Programmable Thermostat with Ramp

[John Larkin]

On Sat, 11 Jan 2020 15:38:09 -0600, John S <Sophi.2@invalid.org>
wrote:

On 1/11/2020 2:14 PM, Rick C wrote:
On Saturday, January 11, 2020 at 2:46:13 PM UTC-5, Winfield Hill wrote:
Rick C wrote...

On Saturday, January 11, 2020, Winfield Hill wrote:
Rick C wrote...

My heatpump runs anytime the temperature is above 40F
= 4.4C (this is adjustable). The thermostat calls for
"aux" heat (oil furnace) when the outside temperature
is below that. When aux heat runs, the heatpump is
entirely off. It's a 2014 Carrier "edge" thermostat.

I suspect if you check with someone who knows, your backup
heat will also run under two other conditions. One is the
system detects ice on the outside coils. With a 40 degree
cut off, your system might not worry with deicing.

Good point, maybe. The instructions don't say anything
about limitations or features if I lower the threshold.
It may not have an ice-detection feature.

The other condition is when the system runs long enough that
it decides the heat pump is not doing the job and switches
to backup heat. Oops, another condition is if the inside
temperature drops too far bellow the set temperature.

It's possible I don't have the first mode. It will add
the aux heat, if inside temp drops below 45F. It does
run the system differently with the heatpump (which draws
5kW when running), than with the furnace. In the former
case it runs the forced-air blower much slower, and it
appears to start the morning temp rampup much earlier.

Mine runs the blower fast with both types of heat, but runs it slower after the compressor has shut off to capture the last residual heat without lowering the temperature of the air from the vents.


I haven't been able to observe the heatpump unable to
get the house up to temp on its own. Our heating/HVAC
system started as an oil furnace and air-conditioner,
but they upgraded the compressor to heat pump (modest
low cost). But the hybrid thermostat labels the heat
pump as primary, and the oil furnace as auxiliary.

Of course. Better to run the more economical heat source when you can.


The heat-pump compressor's 24-page manual mentions an
optional Secondary Outdoor Thermostat, which can turn
on a 3rd-stage of supplemental electric heaters, to
avoid ice buildup, I suppose. I doubt we have that.
So far I'm happy with the default 40-degree setting.
But, if our aux heat was electric baseboard, etc.,
of course that'd be another matter entirely.

If/when oil goes back up to $4 a gal you may rethink that.


If we ever decide to forgo using oil, as some suggest,
we'll upgrade to a proper geothermal heat pump system.
But that might trigger a complete HVAC makeover, and
could involve adding more roof solar panels as well.
Our installer, next town over, in Melrose, MA, has
such a system, and is a big fan of that approach.


Not sure why it might need more solar panels. If anything it would be less. I suppose since it will run all the time including really cold nights, it will need to move more heat than your current heat pump, but with the constant temperature of the ground it would have a much easier time of it. The whole point of the geothermal is to *reduce* your heating bill. If you need more solar panels you are doing something wrong.

Consider the actual work required. Lifting 2 tons of goods by 15 feet or lifting 2 tons of good 5 feet. Which is more work?

The more I think about it the less I like the idea of the 40°F cutoff on the heat pump. It's barely doing anything for you. It's just doing the light duty work and less of it.


What is your quest? You need to save money, or what?

That is a recurrent theme.


--

John Larkin Highland Technology, Inc trk

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

[Rick C]

On Saturday, January 11, 2020 at 5:25:17 PM UTC-5, John S wrote:

On 1/11/2020 3:47 PM, Rick C wrote:
On Saturday, January 11, 2020 at 4:38:06 PM UTC-5, John S wrote:

What is your quest? You need to save money, or what?

Why does that matter? Are you going to analyze my justification for wanting this?


Yes. Why else would I ask? Can you answer civilly? Or are you just being
a troll?

My questions were asked civilly. I asked why you cared about my reason for wanting to do this. Can't you answer a civil question? I would point out that you simply should not respond to trolls at all.

I'm looking to optimize my electrical usage. That's all. The money involved is likely minimal, maybe $1 a day. When my ToU peak period is over I get notices that my electrical usage in that hour has exceeded a threshold that I set to inform me that the backup heat is likely running, 10 kWh or something like that. That is wasteful and not needed, so I'd like to eliminate it.

I honestly thought this is something that has happened to many other people and there likely was a thermostat available that would handle the issue. If all I needed to do was pay $50 or $100 for a new thermostat, then Bob's your uncle. But it would seem no one else here has ever given any thought to the matter, so I am in the same place I was before I asked. Ok, so I'll ask some professionals and/or keep looking at available units.

