PT1000 Sensors

[Robby]

Need electronics help. I have two differential controllers, one that interfaces between solar and boiler systems ( it has 6 inputs) and the second that controls boiler to storage tank(3 inputs). Solar and boiler share 1200 gal pressurized tank via coil in tank.

1. Can two (or more) controllers or thermometers share PT1000 sensor? They are straight resistance value = temperature.

2. Does anyone know where I can purchase a thermometer that uses PT1000 sensors? I can always buy another controller and just use it as a thermometer, but I was hoping to do it less costly.

Nofossil, maybe you would be able to direct me!!


Robby

 

[BrownianHeatingTech]

Is it theoretically possible to share a sensor between multiple controllers? Yes.

Is it likely that the controllers you have are capable of doing that? Probably not.

Any reason you want to share sensors, anyway? Putting two right next to each other usually poses no real problem...

Joe

 

[jdeere5220]

Electronic boards measure the temp of resistive sensor by applying a voltage and using what's called a "voltage divider", i.e. tje control board also supplies's it's own fixed resistor for the circuit, and it's actually by measuring the voltage between the two resistors (the temp sensor and the internal resister) that the control board measures temp.

Placing two controls in parallel, using the same temp sensor, will throw off both because now the internal resisters are in parallel and neither controller will read the temp correctly.

At least that's my experience, but maybe I'm all wet.

 

[steam man]

Yes, you can use one RTD for two controllers but you would need an PT 1000 RTD signal splitter/conditioner which would use an external power source. This will isolate the signal for each controller. Typically you will spend alot more trying to make this work than just running another RTD. An example of one is at http://www.apcs.com/ssp235/ssp235.html but there are others. Do a search.

Mike

 

[BrownianHeatingTech]

Electronic boards measure the temp of resistive sensor by applying a voltage and using what's called a "voltage divider", i.e. tje control board also supplies's it's own fixed resistor for the circuit, and it's actually by measuring the voltage between the two resistors (the temp sensor and the internal resister) that the control board measures temp.

Placing two controls in parallel, using the same temp sensor, will throw off both because now the internal resisters are in parallel and neither controller will read the temp correctly.

At least that's my experience, but maybe I'm all wet.

That's correct. As steam man notes, there are conditioners that can take care of it. If periodic readings (say, once per minute) are sufficient, it's also possible to use a sequencer that gives each control a reading, in turn.

However, a second sensor is a lot cheaper...

Joe

 

[Robby]

Well heck, that answers that question.

Does anyone know where I can purchase the PT1000 with silicon coated wire that is good to 350F. I will need some of these as the standard ones that came with controllers only 160F.

I attached picture, hope it worked of the sensors.

Robby

 

[steam man]

I got my PT1000 sensors with a Resol controller at http://www.sssolar.com/. In use 2 (if I remember correctly) silicon insulated wired ones and two regular ones. One silicon one is outside and another I put down a long thermowell into a tank that has been to 170deg with no ill affect. They have both available.

Mike

 

[Robby]

OK first part sorted out. I was contacted privately and lead to thermometer site.

WATER STORAGE: I have about 10,000 lbs of stroage (1200 gal). The tank weighs about 2000 lbs. Do you add the steel weight to the overall storage capacity? Steel does not store as well as water, but it still stores?

Thanks,

Robby