Conversion of prefab fireplace to direct vent gas fireplace

[Rudyjr]

I am in the process of helping my brother with a project at his house. He has a builder grade prefab fireplace which is on an exterior wall with a gas vented log set. The bump out for the fireplace and chimney are veneer stone. The chimney is approximately 20 feet straight vertical run. The existing fireplace is a Superior BR-36-2. He is doing some extensive interior remodeling and in the process removed the drywall and tile around the firebox. We have been considering pulling this unit out from the front because we can remove and re install the header of the opening quite easily. We have found a Superior direct vent unit that dimensionally appears to fit the framed opening that he has. It is the Superior DRT3040 millivolt clean face unit. We are thinking that we can remove the existing liner from the top and install the smaller secure vent from the top as well. We should be able to make the connection easily at the fireplace with the header removed and re install once done. I cant see how assembling and lowering 20 feet of Secure Vent pipe from the top could be that difficult with a couple of guys working from ladders it doesnt appear to be very heavy. Any helpful suggestions on this would be appreciated.

 

[DAKSY]

If you are installing a DV unit - I haven't looked at the manual - vent straight off the back for the best results.
The only reason I wouldn't do that is if the prevailing wind blows directly into the horizontal cap.
I realize you have to cut stone, but it can be done, & additional framing - use Pressure-Treated 2x4s (or smaller)
- will be needed to secure the cap on the outside of the chase. The framing is to "bump out"
the vent cap to the thickness of the stone veneer..
Removing the ZC Wood box is not too hard using the interior method. Once you get the facing
material off, the first thing you have to do is break the wood vent loose from the fire box.
Pry the venting UP & OFF the unit & secure it with plumber's strapping & zip screws to the chase framing.
Now you can safely remove the unit. One man can get into the chase & hold the venting while the strapping
is released. It will be heavy, but probably less than 100 lbs if it's two piece co-axial construction.
The entire length can be lowered to the floor & then separated by two guys & removed in 4' sections.
You'll have to cap the chase top with SS or aluminum sheet.
Measure, locate & cut the opening for the horizontal cap & frame the opening as needed to secure the cap.
If the interior chase walls are open, now it the time to insulate with a Craft Faced, HIGH R-Value fiberglass
& sheetrock the walls up at least 4', but if your new unit is taller, you can go as far as needed.
Cut the sheetrock for the vent once it's secured to the back wall. A sawzall makes quick work of the job.
Build a deck above the new unit's top standoffs from 2x4 framing, with a partial sheet of drywall on top of the framing &
as much faced insulation as you want, covering the entire deck.
Seal every seam in the sheetrock with aluminum tape or caulk to create as warm of an enclosure as possible.
Install the horizontal firestop inside the chase vent opening
Run the gas line. Install the needed length of vent on the new gas unit & slide it into position with the vent thru the firestop.
Install the cap & caulk it to the framing...
finish the interior work, set up the logs & fire that bad boy up.
Got it?