Eliminate Thermostat

[apostolakisl]

I wouldn't trust anything important to a Raspberry Pi.

 

 

One reason I like the Honeywell (TH8320ZW1000) Z-Wave thermostat is that the (hidden, not Z-wave settable) installer settings include "range stops" ( high and low limits for setting heat and cooling target temperatures), as well as safeguards for "Compressor Protection" and cycles per hour (CPH) to avoid short-cycling.   This all makes it a little less likely that end-user error will cause major problems.

 

Additionally, if the network connectivity drops out or Z-Wave module stops talking, the thermostat defaults back to acting as a normal programmable thermostat.

 

The Insteon thermostat has short cycle protection in it as well.  You can go into the "hidden" level programming on it and alter the time-out periods, but by default it is set to something like 5 minutes.

 

But as LFMc mentions, The HVAC units themselves have their own short-cycle protection circuits built-in.

 

Personally, the only gripe I have with the Insteon thermostats is that the "cooling" and "heating" state of the thermostat is not an insteon "status".  It is a "control" event which means if it gets out of sync, the only way to get it in sync is to cycle it (a query doesn't do it).  

[LFMc]

Personally, the only gripe I have with the Insteon thermostats is that the "cooling" and "heating" state of the thermostat is not an insteon "status".  It is a "control" event which means if it gets out of sync, the only way to get it in sync is to cycle it (a query doesn't do it).  

 

My main grip of the Insteon thermostat would be the large hysteresis on the AC on/off side. I sleep on the edge of temperature comfort and the +/- 1 degree swing (2 degrees between off/on) wakes me up on the high side of this swing at night (throwing off the sheet, flipping the pillow over, etc.). So I wrote a program on the ISY that monitors the thermostat and cycles it on more of a +/- .5F swing. So instead of the AC going on/off every 2 hours, it cycles about every 30 minutes and the smaller temperature swing is much more comfortable. 

 

I wish there was a setting on the thermostat itself, but I haven't found one. I have had other thermostats that allow you to adjust the hysteresis. 

[Teken]

When I built my home almost nine years ago geo thermal was very high on the list of wants. Like others when I saw the different quotes from the vendors it simply didn't pencil out for me over a 25 year period.

 

25 years is a freaking long time and if it doesn't pencil out in more than two and half decades it makes little sense.

 

One thing which really depends upon how much electricity is in your location is the crazy standby power draw for these systems. I honestly don't believe these systems were ever designed for a small home and thus at the minimum a home would need to be at least 1800 and larger to make sense. Reviewing a few members who have a Brultech Dash Box & Green Eye Monitor the cost to run these systems was quite shocking.

 

This doesn't even address those who have a HRV system that runs all the time . . .

 

I came very close in pushing the button on integrating these systems into my home but after more review and monitoring the cost benefit ratio made little sense. 

 

Then again I'm probably on the fringe scale of energy consumption when compared to most I know so maybe not a good reference point. When I see people who have electrical bills before any tax's or other charges that exceed $300 ~ 1100.00 per month it just shocks me. 

[ScottAvery]

My main grip of the Insteon thermostat would be the large hysteresis on the AC on/off side. I sleep on the edge of temperature comfort and the +/- 1 degree swing (2 degrees between off/on) wakes me up on the high side of this swing at night (throwing off the sheet, flipping the pillow over, etc.). So I wrote a program on the ISY that monitors the thermostat and cycles it on more of a +/- .5F swing. So instead of the AC going on/off every 2 hours, it cycles about every 30 minutes and the smaller temperature swing is much more comfortable. 

 

I wish there was a setting on the thermostat itself, but I haven't found one. I have had other thermostats that allow you to adjust the hysteresis. 

 

Please share your programs!

[mwester]

Regarding the geothermal.  I think it is very dependent on your local conditions.  I got a quote when I built my house.  It was absolutely CRAZY expensive.  No way in the world it would ever even come close to paying off.  Even if it were so effiiient that it cut my hvac energy use to zero, it would not pay for itself.  I think it was like $80k more expensive than the SEER 19 Carrier infinity system I put in.

 

Having said that, if you live somewhere where you can drill a single well and pump ground water up maybe 30 feet and then you have someplace to dump that ground water, then I think you would totally be in business.  That sort of well is very cheap and if you have ground water between 40 and 60, it would be really efficient.

 

But where I live groundwater is 500 feet down.  So they wanted to drill like 6 or 8 holes in the ground and run loops to cool/warm a circuit of antifreeze they pump through the system.  Furthermore, I have read that toward the end of the season, the ground around the holes warms/cools to the point where it is hotter/colder than the outside air.  

