I need a double pull 20 amp trillianiant breaker

SOURCE: Washer Tripping 20 Amp Breaker

probably a faulty heater.

SOURCE: I need to install a GFI breaker on a Baptistry.

You could install a standard GFCI in line at each component ( heater, pump & timer) or you could install AFCI breakers similar to what are required in many residential codes (provide the same protection at the panel not at the location... http://www.cpsc.gov/CPSCPUB/PUBS/afcifac8.PDF

The AFCI breakers will need to match your panel type (siemens, GE or Square-D) and the amperage/configuration.

I would install them at the lowest level (closest to the components) in the system to reduce possibility of fire in the wiring between the components and the afci breaker.

SOURCE: Need Alternate for Federal Pacific Breaker

Does the panel have room for the breaker?

Federal Pacific is a brand name panel and you may be able to find breakers at Home Depot, Menards, or Lowes if those stores are in your area. Bring the panel number to the store with you.

Here's a link for additional info:

http://www.baybreakers.com/catalog/Federal-Pacific-FPE.html

There have also been some recalls for these panel breakers. See:
http://www.philadelphiaelectric.com/recall__federal_pacific_breaker.htm

SOURCE: When pulling the trigger it trips 20 amp breaker.

You have have an earth fault. have it tested for your own safety.

SOURCE: Gfi Breaker 2 Pole 20 Amp: installed 20 amp dbl pole breaker to hot tub. Keep...

When Working with Household Electricity you want to always keep in mind that the BLACK wire ALWAYS carries DEATH. What I mean by this is that working with a Single Phase Circuit (one that uses 120VAC) the only wire that should be carrying a voltage is the BLACK one, the other 2 wires (typically the White Neutral and Green Ground) should both be electrically connected to Earth Ground (usually by being attached to your water pipe.)

It is also possible that your hot tub may use more than 20 Amps.