Temperatures Sensor Type.....

[badpaddler]

I'm new to the site, but have started farting around with my monitor and have my first question. I already asked the tech folks at MPI, and they have no idea. I am wondering what type of sensor the temperature sensor on a 441 is. I know it is 10k, but when I measure it at known temps, and compare it to 2 known good other 10k sensors (Type 3 and Type 2) it is not the same as either one. Not even within 10-20% of correct. I have compared it to every resistance table for thermistors (Dale/NTC/Type3/Type2/etc....) I can find, but it doesn't seem to be the same as anything listed. It is making me wonder if the sensor is shot.

Thanks in advance, I am sure I will have more questions after I start digging into it.

[hawkins111]

Monitor room sensor

What makes a big difference is, what is reading the resistance. In order for the Monitor 10K thermistor to read correctly it needs to hooked up to a Monitor indicator circuit board. You have no idea how any other board is calibrated so it will read a value that may or may not be correct. If you expound on what you are trying to do, there are others on here that will be able to figure out how to help you.

Tom

[badpaddler]

What makes a big difference is, what is reading the resistance. In order for the Monitor 10K thermistor to read correctly it needs to hooked up to a Monitor indicator circuit board. You have no idea how any other board is calibrated so it will read a value that may or may not be correct. If you expound on what you are trying to do, there are others on here that will be able to figure out how to help you.

Tom

I work as a systems programmer and controls technician for a HVAC Controls contractor, and have all sorts of sensors sitting around. I just want to lengthen the existing wiring down into the crawlspace, and back up to a cut in box on another wall, and mount a stainless wallplate sensor there. The thing that has me worried is that the sensor that was plugged into the Monitor is not even remotely close to being the same as any 10k thermistor I can find. It shouldn't matter what is reading it, as resistance is resistance. Unless monitor had these thermistors actually engineered specifically for them which would be extremely odd. I am wondering if anyone has seen a complete resistance table for the sensor, knows whether they used a completely new engineered thermistor, or what type it is so I can replace/compare. I could always just lengthen the cable and epoxy the existing sensor to the back of a stainless wallplate, but I want to make sure the thing isn't bad before I go through the efforts.

Thanks,

Seth

[badpaddler]

What makes a big difference is, what is reading the resistance. In order for the Monitor 10K thermistor to read correctly it needs to hooked up to a Monitor indicator circuit board. You have no idea how any other board is calibrated so it will read a value that may or may not be correct. If you expound on what you are trying to do, there are others on here that will be able to figure out how to help you.

Tom

On a side note, I was in Bethel about a month ago on the way to Scammon Bay to do some work.

[HayZee518]

I would check with mouser electronics

I would check with mouser electronics in texas. they have all sorts of thermistors of varying valurs and temperature ranges.
the thermister is akin to an RTD for temperature monitoring.
I have extended my thermister by using a 28-30 gauge telephone wire without a great fluctuation to the resistance.
I must have about 25 feet that I can extend the thermistor to.

[hawkins111]

Monitor room sensor

Seth,

The Monitor thermistor is the same part that has been in production for 20 years now. The new ones have a new style connector but that's about it. You should recognize that the Monitor is really a space heater. If you remove the thermistor to another room and try to bring the temp up there, the room the heater is in will be very hot. There is no way to have more than one room sensor in the circuit at a time. If you want to heat another space you can just turn the heater up, as that is what will happen if you move the sensor to another location. These vented heaters have their place, unfortunately they don't do real good heating multiple rooms that are separate. I have never seen a chart for the room sensor. Toyotomi has a chart for their water heater temp sensor, but that is completely different. If the room senor wire is intact I would think the sensor is working correctly. The sensor is very seldom bad. Who were you working for in Scammon? I flew out of Bethel for 20 years and was a part owner of Hagelands/ ERA until 1996.

Tom

[badpaddler]

Seth,

The Monitor thermistor is the same part that has been in production for 20 years now. The new ones have a new style connector but that's about it. You should recognize that the Monitor is really a space heater. If you remove the thermistor to another room and try to bring the temp up there, the room the heater is in will be very hot. There is no way to have more than one room sensor in the circuit at a time. If you want to heat another space you can just turn the heater up, as that is what will happen if you move the sensor to another location. These vented heaters have their place, unfortunately they don't do real good heating multiple rooms that are separate. I have never seen a chart for the room sensor. Toyotomi has a chart for their water heater temp sensor, but that is completely different. If the room senor wire is intact I would think the sensor is working correctly. The sensor is very seldom bad. Who were you working for in Scammon? I flew out of Bethel for 20 years and was a part owner of Hagelands/ ERA until 1996.

Tom

We are heating the same room, but the Monitor is smack dab in between 2 windows, so there really isn't anywhere decent to put the sensor. Regardless of where we put it on that wall within 5 or so feet they give you, it is about 5-10 degrees colder than it actually is. I just wanted to move to a non-outside wall. We will be replacing the windows next year, but I figure this would make it control better anyway. We use a simple air redistribution system to get the warm air into the other parts of the house (Small house).

We do a lot of work with LYSD, so I spend a fair amount of time in St. Mary's, Mountain Village, Scammon and Kotlik.

[badpaddler]

I would check with mouser electronics in texas. they have all sorts of thermistors of varying valurs and temperature ranges.
the thermister is akin to an RTD for temperature monitoring.
I have extended my thermister by using a 28-30 gauge telephone wire without a great fluctuation to the resistance.
I must have about 25 feet that I can extend the thermistor to.

I wouldn't imagine it would effect it that much as we run some thermistors (10kT3) out up to a hundred feet without substantial loss of accuracy. I was just hoping someone had run across this since even the Monitor techs couldn't tell me what the scale is on it. :-/