HVAC control wiring...

[Don Y]

In the US, HVAC systems are controlled via low-voltage wiring
(to the \"thermostat\").

In most homes that I\'ve seen, this is just \"bell wire\" run
through the wall interior exiting through an /ad hoc/ hole
to connect to the thermostat from the rear.

Has anyone encountered a Jbox in this location (devoid
of mains voltage)?

 

[John Larkin]

On Mon, 3 Aug 2020 09:20:42 -0700, Don Y <blockedofcourse@foo.invalid>
wrote:

In the US, HVAC systems are controlled via low-voltage wiring
(to the \"thermostat\").

In most homes that I\'ve seen, this is just \"bell wire\" run
through the wall interior exiting through an /ad hoc/ hole
to connect to the thermostat from the rear.

Has anyone encountered a Jbox in this location (devoid
of mains voltage)?

I\'ve never see a box for thermostat wiring.

In our cabin, I have a secret relay that parallels the thermostat, to
force the heat on remotely. More ad-hoc wiring!

 

[Carl]

\"Don Y\" wrote in message news:rg9dgt$ur2$1@dont-email.me...

In the US, HVAC systems are controlled via low-voltage wiring
(to the \"thermostat\").

In most homes that I\'ve seen, this is just \"bell wire\" run
through the wall interior exiting through an /ad hoc/ hole
to connect to the thermostat from the rear.

Has anyone encountered a Jbox in this location (devoid
of mains voltage)?

No idea why you are asking but if you want \"proof of concept\" , I have
seen a picture of a box like those used for a single light switch or duplex
outlet. It was in a picture in a review of a particular Honeywell home
thermostat and the reviewer was complaining that the back plate of the
thermostat wasn\'t big enough to cover the box . If you want to see it,
go to
https://www.lowes.com/pd/Honeywell-5-2-Day-5-2-Day-Programmable-Thermostat/1000343831
and scroll to the review by Mellocello titled Beware the mounting system.
The six or seven thermostats I\'ve had apart personally all just had a crude
hole poked in the drywall or paneling.

--
Regards,
Carl Ijames

 

[server]

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

 

[DJ Delorie]

John Larkin <jlarkin@highland_atwork_technology.com> writes:

In our cabin, I have a secret relay that parallels the thermostat, to
force the heat on remotely. More ad-hoc wiring!

Ha! In our house, at one point, we had a secret *thermostat* set to
50F, to force on the heat when the \"smart controller\" wasn\'t smart
enough.

 

[John Larkin]

On Mon, 03 Aug 2020 16:40:34 -0400, DJ Delorie <dj@delorie.com> wrote:

John Larkin <jlarkin@highland_atwork_technology.com> writes:
In our cabin, I have a secret relay that parallels the thermostat, to
force the heat on remotely. More ad-hoc wiring!

Ha! In our house, at one point, we had a secret *thermostat* set to
50F, to force on the heat when the \"smart controller\" wasn\'t smart
enough.

We had a smart thermostat, and various guests would leave it in
zillions of crazy states. I replaced it with one with a dial and a
heat-fan-on-off slide switch.

The remote cabin warmup is a relay across the \"heat\" contacts, and a
software thermostat based on an RTD. So we can warm up the cabin
before we get there. I pass commands and data and camera snapshots
through Dropbox.

 

[Don Y]

On 8/3/2020 1:36 PM, klaus.kragelund@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?

Traditionally, it has been a wired connection between the thermostat
and the \"furnace\". Approximately half dozen wires that tend to
*reasonably* adhere to a preestablished color-code connecting to
cryptically labeled contacts on the thermostat.

Legacy thermostats did not require power -- just a thermostatically
driven (coiled bimetal strip) mercury switch that would short
two contacts to call for heat (a \"heat/cool\" switch essentially
just inverted the sense of the mercury switch to control the
ACbrrr).

Modern \"powered\" thermostats can often be designed to not require
batteries (except as \"data backup\") by stealing phantom power
from the transformer that sources power to this control loop.

