Programmable thermostats (adjustable span ?!?!?)
Wayne
you can set the high and low temp (sometimes called span, or more
correctly called hysteresis) ????
If I set a temp to 72, then most systems will allow a non-adjustable
drop of 1 or 2 degrees before telling the furnace to come on. But what
if I don't want the furnace to come on until 68 during the day and 65 at
night ???
ARG!!! This is so simple! BUT NOBODY does it!!! ???
Or am I wrong?
Paul Fox
: If I set a temp to 72, then most systems will allow a non-adjustable
: drop of 1 or 2 degrees before telling the furnace to come on. But what
: if I don't want the furnace to come on until 68 during the day and 65 at
: night ???
:
: ARG!!! This is so simple! BUT NOBODY does it!!! ???
:
: Or am I wrong?
i think you might be wrong. :-) you're saying that at night you'd be
willing to have the temperature in your house swing by as much as 7
degrees? gradually down to 65, then quick back up to 72, then back
down again? why not just set it to 65 at night, and back to 72 in
the morning, like a normal setback?
most people are more comfortable with constant temperature -- otherwise
you're constantly putting sweaters on and off, or blankets, or whatever...
paul
=---------------------
paul fox, pgf-...@foxharp.boston.ma.us
Wayne
> i think you might be wrong. :-) you're saying that at night you'd be
> willing to have the temperature in your house swing by as much as 7
> degrees? gradually down to 65, then quick back up to 72, then back
> down again? why not just set it to 65 at night, and back to 72 in
> the morning, like a normal setback?
What if I don't want my furnace coming on every few minutes because the temp
drops by one measily degree?
Actually, at night I might set the temp for, say, 65 to 69, but during the day
68 to 71. And that's for winter. Maybe something completely different for
spring, fall and summer.
I value having some flexibility on the on/off span, and in the long run it
probably saves energy (and wear/tear on the furnace and fan).
> most people are more comfortable with constant temperature -- otherwise
> you're constantly putting sweaters on and off, or blankets, or whatever...
I'm not looking for a swing from 50 to 70 here. But I am looking for more
than just the fixed measily 1 or 2 degrees that is built into all electronic
thermostats I've seen so far.
Tom Ruta
>Can someone tell me why nobody makes a home programmable thermostat that
>you can set the high and low temp (sometimes called span, or more
>correctly called hysteresis) ????
>
>If I set a temp to 72, then most systems will allow a non-adjustable
>drop of 1 or 2 degrees before telling the furnace to come on. But what
>if I don't want the furnace to come on until 68 during the day and 65 at
>night ???
>
>ARG!!! This is so simple! BUT NOBODY does it!!! ???
>
>Or am I wrong?
You could do this via X-10 and an Oulett thermostat. Up to
15 degrees.
Tom
==============================================================
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Dan Lanciani
| I'm not looking for a swing from 50 to 70 here. But I am looking for more
| than just the fixed measily 1 or 2 degrees that is built into all electronic
| thermostats I've seen so far.
The only one I've come across is Maple/Chase's "Saverstat" 0960. It allows
you to set the range from 1 to 6 degrees. It has the usual timed setbacks
as well, but it doesn't support any external communications or the like so
I'm not using it anymore...
Dan Lanciani
ddl@danlan.*com
Scott A. Dudoussat
cooling systems. It is an auto changeover thermostat with separate heat and
cool settings (and separate anticipators). It has the capability of being
controlled both locally and by remote control. It offers programmability,
stand-alone operation, and robust, optically isolated communications with
automation systems, utility control systems, and personal computers.
The RC-80 has a sophisticated control system designed to keep you
comfortable while saving energy. Part of the control system is a feature
called "anticipation", which anticipates the need to turn the system on or
off before the temperature is actually at the setting.
As humans, we perceive temperature as a combination of heat in the air and
heat radiated from the walls and surroundings. The thermostat also measures
a combination of air and wall temperature. When heating, the air
temperature rises faster than the wall temperature. The thermostat will
turn the heat off briefly to prevent overheating the air while the wall
temperature catches up. Your comfort is assured without overshooting the
heat setting, which wastes energy.