 

Our system was planned to be horizontal ground loops - because it's a lot cheaper, and we had the space.  As it turns out, over half of the loops encountered a sandstone ledge about 20' into the bore, and they lost the ability to control the direction as they bored through that, with the end result being that several of the loops went downward at a 45 degree angle and ended up far, far below the water table.  The factory techs that came out to test the unit during it's initial operation were pretty impressed with the test results for the loops -- they'd never encountered any field systems with horizontal loops that were that close to the ideal.  By being in the ground water all year, that also eliminates that problem where the ground around the loops cools or warms as the season goes on.

 

Even so, it's hard to get a positive return on the investment.  I like to think that at least there are some animals and trees out there somewhere that might thank me if they could talk... and I have bragging rights when I bump into some of those incredibly annoying, self-righteous tree-huggers.  That's worth something at least!  

[mwester]

...

I wasn't aware of any inherent delays. Is it the pump flow rate that causes the delays or something else?

...

 

It's actually the low temperature delta from a geo.  A normal radiator-based heating system runs at 140 to 160 degrees for the water, most in-floor radiant runs at about 120 degrees, but a geothermal maxes out at about 100 to 105 degrees.  Since heat transfer rates depend on the temperature delta, the geothermal system ends up taking enormous amounts of time to shift an entire house by just a few degrees.  A bigger geo would do better, but it's already huge -- as a data point, it's on its own panel with the water heater, and the geo's circuit breaker is a dual 70A breaker...

[paulbates]

 

Personally, the only gripe I have with the Insteon thermostats is that the "cooling" and "heating" state of the thermostat is not an insteon "status".  It is a "control" event which means if it gets out of sync, the only way to get it in sync is to cycle it (a query doesn't do it).  

 

My biggest gripe was ignitor voltage spikes could completely lock them up. I went through a couple of rounds of replacements from SH on 2 HVAC units, yet still continued to come home or wake up in the middle of the night with temperature climbing through the 80's. It quit communicating when this happened. I was told "the next FW upgrade would fix it", when in fact it was a HW design flaw. The same furnaces using the same wires did not have that effect on the original honeywell dumb stats,  2 different versions of RCS X10 thermostats or 2 versions of the venstar color touch. There's a long thread around here where filtering system was built to prevent it, but I looked elsewhere.

 

I know it doesn't happen to most people, but after 3 rounds of replacements, I was done.

[apostolakisl]

My biggest gripe was ignitor voltage spikes could completely lock them up. I went through a couple of rounds of replacements from SH on 2 HVAC units, yet still continued to come home or wake up in the middle of the night with temperature climbing through the 80's. It quit communicating when this happened. I was told "the next FW upgrade would fix it", when in fact it was a HW design flaw. The same furnaces using the same wires did not have that effect on the original honeywell dumb stats,  2 different versions of RCS X10 thermostats or 2 versions of the venstar color touch. There's a long thread around here where filtering system was built to prevent it, but I looked elsewhere.

 

I know it doesn't happen to most people, but after 3 rounds of replacements, I was done.

 

Fortunately I have never seen this.

 

I did have a bizaare "brown out" that screwed them up.  We have 3 phase power, and 1 phase stayed on like normal.  The other two phaes dropped to 25v (they were supposed to be 120v) for several hours.  The thermostats that went to 25v needed to be hard reset using a "Secret" button that is on the circuit board.  I don't blame anyone but the electric company for that one.  Though they deny it.  They say it must have been us.  Yearh, OK, how exactly do we cause that to happen.  Plus it happened to two buildings which each have their own independent service.

[apostolakisl]

My main grip of the Insteon thermostat would be the large hysteresis on the AC on/off side. I sleep on the edge of temperature comfort and the +/- 1 degree swing (2 degrees between off/on) wakes me up on the high side of this swing at night (throwing off the sheet, flipping the pillow over, etc.). So I wrote a program on the ISY that monitors the thermostat and cycles it on more of a +/- .5F swing. So instead of the AC going on/off every 2 hours, it cycles about every 30 minutes and the smaller temperature swing is much more comfortable. 

 

I wish there was a setting on the thermostat itself, but I haven't found one. I have had other thermostats that allow you to adjust the hysteresis. 

 

Not really a big deal in our situation.  But I can see where it might be in a bedroom.  The other thing is if you have a two stage it has a 5 degree kick on point.  That seems pretty severe to not turn on stage two until stage 1 falls 5 degrees behind.  But again, not an issue in my install.

