How does the hysteresis work on the Honeywell old-style bulb thermostat?

My house has two of those tan round things, with a dial that has
only two indicators.
1. The desired temperature on top, and......
2. The current temperature on bottom.

I understand that the heat overshoots on the current temperature
and that it lets the current temp go below the set temperature,
so that the gas furnaces are not constantly turning on and off
exactly at the set temperature.

That makes sense (from a wear and tear and noise standpoint).

I call that delayed on and off time the "hysteresis" (but you can
call it whatever it's really called).

Pulling off the cover, I see a mercury bulb inside, which is at the
end of a curved metal strip (bi-metallic perhaps?), which explains
the *initial* on/off mechanism is from the expansion and contraction
of the coiled flat strip kicking the mercury switch on and off.

This can't be the actual on/off of the furnace, because hysteresis
decrees that the on time of the furnace itself is after the mercury
turns it on and so is the off time of the furnace being after the
mercury turns it off.

I can easily test this, simply by turning the thermostat to a
high or low temperature, where the actual on/off of the furnace
blower (and later, the heat) is something like a couple of
minutes delayed.

I get all that - but what I don't understand is *where* the
hysteresis is built in? Is it in the computer? Is there a dial
that sets the temperature range of the hysteresis? Is there
a potentiometer?

How do we *change* or *set* how much hysteresis there is?
Specifically, how do I get *more* hysteresis in my furnace?

On 12/26/2015 12:37 PM, Kirk Landaur wrote:
How does the hysteresis work on the Honeywell old-style bulb thermostat?

My house has two of those tan round things, with a dial that has
only two indicators.
1. The desired temperature on top, and......
2. The current temperature on bottom.

I understand that the heat overshoots on the current temperature
and that it lets the current temp go below the set temperature,
so that the gas furnaces are not constantly turning on and off
exactly at the set temperature.

That makes sense (from a wear and tear and noise standpoint).

I call that delayed on and off time the "hysteresis" (but you can
call it whatever it's really called).

Pulling off the cover, I see a mercury bulb inside, which is at the
end of a curved metal strip (bi-metallic perhaps?), which explains
the *initial* on/off mechanism is from the expansion and contraction
of the coiled flat strip kicking the mercury switch on and off.

This can't be the actual on/off of the furnace, because hysteresis
decrees that the on time of the furnace itself is after the mercury
turns it on and so is the off time of the furnace being after the
mercury turns it off.

I can easily test this, simply by turning the thermostat to a
high or low temperature, where the actual on/off of the furnace
blower (and later, the heat) is something like a couple of
minutes delayed.

I get all that - but what I don't understand is *where* the
hysteresis is built in? Is it in the computer? Is there a dial
that sets the temperature range of the hysteresis? Is there
a potentiometer?

How do we *change* or *set* how much hysteresis there is?
Specifically, how do I get *more* hysteresis in my furnace?


The hysteresis is set on the thermostat. I used to have one of those old
Honeywell units and as I recall it had a calibrated sub-dial that set
the hysteresis temperature range. Something like 0.5 degrees to around 3
degrees (F). You simply moved this sub-dial to the over/undershoot range
you desired.

Of course this info may well be searchable, rather than depending on
memory...

John :-#)#

--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
(604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

It's the weight of the mercury that moves the bimetal coil spring such that
it takes a higher temperature to bend the bimetal coil spring so that the
mercury flows back to the other end of the bulb. When the mercury moves to
one end of the bulb, it makes the spring reposition itself so that it takes
a much higher (or lower, depending on heat or cool mode) for the spring to
return back to its original position.
Here's a link to a web page that describes the operation very well, saving
me a lot of typing.
http://inspectapedia.com/heat/Thermo...e_Response.php

Cheers,
Dave M

Kirk Landaur wrote:
How does the hysteresis work on the Honeywell old-style bulb
thermostat?

My house has two of those tan round things, with a dial that has
only two indicators.
1. The desired temperature on top, and......
2. The current temperature on bottom.

I understand that the heat overshoots on the current temperature
and that it lets the current temp go below the set temperature,
so that the gas furnaces are not constantly turning on and off
exactly at the set temperature.

That makes sense (from a wear and tear and noise standpoint).

I call that delayed on and off time the "hysteresis" (but you can
call it whatever it's really called).

Pulling off the cover, I see a mercury bulb inside, which is at the
end of a curved metal strip (bi-metallic perhaps?), which explains
the *initial* on/off mechanism is from the expansion and contraction
of the coiled flat strip kicking the mercury switch on and off.

This can't be the actual on/off of the furnace, because hysteresis
decrees that the on time of the furnace itself is after the mercury
turns it on and so is the off time of the furnace being after the
mercury turns it off.

I can easily test this, simply by turning the thermostat to a
high or low temperature, where the actual on/off of the furnace
blower (and later, the heat) is something like a couple of
minutes delayed.

I get all that - but what I don't understand is *where* the
hysteresis is built in? Is it in the computer? Is there a dial
that sets the temperature range of the hysteresis? Is there
a potentiometer?

How do we *change* or *set* how much hysteresis there is?
Specifically, how do I get *more* hysteresis in my furnace?

On Sat, 26 Dec 2015 12:49:29 -0800, Uncle Monster wrote:

Inside you'll see a sliding resistor called an "Anticipator"
which provides a tiny amount of heat to fool the thermostat.
ヽ(€¢€¿€¢)ノ

Is this the anticipator?
http://i63.tinypic.com/280nvqs.jpg

Mine is currently set at 0.55 I think (if I'm reading the right thing).

Notice the distances get spread out non-linearly to the one end:
(1.2, 1.0, .9, .8, .7, .6, .5, .4, .3, .25, .2, .15, .12, .10)

It has a confusingly labeled slider that has "LONGER" and an arrow
indented on it.

The LONGER indent and the arrow fight each other.