Straight electric heat is not inexpensive though. One winter when the temps were below my 26°F cut off for the heat pump for 72 hours straight, it cost me about $60 for those three days... before I switched to ToU billing. But that's not why I switched. I expected to save some money charging my EV. Turns out I mostly charge for free at the Superchargers since charging at home doesn't do a lot for me. But I optimize my usage partly to lower my bill but also to help lower the coop's costs. There's a reason why they charge more at peak time, because they are paying more for electricity..

Analyze away!

--

Rick C.

-++ Get 1,000 miles of free Supercharging
-++ Tesla referral code - https://ts.la/richard11209

 

[whit3rd]

On Saturday, January 11, 2020 at 12:39:20 PM UTC-8, DecadentLinux...@decadence.org wrote:

whit3rd <whit3rd@gmail.com> wrote in
news:9277545f-c197-4cec-a7f1-0fe0f56ffbcc@googlegroups.com:

On Saturday, January 11, 2020 at 11:42:49 AM UTC-8, Rick C wrote:

I want the heat to be OFF during the peak times of my ToU rates.
Not reduced, not cut back, OFF.

The issue here, is that no man can serve two masters, and no
thermostat can be said to be doing the 'keep temperature constant'
task when it is imperative that the heat be OFF.

I'll would be willing to bet that there is an iPad for your wall,
and an app for that. Should be able to be far more intelligant than
the normal fare.

it might suffice to use a thermostat with a setback, that accepts a 5C lower temperature
during the high-energy-cost hours. The problem is, keeping the thermostat coordinated with
changes (and the seasons: you might want to bump the setpoint UP in summer if
cooling costs count). Making things 'far more intelligent' means they'll trick me.

I still grit my teeth when the cloud does its thing behind my back...

 

[Rick C]

On Saturday, January 11, 2020 at 7:45:59 PM UTC-5, whit3rd wrote:

On Saturday, January 11, 2020 at 12:39:20 PM UTC-8, DecadentLinux...@decadence.org wrote:
whit3rd <whit3rd@gmail.com> wrote in
news:9277545f-c197-4cec-a7f1-0fe0f56ffbcc@googlegroups.com:

On Saturday, January 11, 2020 at 11:42:49 AM UTC-8, Rick C wrote:

I want the heat to be OFF during the peak times of my ToU rates.
Not reduced, not cut back, OFF.

The issue here, is that no man can serve two masters, and no
thermostat can be said to be doing the 'keep temperature constant'
task when it is imperative that the heat be OFF.

I'll would be willing to bet that there is an iPad for your wall,
and an app for that. Should be able to be far more intelligant than
the normal fare.

it might suffice to use a thermostat with a setback, that accepts a 5C lower temperature
during the high-energy-cost hours. The problem is, keeping the thermostat coordinated with
changes (and the seasons: you might want to bump the setpoint UP in summer if
cooling costs count). Making things 'far more intelligent' means they'll trick me.

I still grit my teeth when the cloud does its thing behind my back...

If you read my posts, especially the original post, you will find that is exactly what I am doing. I am using a programmable thermostat to drop the set temperature low enough that it does not come on during the peak time.

The issue I am having has been explained several times including the original post.

--

Rick C.

+-- Get 1,000 miles of free Supercharging
+-- Tesla referral code - https://ts.la/richard11209

 

[Winfield Hill]

Rick C wrote...

On Saturday, January 11, 2020, Winfield Hill wrote:
Rick C wrote...

... A relay would very likely still kick in the backup heat.

How about adding a high-current contactor, with timer,
to disable the backup heat when you want to do so.

I was thinking of something less intrusive, like a properly
programmable thermostat.

Well, like you say, finding a properly programmable model is
a hard aspect to discover. My Carrier thermostat might work,
but it might not.

To my mind, delaying switch-on of the backup heat isn't very
intrusive. It'll think it has added extra heating, and keep
on doing its regulating job. It'll just take a little longer,
as you've ordained, but it won't know about your thwart, or
if it does, it won't be able to do anything about it. I like
the simplicity of it. Man over machine!

You retain all the smart features of your thermostat, seasonal
and hour-by-hour timing, UV control, humidity control, etc.


--
Thanks,
- Win

 

whit3rd <whit3rd@gmail.com> wrote in
news:af384638-6202-48fc-9b2b-f5e8991aa636@googlegroups.com:

snip

I still grit my teeth when the cloud does its thing behind my
back...

