# Habistat thermostat reliability.



## peterf (Jul 27, 2007)

It is interesting to see the posts with regard to various items of equipment and how, in these days of economies, people are often after "the cheapest" products. 
These are often not the best as economies in production have to be achieved somewhere and this is usually in build and component quality and product and customer support.
Some products like thermostats, however are critical pieces of equipment and are so important that cheapness certainly isn't best.
As well as effective control, the most critical aspect of a thermostat is, without doubt it's reliability.
We have been making Habistat thermostats for well over 20 Years now and have been looking recently at reliability and return records.
As most of you know from this forum, we have always had a policy of repairing thermostats, rarely having received receipts with them and often some are very old indeed!
We treat Habistat users like we like to be treated.
I don't want to go into too much detail but here are a few facts. Whils't it is impossible to know how many are being used out there we do have some ideas.
If we assume that there are maybe between 250,000 and 500,000 units out there being used, we have the following returns.
2008- 9 period we received back for repair 387 units. These were all repaired and returned the same day we received them.
Over 50% of these had no faults whatsoever. 
Around 20% of the rest had the fuses in the plugs blown.
Around 30% of the total were over 5 Years old.
Around 90% of the on/ off devices (Temps and mats) have triac failures which is entirely due to inappropriate use with light bulbs.
Most pulse failures were due to triacs being shorted by cooked wires when used with ceramics.
So in very simplistic analytical terms it is true to say that around 25% of the returned thermostats had genuine faults and that would equate to around 100 per annum.
Thats 0.02%- 0.04% return rate Year on Year.
If you look at the industry standards for manufactured electrical goods that is amazing.
Also consider that thermostats are sensitive instruments and very succeptable to damage from other sources. Those genuine failures may well have been caused by household mains surges or more likely short circuits on the heaters and assocated wiring that is attached to them!


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## Graham (Jan 27, 2007)

This is my favourite bit!



> Over 50% of these had no faults whatsoever.
> Around 20% of the rest had the fuses in the plugs blown.


 
We once had a very large display unit returned that we'd made a couple of years previously, it had been shipped out to the USA (it was made to be used with any mains supply worldwide) and had to be shipped back to us at a cost to the client of a couple of thousand pounds. It had stopped working and they couldn't figure out why, even had an electrician look at it apparently and he couldn't fix it, so they decided to send it back.

A couple of minutes work to remove some screws and reset the trip switch inside and it was working perfectly again! We had deliberately chosen a power supply with a trip switch because we didn't know what fuses would be available around the world, and there was even a label on the back explaining how to reset it.


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## Ssthisto (Aug 31, 2006)

peterf said:


> Around 90% of the on/ off devices (Temps and mats) have triac failures which is entirely due to inappropriate use with light bulbs.


Why, out of curiosity, would plugging a light bulb into an on-off device cause a failure in the thermostat? I wouldn't do it because I don't want the slow-motion lightswitch-disco effect, but I don't understand why it would cause something to fail just because it's "supplying power / not supplying power" to an alternative-but-appropriate-wattage piece of equipment.



> Most pulse failures were due to triacs being shorted by cooked wires when used with ceramics.


With this one ... how would an end user avoid this?


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## peterf (Jul 27, 2007)

Ssthisto said:


> Why, out of curiosity, would plugging a light bulb into an on-off device cause a failure in the thermostat? I wouldn't do it because I don't want the slow-motion lightswitch-disco effect, but I don't understand why it would cause something to fail just because it's "supplying power / not supplying power" to an alternative-but-appropriate-wattage piece of equipment.


Light bulbs have a peculiarity in that they often fail short circuit. The element whilst flailing around in the last bit of gas in the bulb can "make and break" a few times. This blows the triac which is in essence a sensitive electronic switch.
This is why you will find a bulb when it blows will sometimes trip your circuit in your home.
Turning bulbs on and off all the time will make this occur frequently and will increase the risk of that shorted bulb.
Now we can make on/ off stats which don't use a triac but use a relay.
This is a mechanical switch and much more robust and suitable for many applications and used in most Chinese thermostats but it has one big problem.
Being mechanical it is sold with a livespan. Making and breaking mains power takes its toll on contact breakers and they are all rated at so many 1000's of operations.
When used in a thermostat as soon as its run its life it is likely to fail.
If the rating is say 250,000 operations and your thermostat is operating 6 times a minute then that is under 5 Years. A long time yes, but looking at the age of Habistats we get back, not unusual!
If the load is higher the life is proportionally lower.



Ssthisto said:


> With this one ... how would an end user avoid this?


To avoid short circuiting your pulse use silicon cable on the holder. Every ceramic holder on the market (except the Euro Rep one) only uses PVC wire which isn't able to withstand the high temperatures ceramics achieve.
This isn't just "high temperature cable" that is readily available this is the highest temperature rated silicon cable and it's not cheap!


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## Ssthisto (Aug 31, 2006)

peterf said:


> To avoid short circuiting your pulse use silicon cable on the holder. Every ceramic holder on the market (except the Euro Rep one) only uses PVC wire which isn't able to withstand the high temperatures ceramics achieve.
> This isn't just "high temperature cable" that is readily available this is the highest temperature rated silicon cable and it's not cheap!


Thank you for clarifying that one.... are there any plans to make a Euro Rep ceramic holder that has some means of fixing it securely into a wooden vivarium without relying on it hanging from the cable? The only images I can find of holders show a ceramic fixture on the end of a cable, with no apparent way to attach it (hanging hook/etc) - which doesn't work too well if you aren't using a clamp lamp or a dome on the top of a mesh-topped enclosure.


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## peterf (Jul 27, 2007)

No plans although I take your comments on board.
The problem you have with ceramics is the heat they achieve.
Any ceramic heater fixed directly to a wooden roof will just get too hot to remain safe. I cringe at the sellers on this site selling ceramic holders that screw on the roof. They are for industrial use and shouldn't be fixed to anything flammable!
I am looking at other methods of fixing and suspending. To an extent the problem is that we have to adapt what is available as whils't the volumes are good, we cannot sell enough for the Chinese makers to find the product viable to make the tooling etc.


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## loxocemus (Sep 2, 2006)

in all the years iv been using ur stats iv never had a malfunction, i never use anything else now, its strange how people spend thousands on the snake and try to cut corners on its support systems (or feed them with bbq tongs, never understood that one)

rgds
ed

ps if anyone does the ceramic fitting to the ceiling put a ceramic tile between it and the wood


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## LFBP-NEIL (Apr 23, 2005)

Ssthisto said:


> Thank you for clarifying that one.... are there any plans to make a Euro Rep ceramic holder that has some means of fixing it securely into a wooden vivarium without relying on it hanging from the cable? The only images I can find of holders show a ceramic fixture on the end of a cable, with no apparent way to attach it (hanging hook/etc) - which doesn't work too well if you aren't using a clamp lamp or a dome on the top of a mesh-topped enclosure.



I designed and make a powder coated bracket to do just that 

Universal Lighting Bracket

It works with the euro rep, lucky reptile and most ceramic bulb holders as well as the screw fit plastic euro rep ones.


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