External T-Stat for Monitor K-1 heater?

[stevecon]

I'd like to add an external thermostat to my 441 or 2400 Monitor heater (I have both units). I haven't messed with either yet, but have no qualms digging into it. I just don't feel the need to "reinvent the wheel" if someone else has already done this.

An external T-stat opens up the ability to retain program memory longer than 30 minutes (we get nailed with power outages weekly at my weekend place in NH), remote control via telephone line, etc.

TIA!

[bucyluca]

I was searching google for this exact topic. I too want to put an external wall thermostat. Its for the lake house. when we get there, its cold , set at 58f. I could get a freeze Alarm box that connects to my phone line and a thermostat, which i can call in a few hours in advance and option for the higher thermostat settings.

If you found a solution, plase post it up.

happy holidays

[HayZee518]

the only thermostat that the monitor uses is on the motherboard. It gets its reference signal from the thermistor. the lead that comes with the "stock" monitor is about five feet long, but you can extend this distance using two wire telephone wire. the 20, 40, 41 has a molex plug and receptacle on the back of the unit. cut off the molex plug off and insert whatever length of telephone wire you want and just splice it in. Locate the thermistor where you want it. It will read that location's temperature and will tell the monitor to fire up and when to shut down once the set point is reached.

[HayZee518]

I have a 2400 unit and the stat is part of the motherboard. a piece of telephone wire spliced into the thermister line will extend your sensing distance to more than the wire which is supplied. My unit is in my dining room outside wall and the thermister is in the living room about 22 feet away.

[stevecon]

T-Stat

Extending the sensor is not really what I was going for - but rather to relocate the ability to control the temperature off from the heater itself. An external T-stat opens up the world of programmable types that retain memory for more than 30 minutes in the event of a power failure. Also, to interface it with a telephone line or internet to have true remote monitoring and control of temperature set points.

Since fuel costs have "gone through the roof", we have simply decided to "board up" our lakehouse until spring, so this is no longer anything I'm interested in pursuing. If I happen to find something - I'll post it here.

Happy Holidays

[bucyluca]

We go to the lake house every weekend, and I know what you mean to arrive at a chilly home, and with toddlers in their coats and hats complaining in the cold house.

It would make a great aftermarket kit if someone comes up with a way to install a thermostat. Cant it be plugged into the thermistor plug behind the monitor, recalculating the room temperature, tricking the monitor heater that its colder, so the monitor increases heat.

Happy Holidays

[HayZee518]

if its something you guys want to pursue by all means go for it - BUT - you void the warranty - you run the risk of totally disabling a $1900 perfectly functioning heater - personally I'm not going to jepardize the heater $1900 is a lot of money to just toss away.

[bucyluca]

All I am saying is that it can be done, but I am no electrical engineer to create it. Its simple logic.

The unit gets the room temp from that thermistor sensor in the back.
From another source (ebay seller): This Temperature Sensor is not a thermostat, and you cannot hook up a thermostat in place of it. It is a Thermistor. The junction of two wires at the end (the black bulb) changes resistance with temperature, and sends this resistance reading back to the control board, where it is translated to temperature and reads out at the LED on the heater.

Its no brain surgery. All is needed is a separate power supply ,a board, and a thermostat. Thermostat sends desired reading to board, converts it to resistance, sends new resistance value to monitor's board, tricking it that extra heat is needed or vise versa. As along as the resistance readings are with in the monitors range, how can that fry the unit?

Hayzee518, thanks for the Monitor repair manual download. I am in 518 too, up by Plattsburgh, NY.

[HayZee518]

I am in Saint Regis Falls - My wife's from Keeseville

[adnadeau]

Mon 441 remote temp control

Do you want complete thermostatic control or just the option of switching between two temperatures remotely? The thermistor is a 10K @ 77°F device. At 70° it has a resistance of approx. 11940 ohms and at 58° it has a resistance of approx. 16400 ohms (from USSensor's web site), difference of 4460 ohms. If you stuck a 5K ten-turn pot in series with the thermistor and switched it with a remote double-throw universal thermostat telephone control, you could switch in for the lower setting, and short it out for normal operation. Adjust the pot for whatever works best. Get a pair of matching Molex connectors to add it into your unit.

[HayZee518]

with NO thermistor connected [open circuit] the unit defaults to 42 degrees no matter what the set point is. I never tried to short it out so I don't know what it'll do. you do have a point tho. use a linear pot in series with a thermostat so you can vary the resistance to a "temperature"

[adnadeau]

I meant short out the 5K pot, not the thermistor.

[bucyluca]

Do you want complete thermostatic control or just the option of switching between two temperatures remotely? The thermistor is a 10K @ 77°F device. At 70° it has a resistance of approx. 11940 ohms and at 58° it has a resistance of approx. 16400 ohms (from USSensor's web site), difference of 4460 ohms. If you stuck a 5K ten-turn pot in series with the thermistor and switched it with a remote double-throw universal thermostat telephone control, you could switch in for the lower setting, and short it out for normal operation. Adjust the pot for whatever works best. Get a pair of matching Molex connectors to add it into your unit.

Thanks, thats what I wanted to know. All I want is to set it either from 58f or 76f. My neighbor is an electr. engineer, and I'll show your post. Hopefully he can come up with the solution.
I alrady have the freeze Alarm box that connects to the phone line, with 2 thermostat in ports built in.

I'll post a followup.

In the meantime, if anyone knows of an existing kit, let me know.

Thanks again for the details.

Happy New Year

[HayZee518]

thermostat is a switch NOT a thermister! end of story.

[paul52446m]

thermostat is a switch NOT a thermister! end of story.

They do make controls that will turn the heat up and down from a remote location, If they are still looking for a control from 3 years ago. paul