Like fashion up a nice big bolt of lightning?

 

[Jasen Betts]

On 2020-01-11, Rick C <gnuarm.deletethisbit@gmail.com> wrote:

I am using a programmable thermostat to turn off the heat and/or air conditioning during the peak usage times as set by the ToU billing with my utility. The problem I have is the heat pump not ramping up the temperature fast enough when it comes back on and the backup straight electric heat coming on. This uses maybe three times the amount of electricity during the time it takes to get up to temperature.

I don't know if this is caused by the thermostat or the heat pump itself. I'm wondering if anyone makes a programmable thermostat that deals with this issue. If the problem is caused by the thermostat not letting the heat pump run long enough that is easy to fix. If the problem is caused by the heat pump itself, then the way to deal with it is for the thermostat to run the heat pump in bursts short enough to keep the back up heat from running.

Is there anthing you can do to make the heat pump produce more heat?
(have you found anything, or am I just restating your question?)

What is the interface from the thermostat to the heat-pump? is it just
one wire for 24V AC, one wire for heat, one wire for fan, and one wire
for ground?



--
Jasen.

 

[Rick C]

On Saturday, January 11, 2020 at 11:30:49 PM UTC-5, Jasen Betts wrote:

On 2020-01-11, Rick C <gnuarm.deletethisbit@gmail.com> wrote:
I am using a programmable thermostat to turn off the heat and/or air conditioning during the peak usage times as set by the ToU billing with my utility. The problem I have is the heat pump not ramping up the temperature fast enough when it comes back on and the backup straight electric heat coming on. This uses maybe three times the amount of electricity during the time it takes to get up to temperature.

I don't know if this is caused by the thermostat or the heat pump itself. I'm wondering if anyone makes a programmable thermostat that deals with this issue. If the problem is caused by the thermostat not letting the heat pump run long enough that is easy to fix. If the problem is caused by the heat pump itself, then the way to deal with it is for the thermostat to run the heat pump in bursts short enough to keep the back up heat from running.

Is there anthing you can do to make the heat pump produce more heat?
(have you found anything, or am I just restating your question?)

I'm not sure what you are asking. Heat pumps tend to be on/off arrangements. I've seen something about two stage heat pumps, but whatever that is, I don't have one. So the way to get more heat out of the pump is to run it longer. But that's not the issue. The heat pump isn't "straining" or undersized. It just has to run for a while in order to bring the temperature up and the thermostat is designed to treat that as a condition where it needs to run the backup heat.

Like some of the other posters, I have no idea where you are going with this.

What is the interface from the thermostat to the heat-pump? is it just
one wire for 24V AC, one wire for heat, one wire for fan, and one wire
for ground?

I haven't taken it apart, but I'm sure it's the standard heat pump with electric backup wiring arrangement. There are actually a number of wires, one for heat, one for cooling, one to run the fan, one to bring in power and I believe a common.

I would only care about that if I want to roll my own thermostat.

Again, where would you be going with this?

--

Rick C.

+-+ Get 1,000 miles of free Supercharging
+-+ Tesla referral code - https://ts.la/richard11209

 

[Dave Platt]

In article <a2c09bec-8688-47be-a3f7-5beb65d3908c@googlegroups.com>,
Rick C <gnuarm.deletethisbit@gmail.com> wrote:

If you read my posts, especially the original post, you will find that is exactly what I am doing. I am using a programmable thermostat to drop the set
temperature low enough that it does not come on during the peak time.

The issue I am having has been explained several times including the original post.

It's perhaps an off-the-wall idea, and may not be esthetically
acceptable for your living space, but you might want to consider using
an industrial temperature controller. Some of them have programmable
ramp-and-soak capabilities.

 

[John Robertson]

On 2020/01/11 5:41 p.m., Winfield Hill wrote:

Rick C wrote...

On Saturday, January 11, 2020, Winfield Hill wrote:
Rick C wrote...

... A relay would very likely still kick in the backup heat.

How about adding a high-current contactor, with timer,
to disable the backup heat when you want to do so.

I was thinking of something less intrusive, like a properly
programmable thermostat.

Well, like you say, finding a properly programmable model is
a hard aspect to discover. My Carrier thermostat might work,
but it might not.

To my mind, delaying switch-on of the backup heat isn't very
intrusive. It'll think it has added extra heating, and keep
on doing its regulating job. It'll just take a little longer,
as you've ordained, but it won't know about your thwart, or
if it does, it won't be able to do anything about it. I like
the simplicity of it. Man over machine!

