John Williamson wrote
Onetap wrote
Mathew Newton wrote

How much simpler do you need it? At first I thought you simply didn't understand, which is fair enough, but now I'm
beginning to think you don't even *want* to understand.

Yeah, we know what it's meant to do; the question is, how does it do it? If you heat the element, it will open
earlier because it's hotter, but how does that help you get a more accurate measurement of the air temperature?

The aim of the design isn't to get an accurate measurement of the air temperature *at the time of the measurement*,
but to anticipate what the air temperature will reach *after the heating is turned off*. As the radiators and the
water they contain as used in most domestic
heating systems hold a fair amount of heat which will be released
after the boiler is turned off, the heat source (boiler) needs to be
turned off *before* the desired air temperature is reached, otherwise
the set temperature will be exceeded. This is why the thermostat has either software anticipation or a hardware heater
built in.

The trouble with that line is that even systems like say
electrical fan heating still see a big improvement in the
hysterises with a bi metallic strip thermostat with a heater.

The real reason that happens is because the heater just turns off the
heating before it would otherwise be turned off by the bi metallic strip.

In an ideal world, the preheat on the thermostat will be calibrated for each installation,

No need, it works fine even when there is no inertia in the heating system.

but most of the time, the normal value as installed is "close enough".

In reality, heating the bi metallic strip ALWAYS reduces the hysteresis.

Blown air heating systems need a different control regime,

Nope, they still get a reduced hysteresis with a heated bi metallic strip thermostat.

preferably a proportional control system,

That just reduces the hysteresis even more by a different approach.

You can do that with a hot water system too.

which takes account of the heat lost by the building,

Thats never constant.

so that the heating runs at a reduced power level at all times, in a steady state.

Yes, thats why the proportional system works even better again.

On 08/03/12 22:28, brass monkey wrote:
"Lieutenant Scott" wrote in message
newsp.wavdvxyaytk5n5@i7-940...
On Thu, 08 Mar 2012 08:42:12 -0000, Mathew Newton
wrote:

On Mar 8, 12:18 am, "Lieutenant Scott" wrote:

Do you want me to photograph the ****ing certificate?

Go on, give us all a laugh.

Shout if you need help uploading it.

Mathew

http://petersphotos.com/temp/Degree.jpg

Is that a better qualification than the "arse-elbow differentiation" course
from the UBS?


Can't find that one http://www.cynical*******s.com/ubs/courses.html





--
djc

On Fri, 09 Mar 2012 07:46:35 -0000, Mathew Newton wrote:

On Mar 8, 11:09 pm, "Lieutenant Scott" wrote:

Do you want me to photograph the ****ing certificate?

Oh my God you actually did it.

Why did you think I wouldn't?

I was hoping for your sake that you wouldn't. It made me cringe.

If you want people to think you know what you're talking about do it
through what you say/write, not by uploading photos of your degree
certificate. Seriously. I don't mean to have a go, but as soon as you
say 'Listen to me - I'm right because I've got x' you lose all
credibility.

I did no such thing. Someone (I forget who) implied I had no education.

--
http://petersparrots.com
http://petersphotos.com

Marital Status: Not Good
Wife's Name: Plaintiff

On Fri, 09 Mar 2012 10:49:29 -0000, djc wrote:

On 08/03/12 22:28, brass monkey wrote:
"Lieutenant Scott" wrote in message
newsp.wavdvxyaytk5n5@i7-940...
On Thu, 08 Mar 2012 08:42:12 -0000, Mathew Newton
wrote:

On Mar 8, 12:18 am, "Lieutenant Scott" wrote:

Do you want me to photograph the ****ing certificate?

Go on, give us all a laugh.

Shout if you need help uploading it.

Mathew

http://petersphotos.com/temp/Degree.jpg

Is that a better qualification than the "arse-elbow differentiation" course
from the UBS?


Can't find that one http://www.cynical*******s.com/ubs/courses.html

Is there or did there actually used to be a Peckham Polytechnic?

--
http://petersparrots.com
http://petersphotos.com

The sailor does not pray for wind, he learns to sail -- Gustaf Lindborg

On Friday, March 9, 2012 7:48:27 AM UTC, Mathew Newton wrote:

It's not about getting a more accurate measurement of the air
temperature, it is about reducing hysteresis and thereby reducing
overshoot.

Mathew

You seem to be have lost sight of the wood amongst all the trees. It is the temperature control sensor and it's sole purpose is the measurement of the air temperature.

The golden rules for installing a temperature sensor include ensuring it is not near any external heat sources (solar, lights, radiators, ventilation discharge grilles, etc.) and it completely undermines its purpose to install a heater within the thermostat casing. However it seems the bi-metallic strip thermostat is so inherently crap at temperature measurement, that a heater can be installed in the thermostat and achieve an improvement in its performance.

