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Slowbutsure

Feb 18, 2018
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Feb 18, 2018
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Hi

I am making a water heater. I have a thermostat that turns power on and off but only low power. The heater takes 3kw but the thermostat cannot handle having 3kw going throug it.

I need the thermostat to turn something on and off that takes lower power to switch it but can take 3kw.

Can anyone tell me what I’m looking for?

Thanks.
 

Bluejets

Oct 5, 2014
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The heater takes 3kw but the thermostat cannot handle having 3kw going throug it.

I need the thermostat to turn something on and off that takes lower power to switch it but can take 3kw.

Can anyone tell me what I’m looking for?

What voltage?
AC or DC..??

Convention with water heaters on AC is to pass through a combination thermostat/overload unit as shown below. They will easily handle 3kW.
There are other requirements for both inlet and outlet pressure/temperature relief and mixing valves for which one must use qualified fitter/installer.
Also pipe sizing, material type and distances from the ground.

Depending which country/state you are going to use the device as to overall requirements.
I trust the moderators will put the brakes on this before someone gets killed.......... :eek:

Why..????? ........check this out.

 

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Slowbutsure

Feb 18, 2018
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Feb 18, 2018
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That’s what I need. AC 220v. What’s it called? It’s hard find things like this here in the Philippines it seems.
 

ivak245

Jun 11, 2021
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Jun 11, 2021
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The first one is a standard contact type thermostat, with a series over-temp klixon. These thermostats are usually limited to around 65C. The overtemp may go at 70-75C, as fitted to standard electric water heaters. As said above, you need a minimum of a PTR on the outlet (pressure/temperature relief valve) , or you may be making a hot water bomb!
 

kellys_eye

Jun 25, 2010
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You need a relay. Use the thermostat contacts to power the relay coil (just a few milli amps so no problem with contact ratings) and the relay contacts themselves to power the heater element.

Look for a DPST relay with AC coil (suited to your local AC voltage) and contacts suitably rated i.e. 16A for a 240V system and 3kW load.

Here's a typical one available from RS Components:

 
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