Installed new Dometic Rooftop A/C - Do I Dicor caulk?

DO you caulk: NO.. You use the manufacturer supplied gasket.

Chris Bryant wrote:

RoyB wrote:
The 14 x 14 inch gasket should be in place to keep water from getting back into the trailer...

You would want any and all water that gets inside the roof mounted housing from its vents etc to freely flow away from the air conditioner unit... We always like to park with alittle tilt to the backside of the trailer just to keep the air conditioner roof drain to go in that direction in lieu coming down on the patio side...

Typical Air Conditioner Install Diagram... Note the large Roof gasket position...

Google Image

Roy ken

Man- I drew that back in 2002, now it's all over :)

FWIW, I usually install countersunk screws back in the screw holes when removing a vent, but each install is different. I believe Dometic units still come with foam spacer blocks on the base- once the blocks hit the roof, it really won't compress any more.

Thank you for the help!!! awesome!

RoyB wrote:
The 14 x 14 inch gasket should be in place to keep water from getting back into the trailer...

You would want any and all water that gets inside the roof mounted housing from its vents etc to freely flow away from the air conditioner unit... We always like to park with alittle tilt to the backside of the trailer just to keep the air conditioner roof drain to go in that direction in lieu coming down on the patio side...

Typical Air Conditioner Install Diagram... Note the large Roof gasket position...

Google Image

Roy ken

Man- I drew that back in 2002, now it's all over :)

FWIW, I usually install countersunk screws back in the screw holes when removing a vent, but each install is different. I believe Dometic units still come with foam spacer blocks on the base- once the blocks hit the roof, it really won't compress any more.

kmb1966 wrote:

dougrainer wrote:
Was there sealant on the OLD AC/Gasket? NO. So why would you think it required some type of sealant? Doug

There was only Fan vent there previously, so yes there was old sealant for the fan vent. Cleaned all that off before putting on new a/c unit.

OK, makes sense. When you install where a roof vent was, you just make sure all the mount screw holes are as FLAT as you can get them with a hammer. As long as you have a clean flat surface for the width of the AC gasket, you do not need any extra sealant. Doug

The 14 x 14 inch gasket should be in place to keep water from getting back into the trailer...

You would want any and all water that gets inside the roof mounted housing from its vents etc to freely flow away from the air conditioner unit... We always like to park with alittle tilt to the backside of the trailer just to keep the air conditioner roof drain to go in that direction in lieu coming down on the patio side...

Typical Air Conditioner Install Diagram... Note the large Roof gasket position...

Google Image

Roy ken

dougrainer wrote:
Was there sealant on the OLD AC/Gasket? NO. So why would you think it required some type of sealant? Doug

There was only Fan vent there previously, so yes there was old sealant for the fan vent. Cleaned all that off before putting on new a/c unit.

harold1946 wrote:
No caulking is required and the torque should be 40 inch pounds.

ok. Understood now. thank you for the info.
I just hand tightened it so far

No caulking is required and the torque should be 40 inch pounds.

kmb1966 wrote:
...they say ***40 lbs*** torque... But the metal inside frame starts BENDING way before the gasket squeezes down...

Forty FOOT Pounds is not correct! INCH pounds maybe, but that many foot pounds is twice the torque for spark plugs, and half way to tightened lug nuts on a car. Would distort the roof, bend the A/C pan...

Firm, even, to the gasket about half compressed with even spacing between A/C and roof, front to rear and side to side.

Twomed wrote:
No sealant... foam gasket compressed 1/2 height.

Thanks for the information. Yes the instructions say to tighten the 4 bolts for the gasket to squeeze down (they say 40 lbs torque). But the metal inside frame starts BENDING way before the gasket squeezes down.