# Pulse stat not heating ceramic



## Everard247 (May 26, 2012)

Ive recently bought a pulse stat for a ceramic bulb, worked fine for a couple of days but now wont heat the bulb. I have tried the bulb without the stat, so I know that works, Ive used the stat on a regular spotlight, so I know the stat works. Ive tried tested the light fitting with both a ceramic and regualr bulb, so I know it isnt a problem with that. Ive tested the fuses, re-wired the plugs and fittings. Anyone have any idea why the stat wont work with the ceramic? Thanks


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## stevier (Feb 15, 2012)

what make and model of stat and what wattage of ceramic?


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## Everard247 (May 26, 2012)

Habistat Pulse Proportional stat and a 40W ceramic


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## Frosty2532 (Nov 30, 2010)

Everard247 said:


> Habistat Pulse Proportional stat and a 40W ceramic


Hi, I think you need to have a minimum load or sixth watts for the stat to operate correctly.


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## Everard247 (May 26, 2012)

Ill try a higher rated ceramic then, cheers. Didnt realise there was a minimum, only thought there was a maximum load for them


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## peterf (Jul 27, 2007)

40 watts is fine for a Habistat Dimmer.
As all the component parts work in isolation, I would suggest that the fault most likely lies with the ceramic making inadequate contact with the terminals in the holder. This is a common fault and can give these erratic working conditions with expansion and contraction.
Make sure the ceramic is making adequate contact in the holder.


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## Everard247 (May 26, 2012)

The contacts were one of the things I checked when I rewired the fittings and plugs. All of the components are working individually, the only problem comes when I run the ceramic through the stat


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## peterf (Jul 27, 2007)

The stat is proven to work as you have tried it on a light bulb where the function can be seen. 40 watts is plenty of load on a Habistat dimmer.
It can only be a faulty ceramic or a mechanical issue with contact somewhere!
Frustrating yes! Quite what it is, I am afraid I don't know!


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## stevier (Feb 15, 2012)

The problem could potentially be the tolerances of a 40w ceramic, I'm not sure how 'accurately' they are manufactured, eg it could be 44w or 36w (possibly?) and for that reason may not be achieving the minimum load. Personally I would try a higher rated ceramic. I can see no other reason why you are having a problem as you have proven all the components in isolation.


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## peterf (Jul 27, 2007)

stevier said:


> The problem could potentially be the tolerances of a 40w ceramic, I'm not sure how 'accurately' they are manufactured, eg it could be 44w or 36w (possibly?) and for that reason may not be achieving the minimum load. Personally I would try a higher rated ceramic. I can see no other reason why you are having a problem as you have proven all the components in isolation.


Possibly but Habistats will work down to around 20 watts or less. 40 watts is advertised to account for such anomolies that you mention!


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## stevier (Feb 15, 2012)

well I'm stumped then - given that every component of the OP's heating system has been proven in isolation, including the ceramic (without the stat).

So on that note - I'm out


Although I'm still interested to find out the final reason.


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## Everard247 (May 26, 2012)

This is the reason Im so confused, Ive tested each component in isolation, rewired the contact points, ensured the cable is heat resistant. Everything I can think of. Ive gone to drawing out a full wiring diagram to make sure everything is in the correct order and power should be flowing to each component. Ive done an electrical engineering course, and cant see any fault. Ill be going into a reptile store tomorrow and seeing if I can get someone to take a look, so I shall post if anything comes up. Thanks for the help, looks like this is confusing everyone though


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## Evie (Jan 28, 2008)

Not that it helps but I have experienced this problem, and like yours, all the components worked separately; just not together. I hope you figure it out 'cos I will be watching this thread for a solution.


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## cherryshrimp (Aug 1, 2012)

Interesting thread, I have one sitting in my old tortoise shed that worked well for years but I gave up trying to fix it when it failed to function. Sounds very similar situation and fault.


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## peterf (Jul 27, 2007)

If you need me to check the Habistat stick it in the post and I will check it and get it back in the post the same day it's received with a report of our findings!
You can send the whole lot back if it's easier and we can test each component.
I hope that helps!
Pete


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## Nodders (May 11, 2009)

peterf said:


> Possibly but Habistats will work down to around 20 watts or less. 40 watts is advertised to account for such anomolies that you mention!


Any difference between pulse and dimmers , the op says it's a pulse stat , you keep saying dimmer stat


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## peterf (Jul 27, 2007)

Nodders said:


> Any difference between pulse and dimmers , the op says it's a pulse stat , you keep saying dimmer stat


Spec savers.com! Old age and I phone screen!
Pulse have no minimum load requirement!
OP sorry for the confusion!!


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## reptiles-ink (Nov 4, 2006)

The most common problem is the centre contact on the holder.
On ceramic bulbs the contact isn't as prominent as other bulbs.
It could work without the stat although not to full efficiency but once the stat is used as it is a pulse of current rather than constant this will highlight the poor connection.
Unplug it and bend the middle contact out towards the bulb to ensure a good connection.


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## jasper1 (Apr 15, 2007)

Where is the stat probe? Could it be too close and switching the stat off when it gets up to temp? What temps is it set at?


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## bev336 (May 10, 2007)

reptiles-ink said:


> The most common problem is the centre contact on the holder.
> On ceramic bulbs the contact isn't as prominent as other bulbs.
> It could work without the stat although not to full efficiency but once the stat is used as it is a pulse of current rather than constant this will highlight the poor connection.
> Unplug it and bend the middle contact out towards the bulb to ensure a good connection.



This is also true for the negative contact on the side of the lampholder. Reptile-Ink and Peterf have both mentioned the contacts, and in my experience it usually is the problem. I have made ceramic bulbs for 16 years and have seen this problem over and over again especially with pulse stats.


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## Everard247 (May 26, 2012)

The shop recommended everything that has been said (contacts, stat problems, bulb problems, etc) but gave me a higher rated bulb to try. Everything is now working, so all they or I can think of is an internal fault with the stat in which it doesnt register a low wattage load. 
It wasnt a problem with the probe being at a temperature where the stat didnt need to provide energy to the bulb, when I tested it I turned off the spot bulb so the ceramic was the only source of heat and nothing was given off by it.
Hope that helps anyone readin this thread with the same problem, only thing I can suggest is try a higher rated bulb, or get the stat checked for any internal problems


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## reptiles-ink (Nov 4, 2006)

It won't be the stat due to the way it works, you can run a 5w heat mat on them.


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## peterf (Jul 27, 2007)

Everard247 said:


> The shop recommended everything that has been said (contacts, stat problems, bulb problems, etc) but gave me a higher rated bulb to try. Everything is now working, so all they or I can think of is an internal fault with the stat in which it doesnt register a low wattage load.
> It wasnt a problem with the probe being at a temperature where the stat didnt need to provide energy to the bulb, when I tested it I turned off the spot bulb so the ceramic was the only source of heat and nothing was given off by it.
> Hope that helps anyone readin this thread with the same problem, only thing I can suggest is try a higher rated bulb, or get the stat checked for any internal problems


Without doubt it will not be the thermostat.
It will be the ceramic or its contacts in the holder.


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## reptiles-ink (Nov 4, 2006)

Years ago I bought 6 ceramics all the same brand and wattage, when I tested them 4 didn't work.
On inspection the 4 that didn't work didn't have quite as much solder on the middle terminal.
I bent the terminal on the holder out for a better contact and then they all worked.


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