The Danfoss graph on figure 5 here

http://randall.danfoss.com/PCMPDF/In...hermostats.pdf

seems to show that the heated thermostat is useless whilst the system is heating up, turning off the heat whilst the temperature is still way below the setpoint, and it only works adequately on the cool-down cycle. It also seems that it is intended to cause rapid cycling of the heating plant, which would cause premature failure of any electric pump and valve motors.

Most of this exchange consists of Harry and Rod ( one person) rubbishing anything I post. If you disregard his/their idiotic ejaculations, there are only about 5 sensible posts in the whole exchange. Harry/Rod has a distorted self-image of himself as some sort of omniscient technocrat, whereas he is a incompetent bodger living on benefits. I find it amusing that while I've been away earning a living, doing chores, reading, cooking, boozing, socialising, etc., Harry/Rod is still pounding away at his keyboard spamming numerous forums with the raging fanaticism of a Japanese stay behind.

On Mar 10, 9:48*am, Onetap wrote:
On Friday, March 9, 2012 7:48:27 AM UTC, Mathew Newton wrote:
It's not about getting a more accurate measurement of the air
temperature, it is about reducing hysteresis and thereby reducing
overshoot.

Mathew

* You seem to be have lost sight of the wood amongst all the trees. It is the temperature control sensor and it's sole purpose is the measurement of the air temperature.

snip

I give up; you're just not getting it.

All the best,

Mathew

On Saturday, March 10, 2012 10:30:27 AM UTC, Mathew Newton wrote:

I give up; you're just not getting it.

On the contrary, you don't get it.

It is the temperature control sensor and it is all about measuring air temperature. I've been involved with room temperature controls for nearly 30 years, and I think I got this one long ago.

On Thu, 08 Mar 2012 21:01:10 -0000, "Lieutenant Scott"
wrote:

On Thu, 08 Mar 2012 12:09:06 -0000, Harry Bloomfield wrote:

The Other Mike was thinking very hard :
On Mon, 05 Mar 2012 11:17:31 -0000, "Lieutenant Scott"
wrote:

I have a degree in Digital Microelectronics.

That explains a lot about the state of the UK today.

All that training and you appear to know nothing about control theory.
No idea about PID, no idea about the bi-metallic strip, no idea about
resistive heating, no idea about basic thermodynamics.

I do find it so very amusing when people have to resort to telling you
their qualifications, just to prove they might know what they are
talking about :')

Well there are a lot of childish people in here who seem to need proof.....

Only so they can make absolutely sure that anyone claiming to be
qualified like you never gets employed by their organisation.


--

On Tue, 13 Mar 2012 11:22:28 -0000, The Other Mike wrote:

On Thu, 08 Mar 2012 21:01:10 -0000, "Lieutenant Scott"
wrote:

On Thu, 08 Mar 2012 12:09:06 -0000, Harry Bloomfield wrote:

The Other Mike was thinking very hard :
On Mon, 05 Mar 2012 11:17:31 -0000, "Lieutenant Scott"
wrote:

I have a degree in Digital Microelectronics.

That explains a lot about the state of the UK today.

All that training and you appear to know nothing about control theory.
No idea about PID, no idea about the bi-metallic strip, no idea about
resistive heating, no idea about basic thermodynamics.

I do find it so very amusing when people have to resort to telling you
their qualifications, just to prove they might know what they are
talking about :')

Well there are a lot of childish people in here who seem to need proof.....

Only so they can make absolutely sure that anyone claiming to be
qualified like you never gets employed by their organisation.

It is best to look at what exactly makes up the qualification.

--
http://petersparrots.com
http://petersphotos.com

Please do not look into laser with remaining eye.

On Fri, 16 Mar 2012 17:56:24 -0000, "Lieutenant Scott"
wrote:

On Tue, 13 Mar 2012 11:22:28 -0000, The Other Mike wrote:

On Thu, 08 Mar 2012 21:01:10 -0000, "Lieutenant Scott"
wrote:

On Thu, 08 Mar 2012 12:09:06 -0000, Harry Bloomfield wrote:

The Other Mike was thinking very hard :
On Mon, 05 Mar 2012 11:17:31 -0000, "Lieutenant Scott"
wrote:

I have a degree in Digital Microelectronics.

That explains a lot about the state of the UK today.

All that training and you appear to know nothing about control theory.
No idea about PID, no idea about the bi-metallic strip, no idea about
resistive heating, no idea about basic thermodynamics.

I do find it so very amusing when people have to resort to telling you
their qualifications, just to prove they might know what they are
talking about :')

Well there are a lot of childish people in here who seem to need proof.....

Only so they can make absolutely sure that anyone claiming to be
qualified like you never gets employed by their organisation.

It is best to look at what exactly makes up the qualification.

That you presumably made it past A level physics in order to get to
university to study in the first place and don't appear to have the
foggiest idea on how to work out the resistance, voltage drop and
power dissipated in a piece of copper is truly staggering. Hell we
all have our moments, but that is up there with the hacksaw, the tow
rope out of the neighbours 'drive' and the handbrake left off incident
amongst others.

