact temp depends on the cost of the two different fuels.
Which is why dual fuel system are sold using those two fuels. "
"In other words, heat pumps become LESS EFFICIENT the lower the
outside temp. Which is exactly the point Hank was making when you
called his post stupid BS. It depends on the relative cost of the
electric and the alternative
fuels, but in many cases below 35, it costs less to use other fuels,
like natural gas. Which is why air based heat pumps are not
generally used in cold northern climates. Or if they are used, they
have a duel fuel system, like nat gas. Maybe you haven't noticed.
you paid attention, the discussion was about Boston. In fact, that
is exactly what the OP has. A heat pump system with additional heat
from propane. "
OK, so putting the numbers for NJ into the calculator you provided,
with a price of gas at $1.50 and electricity at 17.4 cents/KWh, I get
an economic balance point of 32F
Can I ask you a simple question? Why didn't you just provide that
calculator in response to Hank's post instead of starting out by
calling his post stupid? Taking things in context, the post that was
being discussed at the time was Boston, which probably has rates
similar to here in NJ, meaning his 35F number is probably fairly
close. If you live somewhere that has very cheap electricity compared
to gas, then I agree, the crossover point can be signficantly lower,
even down to your 8F.
Hopefully we are in general agreement now?
On Mon, 16 Feb 2009 07:41:06 -0800 (PST), firstname.lastname@example.org wrote:
Thats what it says on my bill. It isnt broken down any further. If Im
not mistaken, Yes, I believe we do have some of the lowest rates.
Obvious? No trader. Nothing you type is obvious. Thats just your way.
All of a sudden, now YOU explained the diff in economic balance and
thermal balance? Wow. You have quite a recollection of things in your
So you are obviously admitting that you think it all works......."Your
Kind of funny then how the govt gives fuel economy ratings on new cars
yet I can find anyone that gets that mileage. It wouldnt have anything
to do with the fact that they are govt ratings and the work like
you....in your own little bubble.
Almost like the rating numbers that come with heat pumps. Have you
ever actually tried to get that exact suction and discharge pressure
with the exact amp draw, and temp rise? It is very very hard to do.
Why you ask? Because it is tested in controlled labratory conditions.
Kind of like "traders bubble".
Yes, its quite funny. Yours shows me 8.8. My Tempstar calculator shows
me 0.0. I would trust mine more since it actually came from a HVAC
equipment manufacturer but I wouldnt use either of those numbers.
Again, in the real world you have to rely on what you have actually
tested and know. That is the part that you lack. Dont worry though.
Most EE's are that way. Claiming to know almost everything, always
wanting to reinvent the wheel yet lack the absolute most basic
knowledge of anything.
You are making me laugh again, trader. IF the govt paid for it, why
does your paycheck always have all those deductions for "Fed, State,
Local and a host of many other deductions. They also show up on your
cable bill, telephone, utiilities, etc. All that money they take from
you and me but yet you think they pay for things? Wow, you really do
live in a different world.
Seems like back peddling again trader. What the discussion was
centered on was you saying 35 or around 35 or close to 35 is what heat
pumps should be set at. Maybe in your little grain of sand in the
world but not anywhere else. Then the fact that you think it can be
done with no input as to the type of house it is being done for is
just pure sillyness. Of course, Stupid is a better word.
and once again, yes you did state that.
I also see in your sentences below that you say it doesnt depend on
the heat loss of the house. You are wrong again. Only an idiot would
not get a heat loss done on a house to determine where to set the heat
pump cut off.
Then you state: "which is why, at some point below 30..." Again,
that is wrong. That is a blanket statement and it is wrong.
Then you say, "in many cases below 35 it is more economical..."
Again, a blanket statement. You are wrong again.
Need I go further?
You continue to "cluck" and come up with the short end. You continue
to show that you dont know even the basics of how something works.
Always trying to reinvent something such as the wheel.........not
making it better....just reinventing it. Just plain silly.
Because you and he were both saying that you set heat pumps at 35.
Anything lower isnt economical. That is just wrong. Maybe if you made
that statement in this newsgroup go only to NJ and no where else then
Id say you were right but you and Hank are both saying heat pumps dont
work below 35 and they DO. They work well at much much lower
temperatures when the electric rates are lower.
hehe. Sorry trader. I dont think that would ever be possible. You and
I are at complete opposite ends of the spectrum.
I will try to be a bit more civil though now that I see what tree you
are swinging from. :-)
You do realize one calculator uses COP for efficiency and the other
Tell us more. Have you done extensive testing of the actual
efficiencies of dual fuel heat pump systems at various outside temps?
I seem to recall that in the other thread, you told Hank to just clamp
on an amp meter and see that the current is less at lower temps. As
if that proves anything about efficiency, without also measuring the
heat being generated by the pump.