On the one hand, the LONGER on one end *implies* that's the end
where the slider makes the hysteresis longer; but, on the other
hand, the arrow points in the opposite direction, which implies
the hysteresis is longer in the other direction?

Do you have experience with this confusing setup?

Mine is currently set to one side, but I want the hysteresis
to be greater.

To increase hysteresis, should I slide the slider toward LONGER?
Or should I slide the slider more towards the direction of the arrow?

Kirk Landaur wrote:
How does the hysteresis work on the Honeywell old-style bulb thermostat?

My house has two of those tan round things, with a dial that has
only two indicators.
1. The desired temperature on top, and......
2. The current temperature on bottom.

I understand that the heat overshoots on the current temperature
and that it lets the current temp go below the set temperature,
so that the gas furnaces are not constantly turning on and off
exactly at the set temperature.

That makes sense (from a wear and tear and noise standpoint).

I call that delayed on and off time the "hysteresis" (but you can
call it whatever it's really called).

Pulling off the cover, I see a mercury bulb inside, which is at the
end of a curved metal strip (bi-metallic perhaps?), which explains
the *initial* on/off mechanism is from the expansion and contraction
of the coiled flat strip kicking the mercury switch on and off.

This can't be the actual on/off of the furnace, because hysteresis
decrees that the on time of the furnace itself is after the mercury
turns it on and so is the off time of the furnace being after the
mercury turns it off.

I can easily test this, simply by turning the thermostat to a
high or low temperature, where the actual on/off of the furnace
blower (and later, the heat) is something like a couple of
minutes delayed.

I get all that - but what I don't understand is *where* the
hysteresis is built in? Is it in the computer? Is there a dial
that sets the temperature range of the hysteresis? Is there
a potentiometer?

How do we *change* or *set* how much hysteresis there is?
Specifically, how do I get *more* hysteresis in my furnace?

What are you trying to accomplish? To make things worse?
That is just dumb thermostat. Only thing you can set is anticipator.
And remember metal fatigue, bimetal strip calibration goes off with
age. I'd just replace them with decent smart digital programmable ones.
With this you can adjust some things in the service mode at initial
installation.

Kirk Landaur wrote:
On Sat, 26 Dec 2015 12:49:29 -0800, Uncle Monster wrote:

Inside you'll see a sliding resistor called an "Anticipator"
which provides a tiny amount of heat to fool the thermostat.
ヽ(€¢€¿€¢)ノ

Is this the anticipator?
http://i63.tinypic.com/280nvqs.jpg

Mine is currently set at 0.55 I think (if I'm reading the right thing).

Notice the distances get spread out non-linearly to the one end:
(1.2, 1.0, .9, .8, .7, .6, .5, .4, .3, .25, .2, .15, .12, .10)

It has a confusingly labeled slider that has "LONGER" and an arrow
indented on it.

The LONGER indent and the arrow fight each other.

On the one hand, the LONGER on one end *implies* that's the end
where the slider makes the hysteresis longer; but, on the other
hand, the arrow points in the opposite direction, which implies
the hysteresis is longer in the other direction?

Do you have experience with this confusing setup?

Mine is currently set to one side, but I want the hysteresis
to be greater.

To increase hysteresis, should I slide the slider toward LONGER?
Or should I slide the slider more towards the direction of the arrow?

General rule of thumb on anticipator is matching the number on dial same
as current draw on your gas valve. You can play with setting it
little higher or lower. I used to set it slightly higher than gas valve
rating considering the length of wiring from furnace to thermostat.
Again go digital.

Dave M wrote:
It's the weight of the mercury that moves the bimetal coil spring such that
it takes a higher temperature to bend the bimetal coil spring so that the
mercury flows back to the other end of the bulb. When the mercury moves to
one end of the bulb, it makes the spring reposition itself so that it takes
a much higher (or lower, depending on heat or cool mode) for the spring to
return back to its original position.
Here's a link to a web page that describes the operation very well, saving
me a lot of typing.
http://inspectapedia.com/heat/Thermo...e_Response.php

Cheers,

Dave M

I think you are thinking backward. Spring controls the position of bulb
depending on temperature. Not the other way around.


Kirk Landaur wrote:
How does the hysteresis work on the Honeywell old-style bulb
thermostat?

My house has two of those tan round things, with a dial that has
only two indicators.
1. The desired temperature on top, and......
2. The current temperature on bottom.

I understand that the heat overshoots on the current temperature
and that it lets the current temp go below the set temperature,
so that the gas furnaces are not constantly turning on and off
exactly at the set temperature.

That makes sense (from a wear and tear and noise standpoint).

I call that delayed on and off time the "hysteresis" (but you can
call it whatever it's really called).

Pulling off the cover, I see a mercury bulb inside, which is at the
end of a curved metal strip (bi-metallic perhaps?), which explains
the *initial* on/off mechanism is from the expansion and contraction
of the coiled flat strip kicking the mercury switch on and off.

This can't be the actual on/off of the furnace, because hysteresis
decrees that the on time of the furnace itself is after the mercury
turns it on and so is the off time of the furnace being after the
mercury turns it off.

I can easily test this, simply by turning the thermostat to a
high or low temperature, where the actual on/off of the furnace
blower (and later, the heat) is something like a couple of
minutes delayed.

I get all that - but what I don't understand is *where* the
hysteresis is built in? Is it in the computer? Is there a dial
that sets the temperature range of the hysteresis? Is there
a potentiometer?

How do we *change* or *set* how much hysteresis there is?
Specifically, how do I get *more* hysteresis in my furnace?

Ralph Mowery wrote:
"Kirk Landaur" wrote in message
...
How does the hysteresis work on the Honeywell old-style bulb thermostat?

My house has two of those tan round things, with a dial that has
only two indicators.
1. The desired temperature on top, and......
2. The current temperature on bottom.

I understand that the heat overshoots on the current temperature
and that it lets the current temp go below the set temperature,
so that the gas furnaces are not constantly turning on and off
exactly at the set temperature.