I asked a member of the family who did A level physics a few decades
ago how she would approach such a problem. She's no engineer, or
physicist, or even much of a DIYer. Her limit of electrical
experience is changing fuses in plugs and stringing Christmas lights
on the tree.

She had the basics of deriving an answer in a few seconds.

So, assuming you haven't had a head injury or a period of oxygen
starvation, then some might suggest you should change your name to
Osmium.

--

"The Other Mike" wrote in message
...
On Fri, 16 Mar 2012 17:56:24 -0000, "Lieutenant Scott"
wrote:

On Tue, 13 Mar 2012 11:22:28 -0000, The Other Mike
wrote:

On Thu, 08 Mar 2012 21:01:10 -0000, "Lieutenant Scott"
wrote:

On Thu, 08 Mar 2012 12:09:06 -0000, Harry Bloomfield
wrote:

The Other Mike was thinking very hard :
On Mon, 05 Mar 2012 11:17:31 -0000, "Lieutenant Scott"
wrote:

I have a degree in Digital Microelectronics.

That explains a lot about the state of the UK today.

All that training and you appear to know nothing about control
theory.
No idea about PID, no idea about the bi-metallic strip, no idea about
resistive heating, no idea about basic thermodynamics.

I do find it so very amusing when people have to resort to telling you
their qualifications, just to prove they might know what they are
talking about :')

Well there are a lot of childish people in here who seem to need
proof.....

Only so they can make absolutely sure that anyone claiming to be
qualified like you never gets employed by their organisation.

It is best to look at what exactly makes up the qualification.

That you presumably made it past A level physics in order to get to
university to study in the first place and don't appear to have the
foggiest idea on how to work out the resistance, voltage drop and
power dissipated in a piece of copper is truly staggering. Hell we
all have our moments, but that is up there with the hacksaw, the tow
rope out of the neighbours 'drive' and the handbrake left off incident
amongst others.

I asked a member of the family who did A level physics a few decades
ago how she would approach such a problem. She's no engineer, or
physicist, or even much of a DIYer. Her limit of electrical
experience is changing fuses in plugs and stringing Christmas lights
on the tree.

She had the basics of deriving an answer in a few seconds.

So, assuming you haven't had a head injury or a period of oxygen
starvation, then some might suggest you should change your name to
Osmium.

LOL, albeit a tad harsh possibly.

On Mon, 19 Mar 2012 12:33:34 -0000, The Other Mike wrote:

On Fri, 16 Mar 2012 17:56:24 -0000, "Lieutenant Scott"
wrote:

On Tue, 13 Mar 2012 11:22:28 -0000, The Other Mike wrote:

On Thu, 08 Mar 2012 21:01:10 -0000, "Lieutenant Scott"
wrote:

On Thu, 08 Mar 2012 12:09:06 -0000, Harry Bloomfield wrote:

The Other Mike was thinking very hard :


I do find it so very amusing when people have to resort to telling you
their qualifications, just to prove they might know what they are
talking about :')

Well there are a lot of childish people in here who seem to need proof.....

Only so they can make absolutely sure that anyone claiming to be
qualified like you never gets employed by their organisation.

It is best to look at what exactly makes up the qualification.

That you presumably made it past A level physics in order to get to
university to study in the first place and don't appear to have the
foggiest idea on how to work out the resistance, voltage drop and
power dissipated in a piece of copper is truly staggering. Hell we
all have our moments, but that is up there with the hacksaw, the tow
rope out of the neighbours 'drive' and the handbrake left off incident
amongst others.

I asked a member of the family who did A level physics a few decades
ago how she would approach such a problem. She's no engineer, or
physicist, or even much of a DIYer. Her limit of electrical
experience is changing fuses in plugs and stringing Christmas lights
on the tree.

She had the basics of deriving an answer in a few seconds.

So, assuming you haven't had a head injury or a period of oxygen
starvation, then some might suggest you should change your name to
Osmium.

You are really rubbish at interpreting what you read aren't you? What I need is a way to MEASURE THE THICKNESS of the copper track. Is that simple enough for you to understand? Do you have a degree in English? No? An O level? Probably not even that.

--
http://petersparrots.com
http://petersphotos.com

Dancing cheektocheek is really a form of floor play.

On Friday, March 9, 2012 12:53:36 AM UTC, Andy Wade wrote:

'Modern digital thermostats',
you will find, implement the same 'anticipator' function in software.
As the sensed temperature gets close to the set point the heating power
input is turned down by controlling the on/off time ratio of the heater
(PWM control, in effect). That's exactly what the accelerator heater
does in a bi-metal 'stat - it creates a band of temperature over which
the heat input is proportional to the temperature error, greatly helping
to reduce overshoot.

You made that up. No-one is going to try to simulate the action of a heater with electronics.

They use PID feedback controls, the derivative constant reduces the output in proportion to the rate of change of the process variable in order to anticipate and reduce overshoot.

The derivative constant is often left at 0 on BMS controllers, since it is reckoned to be unnecessary and causes excessive hunting and premature wear of the control valves.