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HVAC control wiring...

D

Don Y

Guest
On 8/14/2020 2:14 PM, Grant Taylor wrote:
On 8/12/20 11:48 PM, Don Y wrote:
Figure out what problem you\'re trying to solve instead of trying to define a
problem that fits a particular solution.

I did exactly that. I want the system to run for X number of minutes. I
presented multiple example cases of my problem.
\"I want the system to run for X minutes\" is a solution, not a problem
statement. All that follows that statement is *implementation*.

Before I design anything, I survey the likely users to see HOW they expect
a device to \"solve their problem(s)\" -- in this case, keeping the interior
space at a comfortable temperature with minimal intervention. For the
thermostat, that effort was over 100 \"consumer interviews\" -- not
\"paper surveys\" (because people don\'t seem to actively consider what
they are \"saying\").

In each case, I asked folks how they used their current thermostat, what
capabilities it presented, the problems it solved -- and the problems
it didn\'t solve or actually *introduced* (e.g., having to \"program\"
a thermostat is a problem that doesn\'t exist with a non-programmable
thermostat). I asked them how happy they were with the thermostat\'s
performance (letting THEM define performance however they saw fit).
I asked them what goal they had in purchasing that thermostat (better
plant control, energy efficiency/cost savings, \"tech appeal\", ease
of use, etc.) and how it had met/failed-to-meet that goal.

\"Sometimes, when I come into the house, I turn up the thermostat a
degree or two?\" (which is the only way they can cause the plant to fire)

\"Why?\"

\"To get the chill out of the air\"

I.e., they don\'t want the house to STAY \"a degree or two warmer\"; they
just want a temporary injection of heat. I noticed that this was
only the case with GFA plants; oil-fired hot water has so much lag
in it that there is no immediate sense of warmth -- your body acclimates
to the new indoor temperature faster than the environment can be
notably changed. By contrast, standing beside an HVAC register in a GFA
home it\'s obvious that hot air is flowing.

[I leverage that to provide \"max cool\" when occupants are looking for
a noticeable cooldown -- instead of letting the blower run at a slower
rate]

Then, grilled them as to why they hadn\'t purchased a Thermostat5000
or HeatNCool900 or... -- which seemed to also address their needs,
possibly better. Perhaps they were unaware of the product offering?
Or, intimidated by the UI? Or, the price tag and payback period?
Or, intimidated by the installation (do I have to HIRE an electrician)?

*Only* then, set out to figure out how to provide the desired functionality
and price point they seemed to endorse while avoiding the issues that
made them reluctant to adopt some other, existing \"solution\".

You seem to not want to acknowledge or accept my problem. That\'s on you.
You\'re opinion of my problem doesn\'t make my problem any less of a problem to me.
No, I see you sold yourself short in accepting a SOLUTION that popped into
your head instead of exploring what you REALLY wanted to do (\"get the
chill out of the air\"). You subconsciously replaced your real goal with
an artificial goal and then rationalized IT\'S solution as being the
desired solution.

What do you expect to get from your plant from X minutes of runtime?
Other than hearing the blower motor run for X minutes (if that\'s
all you wanted, then just run the FAN for X minutes and RATONALIZE
that you\'ve met your -- now doubly revised --goal)? Would you
accept a thermostat that operated as:

while (FOREVER) {
if (temperature < setpoint) {
run_furnace(X_minutes) // blocks!
}
}

What sort of performance would you expect from it? How would you
know to tweek X for tomorrow\'s conditions?

We have thermostats that control our evaporative coolers, here.
They are largely temperature driven. But, all suffer from a
fatal flaw: without knowledge of the exterior conditions,
they can make the interior WORSE than it would otherwise have
been if they\'d just left the cooler OFF:

\"Gee, temperature is still rising! Better keep the cooler
running on high...\"

[Of course it is rising! The current dewpoint is such that adding
moisture to the air will only cause the REPLACED interior air to
more quickly approach the temperature of the exterior air! E.g.,
if it\'s 100+ outdoors -- even if very dry -- and currently 70 inside,
there\'s almost no case where turning the cooler on will make you more
comfortable.]

They \"solved\" the wrong problem. But, \"it was easy\" -- use an
existing solution that they could con themselves into thinking was
correct (as long as you don\'t think too hard on it)!

[N.B. This remains the case, today. Because it has trained *users* to
compensate for its inadequacies. Like charging systems on electric
wheelchairs...]
 
