direct vent gas fireplace sealing (vacuum, installation, glass, pipe)

[cargoman]

I have a direct vent gas fireplace in the home I just purchased. I have also found some rather large house spiders. I have found said spiders directly near or coming from the vicinity of the gas fireplace. yesterday, I vacuumed under the unit and cleaned the glass and found two very dead and toasted giant spiders on the inside of the glass. These two unlucky ones made into the firebox somehow. I am pretty sure that the fireplace is one of the main entryways into the house. While under the firebox I noticed several large openings. one for the gas pipe into the structure of the house and another on the other side which has nothing going through it. I want to use 3M fireblock foam in those or any other openings I find to seal it off. These openings go into the walls an do not appear to do anything but provide access to piping and hardware. I do not think that plugging these holes will have any effect on the proper functioning of the unit. the 3M foam is rated for up to 240 degrees F. Anyone know how hot it gets under the firebox?

[Nonesuch]

Generally with a "direct vent" unit, there should be no path from the firebox to the inside, so spiders in the firebox almost certainly came in via the exhaust, when the unit was off.

Originally Posted by cargoman

While under the firebox I noticed several large openings. one for the gas pipe into the structure of the house and another on the other side which has nothing going through it.

Can you buy a few small sheets of aluminum, cut holes to fit around the connections, and then overlap them to entirely close off the openings?

... the 3M foam is rated for up to 240 degrees F. Anyone know how hot it gets under the firebox?

The manufacturer should be able to provide minimum clearances to combustible materials; for example, on my Rinnai, for the concentric flue/intake vent the install guide states "Clearance to combustibles for the sleeve and flanges is zero inches."

If you reduce the hole size with a metal plate, you could use a little bit of high-temperature silicone sealant instead of a whole lot of fireblock foam.

[399083453]

Originally Posted by cargoman

While under the firebox I noticed several large openings. one for the gas pipe into the structure of the house and another on the other side which has nothing going through it.

I'm sure that hole has a reason. You should really spend some time looking for the installation manual online to see what that hole is for. Blocking it might cause a fire.

Fireblock foam is NOT for use near fire. It simply resists fire a little better if your home happened to catch on fire, it MIGHT limit damage.