AC Condensers on roof. Why?

I've noticed driving around town in Bullhead and Havasu that some new houses are being built with the AC condensers intslled on the roof instead of on the ground. IMO they are not very attractive to look at and most of these are installed on houses with tile roofs so they have to run a wide strip of composition to install it on which ads to the unattractiveness. Other than saving space on the ground why would you do this?

bundled up on the roof

As far as i understood its suppose to be more efficient since cold air drops the ac system doesnt have to fight to push the air up just to have it drop back down, I may be wrong but thats what i have heard.

Not some of the houses. Almost all the houses in Havasu. My buddy built a new home and wanted his AC on the ground. Can't remember the reason why they do it this way.

I'm guessing for noise.

I also wonder why.

Easier to service on the ground...

Very simple

It's cheaper

pronstar said:

Easier to service on the ground...

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Easier to service but more expensive when I built my house.

bk2drvr said:

I've noticed driving around town in Bullhead and Havasu that some new houses are being built with the AC condensers intslled on the roof instead of on the ground. IMO they are not very attractive to look at and most of these are installed on houses with tile roofs so they have to run a wide strip of composition to install it on which ads to the unattractiveness. Other than saving space on the ground why would you do this?

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Funny... driving home from Vegas to bhc we go through Henderson. All the new houses had roof units. I asked my buddy if he knew why. He didn't

The crane operators union lobbied for it 😂

LargeOrangeFont said:

The crane operators union lobbied for it 

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I think it's local 13 in Vegas/Az area 😊

LargeOrangeFont said:

The crane operators union lobbied for it 

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So did the HVAC union.

Because it's a package unit. 1 piece. The air/fan is in that unit. There's no furnace with a a.c. coil on it.
Sooo, your duct runs start under it in the attic.
If you tried to set that unit on the side of the house duct work would go all over and look like shit

Bobby V said:

So did the HVAC union.

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We did? That's where my fucking money went!

riverroyal said:

We did? That's where my fucking money went!

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I thought you were a pipe fitter. Lol

Your ad here said:

I'm guessing for noise.

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No it's not. When they turn on the room below knows. They do it because it is cheaper and easier.
Mine is in the garage attic with the condenser above the RV garage.

So, roof mounted ACs include the air handler(s) with the units?

Cost, not surprised.

So next question, which method is better? Or what would an HVAC guy put on his own house if given the choice?

stephenkatsea said:

So, roof mounted ACs include the air handler(s) with the units?

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Yes. All in one. Return and flow both go in the bottom of the unit. Easy.

Package units are cheaper to install...no refrigeration lines to run, only have to run electrical to one location instead of two etc.

I would not install a RTU on my house. An RTU cannot get the same SEER rating as a split. You most likely hear it run (harmonics) since it is mechanically fastened to the structure without isolation. Finally it's ugly.

Cost and ease of service/replacement. I just put a new 4 ton on. $2,250 for the unit. $300 for the install, $300 for the crane. Disconnect 1/2 dozen wires, yank it off, drop the new one on, hook up a 1/2 dozen wires and it's done.

My electric bills are running at least $100 bucks a month cheaper over the one I put on in 2002. (That one was a $600 scratch/dent)

Seems to me it would be better on the ground and in some shade.

Disclaimer- I am NOT an AC guy, BUT, I did stay at a holiday in express....
LoL

But one system is split system meaning the fan coil is above the living space inside the attic or crawl space with a condenser outside and there are copper line sets run between the 2 units, higher voltage Ele typicall 40/50 amps is run to the outside condenser and lower voltage is ran to the fan coil, 15/20 amp.

The other is an all in one unit/ package unit

Where the fan coil and condenser is housed in one complete unit, package, I usually see these in a commercial applications ( separate suites)like a tilt up industrial building or a strip mall center with multi tenants. The package unit sits ontop of a curb ( platform ) this would be the roof penetration for the supple / return ducting called plentoms. Electrical is ran to the one unit in a 40/50 amps.

I believe the all in one units are easier to install and to set up but have no idea what the cost difference between the 2 are. The composite shingles roofing on residential are installed for access to the unit, so you don't get an AC guy breaking all your roof tiles when he climbs on your roof to access / service the all in package unit.

I just finished a 5ton split system in my garage in havasu I did most of the work hung the fan coil, ran the line sets, placed the condenser and ran all electrical & disconnects and I had Carey do the final hook ups and make it work type of deal- it's so nice to have air in the garage in havasu!

Carey did an excellent job and did it at a great price!

My house has a 5 ton package unit.


I hope some of this helps you out. And doesn't sound to lame.

I have a ground unit and I wish mine was on the roof. People see your backyard more than they see your roof. These days AC units are lighter and hold more equipment. Less pipe and electricity as well. Machines in the roof aren't working as hard either. I just wanted to give a [emoji106] for AC on da roof....Maybe one day when I need a replacement!

BoatCop said:

Cost and ease of service/replacement. I just put a new 4 ton on. $2,250 for the unit. $300 for the install, $300 for the crane. Disconnect 1/2 dozen wires, yank it off, drop the new one on, hook up a 1/2 dozen wires and it's done.

My electric bills are running at least $100 bucks a month cheaper over the one I put on in 2002. (That one was a $600 scratch/dent)

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We had our 22 year old unit changed out last year and the monthly savings are great. 2 adults, pool pump and heat/chiller for pool and the new split system, highest bill has been $202.00

I'd build a box around it. A couple of valleys and boom you got a chimney.

On the split units, I hear the AC guys love servicing the portion in your attic.

My buddy has a place in north bullhead across from the river lodge. A couple years ago he got to his place turned on the a/c and nothing happened. He goes out back to inspect and finds that the local tweakers had torn apart his unit and stole all the copper. Called a local a/c guy to get it replaced, a/c guy told him its a common problem there so his unit is now on the roof.

Hye Power said:

As far as i understood its suppose to be more efficient since cold air drops the ac system doesnt have to fight to push the air up just to have it drop back down, I may be wrong but thats what i have heard.

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Correct answer!!

riverroyal said:

Because it's a package unit. 1 piece. The air/fan is in that unit. There's no furnace with a a.c. coil on it.
Sooo, your duct runs start under it in the attic.
If you tried to set that unit on the side of the house duct work would go all over and look like shit

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Winner. winner, chicken dinner...

FreeBird236 said:

On the split units, I hear the AC guys love servicing the portion in your attic.

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A Day In The Life Of An HVAC Technician - I think it was a reality TV show.

Either way it looks like shit.

charlyox said:

Either way it looks like shit.

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I agree that's why I started the thread. I mean no offense to anyone that has this setup. It simply doesn't look right to me. Cost is probably the driving factor...as with most things.

Ac on the roof looks like complete shit IMO.

LOL ours is on the roof at the river but so is everyone elses. At home we have 4 units on the ground with air handlers in the home in specially made closets. They are easy to service and the roof line is clean. I cant see a home over $400k with an ac stuck up on the roof like a hood ornament.

That said our river roof top ac is super efficient though. The river casita has a LG split system on the ground and I think it uses less power than a can opener

Instead of a conventional system (condenser on ground and air handler in attic) those are a package system, and maintenance is easier on package unit as well they are more efficient.

charlyox said:

Either way it looks like shit.

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bk2drvr said:

I agree that's why I started the thread. I mean no offense to anyone that has this setup. It simply doesn't look right to me. Cost is probably the driving factor...as with most things.

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2Driver said:

Ac on the roof looks like complete shit IMO.

LOL ours is on the roof at the river but so is everyone elses. At home we have 4 units on the ground with air handlers in the home in specially made closets. They are easy to service and the roof line is clean. I cant see a home over $400k with an ac stuck up on the roof like a hood ornament.

That said our river roof top ac is super efficient though. The river casita has a LG split system on the ground and I think it uses less power than a can opener

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While I agree they don't do much for the looks of the house, part of the reason is adding a swamp cooler which many people do out here in the desert is much easier and more efficient on the roof next to the A/C.
Does everybody hate the look of solar on the roof especially a tiled roof? [emoji16]

DRYHEAT said:

While I agree they don't do much for the looks of the house, part of the reason is adding a swamp cooler which many people do out here in the desert is much easier and more efficient on the roof next to the A/C.
Does everybody hate the look of solar on the roof especially a tiled roof? [emoji16]

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Not really the same. Solar panels are more streamline with the roof than these square and rectangular appendage protruding from the roof.

I do think the older style solar panels that look like sheets of vinyl/rubber were hideous. Still see them around occasionally.

That is not a condenser - it is a complete package heat and cool roof top unit. They are usually used on commercial buildings.

FreeBird236 said:

On the split units, I hear the AC guys love servicing the portion in your attic.

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Ya and I loved putting starters on I/O's in pontoons!!!

We've been going back and forth with our builder on ground mount with air handler in the garage versus a roof mount all in one.
For aesthetic reasons we preferred a ground mount on our new home, but our AC contractor said it was much more efficient having the rooftop unit.
Our air handler location was too far from the front bedrooms and with their southwest exposure, we weren't sure the front bedrooms would be as cool.

I don't really want to look at the rooftop unit either, but I want my system to be as efficient as possible.

When looking at other homes along the golf course in our area, it was about 50-50 on ground vs. roof mount.

Deja_Vu said:

We've been going back and forth with our builder on ground mount with air handler in the garage versus a roof mount all in one.
For aesthetic reasons we preferred a ground mount on our new home, but our AC contractor said it was much more efficient having the rooftop unit.
Our air handler location was too far from the front bedrooms and with their southwest exposure, we weren't sure the front bedrooms would be as cool.