[paulbates]

Fortunately I have never seen this.

 

I did have a bizaare "brown out" that screwed them up.  We have 3 phase power, and 1 phase stayed on like normal.  The other two phaes dropped to 25v (they were supposed to be 120v) for several hours.  The thermostats that went to 25v needed to be hard reset using a "Secret" button that is on the circuit board.  I don't blame anyone but the electric company for that one.  Though they deny it.  They say it must have been us.  Yearh, OK, how exactly do we cause that to happen.  Plus it happened to two buildings which each have their own independent service.

 

I hear you, but older devices like togglincs and original keypads also get "confused" by long brownouts too.  Flaky operation, high pitched noises, flickering backlight, beeping when pressed even though beeping turned off, etc. A factory reset and restore device solves it.

 

Brown outs are a reality of having power for a lot of us. It's possible to create test cases just for that, just like igniter spiking. Its doesn't happen for newer devices bought in the last few years, so maybe this one's been solved. 

 

Paul

[larryllix]

Fortunately I have never seen this.

 

I did have a bizaare "brown out" that screwed them up.  We have 3 phase power, and 1 phase stayed on like normal.  The other two phaes dropped to 25v (they were supposed to be 120v) for several hours.  The thermostats that went to 25v needed to be hard reset using a "Secret" button that is on the circuit board.  I don't blame anyone but the electric company for that one.  Though they deny it.  They say it must have been us.  Yearh, OK, how exactly do we cause that to happen.  Plus it happened to two buildings which each have their own independent service.

I can guess the transformer that feeds your home

 

You have a 3 phase delta to wye transformer. Guess at 8,000 v (system) delta winding primary  to 120/208v wye winding secondary. This may be a Network style service and rated 125//216Vac in order to keep residential consumers happier. Common in high density areas.

 

When one primary phase fuse blows you only have two primary phases  left. This activates one core at 100% voltage, and the other two at a floating 50% each, due to (two core  winding ) being in series between the two remaining live phases. No 208v ac will be available with any combination of voltages in your house but should be about 120vac, and 60 L-N and 60 L-N which will only subtract from the 102vac and not add to a higher voltage being that the three phase has lost it's phase shifts and become single phase only.. This can destroy motors and other sensitive equipment.

 

A diagram would really help explain  this.

[lilyoyo1]

When my house was built, I thought about hiding the thermostats in closets because I knew I would have a couple of touchscreens in the house. In the end, im glad I left them out. Manufactures are making the thermostats to be designer pieces now so they dont look funky like many other units out there. I'm with Teken on the downsides to using something other than a true thermostat for control. Its possible but should the unlikely happen, the cons simply are not worth the look that it gives.

[LFMc]

Please share your programs!

Hey Scott.

It is really fairly simple. As I stated, I hated the 2F temp swings at night under the AC. So I ginned this up in about 15 minutes. It works well for me, but given time to redo it, I could come up with something more sophisticated. 

Basically every 30 minutes, the program bumps down the AC set point by one degree for a predetermined interval and then sets it back up one degree to the original set point. You can obviously vary it to meet your needs.

 

It needs four variables:

1. $sHour_Count (time of day 24 hour counter). This variable already existed in my system from a prior project to develop an ISY based calendar and clock. It is on another forum.

2. $AC_On_Minutes_i  (is the interval to run the AC at a lower temp. (i.e. time the AC set point is reduced). For my system it is set to 5, and that equates to minutes per half an hour interval. )

3. $AC_Wait_Set_i  Is the count down interval. That is set equal to #2. and counts down each minute to trigger the change in the set point going back up 1 degree. 

4. $iHalf_Hour_Set.  This is zero or one. Tells you if the program is on the top of the hour or the bottom of the hour so the set point set back happens every 30 minutes. 

 

Program 1:  Auto AC Drop Temp 1 degree 

If

        $sHour_Count > -1

    And Status  'TStats / Tstat, Down' is Mode Cool

Then

        Set 'TStats / Tstat, Down' Setpoint Down 1°

        $AC_Wait_Set_i  = $AC_On_Minutes_i

        Run Program 'Auto AC Wait Interval' (If)

Else

   - No Actions 

 

 

Program 2: Auto AC Wait Interval

If

        $AC_Wait_Set_i > 0

Then

        $AC_Wait_Set_i -= 1

        Wait  1 minute 

        Run Program 'Auto AC Wait Interval' (If)

Else

        Run Program 'Auto AC Raise Temp 1d' (If)

 

 

Program 3: Auto AC Raise Temp 1 degree

If

        $AC_Half_Hr_Set_i < 1

Then

        Set 'TStats / Tstat, Down' Setpoint Up 1°

        $AC_Half_Hr_Set_i  = 1

        Wait  25 minutes 

        Run Program 'Auto AC Drop Temp 1d' (Then Path)

Else

        Set 'TStats / Tstat, Down' Setpoint Up 1°

        $AC_Half_Hr_Set_i  = 0

 

It turns out to work very well for me and to be pretty resilient to interruptions or to anyone changing the set point up or down at any time. It just readjusts to the new set point. I sleep a lot better now in the summer with this working. 