Actually, YOU're the one that eschews all prior knowledge, saying you
only believe it if you determine it yourself. Engineers rely on
well established laws of science that go back hundreds of years,
precisely so they don't have to re-invent the wheel and do everything
by trial and error.
What I said was that the temp point below which it's more economical
to heat with gas DOES NOT VARY WITH THE HEAT LOSS OF THE HOME. Which
is correct. That's the problem here. About every third paragraph,
you again interject something which is totally WRONG, defies physics
and shows that you really still don't have a grasp of the concepts
If we have any system and put $100 worth of a given fuel in it, we get
X BTUs of heat out. The amount is determined by the efficiency of
the system. With a heat pump, the efficiency declines substantially
with outside temperature. So, at some point, to generate heat,
spending that $100 on gas gets you MORE heat than spending it on
electricity to run the heat pump. It matter not one wit if the heat
being generated is going into an insulated house or into a barn with
the doors wide open. The issue is to generate heat, which costs
less, gas or electric.
For further proof, look at the economic balance point calculator that
I provided and also the one that you provided from a heating eqpt
company. The only inputs into those calculators are:
Cost of elec
Cost of gas
Efficiency of gas furnace
Efficiency of heat pump.
Do you see a heat loss calculation, anything about insulation, load,
etc there? No, because they don't factor into that calculation to
determine the temp below which it's cheaper to generate heat from gas.
If you think those are blanket statements, you need to take a course
in understanding the English language. Also, funny how the Dept of
Energy, KCPL, Tenn Valley Authority, and many others make very similar
Yes, I'd still like to know why you didn't provide the economic
balance point calculator in response to Hank's post. The situation
under discussion was in Boston. If you put my costs for energy here
in NJ into the calculator, you come up with 32F. Which means below
that temp, it's more efficient to heat with gas than with a heat
pump. I suspect it's similar in Boston. Had you just done that,
instead of launching your usual flame war by calling his post stupid,
you would have provided a useful tool that many people here could use.
On Tue, 17 Feb 2009 05:37:21 -0800 (PST), email@example.com wrote:
Actually trader, if you would stop lying and use your freaking brain,
you could look back yourself and see who started this war. It was YOU.
I made a comment to Hank. NOT you. You were still reeling from the
fact that I hammered you on your humidifier post in another thread
which I wont even go into how incorrect you were again.
So what happens..............? You thought you would jump in on my
post to Hank. There in, YOU started the beginning of the flame war not
knowing that you would be wrong again and lying as usual that you
didnt say 35 degrees. You dont have a clue about heat pumps and never
did. You've never installed a single one and dont even have one in
your home yet you act as if you invented them. Ive installed more of
them than you wil ever imagine and have no unhappy customers. Imagine
that trader. I wonder how that happens? Must be "magic" huh?
All of your babbling above is beginning to tire me. You obviously have
nothing better to do. I do. Let me know when you are ready to reinvent
the rock. Im sure you could do a couple hundred pages on that.
Yes, you called his post "stupid BS" when he stated to the guy in
Boston that his heat pump becomes inefficient below 35F. Here's your
first post in that thread with Hank:
"Sorry Hank. That sentence above from you was a totally stupid
statement from one that has no idea what a heat pump can do.
Gee, I wonder why flame wars start around Bubba?
Only incorrect according to Bubba. The rest of us in that thread had
a very reasonable and civil discussion. As usual, it was Bubba
hurling profanities. Also, not incorrect according to both my actual
test and humidifier manufacturer Aprilaire, which you alternate
between bashing and citing as an authority. Aprilaire says to use hot
water to maximize the amount of water the humidifier puts into the
air. And your source that says it isnt so would be? Oh, that's
right as usual, you have no source.
Also, funny that you now want to refocus this thread and restart all
over again on hot water evaporating faster than cold, which I thought
was long over. Since you didn't reply to the core of my previous
post, I take it that you now recognize that the outside temp below
which gas becomes more cost effective to use than a heat pump depends
only on the cost of the fuels and efficiencies. I guess the fact that
the economic transition point calculator that you yourself provided
doesn't need a load calculation was enough to finally convince you.
On Tue, 17 Feb 2009 10:32:26 -0800 (PST), firstname.lastname@example.org wrote:
Nope. Not at all. I'm just tired of arguing with a complete and total
asshole that has no connection with reality whatsoever. That block
head on top of your shoulders full of concrete is totally useless. You
and you can now,
Actually the OP's situation is different from a typical dual-fuel HP.
With a heat pump on a furnace-- regardless of NG, propane, or oil--only
one or the other can run at any given time (except during defrost).
Thus, when the HP's thermal balance point is reached, the HP is turned
off, and the furnace starts. The HP could still be pumping out heat more
economically than the furnace, although not enough to keep the house at
the desired temp. In the OP's case, the gas backup heaters are
independent of the HP, so both can operate at the same time. Of course,
the exact economic balance point with propane or oil will probably vary
with each fill up also, probably more so than with NG. Just my $.02
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.