208 V single phase?

A 32 volt bucking capable of carrying 28 amps will be around 900 watts. A substantial transformer. New cost would be close to $200.
http://www.newark.com/hammond/1182u30/transformer-toroid-60v-1kva/dp/54X7560
You only need a 7.5 kva since the transformer only carries part of the load. Still about $125.
The muffle furnace is rated at 3.8 kva. I calculated the power requirement for a bucking transformer from the bucking voltage x the rated current draw; 32 volts x 28 amps = 896 watts.
If you check out the transformer recommended by the calculator (1S46F), you'll find that it is a 1 KVA transformer capable of bucking or boosting a 7.5 KVA load. It is not a 7.5 KVA tranformer. RJS's calculation is correct. A 1 KVA buck/boost transformer will handle the OP's application.

Tom
 
My mistake for using the calculator. I misread the size from the actual load listed on the first page instead of looking at the specs on the transformer. I haven't done these calculations in about 7 or 8 years.
Proves the old saying "All of us are smarter than one of us."
 
.......... Proves the old saying "All of us are smarter than one of us."
Or "Two heads are better than one." ....... especially when you're taking about draught beer. :beer mugs:
 
I thought I would resurrect this thread with an update. The furnace project hasn't been much of a priority for me, so it's just been sitting. That is until a few weeks ago when a Square D 1S46F transformer came up on eBay for $70, so I snatched it up. I got it wired up and it works great. I powered up the furnace and ran it up to 500*C without issue. My heating element repair seems to be holding so far. I plan on testing it at higher temps soon.

Thanks to all of you that helped!
 
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