 

Enjoy. 

[larryllix]

 

Hey Scott.

It is really fairly simple. As I stated, I hated the 2F temp swings at night under the AC. So I ginned this up in about 15 minutes. It works well for me, but given time to redo it, I could come up with something more sophisticated. 

Basically every 30 minutes, the program bumps down the AC set point by one degree for a predetermined interval and then sets it back up one degree to the original set point. You can obviously vary it to meet your needs.

 

It needs four variables:

1. $sHour_Count (time of day 24 hour counter). This variable already existed in my system from a prior project to develop an ISY based calendar and clock. It is on another forum.

2. $AC_On_Minutes_i  (is the interval to run the AC at a lower temp. (i.e. time the AC set point is reduced). For my system it is set to 5, and that equates to minutes per half an hour interval. )

3. $AC_Wait_Set_i  Is the count down interval. That is set equal to #2. and counts down each minute to trigger the change in the set point going back up 1 degree. 

4. $iHalf_Hour_Set.  This is zero or one. Tells you if the program is on the top of the hour or the bottom of the hour so the set point set back happens every 30 minutes. 

 

Program 1:  Auto AC Drop Temp 1 degree 

If

        $sHour_Count > -1

    And Status  'TStats / Tstat, Down' is Mode Cool

Then

        Set 'TStats / Tstat, Down' Setpoint Down 1°

        $AC_Wait_Set_i  = $AC_On_Minutes_i

        Run Program 'Auto AC Wait Interval' (If)

Else

   - No Actions 

 

 

Program 2: Auto AC Wait Interval

If

        $AC_Wait_Set_i > 0

Then

        $AC_Wait_Set_i -= 1

        Wait  1 minute 

        Run Program 'Auto AC Wait Interval' (If)

Else

        Run Program 'Auto AC Raise Temp 1d' (If)

 

 

Program 3: Auto AC Raise Temp 1 degree

If

        $AC_Half_Hr_Set_i < 1

Then

        Set 'TStats / Tstat, Down' Setpoint Up 1°

        $AC_Half_Hr_Set_i  = 1

        Wait  25 minutes 

        Run Program 'Auto AC Drop Temp 1d' (Then Path)

Else

        Set 'TStats / Tstat, Down' Setpoint Up 1°

        $AC_Half_Hr_Set_i  = 0

 

It turns out to work very well for me and to be pretty resilient to interruptions or to anyone changing the set point up or down at any time. It just readjusts to the new set point. I sleep a lot better now in the summer with this working. 

 

Enjoy. 

 

Nice!

This appears you have created your own PWM stat function. Many commercial stats have this built in.

 

I use Integer variables as constants, like you have and I label them with "c", different style but like this $cAC_ON_MINUTES.  Following the style of some programming languages I also use all caps. This makes constants more easily identifiable.

I have requested a new tab in admin console for this purpose. We''ll see what comes down the pipe. 

[LFMc]

Nice!

This appears you have created your own PWM stat function. Many commercial stats have this built in.

 

I use Integer variables as constants, like you have and I label them with "c", different style but like this $cAC_ON_MINUTES.  Following the style of some programming languages I also use all caps. This makes constants more easily identifiable.

I have requested a new tab in admin console for this purpose. We''ll see what comes down the pipe. 

Thanks Larry,

 

Good info on the constants. I think I will implement that also. 

[larryllix]

Thanks Larry,

 

Good info on the constants. I think I will implement that also. 

I should also mention that after years of rearranging them I have tried to install about 199 blank Integers so that I can install all my constants above the 200 numbers so that I don't have to see them when viewing other "dynamic" variables.

 

Another nice thing about the "c" at the front is they sort into groups of dynamic and static variables when writing program, using the pull-down variable list menus.

OTOH if you use functional text  names first in the variable names (as you appear to have done) they sort into functional groups also.

Then there is the variable sacrificed as titles for variable function groups that I start with "__________________HVAC Things". They also appear despite not wanting them to.