Can I run 2 voltages to HVAC equipment?

[brantmacga]

Existing building being converted to a manufacturing plant.

They will convert a cold storage room to a chemical pilot plant. There’s an existing 208v package unit that is cool-only. HVAC contractor proposed adding 15kw heat strips for heating. There’s a 200A 480v panel in this room feeding a 75kva xfrmr to 200/3 208v panel, and I don’t have the capacity on the xfrmr to add the heat strips.

Can we use 480v heat strips and add a second disconnect at the package unit? I’m unsure on having two different voltages inside the package unit.


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[LarryFine]

Can we use 480v heat strips and add a second disconnect at the package unit? I’m unsure on having two different voltages inside the package unit.

Should be no problem as long as existence and location of each disco is noted at each disco (I think).

 

[Dennis Alwon]

I am sure that there is someone who would turn it down as the unit wasn't approved for the purpose. I would check with the inspector and then label the unit itself with both voltages.

 

[brantmacga]

Thanks. I’ll run it by the inspector and see what he thinks. Maybe with appropriate labeling we can get by with it. Worst case scenario, I add another transformer. Every other unit in the building is 480v; this unit was an addition during the last renovation and idk why they chose 208v when the 480v panel was right there beside it.


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[kwired]

Are these heat strips listed to be used in the unit?

Or is it a separate duct heater?

 

[brantmacga]

Are these heat strips listed to be used in the unit?

Or is it a separate duct heater?

Not a duct heater, strips inside the package unit outside. The mechanical contractor told me he could get 480v strips.

I think I may be ok though with 208v. I was working off as-built drawings and pictures, and I went by and took the panel covers off, and there are a couple of breakers that were indicated as HVAC equipment that is non-existent. The as-built schedules also had some motor loads for mixers that will not be used by the new occupant. Also unsurprisingly, none of the actual hvac equipment they do have matches the original construction drawings in size or location.

It was built as a honey plant, and the new owner is building out a chemical lab and pilot plant.


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[Eddie702]

It should be fine. There is a lot of equipment that have more than one voltage run to it. As long as you have disconnects for both voltages and the disconnects are marked properly it's fine. Hopefully the unit's name plate lists the electric strips as options. Sometimes they do and sometimes they don't. In any event I would have the hVAC contractor provide paperwork like the installation manual that show electric strip heaters being installed in the unit as an option.

lennox I know used to build there RTUs with electric heat so they could be powered by one power supply or two seperate feeds