We have a Heatilator direct vent gas fireplace model NB3630. It was installed 1.5 years ago by the builder of our new home (Lennar).

The fireplace is on an interior wall with a fan, direct vented up to the roof.

Our issue is, even after hours of use per day, the fireplace doesn't seem to produce much heat. Also, the flame is only 3-4 inches, just barely clearing the log set.

We have complained to the builder who had the contractor that installed the fireplace to come out and look at the box, they say all is working as it should.

We have thought about replacing the fireplace with a furnace rating unit, but because of the smaller size of the Heatilator, we can't install a much larger unit without tearing out the wall and mantle to re-frame.

My question is what should we expect for heat on this unit?

How can the heat be measured?

Can we turn up the flame and get some heat?

If this is all the heat we can get, does anyone have suggestions on how to change out the unit with something that will produce some real heat, without re-framing.

thanks