F

Flyguy

Guest
On Monday, August 3, 2020 at 1:37:04 PM UTC-7, klaus.k...@gmail.com wrote:
In Europe it is mostly wireless:

https://www.vvs-eksperten.dk/varme-og-klima-gulvvarme-rumtermostater-til-gulvvarme-wavin-ahc-9000-rumtermostat-tradlos-466331115

Only 80USD for something they can produce for maybe 8 USD. Nice profit margins

Don\'t you use wireless systems in the US?

Cheers

Klaus
The wiring also provides the thermostat with its power (which should be on the same circuit as the furnace), which would have to come from some other source, so you aren\'t saving anything with a wireless control link.
 
K

Klaus Kragelund

Guest
On Saturday, August 15, 2020 at 11:03:10 PM UTC+2, Flyguy wrote:
On Monday, August 3, 2020 at 1:37:04 PM UTC-7, klaus.k...@gmail.com wrote:
In Europe it is mostly wireless:

https://www.vvs-eksperten.dk/varme-og-klima-gulvvarme-rumtermostater-til-gulvvarme-wavin-ahc-9000-rumtermostat-tradlos-466331115

Only 80USD for something they can produce for maybe 8 USD. Nice profit margins

Don\'t you use wireless systems in the US?

Cheers

Klaus

The wiring also provides the thermostat with its power (which should be on the same circuit as the furnace), which would have to come from some other source, so you aren\'t saving anything with a wireless control link.
Installation cost, routing the wires?
 
D

Don Y

Guest
On 8/17/2020 3:29 PM, Klaus Kragelund wrote:
Don\'t you use wireless systems in the US?

The wiring also provides the thermostat with its power (which should be on
the same circuit as the furnace), which would have to come from some other
source, so you aren\'t saving anything with a wireless control link.

Installation cost, routing the wires?
The wires are typically run when the house is still in the \"framing\" stage.
So, the walls are all \"open\" and accessible.

It\'s also unlikely that the thermostat\'s location will ever be changed,
thereafter.

Historically, thermostats were just SWITCHES and didn\'t \"consume\"
power. Rather, they just completed a circuit in the furnace (or AC)
to activate the plant. There\'s a color code and associated \"usage\"
that I think has been defined by convention (not regulation).

For example, a Blue wire is often used as \"common\". Red wire(s) -- one
for heat, the other for cooling -- activate those function(s) in the plant.
A yellow wire controls the compressor. Green controls the fan/blower.
White handles auxilliary heat. Etc.

(though there may be color substitutions and some \"odd\" repurposing,
depending on the previous usage)

<https://thefrisky.com/wp-content/uploads/2019/08/Thermostat-Wiring.jpg>

<https://valkyrie.cdn.ifixit.com/media/2019/06/27113902/thermostat-featured.jpg>

<https://i.stack.imgur.com/hqnQE.jpg>

Increasingly, HVAC systems are moving to more proprietary thermostats.
But, still leverage the existing wires in homes for purposes that
they redefine.

For example, I\'ve located my HVAC controller adjacent to the furnace.
It is wired directly to the furnace, AC compressor, evaporative
cooler and condensate pump. But, I take advantage of the existing
wire bundle to the \"old\" thermostat to power a Nest (TmReg) thermostat
located there.

But, I\'ve \"rooted\" the Nest so that it no longer acts as a thermostat.
Instead, it just acts as a user interface... communicating with my
HVAC controller over those preexisting wires. So, an occupant can
display the current temperature (and other information) sourced from
my controller -- as well as interact with the controller to make changes
to the HVAC system in a more intuitive manner.

[If/when we sell the house, I can remove my controller and reconnect
\"those wires\" to the furnace for a more traditional thermostat\'s use.]

I\'ve gone to great lengths to avoid relying on wireless technologies, here.
 
R

Ricketty C

Guest
On Monday, August 17, 2020 at 6:30:03 PM UTC-4, Klaus Kragelund wrote:
On Saturday, August 15, 2020 at 11:03:10 PM UTC+2, Flyguy wrote:
On Monday, August 3, 2020 at 1:37:04 PM UTC-7, klaus.k...@gmail.com wrote:
In Europe it is mostly wireless:

https://www.vvs-eksperten.dk/varme-og-klima-gulvvarme-rumtermostater-til-gulvvarme-wavin-ahc-9000-rumtermostat-tradlos-466331115

Only 80USD for something they can produce for maybe 8 USD. Nice profit margins

Don\'t you use wireless systems in the US?

