Tragic day for my snakes.

[dkatz4]

The VE's can and do fail. A friend of mine lost a rack of retics when his VE-300 failed wide open.

A thermostat is like any other electronic device; it can break. Running two in line is one way to help ensure that you don't end up with overheated critters. A cheaper option is to put a dimmer switch between the thermostat and the heating appliance. Set the dimmer so the appliance gets uncomfortably warm but not deathly hot if the thermostat fails. The critter's behavior will let you know there's a problem.

Note that dimmers do have power limits so while you can put one on a whole rack running heat tape, if you have a four-high stack of 8' enclosures with 120W RHP's, each RHP will need its own dimmer.

That's is exactly what i do; heating device into dimmer into thermostat (jumpstarts for now) Since i only have 2 snakes each one has its own complete setup, i even have 2 separate dimmers one each tank for the UTH's and the RHP's. For $11 at home depot, i figure why not have each device on its own custom stetting?

[tcutting]

The above is the logical base diagram of what I am building. I did leave out the bulk wiring for the probes simply because the idea of the probes making it back to the parallel bread board. but really outlines the general design. physically wiring is starting now, doing some tests before I start making things form fit.

[The_Godfather]

I feel you man. I lost my 2 balls this summer to heat pad malfunction. One of them I'd raised since a hatchling and got her the month this site was founded before it even had a domain name. Sucked pretty bad. I don't think I'll ever trust anything but bulbs after that.

[Craiga 01453]

The above is the logical base diagram of what I am building. I did leave out the bulk wiring for the probes simply because the idea of the probes making it back to the parallel bread board. but really outlines the general design. physically wiring is starting now, doing some tests before I start making things form fit.

Wow, I see a diagram of boxes, lines and letters. I wish my brain could comprehend what you are doing. Kudos to you for having a working knowledge of that sort of stuff.
I gotta say, it's admirable how dedicated to fixing this problem you have been. I'm still so sorry for your loss, but you should be proud of the way you're reacting and putting in the due diligence to ensure it never happens to your animals again.
Also, like I said before, you may really be on to something. You could be a few years away from a hugely successful business. If you can get yours up and running with proven success, you could venture into a side business and watch it grow. You may be saving the lives of many reptiles and eliminating headaches and stress from many keepers in the near future...

[tcutting]

Wow, I see a diagram of boxes, lines and letters. I wish my brain could comprehend what you are doing. Kudos to you for having a working knowledge of that sort of stuff.
I gotta say, it's admirable how dedicated to fixing this problem you have been. I'm still so sorry for your loss, but you should be proud of the way you're reacting and putting in the due diligence to ensure it never happens to your animals again.
Also, like I said before, you may really be on to something. You could be a few years away from a hugely successful business. If you can get yours up and running with proven success, you could venture into a side business and watch it grow. You may be saving the lives of many reptiles and eliminating headaches and stress from many keepers in the near future...

So that is the physical layout of the wires on the inside. I am going to build a box around it so it will all be contained in one unit with external connections so you can disconnect and connect things as you work on a rack or move snakes.

ideally for most small time keeper it will be nice to have a rack you can shut slots down when they arent in use, or cool cycle a female, or whatever. For larger scale uses imagine running ideally your whole building where wattage is almost unlimited with a system like this.

but the biggest win for this system will be without a doubt, the alerting system. something many of us need. Idea of prevent or catching a fire as early as possible or some other terrible event could save a lot of reptile lives and peoples homes.

[Craiga 01453]

So that is the physical layout of the wires on the inside. I am going to build a box around it so it will all be contained in one unit with external connections so you can disconnect and connect things as you work on a rack or move snakes.

ideally for most small time keeper it will be nice to have a rack you can shut slots down when they arent in use, or cool cycle a female, or whatever. For larger scale uses imagine running ideally your whole building where wattage is almost unlimited with a system like this.

but the biggest win for this system will be without a doubt, the alerting system. something many of us need. Idea of prevent or catching a fire as early as possible or some other terrible event could save a lot of reptile lives and peoples homes.

Seems like a great idea to me!!! Keep up the great work!!!

[Aste88]

I've looked into building a raspberry powered thermostat for a while, unfortunately as a programmer I have little experience with hardware.

One of the reason I really wanted this is being able to log all the readings and connect it to a monitoring and alerting system like it's done for server farms. That way even if you cannot 100% prevent a fail-open you still get an email or sms and rush home to unplug everything.

Are you planning to use proportional relays or write your own on-off function? I couldn't find high voltage dimmers online, so proportional would be the closest solution.

Keep us updated!

[tcutting]

I've looked into building a raspberry powered thermostat for a while, unfortunately as a programmer I have little experience with hardware.

One of the reason I really wanted this is being able to log all the readings and connect it to a monitoring and alerting system like it's done for server farms. That way even if you cannot 100% prevent a fail-open you still get an email or sms and rush home to unplug everything.

Are you planning to use proportional relays or write your own on-off function? I couldn't find high voltage dimmers online, so proportional would be the closest solution.

Keep us updated!

I assume by proportional relays you mean solid state? No i am not using solid state. I am going with normal relays. but with a master high load to shutdown all if a overheat problem is detected. I will be writing my own code from start to finish on this including the logic to handle sensor failures, relay always on, and alarms. The way the heat will run is like I would without being on a dimmer. something that most of us do currently anyway.

Although I am not sure why you would need high voltage dimmers? normal 120v is all you need. Unless you mean high AMP/wattage dimmers? even still my entire system with 20~ft of 12inch heat tape is about 400watt give or take. if you separate out your heat tape to smaller zones you should be able to accommodate that fairly easily. Meaning, cut the tape and have the a dimmer per every X ft and not one long strand of tape, wire in parallel.

[Aste88]

Since I got one of those thermostat with the choice of dimming and pulse-proportional I wouldn't go back to on-off. There are some relays that implement this directly and you control with PWM (like pc fans). The alternative is writing your own pulsing algorithm which might not be easy. I can't find digital dimmers for more than 12v, some suggest putting a servo on an analog one but I don't like the idea.

Any way in your schema to control the power absorption too? That would be an interesting stat to log and one more parameter to check for failures.

[tcutting]

Since I got one of those thermostat with the choice of dimming and pulse-proportional I wouldn't go back to on-off. There are some relays that implement this directly and you control with PWM (like pc fans). The alternative is writing your own pulsing algorithm which might not be easy. I can't find digital dimmers for more than 12v, some suggest putting a servo on an analog one but I don't like the idea.

Any way in your schema to control the power absorption too? That would be an interesting stat to log and one more parameter to check for failures.

So on the dimmer side, when you say more that 12v are you talking DC or AC? because any dimmer light switch in your house is a 120v and should be able to handle this. Unless I am missing something here and what others have suggested as well.

regarding a proportional, or limited always on thermostat, those are made to hold a set temp of the tape and run it at all times if I recall. But I think your point and many others point would be to have a system that does both, limit max temp of the heat tape and turn off at a certain temp? so it would be a hybrid more than one type or the other.

example set dimmer to keep heat tape from exceeding say 100F and then have a thermostat with probe on tape set to 95? should be a slow steady climb to 95 vs the burst or all on/off? is that what you are talking about?

I havent considered going that route but could certainly work that into this design.



side note here is a 120v dimmer https://www.amazon.com/dp/B0000BYEF6..._t1_B01LXDFGHB that would run some heat tape. should handle about 2.5 amps at 120v.