Community Forums

LewTippett · 05-26-2017, 06:29 PM

As some may know, I am changing out old heat pumps for new ones. The new mounting lag screw holes on the new unit do not line up with previous holes.

First, the new holes will be about an inch further in than the previous holes. Do you think I will still hit the stud?

Second, how should I seal the old holes?

Thanks,

crolfmilton · 05-26-2017, 06:51 PM

To seal, use Dicor

GaryKD · 05-26-2017, 06:54 PM

Hi LewTippett,
Newmar reinforces the opening for roof HVAC units. When you say the new holes are " further in than the previous holes" do you mean closer together?
The rafters are on 16" centers. Maybe you can find the aluminum reinforcement "box" Newmar built to hold the HVAC unit. I'm more concerned you will hit this box frame. If you center the new unit in the old box framed opening you should be fine.

Fill the old holes with the sealant of your choice and top off the holes with EternaBond.

PanJH · 05-26-2017, 06:57 PM

What is your roof made of ? TPO,EDPM, Fiberglass ? That will impact what you should use to fill and seal the old holes

GaryKD · 05-26-2017, 06:59 PM

Hi PanJH,
The roof will be Brite-Tec or Fiberglass.

Winemaker2 · 05-26-2017, 07:40 PM

Email Newmar and ask fir roof framing dwgs fir your unit.
I've done this for side walls and they supplied pdf dwgs I requested.

LewTippett · 06-02-2017, 05:47 PM

[QUOTE=GaryKD;3617498]Hi LewTippett,
Newmar reinforces the opening for roof HVAC units. When you say the new holes are " further in than the previous holes" do you mean closer together?
The rafters are on 16" centers. Maybe you can find the aluminum reinforcement "box" Newmar built to hold the HVAC unit. I'm more concerned you will hit this box frame. If you center the new unit in the old box framed opening you should be fine.

OK, the front unit lag screws all bit and tightened down. Passenger side of the rear unit did as well. However, the rear driver side screws hit nothing. Anything short of opening the roof and adding support? If not, anyone point me to a relevant "how to" link?

GaryKD · 06-02-2017, 05:51 PM

Can you slide a piece of wood under the outer roof and screw into the wood making a sandwich to hold the HVAC unit?

LewTippett · 06-02-2017, 09:08 PM

Quote:

Originally Posted by GaryKD

Can you slide a piece of wood under the outer roof and screw into the wood making a sandwich to hold the HVAC unit?

This was what I was thinking, I think. Is there some way to go under the outer roof without cutting into it? I was thinking that I would cut into the roof and place a piece of one by between existing studs, re-cover, seal, and then screw into it? Or, is there an easier way?

bruceisla · 06-03-2017, 12:31 PM

Hey Lew, not sure about your year/model but you mayfind this helpful:

Dometic Brisk II install on Newmar

and here:
Brisk II Install Story by Bruce (bdkolber) | Photobucket

BTW, if I remember correctly, 1 Lag Bolt is longer than the other 3. You are not bolting to crossmembers ... you are bolting to a frame assembly.

This is the frame that is under the A/C: