Replace Mach 8 Rooftop Unit

[BonS]

Originally Posted by Mwoodofd

The screws in mine had about 1.5" of thread to tighten, and one of them was about 1.5" longer than the other 3. Wonder whats up with that?

Weird, poor quality control??

[photraveller]

Same issue as voltdoc our replacement unit did not come with the middle blocking insulation.

Luckily caught it as we were putting the new one on. So we ripped off the insulation from the old unit and had to fetch some HVAC tape to get it secured.

Steve

[voltdoc]

Originally Posted by Mwoodofd

Thanks Gary - I have been researching this for a few weeks and see the differences between all the units. Our's are the Mach 8 AC with Heat Pump and Condense Pump, 15,000 BTU and 6000 BTU Heat Pump.

I did go on the Airxel Web Site and put in my old model number, right off the label and it crossed it to the new number 47024-879B - which I will confirm when I talk to them. - Looks like a easy change since I have access to Fork Lifts.

(looking at Robs image - that looks like a cool lift, but the power lines overhead are a concern)


There is an Electrical Heat Element that can be installed in these, or some of their units, but our rigs don't appear to use that.

That's the same model number as my replacement unit which is an upgrade to the other units I have. New fan assembly is about as quiet now (outside) as the older units with a 3 blade fan and hush kit. Also the capacitors have been relocated.

The lift was pretty cool, portable fold up gizmo. The power lines actually aren't anywhere close.

[voltdoc]

Originally Posted by Mwoodofd

The screws in mine had about 1.5" of thread to tighten, and one of them was about 1.5" longer than the other 3. Wonder whats up with that?

Mine were all the same length, at least 3 inches and appeared to be threaded their entire length. I noticed they go all the way thru the aluminum framing and protrude at least an inch or so into the plenum areas. The return plenum is loaded with wiring so watch out for that. Also the four screws were captive to a metal bracket that in turn attaches to the the bottom pan - so attempting to loosen the screw will lift the entire unit (and twist the pan if each screw isn't loosened a little at a time) - the brackets need to be unbolted to remove the screws.

[voltdoc]

Originally Posted by photraveller

Same issue as voltdoc our replacement unit did not come with the middle blocking insulation.

Luckily caught it as we were putting the new one on. So we ripped off the insulation from the old unit and had to fetch some HVAC tape to get it secured.

Steve

Good catch, guess my installers didn't have a clue. As they were carting the old one away I caught a glimpse of the bottom and noticed the additional foam. It wasn't until a couple weeks later that I remembered that and thought to check the new one. Photo shows my [temporary?] pipe insulation fix, when the bolts are tightened its squished in there pretty tight so I don't think it's going anywhere.

[mlwhitt]

Looks like I’ll be needing to add the foam to mine also. I don’t remember it being on the old unit either. Thanks for the info. ML

[Mwoodofd]

Thanks for all the information, images, and suggestions. Makes me wonder if my other 2 units have the insulation strip between the 2 ducts? I really appreciate this forum and the money and time it has saved me.

Both my number 1 and 2 units are working great (and have been).

My unit will not arrive until after the 4th, so I will be doing this next weekend.

[Skidaver]

For those of you looking for the best deal on a replacement AC, don't forget to check the motorhome factory. That is where I found the best price.

[Mwoodofd]

Received my unit on Wednesday. Will install tomorrow morning.

[Mwoodofd]

Exchange made this morning. Pretty easy exchange once the old unit is off and the new one on the roof. My old AC did have a foam strip between the AC vent and Return Vent on the roof. Positioning the unit was fairly easy to line up the screw, and wire the old unit circuit board control box on the new unit.

One concern is the self tapping screws that the factory used through the threaded inserts on the unit, and straight through the fiberglass and plywood roof. I will end up going back and putting bolts, washers and locking nuts through the unit and roof to make sure the unit is fastened sound. The existing screws did tighten and snug up, but I am going to give myself a little peace of mind, at least on the screws facing the front of the coach.

Overall cost was $1029 for the unit, and about 2 hours of time installing. Beats my original labor quote of 6 hours at $150/hour, and $1600 for the unit.

[Smitty3509]

I had one replaced in Shipshewana by an Amish shop. 30 minutes tops, $1385 total. I can do it myself next time (with a fork lift).

[philnail]

I had mine replaced in Bangor, Maine $1,150 for the ac and $115’install. Took the guy less than an hour to install

Hardest part is getting new unit on the roof and old one off the coach

[photraveller]

Agree about hardest part is getting new AC up there. I've helped push AC's up a ladder before. On the Aspire I setup a simple block and tackle in the barn to raise the new one up. Worked like a champ!

Getting old one down... Tech showed me the easiest way years ago. Just throw it down into the grass. Doesn't leave much of a dent even if it lands on a corner, and who cares about the damage to the unit itself.

Steve

[Mwoodofd]

Originally Posted by photraveller

Agree about hardest part is getting new AC up there. I've helped push AC's up a ladder before. On the Aspire I setup a simple block and tackle in the barn to raise the new one up. Worked like a champ!

Getting old one down... Tech showed me the easiest way years ago. Just throw it down into the grass. Doesn't leave much of a dent even if it lands on a corner, and who cares about the damage to the unit itself.

Steve

I did have a Fork Lift to help me exchange the units at my facility, or I would have paid to have it exchanged. My "fix it" mentality wanted to know how difficult it would be.

I now have a spare AC - looking for options to salvage parts, donate, or have repaired for a spare since I have 2 more that are the same age........