 

[Don Y]

On 8/3/2020 12:54 PM, Carl wrote:

\"Don Y\" wrote in message news:rg9dgt$ur2$1@dont-email.me...
Has anyone encountered a Jbox in this location (devoid
of mains voltage)?

No idea why you are asking but if you want \"proof of concept\" , I have seen
a picture of a box like those used for a single light switch or duplex outlet.
It was in a picture in a review of a particular Honeywell home thermostat and
the reviewer was complaining that the back plate of the thermostat wasn\'t big
enough to cover the box .

That was my initial impression! Granted, you can possibly select a box
that maximizes the chances of the \"hole\" (through the mudring) being
covered -- even if you have to mount a decorative cover plate on which to
mount the thermostat -- but I can\'t see why anyone would go to the
trouble to install a box when none is needed (builders being notoriously
cheap about putting in only what they MUST!)

The six or seven thermostats I\'ve had apart personally all just had a crude hole
poked in the drywall or paneling.

Ditto. Often the cable is adhered to a nearby wall stud which also provides a
robust mount for the thermostat.

Pity the person who \"drops\" the free end INSIDE the wall! :>

 

[Don Y]

On 8/3/2020 12:11 PM, John Larkin wrote:

On Mon, 3 Aug 2020 09:20:42 -0700, Don Y <blockedofcourse@foo.invalid
wrote:

In the US, HVAC systems are controlled via low-voltage wiring
(to the \"thermostat\").

In most homes that I\'ve seen, this is just \"bell wire\" run
through the wall interior exiting through an /ad hoc/ hole
to connect to the thermostat from the rear.

Has anyone encountered a Jbox in this location (devoid
of mains voltage)?

I\'ve never see a box for thermostat wiring.

In our cabin, I have a secret relay that parallels the thermostat, to
force the heat on remotely. More ad-hoc wiring!

Our controls are mounted immediately adjacent to the furnace;
out of sight (we pulled the old thermostat off the wall).
This also applies to the swamp cooler (*two* thermostats?
gimme a break!)

[And, the \"doorbell\" -- for similar reasons]

In the absence of any \"fixed\" thermostat(s), remote control is
straightforward.

 

[Grant Taylor]

On 8/3/20 4:55 PM, Don Y wrote:
> Pity the person who \"drops\" the free end INSIDE the wall!  :>

That might be a reason to add a post-construction / old-work box. I\'ve
fished many a wire through a single gang sized hole in the wall (doing
post-construction network wire installation).

Annoying? Sure.

End of service for the wire? Absolutely not.



--
Grant. . . .
unix || die

 

[Don Y]

On 8/3/2020 6:03 PM, Grant Taylor wrote:

On 8/3/20 4:55 PM, Don Y wrote:
Pity the person who \"drops\" the free end INSIDE the wall! :

That might be a reason to add a post-construction / old-work box. I\'ve fished
many a wire through a single gang sized hole in the wall (doing
post-construction network wire installation).

Annoying? Sure.

End of service for the wire? Absolutely not.

I think the problem with a Jbox for a thermostat is that you don\'t
know how you might be \"covering it\". Witness the example cited by Carl,
upthread.

The smallest 1G boxes are ~2x3\". And, any \"store bought\" cover plate
will likely be a \"blank\" (rectangular) wall plate -- onto which you could
mount a device. But, now you\'ve got a ~3x4\" plate that you either hide
behind the device *or* use to \"set the device off\" (as a bezel of sorts).

[unlikely that any device will have the same aspect ratio as such a plate
so the \"bezel effect\" would be hard to exploit]

I\'ve found that when I want to have a box for some non-standard use,
a 3\" round is usually better; the hole is technically larger but
is smaller, overall, than a circumscribed circle around a 2x3 box.
And, you can find OTS round covers that can be made to look like
decorative/accent bezels -- great if you can massage the device\'s
packaging into a circular form (e.g., the classic Homelywell device);
the circle being a \"universal aspect ratio\", of sorts.

