Kooser55;
We done lots of rebuilds on Century portables.
I agree with Dominick & Kevin...
I would forget the heater and get more vacuum and pump power in a hi-performance portable:
1. Two Hi-perf 3-stage vac motors (486 air watts each) or
New AirWatt Vacs (520 air watts each).
2. Hi-pressure pump w/AC motor delivering at least 1.6 GPM @ 450 PSI. High FLOW with a glided wand & angled jets is key here.
These two factors plus a functional durable rotomolded housing with 10" Wheels will give you top portable performance. 2" Vacuum Inlet is desirable for maximum air flow.
Why are choosing 220 Volt components ??
Current draw ON 115 VOLTS should be less than 15 amps on each cord to eliminate circuit breaker issues.
No Heat, all available electrical power is applied to the pump & vac systems.
Auto Pump-Out with a ShurFlo pump and filter system.
http://www.cobbcarpet.com/poutfilt.jpg
Auto-Fill System:
http://www.cobbcarpet.com/autofil.html
If heat is really required, use drop-in heaters on other electrical circuits.
Larry Cobb