I don't really want to look at the rooftop unit either, but I want my system to be as efficient as possible.

When looking at other homes along the golf course in our area, it was about 50-50 on ground vs. roof mount.

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If your duct work is properly sized and insulated it won't matter. You cannot get a n rooftop unit that is more efficient than a split system. Split systems are getting in excess of 25 SEER. RTUs won't get close to that.

River Lynchmob said:

If your duct work is properly sized and insulated it won't matter. You cannot get a n rooftop unit that is more efficient than a split system. Split systems are getting in excess of 25 SEER. RTUs won't get close to that.

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I guess I should have insisted on the ground mount. But we are past the point of no return on that now.
Hopefully I don't regret that decision too much.

River Lynchmob said:

If your duct work is properly sized and insulated it won't matter. You cannot get a n rooftop unit that is more efficient than a split system. Split systems are getting in excess of 25 SEER. RTUs won't get close to that.

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Curious, but is that SEER reduction based on a split rating combined with a NG FAU, or heatpump and AHU combo. Perhaps what I should be asking is, what's the highest rating for a rooftop package heatpump versus gas-pack ?

Hye Power said:

As far as i understood its suppose to be more efficient since cold air drops the ac system doesnt have to fight to push the air up just to have it drop back down, I may be wrong but thats what i have heard.

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Wrong. Many split systems have the furnace/air handler in the attic anyways. Plus, the convection of the air in a house has VERY little to do with system efficiency or performance.

Deadendgraphics said:

I'd build a box around it. A couple of valleys and boom you got a chimney.

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That would actually hurt the performance. The condenser fan moves so much air a chimney would do nothing for it. Plus, the air is drawn in through the coil all the way around the unit so it would be substantially cutting down on airflow.

rmarion said:

Correct answer!!

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See my first reply.

Taboma said:

Curious, but is that SEER reduction based on a split rating combined with a NG FAU, or heatpump and AHU combo. Perhaps what I should be asking is, what's the highest rating for a rooftop package heatpump versus gas-pack ?

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The SEER reduction really has nothing to do with the heating side of the system. There are actually 2 different SEER ratings for heat pumps. One for heating and one for cooling. Makes sense when it stands for Seasonal Energy Efficiency Rating. The SEER reduction in package units is primarily due to their restriction on coil sizes due to having all components in one box. The evaporators are SUBSTANTIALLY smaller than that of an equally sized split system.

Flying_Lavey said:

The SEER reduction really has nothing to do with the heating side of the system. There are actually 2 different SEER ratings for heat pumps. One for heating and one for cooling. Makes sense when it stands for Seasonal Energy Efficiency Rating. The SEER reduction in package units is primarily due to their restriction on coil sizes due to having all components in one box. The evaporators are SUBSTANTIALLY smaller than that of an equally sized split system.

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Great point I'd overlooked :thumbup:, my package HP at Havasu only has evaps on three sides, not all four.

Deja_Vu said:

I guess I should have insisted on the ground mount. But we are past the point of no return on that now.
Hopefully I don't regret that decision too much.

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Having read your build thread I'd also research performance goals w calcs based on the size of your new house and garage if they're only doing one unit or set. I have a fairly new house at the river (2,500 ft living) and did 2 split systems for the house and a mini split in the garage. It's a lifesaver during storms when you lose a capacitor, etc to still have A/C in part of the house. Plus it cools down or heats up in no time, and I did an extra return air in the master on the system at that end of the house. Just my .02

DC-88 said:

Having read your build thread I'd also research performance goals w calcs based on the size of your new house and garage if they're only doing one unit or set. I have a fairly new house at the river (2,500 ft living) and did 2 split systems for the house and a mini split in the garage. It's a lifesaver during storms when you lose a capacitor, etc to still have A/C in part of the house. Plus it cools down or heats up in no time, and I did an extra return air in the master on the system at that end of the house. Just my .02

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We are installing a LG mini split for the Casita (approx. 400 sq ft) and another for the garage (approx. 1350 sq ft).

The roof mount is for the 2280 ish square feet main house. Hopefully that's enough, I don't have any $$$ left for more upgrades.
I did spend some money upgrading insulation to R50 in the ceiling and R21 in the walls.

Deja_Vu said:

We are installing a LG mini split for the Casita (approx. 400 sq ft) and another for the garage (approx. 1350 sq ft).

The roof mount is for the 2280 ish square feet main house. Hopefully that's enough, I don't have any $$$ left for more upgrades.
I did spend some money upgrading insulation to R50 in the ceiling and R21 in the walls.

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It all comes down to the ductwork. If sized, installed, and designed correctly, the system should work just fine.

Insulation is the absolute best upgrade you can do $ wise.