Temperature sensor shows high

One hardware issue my intergators met many times: temperature sensor works correctly, but shows temperature (on c-touch) 5-10 degrees higher, than actual is. So when is is 20, it shows 30, which is clearly untrue to any client.

Anyone same problem?

 

Yes Nickrusanov,

We had exactly the same problem with 12 temp sensors linked to a c-touch screen. We had the recorded temp level showing for particular zones on the screen. All showed the wrong temp, according to our client. with his mercury thermometer.When we adjusted the target levels for each zone, we removed the temp level from the display.
A problem I hope the tech guys can help with.

 

I was sure, I'm not alone

Did you have any sensor, showing _correct_ temperature?

 

No unfortunately not, all the temp sensors appeared to be calibrated 3-5 deg C above actual temp. We tried several different test thermometers.

 

A bulletin went out about Temperature sensor calibration very early this year.

If a unit is added to the database and then saved to a unit on the network the factory calibration factor is overwritten.

The only way to program a Temperature Sensor and maintain the factory calibration factor is to work on the unit live on the network. Never transfer a SENTEMP configuration from the database to the network.

If the calibration factor becomes overwritten then the unit needs to be returned to the factory for re-calibration.

 

Hello Newman,
The temp sensors were fitted Jan 04, and if I remember they were installed one at a time, and the local network uploaded, targets and margins were then adjusted, and then saved to the database as well as the network. Is this 'working the unit live on the network' ?
We have a few more to fit on other jobs, approx sixteen, complete with c-touch/s. It looks good when the room temp is displayed and we would like to keep this feature.
Being in the UK we dont seem to get Bulitins, can they be found on-line

Is there any way the client can adjust the target temp if it has been set to low/high?
Regards Clyde

 

Clyde

The info in Technical bulletins and the like get collated into a newsletter every once in a while when there's sufficient material to put one together. Previous newsletters can be downloaded from here:

http://www.clipsal.com/cis/lit_installtraining_news.php3

Unfortuantely the issue with calibration of Temperature Sensors hasn't made it to a newsletter yet

Yep, that's it, you should be OK.

Nope, can't do that. It's not trivial getting the temperature out of the temperature sensor, let alone re-configure it on the fly.

The SENTEMP's are fairly sensitive with respects to mounting orientation too. Make sure they're mounted the correct way up on a vertical wall.

 

Thanks Newman

not being funny, but why does the orientation make a difference ?

 

Cyde

It's all to do with where the heat from the PCB inside the unit goes.

In a vertical orientation most of the heat from the unit just goes up and out the unit. It doesn't affect the temperature sensor too much. Mount the unit on it's back however and the heat from the pcb rises up past the sensor giving an artificially high reading.

The heat generated by the PCB isn't much but it's enough to influence the sensor reading by several degrees if mounted the wrong way. This gets worse if the unit is mounted in very still air.

 

Cheers Newman,
Last question for tonight, what about ceiling mounting the temp sensors?

 

Ceiling mount isn't the best idea because of the airflow you can get through the unit. Any air moving from the roof space through the unit and out past the sensor will carry with it heat from the unit PCB.

Air moving throught the unit and out into the roof space is less of a problem.

Don't forget a roof mounted temperature sensor will be reading the hottest air in the room, as hot air rises. Take a thermometer and stick it on your ceiling. Take another one and put it on the floor and you will see the temperature difference!

 

yep sounds logical, thanks for you help Newman

Regards Clyde

 

In addition to self-heating, the temperature sensors have another basic design flaw, in that there is a pathway for airflow from the wall cavity to/from the room. I have found that this can cause readings that are several degrees above/below room temperature, depending on which way the air is flowing and the temperature of the air in the cavity. The effect is most noticeable with sensors mounted on the inside of exterior walls.

I have been able to reduce but not eliminate this with a plastic cover mounted behind the sensor (made from the packing material they come in) and jamming insulation behind them.

I also believe that the sensors need a larger thermal mass in contact with the air. Simply exposing the sensor element to the air as in the current design makes them too sensitive to minor local temperature fluctuations, and contributes to self-heating problems.

 

I did hear talks of a new temp sensor being designed (just before our installation Jan 04), but I have not heard any thing since. Can any one shed any light as to wether a new temp sensor is in development.(without giving too much away)

 

agree

Yes, and Thermostat, which hopefully will work with it.

 

New Temp sensors

If and when thes new sensors are to be released i hope they have the ability to be able to have target temp's set from a c-touch.
Most of my clients are extremely disappointed with this oversight. also the ability to select the heating or cooling functions (or do away with them all togeother).
We tell them we can control anything they want, and that they have 'full' control over anything in the house, but we must 'set' the temperature there house runs at and leave them with it....

 

Whats wrong?

We install new Temp Sensor in network with lots other switches and ets, then scan the network, run unravel feature, readress units and save to database.
Temp Sensor which was found in live network in above process, and saved to database show wrong (high) temperature now.
Whats wrong we do?

 

V2 or Toolkit? V2 had problems overwriting the calibration of Temperature Sensors.

 

to Newman

We use toolkit 1.1.7