help with design

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michalspike

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brooklyn, new york
I have 4 outdoor residential heaters to install. They are 240V 12Amp each.
they need to be control by the Lutron homework system.
I was planning to install relay switch controlling 4 separate step up transformers to control heaters. Do anybody have better idea? I'm open to advice.
 
Why would you want to use step-up transformers? Isn't 240v available? Not familiar with Homeworks but I am pretty sure it offers a dry contact module. Simply use contactors to control the 240 to each heater and a 24v control transformer with the dry contacts to control the contactor coils.

-Hal
 
hbiss said:
Why would you want to use step-up transformers? Isn't 240v available? Not familiar with Homeworks but I am pretty sure it offers a dry contact module. Simply use contactors to control the 240 to each heater and a 24v control transformer with the dry contacts to control the contactor coils.

-Hal[/QUOTE

NYC is 208V so I need step up.
Click to expand...
 
Are these baseboard heaters, or like infrared? 4 3500W heaters put out a good amount of heat...

Options:

1) Buy larger heaters designed to run at 240V so that you get what is desired on a 208V supply; that means oversizing them 33%* on BTU/KW. A 240V heater puts out 75% its rating operating at 208V (*the inverse of 75% (3/4) is 133% (4/3)).

2) Buy a 5th (or 6th) heater to make up for the loss of power running 240V units at 208V

3) See if the 4 heaters will put out enough heat at 208V. If they do, problem solved. If not, see #1, 2, or live with it. If they will work on 208V, they will just stay cycled on a little more.

4) See if heaters are available that are designed to operate at 208V.

I would think a single 208V - 240V 15kva transformer would be cheaper and more efficient than 4 4 or 5kva transformers.
 
michalspike said:
the heaters (https://www.google.com/aclk?sa=l&ai...0ahUKEwjIxe3hg-LUAhXK7IMKHeWzAeMQwzwIcQ&adurl) are already supplied . They wont work. I cald manufacture and they said to me that require 240V otherwise warranty will be void.
I was planning to put contactor switch controlling 4 step up transformers but maybe someone have better ideas.
Click to expand...

Ouch. Well, they do make 208V elements for Bromic, not sure if these fit the heaters you listed (which are 2300W @9.2A, not 12A as you originally mentioned):

http://www.bromicheatingusa.com/Bro...ectric-Heater-Parts/35-736-1389-388/list.aspx

At that price, probably better just to go with your original idea of 4 xfmrs...

I dont suppose the heaters can be returned for 208V units? Even with a restocking fee + shipping, you'd still come out better than buying xfmrs.
 
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