In summer, the thermostat will periodically run the cooling system to
circulate the air and remove humidity when the temperature is close, but not
above the cool setting. You will be more comfortable at a higher cool
setting, which saves energy.
The RC-80 has separate Heating and Cooling anticipators.
The Cooling anticipator adjusts the tendency of the thermostat to run the
cooling system to refresh and dehumidify the air before the temperature
rises to the desired cool setting. A setting of 0 will disable this
feature.
The recommended setting for most forced air cooling systems is 4. A lower
number will decrease the tendency to run the cooling system below the
cooling setting. A lower setting of 2 or 3 may be desired in dry climates.
The Heating anticipator adjusts the tendency of the thermostat to turn the
heating unit off before the desired heat setting is reached. This is done
to avoid overheating the air while the walls and furniture catch up. A
setting of 0 will disable this feature.
A lower setting will decrease the tendency to turn off the heating system
before the desired heat setting is reached. If the heating system response
time is slower, as are most radiant heating systems, a higher number will
help maintain an even space temperature.
Check it out at www.homeauto.com
Scott
Wayne wrote in message <38A1E409...@hotmail.com>...
Carl Porter
on often at night then it's capacity maybe higher than you
need at the moment, can it be scaled back? It will make it
run longer to achieve the same effect so is that better than
switching on & of several times.
Jim Kearney
allow you to set the on/off minimum time. By default, it's 8 minutes, but
can be set by the user. Plus of course it has morning/day/evening/night
settings and is controllable via RS232 or X10. I've been pretty happy with
mine so far.
"Dan Lanciani" <ddl@danlan.*com> wrote in message
news:617...@news1.IPSWITCHS.CMM...
Wayne
before the furnace comes on. Even though it has a computer interface, that
still doesn't allow you to change that 1 degree setting.
Being able to set the minimum run time is usefull, but that should be secondary
relative to the temperature set-points that you want to keep the house at. Why
they don't let you have _different_ minimum on and off times is another
disadvantage.
Wayne
the span to be changed. Once the temp drops by 1 degree from the set point, the
furnace goes on. You can't change it.
"Scott A. Dudoussat" wrote:
> The HAI RC-80 is a precision digital thermostat for single stage heating and
> cooling systems. It is an auto changeover thermostat with separate heat and
> cool settings (and separate anticipators)....
> Wayne wrote in message <38A1E409...@hotmail.com>...
Jim Nagy
I struggled with this a few years ago. What I ended up doing was
rectifying the 24VAC control signal, and using it to switch a very small
(read Radio Shack) relay on with it. This switched a series resistor in
and out of the thermistor circuit (short the resistor when the heat starts
to simulate a rise in temperature). I ended up with two resistors in the
end so I could just throw a switch for the AC (needs an increase in
resistance to simulate a cooler temp, forcing the AC off).
Jim Nagy
Elm Electronics
Integrated Circuits for Experimenters
http://www.elmelectronics.com/
Dan Smith
Jim...any chance that you grew up in Downers Grove Illinois?
Jim Nagy <NoN...@NoSpam.com> wrote in message
news:NoName-1002...@lon-p19.wwdc.com...
Erik Vistica
I'm not sure any of this is possible, but...
I'm guessing that the 2-way model can report the current temp to the PC
via X-10 codes? If so, a little savvy if-then-else logic should be able
to provide the actual hysteresis. Don't let the thermostat control the
temp, do it via the PC (if you really, really want this feature).
Can anyone who actually has one of these confirm the feasability of this
or burst my little logic bubble?
Paul Schumann
<snip>
>
> I struggled with this a few years ago. What I ended up doing was
> rectifying the 24VAC control signal, and using it to switch a very small
> (read Radio Shack) relay on with it. This switched a series resistor in
> and out of the thermistor circuit (short the resistor when the heat starts
> to simulate a rise in temperature). I ended up with two resistors in the
> end so I could just throw a switch for the AC (needs an increase in
> resistance to simulate a cooler temp, forcing the AC off).