Cheers

Klaus

The wiring also provides the thermostat with its power (which should be on the same circuit as the furnace), which would have to come from some other source, so you aren\'t saving anything with a wireless control link.

Installation cost, routing the wires?
What routing??? Every house in the US has the wires from the original construction... unless it is over 100 years old. We have some of those, but even those have already been retrofitted. When we started using electrical thermostats in the US no one used wireless, so now every home has the wires.

I recall an old movie where Darran McGavin fights a furnace which has rods in the wall to control it. It should be pretty easy to convert that to wires. Just drop the cable through the hole!

--

Rick C.

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

Klaus Kragelund

Guest
On Tuesday, August 18, 2020 at 12:59:52 AM UTC+2, Don Y wrote:
On 8/17/2020 3:29 PM, Klaus Kragelund wrote:
Don\'t you use wireless systems in the US?

The wiring also provides the thermostat with its power (which should be on
the same circuit as the furnace), which would have to come from some other
source, so you aren\'t saving anything with a wireless control link.

Installation cost, routing the wires?
The wires are typically run when the house is still in the \"framing\" stage.
So, the walls are all \"open\" and accessible.

It\'s also unlikely that the thermostat\'s location will ever be changed,
thereafter.
What is the cost of having the electrician route 100m cable? (10 zones with 10m cable)

What level of joy do you have when you discover you need to move a thermostat after construction, or add a new one if you expand the house?

Cheers

Klaus
 
R

Ricketty C

Guest
On Tuesday, August 18, 2020 at 3:11:49 PM UTC-4, Klaus Kragelund wrote:
On Tuesday, August 18, 2020 at 12:59:52 AM UTC+2, Don Y wrote:
On 8/17/2020 3:29 PM, Klaus Kragelund wrote:
Don\'t you use wireless systems in the US?

The wiring also provides the thermostat with its power (which should be on
the same circuit as the furnace), which would have to come from some other
source, so you aren\'t saving anything with a wireless control link.

Installation cost, routing the wires?
The wires are typically run when the house is still in the \"framing\" stage.
So, the walls are all \"open\" and accessible.

It\'s also unlikely that the thermostat\'s location will ever be changed,
thereafter.

What is the cost of having the electrician route 100m cable? (10 zones with 10m cable)

What level of joy do you have when you discover you need to move a thermostat after construction, or add a new one if you expand the house?
Thermostat wiring does not require an electrician. The wire would have been installed when the furnace was installed and been a part of the overall installation and so invisible for all intents.

The only wireless thermostat I\'ve seen was on a convector system where they ran Freon pipes around the home rather than air ducts to replace an 80 year old steam system... which already had wires. But the convectors were in the rooms, not in the basement, so the wires were of no use and the convectors had the thermostat internal anyway.

Now the problem is, \"Where is that durn thermostat remote control???\"

--

Rick C.

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

Don Y

Guest
On 8/18/2020 12:11 PM, Klaus Kragelund wrote:
On Tuesday, August 18, 2020 at 12:59:52 AM UTC+2, Don Y wrote:
On 8/17/2020 3:29 PM, Klaus Kragelund wrote:
Don\'t you use wireless systems in the US?

The wiring also provides the thermostat with its power (which should
be on the same circuit as the furnace), which would have to come from
some other source, so you aren\'t saving anything with a wireless
control link.

Installation cost, routing the wires?
The wires are typically run when the house is still in the \"framing\"
stage. So, the walls are all \"open\" and accessible.

It\'s also unlikely that the thermostat\'s location will ever be changed,
thereafter.

What is the cost of having the electrician route 100m cable? (10 zones with
10m cable)
While the house is in an \"open frame\" state? It\'s practically free
(low voltage cabling has few requirements regarding it\'s handling
on which a *carpenter* wouldn\'t be easily educated)

Note that the vast majority of homes are cookie-cutter designs -- same
floor plan (or mirrored) for one of N (N being a small integer) designs
in a given (new) subdivision.

What level of joy do you have when you discover you need to move a
thermostat after construction, or add a new one if you expand the house?
Thermostat (and plant!) don\'t move after construction. It\'s location
is considered when the house plans are drawn up. The same is true for
the \"doorbell\" (button and annunciator).