That makes sense (from a wear and tear and noise standpoint).

I call that delayed on and off time the "hysteresis" (but you can
call it whatever it's really called).
and
Pulling off the cover, I see a mercury bulb inside, which is at the
end of a curved metal strip (bi-metallic perhaps?), which explains
the *initial* on/off mechanism is from the expansion and contraction
of the coiled flat strip kicking the mercury switch on and off.

This can't be the actual on/off of the furnace, because hysteresis
decrees that the on time of the furnace itself is after the mercury
turns it on and so is the off time of the furnace being after the
mercury turns it off.

I can easily test this, simply by turning the thermostat to a
high or low temperature, where the actual on/off of the furnace
blower (and later, the heat) is something like a couple of
minutes delayed.

I get all that - but what I don't understand is *where* the
hysteresis is built in? Is it in the computer? Is there a dial
that sets the temperature range of the hysteresis? Is there
a potentiometer?

How do we *change* or *set* how much hysteresis there is?
Specifically, how do I get *more* hysteresis in my furnace?


Part of it is in the house its self. It takes a while for the air and walls
in the house to heat up. Then the thermostat cuts off, but the air handler
will blow for a while to cool off the frunace heat chamber. The furnace
should have a control for this near the heat chamber. Say the house over
shoots 2 degrees during all of this. Then it cools down and the furnace
starts back up.


That is why blower does not come on with flame on, does not go off with
flame off(this going off delay is usually adjustable at the control board)

"Kirk Landaur" wrote in message
...
How does the hysteresis work on the Honeywell old-style bulb thermostat?

My house has two of those tan round things, with a dial that has
only two indicators.
1. The desired temperature on top, and......
2. The current temperature on bottom.

I understand that the heat overshoots on the current temperature
and that it lets the current temp go below the set temperature,
so that the gas furnaces are not constantly turning on and off
exactly at the set temperature.

That makes sense (from a wear and tear and noise standpoint).

I call that delayed on and off time the "hysteresis" (but you can
call it whatever it's really called).

Pulling off the cover, I see a mercury bulb inside, which is at the
end of a curved metal strip (bi-metallic perhaps?), which explains
the *initial* on/off mechanism is from the expansion and contraction
of the coiled flat strip kicking the mercury switch on and off.

This can't be the actual on/off of the furnace, because hysteresis
decrees that the on time of the furnace itself is after the mercury
turns it on and so is the off time of the furnace being after the
mercury turns it off.

I can easily test this, simply by turning the thermostat to a
high or low temperature, where the actual on/off of the furnace
blower (and later, the heat) is something like a couple of
minutes delayed.

I get all that - but what I don't understand is *where* the
hysteresis is built in? Is it in the computer? Is there a dial
that sets the temperature range of the hysteresis? Is there
a potentiometer?

How do we *change* or *set* how much hysteresis there is?
Specifically, how do I get *more* hysteresis in my furnace?


Part of it is in the house its self. It takes a while for the air and walls
in the house to heat up. Then the thermostat cuts off, but the air handler
will blow for a while to cool off the frunace heat chamber. The furnace
should have a control for this near the heat chamber. Say the house over
shoots 2 degrees during all of this. Then it cools down and the furnace
starts back up.

On Saturday, December 26, 2015 at 1:20:38 PM UTC-8, Tony Hwang wrote:
Kirk Landaur wrote:
How does the hysteresis work on the Honeywell old-style bulb thermostat?

My house has two of those tan round things...
Pulling off the cover, I see a mercury bulb inside, which is at the
end of a curved metal strip (bi-metallic perhaps?)

That is just dumb thermostat. Only thing you can set is anticipator.
And remember metal fatigue, bimetal strip calibration goes off with
age. I'd just replace them with decent smart digital programmable ones.

I think this sounds like new-paint disease. No, there's no metal fatigue
going on, and 'decent smart...' devices don't have a half-century MTBF
like a mercury switch mechanism.

Because this IS a dumb thermostat, the timing adjustments that are wanted
might reside in the furnace room, not the thermostat.

On 12/26/2015 3:55 PM, John Robertson wrote:
The hysteresis is set on the thermostat. I used to have one of those old
Honeywell units and as I recall it had a calibrated sub-dial that set
the hysteresis temperature range. Something like 0.5 degrees to around 3
degrees (F). You simply moved this sub-dial to the over/undershoot range
you desired.
...

That is the "anticipator", not hysteresis setting. It is actually a
heater that warms the thermostat in anticipation of the room heating up
and minimizing overshoot.

On 12/26/2015 3:58 PM, Dave M wrote:
It's the weight of the mercury that moves the bimetal coil spring such that
it takes a higher temperature to bend the bimetal coil spring so that the
mercury flows back to the other end of the bulb. When the mercury moves to
one end of the bulb, it makes the spring reposition itself so that it takes
a much higher (or lower, depending on heat or cool mode) for the spring to
return back to its original position. ...

Yes!

On 12/26/2015 4:14 PM, Kirk Landaur wrote:
On Sat, 26 Dec 2015 12:49:29 -0800, Uncle Monster wrote:

Inside you'll see a sliding resistor called an "Anticipator"
which provides a tiny amount of heat to fool the thermostat.
ヽ(€¢€¿€¢)ノ

Is this the anticipator?
http://i63.tinypic.com/280nvqs.jpg

Yes

...
On the one hand, the LONGER on one end *implies* that's the end
where the slider makes the hysteresis longer; but, on the other
hand, the arrow points in the opposite direction, which implies
the hysteresis is longer in the other direction?
...

The anticipator has nothing to do with hysteresis. It's adjustable to
account for different currents that are drawn by different "heaters".
Once adjusted to the current that your heater draws, it will put heat
into the thermostat to anticipate the room heating up.

