11-01-2007, 10:58 PM
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Gold Star Member
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Join Date: Dec 2005
Location: Lancs
Posts: 6,283
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PeterF who manufactures these thermostats has replied to the person in question about the sad loss of his snake. I thought people might like to see it so I've reproduced it here:
Quote:
Dear Pete,
I am so very sorry to hear about your loss.
These things are very hard to cope with and can make you feel very disillusioned.
First of all, I have no idea if the thermostat failed was one of my Habistats, but in some ways that matters little.
Any instrument or product that is manufactured from a series of parts can fail for a variety of reasons.
I have read the thread and have taken on board the points raised and the suggestions.
As manufacturers of Habistat thermostats and also possibly one of the largest breeders of various reptiles in the UK and abroad, these issues are of utmost importance to us.
We also keep all our precious animals temperatures controlled with Habistat thermostats. Our huge insect colonies are also protected with them.
When a thermostat fails, it can fail in several different ways.
It is a sensitive instrument and, to be accurate it will have some delicate components that are susceptible to damage from many things.
By nature of the way that the components function, they can fail on or off.
In the past we have examined the possibility of a “fail safe” device and have tried many different options.
The problems with “fail safe” or thermal cut outs are several.
As you do not know what component or part of the circuit is going to fail, you cannot know for sure where in the circuit to put the protection.
No fail safe or alarms on any equipment we have looked at have afforded full protection or the ideal solution.
The fail safe device cannot be a part of the circuit as, if it was, it would have to use the thermistor in the probe to sense the temperature in the cage. That would mean that it wouldn’t cut out if that part of the circuit failed.
Older style thermal cut outs are also somewhat inaccurate and are designed for industry. Some of the lower ones start at 40c and all would still need other circuitry to integrate them into a remote sensor.
This means that the only guaranteed protection is a stand alone unit, with its own power in and power out and probe to sense temperature.
As you will have probably gathered, I have just described another thermostat.
In our insect colony buildings we actually have 2 thermostats running through each other. We have never had a failure in these buildings but these Habistats are switching huge 200,000 btu building heaters and clearly any failure of control would wipe out entire colonies of insects.
We have one thermostat plugged into the mains like normal. Into the output (heater) lead of this we plug another thermostat in. The output of the second thermostat then runs the heater.
The probes are kept together.
The second thermostat is set at the desired level and controls the temperature. The first thermostat is set several degrees higher and is never used. If the primary controller failed on, then the second thermostat takes control albeit as several degrees warmer.
Now clearly, I am not suggesting that every one uses 2 thermostats to protect their animals.
I am sure Pete will receive no consolation whatsoever of the fact that failures are rare and I know that he will be uninterested in that fact at the moment.
In reality there are possible half a Million Habistats out there and, as many of you will be aware, we repair all returns almost regardless of age and cause of failure.
In reality we repair maybe 3 or 4 units a week, many of them over 10 Years old and most with failures caused by heater short circuits or failures.
Or often just the fuse in the plug having blown…..
One point I would like to discuss here is probably the biggest cause of failure of all thermostats returned to us for repair.
This issue accounts for maybe 50% of all returns and it is avoidable!
Ceramic heaters.
As we all know, ceramic heats are very effective heaters. They heat very well and, as would go hand in hand with that fact, they get exceptionally hot!
Whilst the face of the ceramic is very hot, a lot of this heat gets up the “stalk” of the heater and into the fitting.
Over the course of time this heat “cooks” the insulation on the wire that connects the holder to the thermostat.
This ultimately causes the insulation to fail and the heater wire short circuits. This damages the triac in the thermostat and causes the failure of the unit.
The temperatures that these holders get to, is way beyond the safety threshold of the normal PVC sheathed wire that most people use (despite warnings on the holders box).
You will even find the reflectors and lamp holders sold by well known USA manufacturers all have only cheap PVC wire on them. This will ultimately cook and fail.
Please, please, please only use the recommended Silicon sheathed cable in ceramic heaters. This is the highest temperature rated cable readily available. It is expensive but essential to avoid this, the commonest of cause of failure.
Now, in conclusion to this very sad situation I will suggest the following.
If Pete’s thermostat is a Habistat, I would like him to post it back to be for examination. I can tell the likely cause of failure and we log all of these event in order to address issues and improve our products.
I am also going to revisit some of the new electronic thermal cut outs now available.
If these prove suitable, I would propose that we look to manufacture a stand alone cut out unit.
It would have to pretty much be a separate thermostat but with a fixed temperature threshold and warning light that would cut your heater off if the temperature went higher than the thermostat.
Please feel free to make any suggestions and comments on my somewhat lengthy post on this forum or to me personally on peterf@eurorep.co.uk
Once again Pete, deeply sorry for your loss.
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No ones fault Im sure you'll agree but very sad all the same. The full story can be found here: http://www.livefoodshop.co.uk/forum/...pic=57436&st=0
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