Even trivial jobs that require the services of a licensed electrician
are costly -- e.g., to add a duplex receptacle is ~$200 -- assuming it\'s
\"near\" a Jbox that it can tap into. Note the cost won\'t typically reflect
any efforts required to restore the wall(s) to their original level of
finish/appearance.

Installing network drops will average ~$150-200 per drop -- assuming the
house\'s construction MAKES IT EASY (i.e., access to wall cavities via an
exposed basement or attic space) and you may have to \"buy\" several to
cover setup charges (e.g., $1000/5).

[Often, folks avoid the use of a licensed electrician in the belief that
there are no Code requirements for low voltage wiring so \"Joe Handyman\"
gets the job]

Folks don\'t tend to \"expand\" their houses. :> If they do, they install
a separate plant in that \"addition\", if it is large enough to overtax
the existing plant. (I have friends with 3 HVAC plants in their residences).

If the addition is too small to warrant it\'s own plant, you can consider
adding a separate zone. But, that requires changes to the plant which
tend to make the addition of a separate thermostat \"small potatoes\", by
comparison (even if the changes are just a motor-driven vent/register).

If you REALLY want to add a second sensing element, you can buy an aftermarket
product that lets you tie into your plant (plant is usually located in a
basement, closet, etc. soas not to be an eyesore; as such, access to power
and the plant wiring isn\'t \"fussy\")


By far, the bigger market is to REPLACE your existing thermostat -- at its
existing location -- with a thermostat that has more features. E.g., time
of day \"temperature setback\"; digital display (instead of analog); more
modern appearance; etc.

The \"classic\" thermostat -- while simple and copied -- is rather dated:

<https://i2.wp.com/www.technologizer.com/wp-content/uploads/2014/06/image22.jpg>

Note it\'s simplicity of design:

<https://www.timothyoffheating.com/wp-content/uploads/2016/11/Honeywell-thermostat-repair.jpg>

The glass tip of the mercury switch (short to call for heat) mounted on
the bimetallic coil can be seen just above the screw at 3:00 in the photo.
You can also just barely see the *heater* that forms the anticipator
riding atop that coil!

E.g., newer thermostats use WiFi to connect to your router and provide
remote accessibility (as well as \"learning functions\" and, of course,
leaking information about your occupancy and activity within the residence!)

But, they harvest power from the thermostat wiring and use an internal
battery to bridge those periods when the thermostat must SHORT the
supply (to activate the remote relay \"load\")
 
K

Klaus Kragelund

Guest
On Tuesday, August 18, 2020 at 11:19:56 PM UTC+2, Don Y wrote:
On 8/18/2020 12:11 PM, Klaus Kragelund wrote:
On Tuesday, August 18, 2020 at 12:59:52 AM UTC+2, Don Y wrote:
On 8/17/2020 3:29 PM, Klaus Kragelund wrote:
Don\'t you use wireless systems in the US?

The wiring also provides the thermostat with its power (which should
be on the same circuit as the furnace), which would have to come from
some other source, so you aren\'t saving anything with a wireless
control link.

Installation cost, routing the wires?
The wires are typically run when the house is still in the \"framing\"
stage. So, the walls are all \"open\" and accessible.

It\'s also unlikely that the thermostat\'s location will ever be changed,
thereafter.

What is the cost of having the electrician route 100m cable? (10 zones with
10m cable)
While the house is in an \"open frame\" state? It\'s practically free
(low voltage cabling has few requirements regarding it\'s handling
on which a *carpenter* wouldn\'t be easily educated)
No such thing as free. Lets say he needs 10 hours for that, 60 USD per hour, that\'s 600 USD. Would be close to 0 for a wireless setup


Note that the vast majority of homes are cookie-cutter designs -- same
floor plan (or mirrored) for one of N (N being a small integer) designs
in a given (new) subdivision.
What level of joy do you have when you discover you need to move a
thermostat after construction, or add a new one if you expand the house?
Thermostat (and plant!) don\'t move after construction. It\'s location
is considered when the house plans are drawn up. The same is true for
the \"doorbell\" (button and annunciator).

Even trivial jobs that require the services of a licensed electrician
are costly -- e.g., to add a duplex receptacle is ~$200 -- assuming it\'s
\"near\" a Jbox that it can tap into. Note the cost won\'t typically reflect
any efforts required to restore the wall(s) to their original level of
finish/appearance.