You retain all the smart features of your thermostat, seasonal
and hour-by-hour timing, UV control, humidity control, etc.

I suspect the only real solution to this thermostat issue is an Aurdino
or similar device with thermal sensors that can monitor temperatures and
have an algorithm that compensates for outdoor vs indoor temp and either
allows the heat pump to over-ride as the primary source, or if the
temperature is below the optimum or falling at a rate that would negate
the heat pump then switches to other source of heat.

Some programming is required...

John :-#)#

 

[John Robertson]

On 2020/01/11 11:22 p.m., John Robertson wrote:

On 2020/01/11 5:41 p.m., Winfield Hill wrote:
Rick C wrote...

On Saturday, January 11, 2020, Winfield Hill wrote:
Rick C wrote...

... A relay would very likely still kick in the backup heat.

  How about adding a high-current contactor, with timer,
  to disable the backup heat when you want to do so.

I was thinking of something less intrusive, like a properly
programmable thermostat.

  Well, like you say, finding a properly programmable model is
  a hard aspect to discover.  My Carrier thermostat might work,
  but it might not.

  To my mind, delaying switch-on of the backup heat isn't very
  intrusive.  It'll think it has added extra heating, and keep
  on doing its regulating job.  It'll just take a little longer,
  as you've ordained, but it won't know about your thwart, or
  if it does, it won't be able to do anything about it.  I like
  the simplicity of it.  Man over machine!

  You retain all the smart features of your thermostat, seasonal
  and hour-by-hour timing, UV control, humidity control, etc.



I suspect the only real solution to this thermostat issue is an Aurdino
or similar device with thermal sensors that can monitor temperatures and
have an algorithm that compensates for outdoor vs indoor temp and either
allows the heat pump to over-ride as the primary source, or if the
temperature is below the optimum or falling at a rate that would negate
the heat pump then switches to other source of heat.

Some programming is required...

John :-#)#

You might want to start here for ideas:

https://www.smarthomeblog.net/smart-arduino-thermostat/

John :-#)#

 

[Whoey Louie]

On Saturday, January 11, 2020 at 7:45:59 PM UTC-5, whit3rd wrote:

On Saturday, January 11, 2020 at 12:39:20 PM UTC-8, DecadentLinux...@decadence.org wrote:
whit3rd <whit3rd@gmail.com> wrote in
news:9277545f-c197-4cec-a7f1-0fe0f56ffbcc@googlegroups.com:

On Saturday, January 11, 2020 at 11:42:49 AM UTC-8, Rick C wrote:

I want the heat to be OFF during the peak times of my ToU rates.
Not reduced, not cut back, OFF.

The issue here, is that no man can serve two masters, and no
thermostat can be said to be doing the 'keep temperature constant'
task when it is imperative that the heat be OFF.

I'll would be willing to bet that there is an iPad for your wall,
and an app for that. Should be able to be far more intelligant than
the normal fare.

it might suffice to use a thermostat with a setback, that accepts a 5C lower temperature
during the high-energy-cost hours. The problem is, keeping the thermostat coordinated with
changes (and the seasons: you might want to bump the setpoint UP in summer if
cooling costs count). Making things 'far more intelligent' means they'll trick me.

I still grit my teeth when the cloud does its thing behind my back...

The problem is not the setback. The problem is that if the temp drops
more than a couple degrees, the typical thermostat for a heat pump
then kicks in aux electric heat to help close the delta. Which is one
reason many, maybe most heat pump homes don't set them back at night.

 

[Whoey Louie]

On Saturday, January 11, 2020 at 4:03:28 PM UTC-5, Rick C wrote:

On Saturday, January 11, 2020 at 3:44:58 PM UTC-5, Winfield Hill wrote:
Rick C wrote...

... A relay would very likely still kick in the backup heat.

How about adding a high-current contactor, with timer,
to disable the backup heat when you want to do so.

I was thinking of something less intrusive, like a properly programmable thermostat.

I just thought someone here might have seen this before. I did a search of thermostats, but all the hype and BS gets in the way of seeing what many of them actually do. Even Consumer Reports doesn't seem to have considered this issue and they seem to reflect what the thermostat makers provide, so maybe it's not out there and I need to roll my own.

There is a fairly cost effective FPGA board with a large LCD display. That might be a good choice, but I'm not ready to start designing just yet.

--

Rick C.

--+ Get 1,000 miles of free Supercharging
--+ Tesla referral code - https://ts.la/richard11209

The only way you're likely to find that level of detail is to download
the install manuals for various possible thermostats.

