Rod Speed wrote:


The problem is shortly after the temperature dropped
to the setback temperature, the heat pump would end
up running steady just to get back up to temperature.

Wrong with the situation being discussed, with
more than one system so it doesnt take a long
time to get it up to the normal temp again.

That is sure economically viable.

To get a heat pump to work with setback, you are oversizing the system.
Either a single oversized unit, or multiple units. It takes a
rediculous situation to make setback work on a heat pump.


Typically in the temperate states where air source heat pumps are
used, they are sized with the cooling load in mind and use the heat
strips. One sized for the full heat load will be grossly oversized
for cooling resulting in summer time humidity control problems.

And what was being discussed was having more than one
system and doing that so it doesnt take a long time to get back
to the normal temp and doesnt use the heat strips to do that.

Yes multiple systems, now as high as three, just to prove a point that
you can setback a heat pump.

The only way set back works with a
heat pump is if it is grossly oversized.

Wrong again.

No not wrong

Yep, completely wrong.

Sure, buy 3 heatpumps to prove set back. Spend extra money on the
ductwork involved for three systems, including back draft dampers, lol
what a crock

just unsucessful in educating you.

You cant even keep track of what was actually being discussed.

Well I believe you were speaking first of two systems, then realized
you needed three, so as not to be short cylcing in the heating mode,
and in the summer having too much sensible cooling that the stat would
be satisfied in 5 minutes run time.



All that accomplishes is set back without auxiliary heat.
It would short cycle inefficiently except for when it was
trying to recover from a set back.

Not if you one of the systems sized so that doesnt happen.

Three systems sure, that is practical,


So you are saying size one for the cooling load, one for the
heating load and one for speedy recovery from set back then?

Three heat pumps now.

Yep, I mentioned 3 for a reason.

Plus all the ductwork and backdraft dampers.

You dont have to duplicate/triplicate all of those.

No you could have three systems share a common supply and return, just
get it to work there einstein.

Let's try to keep this practical and not go to
hypothetical extremes to prove this is possible.

Wasnt doing anything like that.

No not at all just install three heat pumps. Or two heat pumps and a
central AC. Hey maybe you could get a two stage one and a central AC.
SUre is a lot of tap dancing to prove that you could viably set back a
heat pump.

Noah er I mean Nick is a bad influence on you.

Nothing to do with Nick at all.

In an environment with an ambient dewpoint above 60F there will
be problems with a grossly oversized system in cooling mode.

Again, not if you have more than one system.

Well like I said if you want to install
three heat pumps, knock yourself out.

Two and three was what was being discussed.

Your claim that setback has no value is just plain wrong with THAT situation.

Setback has a value, just not with heat pumps.

A fossil fuel system sized right on the money for the heat load in a
high thermal mass home may not be the best system to be setting back
either.