>
> Jim Nagy
> Elm Electronics
> Integrated Circuits for Experimenters
> http://www.elmelectronics.com/
This is exactly what X-10's setback device does...
William Olsen
A "more better" way to implement scaling back a system to prevent
overheating and increase operating economy is to vary the plenum temperature
(for forced air systems) or the boiler water temperature (in hot water
radiation systems) in response to changes to the outdoor temperature. This
concept is called "outdoor reset" and has been in use for decades. Several
manufacturers of both residential and commercial heating and cooling control
systems such as Honeywell, Minneapolis MN market several products suitable
for this task. They are not difficult to install and are very effective, I
use a similar technique in my home in the northeast. One caveat, Steam heat
is not a good medium to apply this concept to.
Bill Olsen
"Carl Porter" <cpor...@swbell.net> wrote in message
news:38A2FF09...@swbell.net...
> Your other option in to look at the furnace. If it is coming
> on often at night then it's capacity maybe higher than you
> need at the moment, can it be scaled back? It will make it
> run longer to achieve the same effect so is that better than
> switching on & of several times.
>
> Wayne wrote:
> >
Wayne
begin to feel uncomfortable. Because of the variability of outside conditions
(temp, wind, etc) this temp can not be reached reliably simply by setting a
delay time.
Naturally, if I set the low temp to 50 F then sure, I'd be uncomforable. It's
funny, but it wouldn't require any additional components to the garden-variety
electronic thermostat to enable the user to set the low temp or, at least, set
the span (1 degree, 5 degrees, etc).
What's the difference between a furnace that comes on at 71 and goes off at 72
vs. one that comes on at 70 and goes off at 72? From an occupant point of
view, I doubt it's noticable. From the furnace point of view, you'd probably
cut the number of heating cycles in half, and probably save some energy from
the lost heat up the chimney at the end of every cycle. Fewer fan cycles can
only be good for the blower.
Ken Duckworth wrote:
> do you really want to control the amount of time the furnace is on or the
> room temperature. if you want to control the amount of time the furnace is
> on, put a timer in the control box for the furnace such that the thermostat
> will not call for the furnace to come back on for x minutes after called
> for. The adjustments in the thermostat will then be blocked out for that
> delay time. I think you will find that the house will gradually cool down
> during the heating period. I also think it would be very uncomfortable.
> your choice.
Wayne
Hysteresis is sometimes a desired characteristic and sometimes not. A car
steering wheel with hysteresis is not a good thing.
I dare anyone to argue that a thermostat with a programmable hysteresis (span,
dead-band, etc) is NOT better than one without.
Walter Driedger wrote:
> Wayne:
>
> Hysteresis is what happens in a sticky valve. Of course a switch with
> hysteresis could be used to provide a deadband but it would not be
> adjustable. That's called making a virtue of a necessity. Progammers
> call it a feature. But the deadband cannot be less than the
> hysteresis.
Bruce Robin
have what's called an "anticipator circuit" that in essence does what you're
looking for. Maybe an HVAC contractor could shed some light on this. The
Honeywell T8600 Programmable lists an "adjustable heating cycle" feature in
its description. This can be found at www.honeywell.com.
"Wayne" <sm...@hotmail.com> wrote in message
news:38A999CC...@hotmail.com...
Dan Smith
You could "build" your own with a Leopard touch screen, Bobcat Temp sensor
and a RLY08 module from ADI. This will allow you to create any span or
hysteresis you wish and also gives you unlimited setback possibilities. You
can control it with IR, X10 or the touch screen. Add our up and comming
video overlay module and you can display the temp and setpoints on your TV!
(why?..I have no idea but I thought it sounded cool;) While this is a more
expensive route (than a setback thermostat) you have the heart of a complete
HA system as well. As always...wire a cheap $12 manual Tstat in as a saftey
against frozen pipes or melted candles.