If I were the thermostat maker, I would include a setting where it
estimates how long it will take to close any given delta using only
the heat pump and give you the ability to say that if that time is
less than X minutes, then don't use aux heat.

 

[Whoey Louie]

On Saturday, January 11, 2020 at 8:42:04 PM UTC-5, Winfield Hill wrote:

Rick C wrote...

On Saturday, January 11, 2020, Winfield Hill wrote:
Rick C wrote...

... A relay would very likely still kick in the backup heat.

How about adding a high-current contactor, with timer,
to disable the backup heat when you want to do so.

I was thinking of something less intrusive, like a properly
programmable thermostat.

Well, like you say, finding a properly programmable model is
a hard aspect to discover. My Carrier thermostat might work,
but it might not.

To my mind, delaying switch-on of the backup heat isn't very
intrusive. It'll think it has added extra heating, and keep
on doing its regulating job. It'll just take a little longer,
as you've ordained, but it won't know about your thwart, or
if it does, it won't be able to do anything about it. I like
the simplicity of it. Man over machine!

You retain all the smart features of your thermostat, seasonal
and hour-by-hour timing, UV control, humidity control, etc.


--
Thanks,
- Win

You don't need a high current contactor, unless Carrier is doing something
proprietary to screw you. Normal thermostats have a low voltage wire
that calls for aux heat. If you want to disable it with a hack, just
use that.

 

[Winfield Hill]

Jasen Betts wrote...

Is there anthing you can do to make the heat pump
produce more heat?

My 3-ton R410a heat pump condenser, which maybe
cost $3.8k, goes full-blast when running, draws
5kW from 230Vac, and chills the outside air 5kW
worth. The only way to increase its heating rate
would be to replace it with a bigger model.


--
Thanks,
- Win

 

[Winfield Hill]

Winfield Hill wrote...

My 3-ton R410a heat pump condenser, which maybe
cost $3.8k ...

Looks like that should be more like $1.8 to 2k.
But of course we don't know exactly how much of
our HVAC rebuild price was due to the heat pump.
I recall mention of an extra $800 charge for a
heat pump over a simple compressor, easy choice.


--
Thanks,
- Win

 

[Rick C]

On Sunday, January 12, 2020 at 9:30:43 AM UTC-5, Whoey Louie wrote:

On Saturday, January 11, 2020 at 4:03:28 PM UTC-5, Rick C wrote:
On Saturday, January 11, 2020 at 3:44:58 PM UTC-5, Winfield Hill wrote:
Rick C wrote...

... A relay would very likely still kick in the backup heat.

How about adding a high-current contactor, with timer,
to disable the backup heat when you want to do so.

I was thinking of something less intrusive, like a properly programmable thermostat.

I just thought someone here might have seen this before. I did a search of thermostats, but all the hype and BS gets in the way of seeing what many of them actually do. Even Consumer Reports doesn't seem to have considered this issue and they seem to reflect what the thermostat makers provide, so maybe it's not out there and I need to roll my own.

There is a fairly cost effective FPGA board with a large LCD display. That might be a good choice, but I'm not ready to start designing just yet.

--

Rick C.

--+ Get 1,000 miles of free Supercharging
--+ Tesla referral code - https://ts.la/richard11209

The only way you're likely to find that level of detail is to download
the install manuals for various possible thermostats.

If I were the thermostat maker, I would include a setting where it
estimates how long it will take to close any given delta using only
the heat pump and give you the ability to say that if that time is
less than X minutes, then don't use aux heat.

Just as thermostat makers give nice, fancy terms to the early onset to ramp the temperature up, I would expect a feature like this to have a nice, fancy name and in particular note the savings in cost by not kicking in the backup heat. So, no, while it may require reading a *lot* of ad copy, I don't think it will require reading "install manuals". In fact, having read a number of "install manuals" over the years, I don't think that info would be in them unless it was programmable in some way.

But there's only one way to tell for sure. I would contact an installer, but from the blank stares I'm getting from this crowd I rather doubt the installer community would understand what I'm talking about. My previous encounters with the HVAC crowd tells me they are not the most intellectual crowd often knowing much less about topics than I do. But they have the experience I don't and they know the jargon I don't. Sounds like doctors.

--

Rick C.

++- Get 1,000 miles of free Supercharging
++- Tesla referral code - https://ts.la/richard11209

 

[Rick C]

On Sunday, January 12, 2020 at 9:33:09 AM UTC-5, Whoey Louie wrote:

On Saturday, January 11, 2020 at 8:42:04 PM UTC-5, Winfield Hill wrote:
Rick C wrote...

