3phase heater to single phase?

[freebo86]

How difficult would it be to convert a 3phase unit heater to single phase? See pictures attached of wiring diagram for the heater - not even sure if this is possible?

Unit in question is 3kW rated at 208V. Voltage available to me is 240V single phase. Keep in mind the reason I'm talking 208 & 240 is due to the fact I'm in Canada.

 

[larry_g]

It's kinda hard to tell without knowing if the motor and the contactor coil can handle the 240 volts. The heaters are 1 kw at 208 so would put out 1150 watts at 240, they may or may not handle the increased voltage. I would suggest that you check and see if the heaters and other parts are used in the single phase units, if one is available in that brand.

Give us the brand and part number and better answers may come your way.

lg
no neat sig line

 

[freebo86]

Its a Westcan WFA 332T

Yah that's what I was thinking that the elements couldn't handle the extra voltage..

 

[wyliesdiesels]

208Y/120 and 240v 3 phase arent exclusive to canada.

The US has the same voltages.

 

[Radix2]

I would contact the manufacturer to see if they support rewiring for single phase. I doubt that the voltage difference is great enough to be an issue, the issue is whether the heaters can be physically connected in parallel and if the internal wiring can handle the higher current. I think there is a reasonable chance that the parts used are good for either since that gives a broader market.

 

[freebo86]

Seems like a whole lot of work lol...

This unit here is going on sale for $99 next Tuesday. I'll just pick this up and be good. It's brand new and has warranty.

http://www.princessauto.com/en/detail/5-000w-construction-heater/A-p8678294e

Which appears to be the same unit as a ProFusion EH-4604 I am just wondering if I'll be able to run a thermostat to or a simpler way of turning it on/off then climbing up there?

 

[Norcal]

The factory diagram does not list a way to connect it for 1Ø input, so it would violate any listings, & doubt that CEC rules allow 208V elements to be supplied w/ 240V, there is no correct way to do it, IMHO.

 

[freebo86]

Seems like a whole lot of work lol...

This unit here is going on sale for $99 next Tuesday. I'll just pick this up and be good. It's brand new and has warranty.

http://www.princessauto.com/en/detail/5-000w-construction-heater/A-p8678294e

Which appears to be the same unit as a ProFusion EH-4604 I am just wondering if I'll be able to run a thermostat to or a simpler way of turning it on/off then climbing up there?[/QUOTE]


Here is a post on what was done for a similar heater per the units wiring diagram. Depends on your electrical skill level whether one wants to do likewise with their heater. Just be sure the wall switch control cannot be confused as a main disconnect for the heater.... as it IS NOT. JMO
http://www.garagejournal.com/forum/showpost.php?p=6067464&postcount=8

Easy peasy, might just have to do this! I don't see myself constantly messing with the 3kw, 4kw or 5kw settings so once its set I'd leave it be and then this switch would just interrupt the running of the unit.

Wondering if this switch should be motor rated?

 

[klassenl]

Yes you can change it to single phase. It may run forever, it may not.

 

[ctfjr]

It's kinda hard to tell without knowing if the motor and the contactor coil can handle the 240 volts. The heaters are 1 kw at 208 so would put out 1150 watts at 240, they may or may not handle the increased voltage. I would suggest that you check and see if the heaters and other parts are used in the single phase units, if one is available in that brand.

Give us the brand and part number and better answers may come your way.

lg
no neat sig line

Not so sure about your math here Larry. Power is a function of E squared. Going from 208 to 240 is ~1.15 voltage increase. Squaring that yields 1.33X power increase. So your 1kw element is now 1300 watts. Pretty big jump. Need more air

 

[Gooch]

Not so sure about your math here Larry. Power is a function of E squared. Going from 208 to 240 is ~1.15 voltage increase. Squaring that yields 1.33X power increase. So your 1kw element is now 1300 watts. Pretty big jump. Need more air

Power (watts) is not a function of E (volts) squared. Watts=volts x amps

First you need to find the resistance of the heating element. R=E÷I, 43.3

Then you need to find current draw at new voltage. I=ExRn 5.54

Now you can find your new power. Which is 1331 watts

 

[Radix2]

Power (watts) is not a function of E (volts) squared. Watts=volts x amps

First you need to find the resistance of the heating element. R=E÷I, 43.3

Then you need to find current draw at new voltage. I=ExRn 5.54

Now you can find your new power. Which is 1331 watts

)
Gooch - what do you suppose the equation for watts look like if you substitute the equation for amps into it - amps=volts/resistance ? .... watts= volts^2/resistance.

Check your equation for I

Actually it is more bit complicated than this anyway. Nichrome wire used for heating elements has a decent increase in resistance as it gets hotter - this will tend to lessen the the increase in watts as the voltage rises. It will depend on the fan and what the new equilibrium temperature is.

 

[freebo86]

Here is the diagram for the heater. Not sure where exactly I'd tie the switch to in order to be able to cut the power

 

[Radix2]

Here is the diagram for the heater. Not sure where exactly I'd tie the switch to in order to be able to cut the power

The safest an easiest thing to do is get a temperature controller and wire it in before the unit. Get a wall themostat made for electric heat and rated for at least 21A.

Here is a simple one https://www.platt.com/CutSheets/Cadet/T410 Series Stats.pdf

 

[matt_i]

Assuming compatibility with 240vac, imo the biggest problems are 1) making sure all three elements go across L1 to L2. In other words you can't just hook power into existing L1 and L2 and abandon L3 with no other changes, as this will only energize 1 of 3 elements and 2) the control circuit(s) also has/have to run across L1 and L2.

 

[freebo86]

Yah so I picked that heater up, it is a ProFusion EH-4604 even tho the web site just lists it as a general construction heater.

I'll have to get on the wiring and tie it to a switch or thermostat for controls from the floor..