Our furnace is only 3years old, it was expensive. There is a round psi gauge on the front that is always at 0, I've never seen it move. The gauge looks like it is brand new. Could this be the reason we are burning 100 gallons a week, and keeping the thermostat at 60degrees. HELP, we just had it cleaned and nothing was mentioned (perhaps he didn't run it long enough?)
What can I do to try and fix it.

Hi SS...

If you have a forced hot water boiler then it sounds like the boiler isn't filled properly with water.

Most likely, the automatic boiler fill valve has failed and needs to be replaced or it could even be as simple as someone shutting off the water feed into the boiler.

Here, a forced hot water boiler should have about 12-15 PSI for a reading at that gauge.

I would fill the boiler system with water and purge all the air out of the system (zone(s)) and then see what happens.

Be clear that once the old fill valve is disturbed it will probably fill the boiler no problem, but here, the fill valve may not close back down and could cause the boiler to overfill and that could cause the boiler to flood the floor.

If you are unsure of all I posted on this contact a qualified heat technician/plumber to investigate this for you. I would not call the service technician that cleaned the boiler as they really should have mentioned/noticed this, OK?

Mark