Installing network drops will average ~$150-200 per drop -- assuming the
house\'s construction MAKES IT EASY (i.e., access to wall cavities via an
exposed basement or attic space) and you may have to \"buy\" several to
cover setup charges (e.g., $1000/5).

[Often, folks avoid the use of a licensed electrician in the belief that
there are no Code requirements for low voltage wiring so \"Joe Handyman\"
gets the job]
If it is SELV rated, then average Joe could do it

Folks don\'t tend to \"expand\" their houses. :> If they do, they install
a separate plant in that \"addition\", if it is large enough to overtax
the existing plant. (I have friends with 3 HVAC plants in their residences).

If the addition is too small to warrant it\'s own plant, you can consider
adding a separate zone. But, that requires changes to the plant which
tend to make the addition of a separate thermostat \"small potatoes\", by
comparison (even if the changes are just a motor-driven vent/register).

If you REALLY want to add a second sensing element, you can buy an aftermarket
product that lets you tie into your plant (plant is usually located in a
basement, closet, etc. soas not to be an eyesore; as such, access to power
and the plant wiring isn\'t \"fussy\")


By far, the bigger market is to REPLACE your existing thermostat -- at its
existing location -- with a thermostat that has more features. E.g., time
of day \"temperature setback\"; digital display (instead of analog); more
modern appearance; etc.

The \"classic\" thermostat -- while simple and copied -- is rather dated:

https://i2.wp.com/www.technologizer.com/wp-content/uploads/2014/06/image22.jpg

Note it\'s simplicity of design:

https://www.timothyoffheating.com/wp-content/uploads/2016/11/Honeywell-thermostat-repair.jpg
45 USD:

https://www.homehardware.ca/en/manual-round-thermostat/p/5570456

That is same price as the wireless thermostats
The glass tip of the mercury switch (short to call for heat) mounted on
the bimetallic coil can be seen just above the screw at 3:00 in the photo.
You can also just barely see the *heater* that forms the anticipator
riding atop that coil!

E.g., newer thermostats use WiFi to connect to your router and provide
remote accessibility (as well as \"learning functions\" and, of course,
leaking information about your occupancy and activity within the residence!)

I would rely more on the proprietary protocols with 868MHz. Wifi dubious if you install a new router, if the Thermostats don\'t use WiFi Direct
But, they harvest power from the thermostat wiring and use an internal
battery to bridge those periods when the thermostat must SHORT the
supply (to activate the remote relay \"load\")
 
R

Ricketty C

Guest
On Wednesday, August 19, 2020 at 8:56:13 AM UTC-4, Klaus Kragelund wrote:
On Tuesday, August 18, 2020 at 11:19:56 PM UTC+2, Don Y wrote:
On 8/18/2020 12:11 PM, Klaus Kragelund wrote:
On Tuesday, August 18, 2020 at 12:59:52 AM UTC+2, Don Y wrote:
On 8/17/2020 3:29 PM, Klaus Kragelund wrote:
Don\'t you use wireless systems in the US?

The wiring also provides the thermostat with its power (which should
be on the same circuit as the furnace), which would have to come from
some other source, so you aren\'t saving anything with a wireless
control link.

Installation cost, routing the wires?
The wires are typically run when the house is still in the \"framing\"
stage. So, the walls are all \"open\" and accessible.

It\'s also unlikely that the thermostat\'s location will ever be changed,
thereafter.

What is the cost of having the electrician route 100m cable? (10 zones with
10m cable)
While the house is in an \"open frame\" state? It\'s practically free
(low voltage cabling has few requirements regarding it\'s handling
on which a *carpenter* wouldn\'t be easily educated)


No such thing as free. Lets say he needs 10 hours for that, 60 USD per hour, that\'s 600 USD. Would be close to 0 for a wireless setup
How does a wireless system get power without wires? BTW, I think your numbers are rather high. Maybe you aren\'t familiar with how houses are built. I\'ve installed systems in houses and running a thermostat wire would take an hour including the drive to the site. It doesn\'t take an electrician, it is done by the people installing the heating system... by people like me when I was barely out of high school working for not much over minimum wage..


Note that the vast majority of homes are cookie-cutter designs -- same
floor plan (or mirrored) for one of N (N being a small integer) designs
in a given (new) subdivision.
What level of joy do you have when you discover you need to move a
thermostat after construction, or add a new one if you expand the house?
Thermostat (and plant!) don\'t move after construction. It\'s location
is considered when the house plans are drawn up. The same is true for
the \"doorbell\" (button and annunciator).

