I just had a 240 volt air conditioner, 24,000 BTU, installed and my electrical bill tripled. I don't know if it is because of more electricity being consumed or the bad electrical installation.
Instead of installing a double breaker in a 240 volt breaker box he ran one of the a/c wires to a single breaker in a 120 volt breaker box that I have in the house and the second wire from the a/c was hooked up to a single 120 volt breaker in a different breaker box in my workshop. The a/c works but the consumption is crazy. Please advise

Sounds like code violations but not the likely cause of your high electric bill. Hope that wasn't a licensed electrician.
24,000 btu/hr equates to about 7,000 watts per hour.
If in full operation for 10 hours, 70 KW at $ 0.15 per KW (our rate that just went into effect, a 50% increase thru a regulated power company), you would be spending over $10 per day for 10 hours of A/C operation approximately. That alone is $ 300 per month exclusive of possible water heater and other large appliances.

Thank you for the answer. Very helpful

Never use 2 different 120VAC circuits to connect for 240VAC. In a breaker box, a 240 VAC breaker pulls from both incoming feeds. Connected the way you say they are, they could be only pulling off 1 side. Correct it using a 240 breaker.

Just think, Obama's new energy plan will double that bill very soon through carbon taxes.