Tony Hwang wrote:

Dave M wrote:
It's the weight of the mercury that moves the bimetal coil spring such that
it takes a higher temperature to bend the bimetal coil spring so that the
mercury flows back to the other end of the bulb. When the mercury moves to
one end of the bulb, it makes the spring reposition itself so that it takes
a much higher (or lower, depending on heat or cool mode) for the spring to
return back to its original position.
Here's a link to a web page that describes the operation very well, saving
me a lot of typing.
http://inspectapedia.com/heat/Thermo...e_Response.php

Cheers,

Dave M

I think you are thinking backward. Spring controls the position of bulb
depending on temperature. Not the other way around.


They are interactive.

Kirk Landaur wrote:

How does the hysteresis work on the Honeywell old-style bulb thermostat?

My house has two of those tan round things, with a dial that has
only two indicators.
1. The desired temperature on top, and......
2. The current temperature on bottom.

I understand that the heat overshoots on the current temperature
and that it lets the current temp go below the set temperature,
so that the gas furnaces are not constantly turning on and off
exactly at the set temperature.

That makes sense (from a wear and tear and noise standpoint).

I call that delayed on and off time the "hysteresis" (but you can
call it whatever it's really called).

Pulling off the cover, I see a mercury bulb inside, which is at the
end of a curved metal strip (bi-metallic perhaps?), which explains
the *initial* on/off mechanism is from the expansion and contraction
of the coiled flat strip kicking the mercury switch on and off.

This can't be the actual on/off of the furnace, because hysteresis
decrees that the on time of the furnace itself is after the mercury
turns it on and so is the off time of the furnace being after the
mercury turns it off.

I can easily test this, simply by turning the thermostat to a
high or low temperature, where the actual on/off of the furnace
blower (and later, the heat) is something like a couple of
minutes delayed.

I get all that - but what I don't understand is *where* the
hysteresis is built in? Is it in the computer? Is there a dial
that sets the temperature range of the hysteresis? Is there
a potentiometer?

How do we *change* or *set* how much hysteresis there is?
Specifically, how do I get *more* hysteresis in my furnace?


Have you read the instructions for the thermostat?

https://customer.honeywell.com/resources/techlit/TechLitDocuments/60-0000s/60-0830.pdf

On Sat, 26 Dec 2015 14:20:25 -0700, Tony Hwang wrote:

What are you trying to accomplish?

I'm simply trying to make the hysteresis of longer duration.

On Sat, 26 Dec 2015 21:14:41 +0000, Kirk Landaur wrote:

Is this the anticipator?
http://i63.tinypic.com/280nvqs.jpg

This seems to be the correct URL to the picture.
http://oi63.tinypic.com/280nvqs.jpg

Notice the "LONGER" and "------" fight each other.

Kirk Landaur wrote:
On Sat, 26 Dec 2015 14:20:25 -0700, Tony Hwang wrote:

What are you trying to accomplish?

I'm simply trying to make the hysteresis of longer duration.

Then move the anticipator to higher number from what it is now.
When we were running 4 stores in the past, one store had that
old thermostat, I played with it during summer cooling, winter heating
months.
After all that time spent, I drew a conclusion original setting was best
optimized setting. Eventually I replaced it with digital 7 day
programmable thermostat which realized some savings on utility bill.

Zus ****ing Christ all the misinformation here.

First of all you start talking anticipators on December we are going to assume you mean on a heating thermostat. now for one, I disagree with going digital, digital is ****. In fact I am looking for appliances like microwaves, stoves and fridges that have the old style dial and no IC to go bad that you can't get once the thing is six months old. On the old stuff we can go to a plumbing supply (not DIY, where the real plumbers go, I have been there many times) and still even get parts for old steam controlled systems. now on tho9se the anticipator was a whole different story. But back to the lectric now -

In the heating mode, the anticipator heats the thermostat to delay the furnace from turning on. Every time a forced air furnace cyles on and off it wastes energy. the anticipator delays the turn on by heating, by a SPECIFIC caloric amount, the thing that turns the furnace on, in most cases on old stuff, a bimetallic strip rolled into a coil.

the mercury in the switch is heavy in relation to everything else and when it flops to the other side it creates its own hysteresis. That is the minimum. They want more.

They want more because it saves money to overshoot the temperature called for and let it have longer to cool down, and it also helps to not have it kick in too soon either. These cycles throw energy away, in most cases. Some systems are actually throttled but they are expensive. So since we have a binary input - on or off - we must use it wisely.

You can make a system that will keep the temperature within like a half a degree, but that costs more in energy.

The anticipator is usually set to the draw of the gas valve, but that is in older systems. In older systems, the thermostat directly controlled the gas valve and then another thermostat in the plenum controlled the blower. That was a good system.

However, now that we have induced draft systems, the thermostat turns on the induction motor and the computer checks for presssure in the flue. After blowing for a while and not seeing any significant pressure it will turn on the gas and the tubular heat exchanger will get hot, at a certain calculated rate. After a timer in the computer says it is long enough, the main blower turns on.

Once the thermostat is satisfied, meaning its setpoint has been reached, the computer turns the gas off and the blower runs for a predetermined period to keep putting the heat into the house rather than the chimney. This is usually settable by DIP switches on the PC board in the furnace.

That means more than the anticipator really, as it is set based on how long the ductwork is. On a smaller system you might want to set the afterrun shorter but on a bigger system maybe longer.

If you have an induced draft furnace, the anticipator only counts for the turn on really. The timer on the board controls when the blower shuts off. Many of them run the blower too long and put out cold air. People bitch about it and the guy comes and sets it shorter.

The control set really did work better, but those tubular heat exchangers with induced draft are marginally more efficient. Really, the difference is NOT night and day like the furnace guy tells you. The old ones could easily be 80 % efficient and many were. Even some gravity furnaces, if the dampers are set right. But people today do not want to **** with it, this unit does it all, it is easy. There is only one advertising word better than easy in this world.