Just a thought...Dan Smith
Jim Cirillo
I was actually planning on doing this! But doesn't the Leopard have it's own temp
sensor built in? Can you give more details about the Bobcat? And, while I'm asking -
will the LCD-80 still have a temp sensor built in?
Jim
Dan Smith <des...@appdig.com> wrote in message
news:VXhq4.1366$l06.1...@news1.primary.net...
Dan Smith
The current rev Leopard does not have the temp sensor installed...once we
get caught up to the orders on the books, we will begin the enhancements..
LCD-80....??I'm not sure..I haven't been involved with that one latley...Mr
Boone? wanna add?
Dan Smith
Jim Cirillo <james_...@my-dejanews.com> wrote in message
news:2000Feb16....@npt.nuwc.navy.mil...
Dan D. Boone
modules.
The LCD-80 will have a temperature sensor, but I would go with the new
Bobcat as the Bobcat will hit the market first. Bobcats are inexpensive,
small (about the size of a pack of matches) modules that provide
environmental information. The first Bobcat provides temperature AND
humidity information. The second Bobcat provides a 232/485/I-button
interface for interfacing with other manufacturers thermostats, controllers,
etc. The third Bobcat provides liquid sensing (water in the basement, etc.)
The fourth Bobcat provides a relay output. Our engineers have a whole family
under development including current sense, video sense, light detection,
etc.
Production will begin after we fill the existing backlog of Ocelots,
Leopards, and Speak-EZ's.
Dan Boone
Applied Digital, Inc.
Dan Smith <des...@appdig.com> wrote in message
news:94Jq4.1539$l06.1...@news1.primary.net...
Raventhorne
Tom Ruta wrote in message ...
>Wayne <sm...@hotmail.com> wrote:
>
>>Can someone tell me why nobody makes a home programmable thermostat that
>>you can set the high and low temp (sometimes called span, or more
>>correctly called hysteresis) ????
>You could do this via X-10 and an Oulett thermostat. Up to
>15 degrees.
Got a URL for Oulett? I'm not having much luck finding them.
Regards,
John
Dan D. Boone
statements.
The first Bobcat supports temperature only. It reports to the Ocelot (or
Leopard) that it is a temperature module.
We are offering a separate humidity sensing Bobcat that reports to the
Ocelot (or Leopard) that it is a humidity module.
The engineer reports that all the components for both, cannot be squeezed
into the tiny box.
Likewise, three separate modules are provided for 232/485 and I-button.
Dan Boone
Applied Digital, Inc.
Dan D. Boone <ddb...@appdig.com> wrote in message
news:mVJq4.1544$l06.1...@news1.primary.net...
Tom Ruta
Wayne
> >Got a URL for Oulett? I'm not having much luck finding them.
>
> Vive la France! <g> http://www.ouellet.com/index2.html
> Tom
France? They're in Quebec.
Uh, wait a minute. France. Quebec. Ok, not much difference.
But their thermostats only seem to control electric heating systems. Which
makes sense for Quebec.
Tom Ruta
>Tom Ruta wrote:
>
>> >Got a URL for Oulett? I'm not having much luck finding them.
>>
>> Vive la France! <g> http://www.ouellet.com/index2.html
>
>> Tom
>
>France? They're in Quebec.
>
>Uh, wait a minute. France. Quebec. Ok, not much difference.
>
That's a Canadian reference to a famous speech - you had to
be there <g>
>But their thermostats only seem to control electric heating systems. Which
>makes sense for Quebec.
Yeah, sorry. Electric only - but thy are AFAIK the only
place to get X-10 for 220v systems
Tom
Robert L Bass
memorized:
A.. eh
B.. eh
C.. eh
D.. eh
E.. :)
Daniel Born <so...@no.spam.for.me> wrote in message
news:88jv7g$r4b$1...@dns3.cae.ca...
: > France? They're in Quebec.
: >
: > Uh, wait a minute. France. Quebec. Ok, not much difference.
:
: Only if you've never been to either... Would you say that "USA = England ?"
: Did you know that French movies from Quebec are subtitled for France? (no
: kidding!)