Even trivial jobs that require the services of a licensed electrician
are costly -- e.g., to add a duplex receptacle is ~$200 -- assuming it\'s
\"near\" a Jbox that it can tap into. Note the cost won\'t typically reflect
any efforts required to restore the wall(s) to their original level of
finish/appearance.

Installing network drops will average ~$150-200 per drop -- assuming the
house\'s construction MAKES IT EASY (i.e., access to wall cavities via an
exposed basement or attic space) and you may have to \"buy\" several to
cover setup charges (e.g., $1000/5).

[Often, folks avoid the use of a licensed electrician in the belief that
there are no Code requirements for low voltage wiring so \"Joe Handyman\"
gets the job]


If it is SELV rated, then average Joe could do it

Folks don\'t tend to \"expand\" their houses. :> If they do, they install
a separate plant in that \"addition\", if it is large enough to overtax
the existing plant. (I have friends with 3 HVAC plants in their residences).

If the addition is too small to warrant it\'s own plant, you can consider
adding a separate zone. But, that requires changes to the plant which
tend to make the addition of a separate thermostat \"small potatoes\", by
comparison (even if the changes are just a motor-driven vent/register).

If you REALLY want to add a second sensing element, you can buy an aftermarket
product that lets you tie into your plant (plant is usually located in a
basement, closet, etc. soas not to be an eyesore; as such, access to power
and the plant wiring isn\'t \"fussy\")


By far, the bigger market is to REPLACE your existing thermostat -- at its
existing location -- with a thermostat that has more features. E.g., time
of day \"temperature setback\"; digital display (instead of analog); more
modern appearance; etc.

The \"classic\" thermostat -- while simple and copied -- is rather dated:

https://i2.wp.com/www.technologizer.com/wp-content/uploads/2014/06/image22.jpg

Note it\'s simplicity of design:

https://www.timothyoffheating.com/wp-content/uploads/2016/11/Honeywell-thermostat-repair.jpg

45 USD:

https://www.homehardware.ca/en/manual-round-thermostat/p/5570456

That is same price as the wireless thermostats

The glass tip of the mercury switch (short to call for heat) mounted on
the bimetallic coil can be seen just above the screw at 3:00 in the photo.
You can also just barely see the *heater* that forms the anticipator
riding atop that coil!

E.g., newer thermostats use WiFi to connect to your router and provide
remote accessibility (as well as \"learning functions\" and, of course,
leaking information about your occupancy and activity within the residence!)

I would rely more on the proprietary protocols with 868MHz. Wifi dubious if you install a new router, if the Thermostats don\'t use WiFi Direct
The whole wireless thing is dubious for something as permanent as a thermostat. Wireless can be interfered with. Do you really want to be up in the middle of the night trying to figure out why your house is so cold simply because some neighbor added some gadget that is interfering with your signal or because a ham operator is on the air when the reception is good? I can\'t see any reason to not use the $20 wire that is in the house or cost $50 to put in when the house was built. Nope, zero reason. In fact, I\'m not sure what an installer will do if you want to keep your old thermostat. They tell me they don\'t guarantee the system if you don\'t use their brand thermostat. Seems there is a bit more to them than just turning the heat on and off with the temperature.

--

Rick C.

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

Don Y

Guest
On 8/19/2020 5:56 AM, Klaus Kragelund wrote:
On Tuesday, August 18, 2020 at 11:19:56 PM UTC+2, Don Y wrote:
On 8/18/2020 12:11 PM, Klaus Kragelund wrote:
On Tuesday, August 18, 2020 at 12:59:52 AM UTC+2, Don Y wrote:
On 8/17/2020 3:29 PM, Klaus Kragelund wrote:
Don\'t you use wireless systems in the US?

The wiring also provides the thermostat with its power (which
should be on the same circuit as the furnace), which would have to
come from some other source, so you aren\'t saving anything with a
wireless control link.

Installation cost, routing the wires?
The wires are typically run when the house is still in the \"framing\"
stage. So, the walls are all \"open\" and accessible.

It\'s also unlikely that the thermostat\'s location will ever be
changed, thereafter.