The tubular heat exchangers are really good in a few wways. first of all their recovery is like lightning, and second of all as long as the system is working properly you CANNOT get carbon monoxide poisoning in the house. The pressure where the fuel is burned is always below atmospheric, so if it is putting out CO it is going up the chimney or flue, not into the house.

The problem with that system is that because of how it works with the temp changes and all that, There is no effective way to quickly and accurately measure the temperature, otherwise that would control the blower, maybe albeit from the computer, but still that would be the optimum way.

But those things are stainless steel and being used under those conditions should not have any holes drilled into it or things welded to it because that would compromise its long term integrity. Even if it won't kill you, you still don't want any leaks. (some of them do leak but nobody really notices)

Anyway, just set the anticipator to mid range. Sure you can go down there and get the rating of the gas valve but that does not always result in the optimum setting anyway. That depends on the house, and not just the square footage, the shape of it, the position of the furnace relative to the entire perimiter and what parts of the house are important to you to heat.

That is why those guy made the money. I say made because I doubt anyone gives alot of thought to it anymore.

Like installing a single heat and air system in a two story house. I must be the only mother****er out there who can really balance one right, and I have never been to school for this ****. People in the business are like any business, get er done and get out. handle the problems later, and if not, call our lawyer.

Set it in the middle. If the house gets too hot before the furnace kicks off, move the anticipator in the direction to close the shunt across the resistor they hang under the bimetallic strip.

It is the opposite with cooling. In the cooling mode the anticipator is in series with the adjustment and the resistor is of a higher value. What it does them is heats the thermostat while the AC is running to make it run longer, and then it will stay off longer. The net energy is almost the same except for the starts.

Money is spent when you start and stop, that is why it is good to use the cruise control on long trips if possible. whenever you use the brakes you are wasting the gasoline you used to get the car moving. You convert it to heat.

With climate control, in the winter, once you get the walls warm it is cheap unless you got no insulation and those winds really blow. In the summer, once the place is cooled off it is not that hard to keep it that way unless there is a hell of alot of sun.

Like they said - keep an even keel. though it seems to be the opposite here, once you understand the principles involved, the anticipator does that, in a backwards kind of way.

Bob Engelhardt wrote: "That is the "anticipator", not hysteresis setting. "

Yes! Digital programmables have replaced
the heat anticipator with a set of "firing length"
options: 1 for shorter firing time, 2 for normal,
and 3 for longer.

On 12/26/2015 5:37 PM, Michael A. Terrell wrote:


Have you read the instructions for the thermostat?

https://customer.honeywell.com/resources/techlit/TechLitDocuments/60-0000s/60-0830.pdf


Men never read instructions. Nor ask travel
directions. It's part of the male code. We
can also pretty much always find a place to
go potty, even if it's behind second base in
a crowded baseball theatre. No guy will ever
comment on another guy who is.... no comment.

When I was doing AC installs, we'd jump R to W
with AC ammeter, and then use that figure to set
the slider in the old style round stat.

--
..
Christopher A. Young
learn more about Jesus
.. www.lds.org
..
..

Kirk Landaur wrote:
On Sat, 26 Dec 2015 21:14:41 +0000, Kirk Landaur wrote:

Is this the anticipator?
http://i63.tinypic.com/280nvqs.jpg

This seems to be the correct URL to the picture.
http://oi63.tinypic.com/280nvqs.jpg

Notice the "LONGER" and "------" fight each other.



No they don't. Following your picture in the URL above,
the numbers on the scale go from 1.2 to .10 (left to right).

The 'LONGER' label indicates what happens when you move the pointer in
the direction indicated below it by the arrow. Moving the pointer to
the left, to a higher number say from .2 to .3, in the direction of the
arrow, makes whatever you are adjusting 'LONGER'. No ambiguity there at
all, except for what that 'LONGER' adjustment is specifically doing (I
guess that would be in the manual).

S.

On Saturday, December 26, 2015 at 3:58:55 PM UTC-5, Dave M wrote:
It's the weight of the mercury that moves the bimetal coil spring such that
it takes a higher temperature to bend the bimetal coil spring so that the
mercury flows back to the other end of the bulb. When the mercury moves to
one end of the bulb, it makes the spring reposition itself so that it takes
a much higher (or lower, depending on heat or cool mode) for the spring to
return back to its original position.
Here's a link to a web page that describes the operation very well, saving
me a lot of typing.
http://inspectapedia.com/heat/Thermo...e_Response.php

Cheers,
Dave M

Kirk Landaur wrote:
How does the hysteresis work on the Honeywell old-style bulb
thermostat?

My house has two of those tan round things, with a dial that has
only two indicators.
1. The desired temperature on top, and......
2. The current temperature on bottom.

I understand that the heat overshoots on the current temperature
and that it lets the current temp go below the set temperature,
so that the gas furnaces are not constantly turning on and off
exactly at the set temperature.

That makes sense (from a wear and tear and noise standpoint).

I call that delayed on and off time the "hysteresis" (but you can
call it whatever it's really called).

Pulling off the cover, I see a mercury bulb inside, which is at the
end of a curved metal strip (bi-metallic perhaps?), which explains
the *initial* on/off mechanism is from the expansion and contraction
of the coiled flat strip kicking the mercury switch on and off.

This can't be the actual on/off of the furnace, because hysteresis
decrees that the on time of the furnace itself is after the mercury
turns it on and so is the off time of the furnace being after the
mercury turns it off.

I can easily test this, simply by turning the thermostat to a
high or low temperature, where the actual on/off of the furnace
blower (and later, the heat) is something like a couple of
minutes delayed.

I get all that - but what I don't understand is *where* the
hysteresis is built in? Is it in the computer? Is there a dial
that sets the temperature range of the hysteresis? Is there
a potentiometer?

How do we *change* or *set* how much hysteresis there is?
Specifically, how do I get *more* hysteresis in my furnace?

