We did this and had a ventless system put in. No heat loss as the flue stays closed.

We have a vented one. Have not noticed and heat loss. We turn off the pilot in the off season but leave it on all winter.

OP here, there are three tyoes of gas fireplaces:

- vented- which is what we want. simplay gas logs in a regular fireplace.
-direct vent where the unit is sealed with two pipes run insude your chimney, one for exhaust one for air intake.
- ventless which is sealed unit with "no" exhaust. (but it ultimately vents into your home.)


My question is how much heat can be lost through a fireplace in winter with glass doors and a mesh screen. We are from Southern CA so I have no reference point.

if it's a sealed gas unit, you lose nothing from your living space.

I live in DC and have a gas fireplace with no flue at all. I'd be surprised if MD actually had a law requiring a flue, let alone requiring it to be open all the time, for a gas fireplace.

We are in Maryland and want to convert our fireplace to gas from wood. The chimney company told us that once the gas logs are installed the law requires that our flue be kept permanently open in order to let the pilot light fumes escape.

Here are my questions:

- since the fireplace will have a mesh screen and glass doors how much heat loss will actually happen?
- if the unit inculdes electronic ignition will we even have a pilot light?
- and can't we just turn off the gas and close the flue until we want to use it...?