[I use such a mudring for a FLUSH ceiling mounted \"siren\", here]

OTOH, poking a small (1/2\") hole through the wallboard and fishing
the cable through gives you lots of flexibility in how you can
cover that \"blemish\" -- regardless of whether your chosen device is
round, square, etc.

 

[Ricketty C]

On Monday, August 3, 2020 at 3:55:02 PM UTC-4, Carl wrote:

\"Don Y\" wrote in message news:rg9dgt$ur2$1@dont-email.me...

In the US, HVAC systems are controlled via low-voltage wiring
(to the \"thermostat\").

In most homes that I\'ve seen, this is just \"bell wire\" run
through the wall interior exiting through an /ad hoc/ hole
to connect to the thermostat from the rear.

Has anyone encountered a Jbox in this location (devoid
of mains voltage)?

No idea why you are asking but if you want \"proof of concept\" , I have
seen a picture of a box like those used for a single light switch or duplex
outlet. It was in a picture in a review of a particular Honeywell home
thermostat and the reviewer was complaining that the back plate of the
thermostat wasn\'t big enough to cover the box . If you want to see it,
go to
https://www.lowes.com/pd/Honeywell-5-2-Day-5-2-Day-Programmable-Thermostat/1000343831
and scroll to the review by Mellocello titled Beware the mounting system.
The six or seven thermostats I\'ve had apart personally all just had a crude
hole poked in the drywall or paneling.

Every thermostat I\'ve seen was mounted ON the wall with no box, just a small hole for the wire. In the old days the thermostat was a mercury switch on a spiral bi-metal spring that would wind/unwind with temperature changes and tip the switch. So to be accurate the thermostat had to be mounted level. Two mounting screw slots were provided. One to allow play left right in the screw position and another to allow adjusting the level of the thermostat.

Can\'t get much simpler than that.

--

Rick C.

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

 

[Grant Taylor]

On 8/4/20 1:30 AM, Don Y wrote:

I think the problem with a Jbox for a thermostat is that you don\'t
know how you might be \"covering it\". Witness the example cited by
Carl, upthread.

Agreed.

OTOH, poking a small (1/2\") hole through the wallboard and fishing
the cable through gives you lots of flexibility in how you can cover
that \"blemish\" -- regardless of whether your chosen device is round,
square, etc.

I was talking about adding a post-construction / old-work box *after*
someone shoved the wire back into the wall through the small hole. As a
way to recover the wire and continue to use it.



--
Grant. . . .
unix || die

 

[Don Y]

On 8/4/2020 12:09 PM, Grant Taylor wrote:

On 8/4/20 1:30 AM, Don Y wrote:

OTOH, poking a small (1/2\") hole through the wallboard and fishing the cable
through gives you lots of flexibility in how you can cover that \"blemish\" --
regardless of whether your chosen device is round, square, etc.

I was talking about adding a post-construction / old-work box *after* someone
shoved the wire back into the wall through the small hole. As a way to recover
the wire and continue to use it.

Ah, OK.

No, I\'d just open the wall, fish the wire out and patch/paint the wall.

[I\'ve run almost 3 miles of cable in a home with no attic or basement.
Patching drywall is second nature, now! :> ]

But, if you\'d anchored the wire (wire staple) to a nearby stud to begin
with, you\'d likely not have that problem (unless you tired really hard
to \"lose\" the wire!)

 

[Cydrome Leader]

DJ Delorie <dj@delorie.com> wrote:

John Larkin <jlarkin@highland_atwork_technology.com> writes:
In our cabin, I have a secret relay that parallels the thermostat, to
force the heat on remotely. More ad-hoc wiring!

Ha! In our house, at one point, we had a secret *thermostat* set to
50F, to force on the heat when the \"smart controller\" wasn\'t smart
enough.

My last interaction with a programmable thermostat was throwning into the
floor as hard as possible. Nothing beats a device with a definite and
visible set point that doesn\'t change in stupid ways.

 

[server]

There is a box in this house but I am not sure why. There is really no need for it.

You also cannot put low voltage wiring, like for phones thermostats, doorbells and whatever in the same box or conduit as house power wiring like 120 volts.