The voice of wisdom speaks. Thank you Dave. If you take the thermostat off the wall and tilt it left and right you can see the heavy mercury drop flop back and forth causing the hysteresis in the temperature by-metal spring. An elegant design from old school physics that does not require microprocessors and such. I would add more reliable as well.

There is a lot of information both accurate and not-so-much in the replies, so, in summary:

a) correct that the mercury bulb is designed as slow on/less slow off. This allows for the over/undershoot.
b) the anticipator matches the nichrome resistor load to the power available from the gas valve. Keep in mind that back in the day, many hydronic systems ran on gravity, no circulator, no mains power. So, power was supplied by a 'millivolt pile' heated by the standing pilot. The anticipator in this case would be at the lowest setting. As gravity systems were slow start-high overshoot systems, the stat would want to respond directly to ambient temps as overshoot was built in.
c) systems with circulators were more capable of holding a steady temp, ran the gas valve at higher voltages, and used limit switches to manage system response. The trick noted of using the MA setting on a VOM is the way to go here.

Now, if one lives as we do in a 4,200 s.f. 3 story center hall colonial built in 1890 with an hydronic heating system installed in 1928, such a stat would not be suitable unless several were used in a zoned set-up. Our system uses a gas-fired, modulating, condensing boiler with sensor for supply and return water temps, external air temp, and response time (a function of the change in return water temp over time). We use a smart-stat that also learns, so that it will reach temps 'as timed', rather than starting to heat at a set time. That, too, has a outside temp function. This can get very efficient such that even this big house is quite reasonable to heat.


Peter Wieck
Melrose Park, PA

On 12/26/2015 02:37 PM, Kirk Landaur wrote:

[snip]

I get all that - but what I don't understand is *where* the
hysteresis is built in? Is it in the computer? Is there a dial
that sets the temperature range of the hysteresis? Is there
a potentiometer?

The mercury switch provides some hysteresis.

How do we *change* or *set* how much hysteresis there is?
Specifically, how do I get *more* hysteresis in my furnace?



--
Mark Lloyd
http://notstupid.us/

"In fact, when you get right down to it, almost every explanation Man
came up with for *anything* until about 1926 was stupid." [Dave Barry]

Tony Hwang wrote:
Dave M wrote:
It's the weight of the mercury that moves the bimetal coil spring
such that it takes a higher temperature to bend the bimetal coil
spring so that the mercury flows back to the other end of the bulb. When
the mercury moves to one end of the bulb, it makes the spring
reposition itself so that it takes a much higher (or lower,
depending on heat or cool mode) for the spring to return back to its
original position. Here's a link to a web page that describes the
operation very well,
saving me a lot of typing.
http://inspectapedia.com/heat/Thermo...e_Response.php

Cheers,

Dave M

I think you are thinking backward. Spring controls the position of
bulb depending on temperature. Not the other way around.


Kirk Landaur wrote


Yep, I understand that the "Spring controls the position of bulb depending
on temperature". That was, I thought, my intention to describe. When the
spring bends far enough to tip the bulb, the weight of the mercury in the
bulb swings the bulb a bit farther , requiring the temperature to cause a
greater swing in the other direction to make it switch back. That's where
the hysteresis comes from. That was the question from the OP, which is what
I was trying to answer.

cheers,
Dave M

ssinzig wrote: "arrow, makes whatever you are adjusting 'LONGER'. No ambiguity there at all, except for what that 'LONGER' adjustment is specifically doing (I "

Should be pretty obvious what is happening
for a "longer" period of time: the boiler or
furace is running longer! Moving that slider
toward Shorter results in shorter, more frequent
run times of the boiler or furnace.

Assuming setpoint = 68.0F
Longer means swing from 66 to 70,
but house gets hot and cold.
Shorter means swing from 67.8 to
68.2, but heat cycles on and off
constantly.

Just right(anticipator setting measured
with meter) and you should stay between
67.5 - 68.5F.

Same concept with digital "Firing length"
3-4 position menu setting.

"Mark Lloyd" wrote in message
...
On 12/26/2015 02:37 PM, Kirk Landaur wrote:

[snip]

I get all that - but what I don't understand is *where* the
hysteresis is built in? Is it in the computer? Is there a dial
that sets the temperature range of the hysteresis? Is there
a potentiometer?

The mercury switch provides some hysteresis.

How do we *change* or *set* how much hysteresis there is?
Specifically, how do I get *more* hysteresis in my furnace?



--

That's the main reason it is so important to level the t-stat.

Dave M wrote:
Tony Hwang wrote:
Dave M wrote:
It's the weight of the mercury that moves the bimetal coil spring
such that it takes a higher temperature to bend the bimetal coil
spring so that the mercury flows back to the other end of the bulb.
When the mercury moves to one end of the bulb, it makes the spring
reposition itself so that it takes a much higher (or lower,
depending on heat or cool mode) for the spring to return back to its
original position. Here's a link to a web page that describes the
operation very well,
saving me a lot of typing.
http://inspectapedia.com/heat/Thermo...e_Response.php

Cheers,

Dave M

I think you are thinking backward. Spring controls the position of
bulb depending on temperature. Not the other way around.


Kirk Landaur wrote


Yep, I understand that the "Spring controls the position of bulb
depending on temperature". That was, I thought, my intention to
describe. When the spring bends far enough to tip the bulb, the
weight of the mercury in the bulb swings the bulb a bit farther ,
requiring the temperature to cause a greater swing in the other
direction to make it switch back. That's where the hysteresis comes
from. That was the question from the OP, which is what I was trying
to answer.
cheers,
Dave M

I forgot to add that, in more direct response to the OP's question, that the
hysteresis (temperature difference required to switch the HVAC unit from off
to on, and back to off) is created by the temperature characteristics of the
bimetal spring, the weight of the mercury ball (both unchangeable by the
user), and modified by the anticipator resistor.

