# Heating a water tank with an Immersion heater

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#### miked61

##### New Member
I'm heating a water tank with an Immersion heater, I want to use 110v power supply and I have a temp control which is rated 110v 10a.
My question is can I use a 3kw element with 110v power supply or do I need to use a 1kw element.
The power isn't important as I'm only heating the water to 20c
thanks
Mike

#### Nigel Goodwin

##### Super Moderator
As far as I'm aware you can't get 3KW from 110V sockets, and your control is only rated for 1KW as well. Best to get a 1KW immersion heater, or a 220V supply for the 3KW heater and a higher power control.

#### shortbus=

##### Well-Known Member
It will work if you have a 30Amp circuit. But you need some more information to make a real calculation, like is there flow involved, or is this just heat a static volume of water?

#### miked61

##### New Member
Thanks for the reply, I realise that I would need a 30 amp circuit but I cant get the controller with 30 amp, they only come in 10 amps. I have used a 3kw element in the 110v circuit and it seems to work OK, if only heating very slowly, the question is, will it blow the 10 amp control ??

#### alec_t

##### Well-Known Member
I have used a 3kw element in the 110v circuit and it seems to work OK, if only heating very slowly, the question is, will it blow the 10 amp control ?
I'm surprised it hasn't already! Why is it only heating slowly?

##### Well-Known Member
It sounds from the OP that there is an attempt to use a 240v 3kw Htr on 120v?
If so the current will be within the 120v supply rating. but a little high for the 10a controller.
What is the nature of the controller,BTW?
Max.

#### gary350

##### Well-Known Member
I use hot water heating elements for high power resistors. There are numbers on the side next to the hex nut. Mine say, 2400w 240v. One heater is 10 amps on 240v. Use your ohm meter to test your heating element find out how many ohms it is. You can do an experiment, connect 120v plug wires to your heating element, put the heating element in water then plug it into the 120v wall outlet. Check 1 wire with an amp clamp then you know how many amps it pulls. My 2400w 240v elements do not trip the 15a breaker on 120v. If you have a variac you can use it to test your heating element starting at a very low voltage, check the current as you turn up the voltage.

#### Pommie

##### Well-Known Member
If you run a 240V 3kW heater on 120V won't it just draw half the current and produce 1/4 of the heat. That's slightly more than 6A at 120V.

Mike.
Edit, never worked with 110V systems so not sure if there's some quirkyness about it. I do remember NTSC and found that very quirky.

#### gary350

##### Well-Known Member
If you run a 240V 3kW heater on 120V won't it just draw half the current and produce 1/4 of the heat. That's slightly more than 6A at 120V.
Mike.

That is what I get with my heating elements 1/4 watts with 1/2 the voltage. My fuji temperature controller is accurate to 1/2 degree F but only rated 3 amp. The temperature controller turns a motor starter ON/OFF like a relay to turn the heating element on/off. Used motor starters make good cheap high amp relays they are low cost on Ebay. I only paid 15¢ per lb for my 30+ motor starters at the scrap yard. Relay coils are rated 120vac the contacts are rated 600v, amp can be changed by swapping out the over loads.

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