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Heating elements for own built terranium

Discussion in 'General Electronics Discussion' started by Stephen Mifsud, Sep 29, 2015.

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  1. Stephen Mifsud

    Stephen Mifsud

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    Sep 29, 2015
    Hi, I am building an own incubator/terranium. I have a programmable thermostat that until it reach a preset temp, it bypass 240V ac to a heating element. I bought some cheap 240V element but they were two small making a max environment temp of 30C (I need up to 45C).

    Then I found an old Sanyo microwave and I took it's elements to be used as heating element. These come in a dense coil (about 200 turns) inside a white glass tube. They are ac and rated 110V. As I said the supply voltage is 240vac. I think they are InfaRed emitters which would be great for my use:
    http://hkquartz.en.made-in-china.co...ing-Element-Ceramic-Infrared-Heater-Lamp.html


    Logic says I can't but I want to ask just the same if I can apply 240Vac to them, and what would happen? I think they were connected in series (not sure) so I wonder if I connect them in parallel would the voltage divide.

    I really wish to use these!
     
  2. Stephen Mifsud

    Stephen Mifsud

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    1
    Sep 29, 2015
    P.s. from a short research, most of the advertised quartz heating tubes are 115V, but I am reluctant to stick them into a 240V! Myabe they are meant to be in parallel? Wattage 450W each
     
  3. Kiwi

    Kiwi

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    85
    Jan 28, 2013
    They would have to be connected in series. Each will run at about 120v.
    If you connect them in parallel each will have 240v on it. Will get very hot, very quickly, and burn out.
     
  4. Stephen Mifsud

    Stephen Mifsud

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    Sep 29, 2015
    Thanks - it explains it all!! I've experience in DC, but in AC very little!
     
  5. Stephen Mifsud

    Stephen Mifsud

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    Sep 29, 2015
    Thanks, I confirm that they worked and get very hot and very fast. If I would like to include only one in my setup, what type of component do i need to use to replace one of the heater? A high wattage resistor of the same Ohms of the heater element. I am afraid that two elements is too much, and more work to hold and manipulate. I am glad to have found them from a dumped microwave!
     
  6. GPG

    GPG

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    66
    Sep 18, 2015
    You need to control the input to both elements. Do you know the current they draw? You could use phase control
    https://en.wikipedia.org/wiki/Phase-fired_controllers
    Like a incandescent light dimmer
    I tried searching for an integral cycle controller but without success seems unavailable now? however there are zero crossing triac controllers but this would require a lower voltage controller. This may not be a problem if you want the temp controlled.
     
  7. Stephen Mifsud

    Stephen Mifsud

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    1
    Sep 29, 2015
    I was going to suggest step down transformers to 120 or even 60 Vac to produce a more subtle heat, but the light dimmer rotary switch is perhaps more useful! Does this work by regulating the ac voltage to the load?
     
    Tinker Unique likes this.
  8. Minder

    Minder

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    651
    Apr 24, 2015
    You probably need to get the hand tool version of variable control rather than the lighter lamp style, also needs to be 240v rated if using them in series.
    M.
     
  9. Bluejets

    Bluejets

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    977
    Oct 5, 2014
    Maybe consider using the heat lamps from bathroom 3 in 1 units.

    Just have to watch loading if using a dimmer as each lamp is about 200w I think and standard dimmers are 400VA.

    You could switch them to get the total heat but they do put out a fair amount of heat and might cook what you are trying to warm.
    Other than that, you might be surprised how much heat is stored from using 15W oven bulbs.
     

    Attached Files:

  10. Stephen Mifsud

    Stephen Mifsud

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    1
    Sep 29, 2015
    Actually my current the problem is what type of heating elements / source to use. I am trying to get up to 50C in a glass vivarium of dimensions 80cm x 40cm x 30cm. Heat source is from above, held with a canvas lid.

    These heating elements rapidly raise the temp, but they are very hot and there is not even distribution of heat. I placed a fan inside for convection, improved but stil concerned of the 1000C. I am now going to seperate the heating elements apart, one on the left and one on the right. I will send images later because I am off to work. Keep sending ideas for alternative heating sources or ac controllers. i was going to try a kettle or gyser heating element next.

    The heating elements are rated 450W, and being in series they consume 900W.
     