More Cheers,
Dave M

wrote:
ssinzig wrote: "arrow, makes whatever you are adjusting 'LONGER'. No
ambiguity there at all, except for what that 'LONGER' adjustment is
specifically doing (I "

Should be pretty obvious what is happening for a "longer" period of
time: the boiler or furace is running longer! Moving that slider
toward Shorter results in shorter, more frequent run times of the
boiler or furnace.

Assuming setpoint = 68.0F Longer means swing from 66 to 70, but house
gets hot and cold. Shorter means swing from 67.8 to 68.2, but heat
cycles on and off constantly.

Just right(anticipator setting measured with meter) and you should
stay between 67.5 - 68.5F.

Same concept with digital "Firing length" 3-4 position menu setting.



Okay, that seems reasonable. Although I would argue that it is not
'pretty obvious' what is happening for a 'longer' period of time,
without already being familiar with its operation or consulting an
operating manual.

Is the scale (1.2 to .10) measured in seconds, minutes, or hours?
Is it a multipler, ie. 0.8 x burn duration?
Is it the time the burner stays on?
Is it a time delay before the burner comes on?
Is it a time delay before the burner turns off?

Everything is always 'pretty obvious' when you are
already familiar with how it works.

S.

"Now, if one lives as we do in a 4,200 s.f. 3 story center hall colonial built in 1890 with an hydronic heating system i"

That changes things. In a hot water system there is little to no overhead in starting and stopping the system. Also the water has thermal mass so it evens it all out.

For most places, hydronic heating is much superior to forced air. The only problem is it does not filter the air, and AC cannot be easily added. If you ever want AC don't let anyone talk you out of that system, make them put in a separate air box for it. Then you will have not only balanced heat, but balanced AC, which is extremely difficult to achieve with a combined system in a multi story house. With separate systems you will be much more comfortable.

But the bottom line here is that in a hot water system, the anticipator makes little to no difference in performance or efficiency. You don't have to worry about it.

On Sunday, December 27, 2015 at 8:14:07 AM UTC-5, Stormin Mormon wrote:
On 12/26/2015 5:37 PM, Michael A. Terrell wrote:


Have you read the instructions for the thermostat?

https://customer.honeywell.com/resources/techlit/TechLitDocuments/60-0000s/60-0830.pdf


Men never read instructions. Nor ask travel
directions. It's part of the male code.

Here here , I second that. IKEA furniture being the only exception.

We
can also pretty much always find a place to
go potty, even if it's behind second base in
a crowded baseball theatre. No guy will ever
comment on another guy who is.... no comment.

When I was doing AC installs, we'd jump R to W
with AC ammeter, and then use that figure to set
the slider in the old style round stat.

--
.
Christopher A. Young
learn more about Jesus
. www.lds.org
.
.

There are always a few (not so few around here) outlyers. Gravity systems have a *huge* overshoot such that the stat must be set properly! Keep in mind that most (very nearly all) of these systems were built without mains power, and, of course no circulators. So it is critical that the stat responds to ambient temps fairly closely. It takes *time* before the differential on the supply side is enough to restart circulation once equalized. So, the under/over is established in part already. In such cases, the stat should respond very nearly to ambient temperatures (and should be on an inside wall not facing a radiator).

When we moved into this house, I - with more than a little help - removed a 400,000 BTU steel jacket oil burner and replaced it with a Weil Mclain 230,000 BTU gas fired Ultra that also makes our hot water. The system was originally gravity, with 4" ID risers in a 2-pipe configuration. During the install, I added two circulators on the heat side, one for the hot water - the computer on board the boiler manages the dance for all three. But what it means is that all 38 radiators are at the same temperature unless otherwise managed. This allowed me to install thermostatic valves in strategic locations (17 in total) such that we have lots of flexibility. In 8 winters, we have never had a lick of trouble.

But a smart stat is essential to keeping all this in balance.

Peter Wieck
Melrose Park, PA

Yabbut.....IKEA uses *pictures*!!

That is an exception!

Peter Wieck
Melrose Park, PA

wrote in message
...


" In such cases, the stat should respond very nearly to ambient temperatures
(and should be on an inside wall not facing a radiator)."

Peter Wieck
Melrose Park, PA

++++++++++++++++++++++++++++++++++++++++++++++++++ ++++++++++++++

And don't forget to consider what is inside the wall. Such as hot and cold
water pipes, return air ducts, wiring,...

"There are always a few (not so few around here) outlyers. Gravity systems have a *huge* overshoot such that the stat must be set properly! "

Except if it is a thermopile system. If so, there is no anticipator.

ssinzig wrote:
wrote:
ssinzig wrote: "arrow, makes whatever you are adjusting 'LONGER'. No
ambiguity there at all, except for what that 'LONGER' adjustment is
specifically doing (I "

Should be pretty obvious what is happening for a "longer" period of
time: the boiler or furace is running longer! Moving that slider
toward Shorter results in shorter, more frequent run times of the
boiler or furnace.

Assuming setpoint = 68.0F Longer means swing from 66 to 70, but house
gets hot and cold. Shorter means swing from 67.8 to 68.2, but heat
cycles on and off constantly.

Just right(anticipator setting measured with meter) and you should
stay between 67.5 - 68.5F.

Same concept with digital "Firing length" 3-4 position menu setting.



Okay, that seems reasonable. Although I would argue that it is not
'pretty obvious' what is happening for a 'longer' period of time,
without already being familiar with its operation or consulting an
operating manual.

Is the scale (1.2 to .10) measured in seconds, minutes, or hours?
Is it a multipler, ie. 0.8 x burn duration?
Is it the time the burner stays on?
Is it a time delay before the burner comes on?
Is it a time delay before the burner turns off?

It's the current draw for the solenoid valve.

In sci.electronics.repair Tony Hwang wrote:
Ralph Mowery wrote:
"Kirk Landaur" wrote in message
...
How does the hysteresis work on the Honeywell old-style bulb thermostat?

My house has two of those tan round things, with a dial that has
only two indicators.
1. The desired temperature on top, and......
2. The current temperature on bottom.