I though this would be better, like where my friend works. The thermostat puts out a variable resistance and with software he determines the \"flash\" range and how much hot deck and cold deck air they get.

Works at Case University. I had to teach him basic electronics to get it but now he tells me about all this cool shit they do there. Very advanced system. Plus they got bio labs which need special attention. You must heat and cool them but they always must have a negative air pressure.

And here I am thinking about how to balance heating and cooling on two floors of residential... (try it, I finally got it figured out)

 

[Don Y]

On 8/10/2020 11:37 AM, jurb6006@gmail.com wrote:

You also cannot put low voltage wiring, like for phones thermostats,
doorbells and whatever in the same box or conduit as house power wiring like
120 volts.

Actually, there are at least two exceptions that I\'ve relied upon:
- they can share a Jbox if a permanent barrier is installed between them
- if the power is only present to power the comm equipment from which the
comm wires originate/terminate; in this case, a 1/2\" separation is
required

The first one can be a PITA as many Jboxes aren\'t designed to \"support\"
barriers. And, it\'s near impossible to PURCHASE those barriers at your
local electrical supply house (I doubt any of the big box stores would
even be aware of them!)

Often, it can be cosmetically better (and simpler from a regulatory
perspective) to use two separate boxes. E.g., I have two ethernet+phone
\"outlets\" located on our kitchen counter. They are each \"near\" one of
the mandatory counter outlets -- but don\'t share Jboxes with them.

OTOH, in the living room, I have outlets and CATV+phone+ethernet in the
same Jbox (and under the same wall plate). It would look far less
appealing to have two -- or even THREE -- \"nearby\" Jboxes in that scenario.

 

[Michael Terrell]

On Monday, August 10, 2020 at 5:13:47 PM UTC-4, Don Y wrote:

On 8/10/2020 11:37 AM, jurb6006@gmail.com wrote:
You also cannot put low voltage wiring, like for phones thermostats,
doorbells and whatever in the same box or conduit as house power wiring like
120 volts.

Actually, there are at least two exceptions that I\'ve relied upon:
- they can share a Jbox if a permanent barrier is installed between them
- if the power is only present to power the comm equipment from which the
comm wires originate/terminate; in this case, a 1/2\" separation is
required

The first one can be a PITA as many Jboxes aren\'t designed to \"support\"
barriers. And, it\'s near impossible to PURCHASE those barriers at your
local electrical supply house (I doubt any of the big box stores would
even be aware of them!)

Often, it can be cosmetically better (and simpler from a regulatory
perspective) to use two separate boxes. E.g., I have two ethernet+phone
\"outlets\" located on our kitchen counter. They are each \"near\" one of
the mandatory counter outlets -- but don\'t share Jboxes with them.

OTOH, in the living room, I have outlets and CATV+phone+ethernet in the
same Jbox (and under the same wall plate). It would look far less
appealing to have two -- or even THREE -- \"nearby\" Jboxes in that scenario.

These have been around for at least a decade:

<https://www.homedepot.com/p/Carlon-2-Gang-Old-Work-PVC-Dual-Voltage-Box-Bracket-E-18-4-DVR/202664434>

 

[Don Y]

On 8/10/2020 3:32 PM, Michael Terrell wrote:

On Monday, August 10, 2020 at 5:13:47 PM UTC-4, Don Y wrote:
On 8/10/2020 11:37 AM, jurb6006@gmail.com wrote:
You also cannot put low voltage wiring, like for phones thermostats,
doorbells and whatever in the same box or conduit as house power wiring like
120 volts.

Actually, there are at least two exceptions that I\'ve relied upon:
- they can share a Jbox if a permanent barrier is installed between them
- if the power is only present to power the comm equipment from which the
comm wires originate/terminate; in this case, a 1/2\" separation is
required

The first one can be a PITA as many Jboxes aren\'t designed to \"support\"
barriers. And, it\'s near impossible to PURCHASE those barriers at your
local electrical supply house (I doubt any of the big box stores would
even be aware of them!)