  11. Stephen Mifsud

    Stephen Mifsud

    15
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    Sep 29, 2015
  12. Stephen Mifsud

    Stephen Mifsud

    15
    1
    Sep 29, 2015
    Hi GPG, I think you were refering to something like this: http://www.ebay.com/itm/AC-Motor-FA...bled-Kit-/130955911790?_trksid=p2054897.l4275

    I think that is a good solution. Just a question, my two IR heaters are 450W each, total 900W. However it is just a bit lower from 1000W of this circuit.
    1. Can I modify the circuit to make it say 1200W?
    2. How can I check the actual wattage of my current heaters. Total resistance when cold is 53Ohms so theoretically V2/R gives 1100W!
     
  13. Bluejets

    Bluejets

    4,614
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    Oct 5, 2014
    (As an example).............We used to keep electric welding rods dry ( and hot) by using a single 15W oven bulb running 24/7 inside an old refrigerator.(10cu ft)
    These were almost too hot to handle so it shows just how litte a heating element you will require.
    Granted your enclosure is glass and subject to higher heat losses but you are only looking for a minimal temp rise after all.
     
  14. GPG

    GPG

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    Sep 18, 2015
    The triac package (TO218) suggests to me that it is capable of more than 1kw, without knowing the number.. Add a small heatsink and you'll be ok And its cheaper unassembled
     
  15. Stephen Mifsud

    Stephen Mifsud

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    Sep 29, 2015
    Ok might a try, then explain me what is meant add a small heat sink in the sense how it would decrease power!
     
  16. Stephen Mifsud

    Stephen Mifsud

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    1
    Sep 29, 2015
    Here are some photos of my prototype.

    IncubatorProject_V1a.jpg IncubatorProject_V1b.jpg IncubatorProject_V1c.jpg

    I need to add uv bulb and light bulb, switches, panel, and extrector fan to cool, but at the moment I am working to have a more stabilised temp. The thermostat is set at 42, and since there is powerful heat, the temp rises up to about 44 when the elements are cutoff. The heatsinks above the elements reduced drastically the temp on the plastic canvas lid. Previous prototpe, the heat softened the lid, now that problem is solved. Temperature reaches 25C to 42 in just 4mins.

    I have an issue with the thermostat and probably it is fault. I don't know if you have used these, but when the set temp is reached, the temp display skips 1 Celcius as follows:
    42.7, 42.8, 42.9, 44.0, 44.1, 44.2.....44.8, 44.9, 46.0 ???
    Same when cooling down but works fine when temp rises from ambient to set temp.

    I also wish a more uniform temp within the incubator, which is a bit colder at the perimeter, and hotter further up.

    I am using this to:

    Dry seeds
    Germination of plants at warm temp (30 C)
    Growth of moulds at 37C
    Drying silica gel (50C)
    No water is inside but will vapour (say from humid soil) be an hazard issue?
     
  17. Stephen Mifsud

    Stephen Mifsud

    15
    1
    Sep 29, 2015
  18. Bluejets

    Bluejets

    4,614
    977
    Oct 5, 2014
    Appears you are using way too much heat to begin with.
    A remedy might be if you use a heat box seperate from your main unit and regulate heat into the main via a fan and regulator flap driven by a servo.
     
  19. GPG

    GPG

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    Sep 18, 2015
    I think you have answered with the one you bought
    http://www.ebay.co.uk/itm/221810230062?_trksid=p2057872.m2749.l2649&var=520676661904&ssPageName=STRK:MEBIDX:IT
    You can see the heatsink, there are a few available
    .https://www.google.com/search?q=to2...oTCPLD-dn6o8gCFaUXpgodAnYDLA&biw=1024&bih=635
    It increases power handling by keeping the triac cooler
     
    Last edited: Oct 2, 2015
  20. Stephen Mifsud

    Stephen Mifsud

    15
    1
    Sep 29, 2015
    The triac arrived but it was f* faulty. The output voltage remained 240V at any setting of the rotary variable resistor. I would attempt to fix it if I know what's wrong (there's just 10 components). During operation, nothing gets warm. Resistor working well.

    check video here:

    http://www.marz-kreations.com/!up/TiracNotWorking.MOV
     

    Attached Files:

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