240V - 110V step down transformers

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rmt38

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#195720 1-May-2016 12:49

I'm buying some 16W 110V plant propagators from Amazon, where the power is used for heat pads, and am wondering about whether to get a step down transformer.

Do I need one? Or just adaptors?

If I do need one, are there any options people recommend? This seems to be the best option, providing 2 outlets, and running at about $115 delivered.

hyperman

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#1544840 1-May-2016 13:02

a couple of points

that seems VERY cheap for 1Kw

the trader mentions "for safety reasons make sure any appliance is no more than 700w" <-- dodgy!!!! what is it really rated to?

it is a complete OVERKILL when your requirements are 16W!

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gzt

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#1544853 1-May-2016 13:07

Depends how many will run at one time.

Is replacing the 110v heatpad with a local 240v pad an option?

That would keep things simple.

blackjack17

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#1544858 1-May-2016 13:13

are you getting something like this

if so a better option would be these

http://www.brewshop.co.nz/brewing-equipment/fermenting-equipment/heat-pad.html

coupled with http://www.bunnings.co.nz/romberg-claude-24-pots-tray-propagator_p00234903

or even

http://www.egmontseeds.co.nz/accessories/early-grow-3-bay-propagator

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richms

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#1544859 1-May-2016 13:15

They rate them at peak output which is how things are allowed to be rated in the US for some obscure reason, so they always say to derate them for continuous use.

I have had a couple of those type in the past, and they are noisy as, and get even worse depending on the load you put on them, Put something with a dimmer and they start to buzz like crazy because the transformer is an open type in side them.

The box full of resin around the transformer type are much quieter if that is something important to you.

Richard rich.ms

gzt

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#1544862 1-May-2016 13:19

hyperman:
a couple of points

that seems VERY cheap for 1Kw

the trader mentions "for safety reasons make sure any appliance is no more than 700w" <-- dodgy!!!! what is it really rated to?

it is a complete OVERKILL when your requirements are 16W!

It does seem very cheap, but that is 1000W @ 110v so input is a bit over half that. Not so big.

Maybe price is not unrealistic.

The 700W appliance rating could be just a fudge to allow for power factor in real world conditions.

/speculation.

Edit: I'll go with richms explanation on the rating.

rmt38

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#1544891 1-May-2016 14:46

blackjack17:

are you getting something like this

if so a better option would be these

http://www.brewshop.co.nz/brewing-equipment/fermenting-equipment/heat-pad.html

coupled with http://www.bunnings.co.nz/romberg-claude-24-pots-tray-propagator_p00234903

or even

http://www.egmontseeds.co.nz/accessories/early-grow-3-bay-propagator

That's the exact model I have ordered in your top link.

The egmonts model is out of stock and has been for a while. Note that the brewshop heating mat is half the size of the one that comes with the amazon propagator. So I'd need to buy four plus shipping to equal the amazon model, then buy the lidded trays over and above that.

What should I know about the downsides of just plugging them into an adaptor?

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blackjack17

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#1544899 1-May-2016 15:23

The amazon one is 11 inches by 22 inches so you would only need two of the homebrew ones.

I would say the disadvantage of the transformer is cost plus power wastage.

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rmt38

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#1544900 1-May-2016 15:26

blackjack17: The amazon one is 11 inches by 22 inches so you would only need two of the homebrew ones.

I would say the disadvantage of the transformer is cost plus power wastage.

No, I'm buying two of the propagators. Hence the four.

Sideface

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#1544901 1-May-2016 15:32

rmt38:

<snip> What should I know about the downsides of just plugging them into an adaptor?

By "adapter" do you mean a gadget that converts a US mains plug into an Australian/NZ mains plug?

If so, you would be putting 240 volts into a device designed for 110 volts.

Bad idea. If you are lucky it would blow a fuse before it caught fire.

Sideface

rmt38

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#1544902 1-May-2016 15:40

Sideface:

By "adapter" do you mean a gadget that converts a US mains plug into an Australian/NZ mains plug?

If so, you would be putting 240 volts into a device designed for 110 volts.

Bad idea. If you are lucky it would blow a fuse before it caught fire.

Oh well, cancelled the order. Thanks. I might email egmonts to see if they can get their propagator back in stock, and fall back on the brewshop option otherwise.

SepticSceptic

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#1545151 2-May-2016 09:15

If they are plain resistive heating mats, and no other thermostatic controls, you could wire 2 of them in series, for each 240v source.

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rmt38

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#1545201 2-May-2016 10:07

Thanks for the tip. However, the more I think about it, it's just not worth it to jerry-rig something up. Beyond the insurance liability if it goes pear-shaped, or the noise from a transformer, etc.. Having a reputable local company responsible for it under consumer guarantees and NZ power setup from the get-go, is worth it. I've contacted Egmonts and hopefully they'll get some more in sometime soon.