What is the cost of having the electrician route 100m cable? (10 zones
with 10m cable)
While the house is in an \"open frame\" state? It\'s practically free (low
voltage cabling has few requirements regarding it\'s handling on which a
*carpenter* wouldn\'t be easily educated)

No such thing as free. Lets say he needs 10 hours for that, 60 USD per hour,
that\'s 600 USD. Would be close to 0 for a wireless setup
I suspect an electrician can run mains power throughout most homes in 10 hours!
I know I could easily have wired the 100+ network drops in THIS house in
less than 10 hours if the walls and ceilings had been \"open\": drill hole in
stud, pull wire, repeat until at destination, cut. Next.

Installing network drops will average ~$150-200 per drop -- assuming the
house\'s construction MAKES IT EASY (i.e., access to wall cavities via an
exposed basement or attic space) and you may have to \"buy\" several to
cover setup charges (e.g., $1000/5).

[Often, folks avoid the use of a licensed electrician in the belief that
there are no Code requirements for low voltage wiring so \"Joe Handyman\"
gets the job]

If it is SELV rated, then average Joe could do it
It\'s not a question of who \"could\" do it but, rather, who would do it
to Code.

For example, there are places, here, that run all mains in hard conduit.
The Average Joe would likely use tape or tywraps to adhere a network
cable to that conduit for mechanical support. Not allowed.
The Average Joe would merrily drill through firestops and not realize that
the excess diameter in that hole needs to be filled with fire-retardent
compound.
The Average Joe would run phone/CATV/network cabling in the same bundle
as mains cable. Not allowed.
The Average Joe would run network cables across the top sides of suspended
ceiling tiles. Not allowed.
The Average Joe would see the HVAC ductwork as an ideal way of running
wire from one room to the next. Not allowed.

By far, the bigger market is to REPLACE your existing thermostat -- at
its existing location -- with a thermostat that has more features. E.g.,
time of day \"temperature setback\"; digital display (instead of analog);
more modern appearance; etc.

The \"classic\" thermostat -- while simple and copied -- is rather dated:

https://i2.wp.com/www.technologizer.com/wp-content/uploads/2014/06/image22.jpg



Note it\'s simplicity of design:

https://www.timothyoffheating.com/wp-content/uploads/2016/11/Honeywell-thermostat-repair.jpg


45 USD:

https://www.homehardware.ca/en/manual-round-thermostat/p/5570456

That is same price as the wireless thermostats
But the wireless thermostat doesn\'t hookup to the existing wires in the home!
So, the Average Joe has to find the connections to the plant and tie the
\"receiver\" in to that wiring. Then, mount and maintain the battery in the
\"remote control\".

The glass tip of the mercury switch (short to call for heat) mounted on
the bimetallic coil can be seen just above the screw at 3:00 in the
photo. You can also just barely see the *heater* that forms the
anticipator riding atop that coil!

E.g., newer thermostats use WiFi to connect to your router and provide
remote accessibility (as well as \"learning functions\" and, of course,
leaking information about your occupancy and activity within the
residence!)

I would rely more on the proprietary protocols with 868MHz. Wifi dubious if
you install a new router, if the Thermostats don\'t use WiFi Direct
Anything wireless represents an attack surface that doesn\'t exist with wired.

My neighbor was having problems with his garage door being open, unexpectedly.
It wasn\'t likely that he\'d FORGOTTEN to close it.

One day, he happened to be outside as I drove into our driveway and commanded
MY GDO to open. Suddenly, he understood why HIS was \"acting up\"! Yet, the
openers *supposedly* had unique codes...

I have ~100+ \"remote devices\", here, all \"wired\" (distributes power, timing
and comms). Should all of them have been competing for bandwidth over-the-air?
To save me the (considerable!) effort of running all that cable?

What would I do if some adversary parked his car out front and started
(illegally!) jamming my comms? Suddenly, nothing would work. Imagine if
I wasn\'t home at the time and the temperature in my house dropped below
freezing (not likely *here*). Or, if none of my surveillance cameras could
deliver video to <whatever>?

Wire is cheap. It\'s just my bad luck that I live in a FINISHED house
instead of one that is \"under construction\"!

(And, if I was a commercial establishment, it would just be part of
the cost of doing business.)

But, they harvest power from the thermostat wiring and use an internal
battery to bridge those periods when the thermostat must SHORT the supply
(to activate the remote relay \"load\")
Note the battery is rechargeable, \"recovering\" when the circuit to the
plant is \"interrupted\" (not commanded to provide heat/cool).
 
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