I understand that the heat overshoots on the current temperature
and that it lets the current temp go below the set temperature,
so that the gas furnaces are not constantly turning on and off
exactly at the set temperature.

That makes sense (from a wear and tear and noise standpoint).

I call that delayed on and off time the "hysteresis" (but you can
call it whatever it's really called).
and
Pulling off the cover, I see a mercury bulb inside, which is at the
end of a curved metal strip (bi-metallic perhaps?), which explains
the *initial* on/off mechanism is from the expansion and contraction
of the coiled flat strip kicking the mercury switch on and off.

This can't be the actual on/off of the furnace, because hysteresis
decrees that the on time of the furnace itself is after the mercury
turns it on and so is the off time of the furnace being after the
mercury turns it off.

I can easily test this, simply by turning the thermostat to a
high or low temperature, where the actual on/off of the furnace
blower (and later, the heat) is something like a couple of
minutes delayed.

I get all that - but what I don't understand is *where* the
hysteresis is built in? Is it in the computer? Is there a dial
that sets the temperature range of the hysteresis? Is there
a potentiometer?

How do we *change* or *set* how much hysteresis there is?
Specifically, how do I get *more* hysteresis in my furnace?


Part of it is in the house its self. It takes a while for the air and walls
in the house to heat up. Then the thermostat cuts off, but the air handler
will blow for a while to cool off the frunace heat chamber. The furnace
should have a control for this near the heat chamber. Say the house over
shoots 2 degrees during all of this. Then it cools down and the furnace
starts back up.


That is why blower does not come on with flame on, does not go off with
flame off(this going off delay is usually adjustable at the control board)

That depends on the furnace. MY blower comes on as soon as the burner
ignites, it's a high efficiency furnace, so the blower must start to
cool the secondary heat exchanger.

ssinzig wrote: "- show quoted text -
Okay, that seems reasonable. Although I would argue that it is not
'pretty obvious' what is happening for a 'longer' period of time,
without already being familiar with its operation or consulting an
operating manual.

Is the scale (1.2 to .10) measured in seconds, minutes, or hours?"
No time bearing whatsoever. It's VOLTAGE.
"Is it a multipler, ie. 0.8 x burn duration? "
No.
"Is it the time the burner stays on? "
Yes!!
"Is it a time delay before the burner comes on? "
Sort of. You're starting to get it.
"Is it a time delay before the burner turns off? "
Getting warmer!(pardon the pun). It's function
is determined by voltage(the numbers on the
anticipator slider are in Volts).

A heat anticipator generates 'false heat' - it tricks a
traditional bulb-stat into firing the boiler in a more
energy efficient manner, by generating a small
amount of local heat within the wall unit itself.

The correct amount of false heat both prevents
the thermostat from calling for heat too soon after
it drops below set point(what you the user set it for),
and prevents thermostat from running so long that it
overshoots that set point by significant amount.

At its extremes, a heat anticipator could cause too
frequent and short boiler runs, or not so frequent boiler
runs between which the house gets too cold, and then
gets too hot before the boiler turns off. Set properly, the
anticipator will turn the unit off just before reaching the
setpoint, so that remaining hot water(or air) in the system
can be pushed through the system without a significant
overshoot.

Succinctly, you want neither a scenario where the boiler
turns on and off every three minutes, nor where it turns
on for one half hour, and is then off for nearly one half
hour. The anticipator, when properly calibrated, prevents
both situations, and keeps the temp. within a tolerable
range.

"Everything is always 'pretty obvious' when you are
already familiar with how it works. "

S. "

That's why we're here to share knowledge.

Jerry Peters wrote:
In sci.electronics.repair Tony Hwang wrote:
Ralph Mowery wrote:
"Kirk Landaur" wrote in message
...
How does the hysteresis work on the Honeywell old-style bulb thermostat?

My house has two of those tan round things, with a dial that has
only two indicators.
1. The desired temperature on top, and......
2. The current temperature on bottom.

I understand that the heat overshoots on the current temperature
and that it lets the current temp go below the set temperature,
so that the gas furnaces are not constantly turning on and off
exactly at the set temperature.

That makes sense (from a wear and tear and noise standpoint).

I call that delayed on and off time the "hysteresis" (but you can
call it whatever it's really called).
and
Pulling off the cover, I see a mercury bulb inside, which is at the
end of a curved metal strip (bi-metallic perhaps?), which explains
the *initial* on/off mechanism is from the expansion and contraction
of the coiled flat strip kicking the mercury switch on and off.

This can't be the actual on/off of the furnace, because hysteresis
decrees that the on time of the furnace itself is after the mercury
turns it on and so is the off time of the furnace being after the
mercury turns it off.

I can easily test this, simply by turning the thermostat to a
high or low temperature, where the actual on/off of the furnace
blower (and later, the heat) is something like a couple of
minutes delayed.

I get all that - but what I don't understand is *where* the
hysteresis is built in? Is it in the computer? Is there a dial
that sets the temperature range of the hysteresis? Is there
a potentiometer?

How do we *change* or *set* how much hysteresis there is?
Specifically, how do I get *more* hysteresis in my furnace?


Part of it is in the house its self. It takes a while for the air and walls
in the house to heat up. Then the thermostat cuts off, but the air handler
will blow for a while to cool off the frunace heat chamber. The furnace
should have a control for this near the heat chamber. Say the house over
shoots 2 degrees during all of this. Then it cools down and the furnace
starts back up.


That is why blower does not come on with flame on, does not go off with
flame off(this going off delay is usually adjustable at the control board)

That depends on the furnace. MY blower comes on as soon as the burner
ignites, it's a high efficiency furnace, so the blower must start to
cool the secondary heat exchanger.

How high efficiency? Ours are 96% 2 stage one. There is built-in delay
for blower to come one. Off delay is adjustable by dip switches. Inducer
blower purges vent already before ingnition comes on.