:
: By the way, I have the Ouellet thermostats (15) and they're great (for
: baseboard heaters)
:
: Daniel
: Montreal, Quebec, Canada
:
:
:
Robert Hartline, Jr.
deadband. You might check with them. It was less than $ 75.00
"Wayne" <sm...@hotmail.com> wrote in message
news:38A998EA...@hotmail.com...
anto...@aol.com
searching for info because my Hunter Energy Monitor II PLus failed
again. It's the second unit that failed. I think I'll buy someone else's
unit this time.
In article <RX_r4.1133$m04....@news4.mco>,
Sent via Deja.com http://www.deja.com/
Before you buy.
Glen Hadley
(sci.engr.control) newsgroup and am trying to catch up. I
just bought a LUX 9000 Series Smart Electronic Thermostat,
which has exactly that, an adjustable deadband. They call
it temperatur swing, adjustable from around 0.1 to about 2
degrees. Bought it at a local discount home center for
about $25. Hope this helps . . .
Wayne wrote:
>
> This doesn't help me source a thermostat with this capability.
>
> Hysteresis is sometimes a desired characteristic and sometimes not. A car
> steering wheel with hysteresis is not a good thing.
>
> I dare anyone to argue that a thermostat with a programmable hysteresis (span,
> dead-band, etc) is NOT better than one without.
>
> Walter Driedger wrote:
>
> > Wayne:
> >
> > Hysteresis is what happens in a sticky valve. Of course a switch with
> > hysteresis could be used to provide a deadband but it would not be
> > adjustable. That's called making a virtue of a necessity. Progammers
> > call it a feature. But the deadband cannot be less than the
> > hysteresis.
--
glh :<)
Michael Bush
old-style mechanical thermostats have this feature... as I recall, they
call it the "pre-heat setting" on most models...
If you take off the cover, you will find a little lever inside, copper on
the classic round Honeywell models... This is essentially a variable
resistor; when the thermostat is passing current (e.g., the heat is "on") it
heats the environment inside the thermostat, causing it to reach temp
somewhat sooner than the room does... by playing with this setting, you can
vary the amount of hysterisis in the system... Essentially, you match the
lag time of the heating plant to the hysterisis of the thermostat. It's
not directly settable to "0.5 degrees", but any good heating repair man can
make it work pretty well....
Glen Hadley <gl...@www.mebbs.com> wrote in message
news:38C0B5B0...@www.mebbs.com...
Ted
Try Danfoss-Randall (www.danfoss-randall.co.uk) or ACL Drayton (part of
Invensys) they do programmable thermonstats. You can set different
temperatures for different times of the day as you wish.
Ted
"Wayne" <sm...@hotmail.com> wrote in message
news:38A1E409...@hotmail.com...
> Can someone tell me why nobody makes a home programmable thermostat that
> you can set the high and low temp (sometimes called span, or more
> correctly called hysteresis) ????
>
Walter Driedger
The pre-heat feature has quite the opposite effect of a deadband.
Pre-heating the thermostat will cause it to shut off SOONER. A
deadband would cause it shut off LATER. However if you would like a
larger time interval between on and off, reducing the pre-heat to zero
will help.
Walter.
Michael Bush
in most domestic heating systems, the "natural" dead-band (with no
thermostat pre-heat) is usually on the order of 5 or more degrees (F)...
Generally speaking, the problem is to reduce the deadband, not to increase
it. I suppose that if you had a system with too small a natural deadband
this would present a problem, but that's a fairly rare beast in the real
world...
Walter Driedger <drie...@cadvision.com> wrote in message
news:38C1A461...@cadvision.com...
news.attcanada.net
It does not have seriel comunication, but it has 4 weekday and 2 weekend
timed/temp settings. I have gas heating, but it will do electric and oil
heating. It even does Ferenheit and Centigrade.
the web site is www.honeywell.com and do search on "thermostat"
Ted <t...@127.0.0.1.andersons.force9.co.uk> wrote in message
news:Jghw4.6220$O5.217122@stones...