Often, it can be cosmetically better (and simpler from a regulatory
perspective) to use two separate boxes. E.g., I have two ethernet+phone
\"outlets\" located on our kitchen counter. They are each \"near\" one of
the mandatory counter outlets -- but don\'t share Jboxes with them.

OTOH, in the living room, I have outlets and CATV+phone+ethernet in the
same Jbox (and under the same wall plate). It would look far less
appealing to have two -- or even THREE -- \"nearby\" Jboxes in that scenario.

These have been around for at least a decade:

https://www.homedepot.com/p/Carlon-2-Gang-Old-Work-PVC-Dual-Voltage-Box-Bracket-E-18-4-DVR/202664434

They\'re plastic. Ick, ick, ick. (I replaced all of the plastic Jboxes with
new-work metal boxes, here. More cubic inches as well as more durable
when removing/reinstalling devices).

And, you can\'t get the low voltage compartment to be \"the center of a 3G\"
or \"second in from the left in a 4G\", or \"two ends of a 3G\", etc.

(You can buy METAL Jboxes that support the installation of barriers. You just
don\'t find them at your local retail/industry outlet)

 

[Michael Terrell]

On Monday, August 10, 2020 at 7:17:51 PM UTC-4, Don Y wrote:

On 8/10/2020 3:32 PM, Michael Terrell wrote:
On Monday, August 10, 2020 at 5:13:47 PM UTC-4, Don Y wrote:
On 8/10/2020 11:37 AM, jurb6006@gmail.com wrote:
You also cannot put low voltage wiring, like for phones thermostats,
doorbells and whatever in the same box or conduit as house power wiring like
120 volts.

Actually, there are at least two exceptions that I\'ve relied upon:
- they can share a Jbox if a permanent barrier is installed between them
- if the power is only present to power the comm equipment from which the
comm wires originate/terminate; in this case, a 1/2\" separation is
required

The first one can be a PITA as many Jboxes aren\'t designed to \"support\"
barriers. And, it\'s near impossible to PURCHASE those barriers at your
local electrical supply house (I doubt any of the big box stores would
even be aware of them!)

Often, it can be cosmetically better (and simpler from a regulatory
perspective) to use two separate boxes. E.g., I have two ethernet+phone
\"outlets\" located on our kitchen counter. They are each \"near\" one of
the mandatory counter outlets -- but don\'t share Jboxes with them.

OTOH, in the living room, I have outlets and CATV+phone+ethernet in the
same Jbox (and under the same wall plate). It would look far less
appealing to have two -- or even THREE -- \"nearby\" Jboxes in that scenario.

These have been around for at least a decade:

https://www.homedepot.com/p/Carlon-2-Gang-Old-Work-PVC-Dual-Voltage-Box-Bracket-E-18-4-DVR/202664434

They\'re plastic. Ick, ick, ick. (I replaced all of the plastic Jboxes with
new-work metal boxes, here. More cubic inches as well as more durable
when removing/reinstalling devices).

And, you can\'t get the low voltage compartment to be \"the center of a 3G\"
or \"second in from the left in a 4G\", or \"two ends of a 3G\", etc.

(You can buy METAL Jboxes that support the installation of barriers. You just
don\'t find them at your local retail/industry outlet)

Whatever. These work, and are great for an office, or behind a TV or home computer. Not all metal boxes are great. Some are flimsy, and others are less than an inch deep. I had to rewire my girlfriend\'s family home, back in the \'60s. All of the boxes on exterior walls used those. Their furnace failed while they were at a Christmas party. The damage was the worst around the furnace, but the smoke and water damaged the entire house. All the drywall had to be removed, along with the insulation. Since the block home was stripped to bare suds, they decided to replace all of the wiring. Some early Romex hardened and cracked fro the heat in the attic, and along the exterior walls. It took a lot of work. I would ride her school bus after school and work with them until 9:00 PM, then my dad would pick me up. I would do my homework, and get what sleep that I could. It was a true labor of love. It was our Junior year of high school. Sadly, she passed away at 48, 20 years ago.