On Saturday, January 11, 2020, Winfield Hill wrote:
Rick C wrote...

... A relay would very likely still kick in the backup heat.

How about adding a high-current contactor, with timer,
to disable the backup heat when you want to do so.

I was thinking of something less intrusive, like a properly
programmable thermostat.

Well, like you say, finding a properly programmable model is
a hard aspect to discover. My Carrier thermostat might work,
but it might not.

To my mind, delaying switch-on of the backup heat isn't very
intrusive. It'll think it has added extra heating, and keep
on doing its regulating job. It'll just take a little longer,
as you've ordained, but it won't know about your thwart, or
if it does, it won't be able to do anything about it. I like
the simplicity of it. Man over machine!

You retain all the smart features of your thermostat, seasonal
and hour-by-hour timing, UV control, humidity control, etc.


--
Thanks,
- Win

You don't need a high current contactor, unless Carrier is doing something
proprietary to screw you. Normal thermostats have a low voltage wire
that calls for aux heat. If you want to disable it with a hack, just
use that.

Disabling the backup heat won't necessarily work anyway. I had a heat pump backed by an oil burner. The oil burner stopped lighting one day and the system just didn't work. Seems they turn off the heat pump when running the back up heat and if the backup heat doesn't work you are then stuck with no heat even though the primary heat works!

--

Rick C.

+++ Get 1,000 miles of free Supercharging
+++ Tesla referral code - https://ts.la/richard11209

 

[Winfield Hill]

Rick C wrote...

Disabling the backup heat won't necessarily work anyway.
I had a heat pump backed by an oil burner. The oil burner
stopped lighting one day and the system just didn't work.
Seems they turn off the heat pump when running the back
up heat and if the backup heat doesn't work you are then
stuck with no heat even though the primary heat works!

Yes, our system works that way.


--
Thanks,
- Win

 

[Jasen Betts]

On 2020-01-12, Rick C <gnuarm.deletethisbit@gmail.com> wrote:

On Saturday, January 11, 2020 at 11:30:49 PM UTC-5, Jasen Betts wrote:
On 2020-01-11, Rick C <gnuarm.deletethisbit@gmail.com> wrote:
I am using a programmable thermostat to turn off the heat and/or air conditioning during the peak usage times as set by the ToU billing with my utility. The problem I have is the heat pump not ramping up the temperature fast enough when it comes back on and the backup straight electric heat coming on. This uses maybe three times the amount of electricity during the time it takes to get up to temperature.

I don't know if this is caused by the thermostat or the heat pump itself. I'm wondering if anyone makes a programmable thermostat that deals with this issue. If the problem is caused by the thermostat not letting the heat pump run long enough that is easy to fix. If the problem is caused by the heat pump itself, then the way to deal with it is for the thermostat to run the heat pump in bursts short enough to keep the back up heat from running.

Is there anthing you can do to make the heat pump produce more heat?
(have you found anything, or am I just restating your question?)

I'm not sure what you are asking. Heat pumps tend to be on/off arrangements. I've seen something about two stage heat pumps, but whatever that is, I don't have one. So the way to get more heat out of the pump is to run it longer. But that's not the issue. The heat pump isn't "straining" or undersized. It just has to run for a while in order to bring the temperature up and the thermostat is designed to treat that as a condition where it needs to run the backup heat.

Like some of the other posters, I have no idea where you are going with this.


What is the interface from the thermostat to the heat-pump? is it just
one wire for 24V AC, one wire for heat, one wire for fan, and one wire
for ground?

I haven't taken it apart, but I'm sure it's the standard heat pump with electric backup wiring arrangement. There are actually a number of wires, one for heat, one for cooling, one to run the fan, one to bring in power and I believe a common.

I would only care about that if I want to roll my own thermostat.

Again, where would you be going with this?

I'm trying to identify the problem space.

If the thermostat can't call for extra heat (more neat the regular
heat) it also can't control what the heat-pump does to provide the heat.


Perhaps the compressor is reading something into it length of the
heat command. maybe if you blip the heat command off for 30 seconds
every 15 minutes it won't fire up the resistive heater.


If it can call for extra heat you'll need a script that queries
the thermostat for the current temperature (I expect a smart
thermostat knows the current temperature) and then puts the set point
just a few degrees warmer so that the thermostat doesn't go into rush
mode and ask for extra heat (just ask for regular heat).

--
Jasen.