Central Air Condenser on the roof or in a cage?

Question

Hi,

I just had a HVAC guy come out and give me an estimate on 2 central air units for a 2 flat. The top floor gets pretty hot in the summer, flat roof. First floor is obviously much cooler. The quote they gave me has a 2.5 ton setup for the second floor, and 2 ton for the first. Does that sound about right? Each unit is 1000 square feet, 3/1. Thanks!

Scott Mac · Answer

Roof mounted MIGHT sound like big humming noise on the entire top floor whenever the units are on.

No way to tell ahead of time.

Cages on ground units, keep inquisitive hands off the units.

In some areas the roofs are alive (and dead) with people.

I know a man that was evicting renters (w/o court approval, self-help tough guy eviction) for being on the roof, he went up there himself when he caught them up there, they left and he fell off and died.

Next owner same building, different renters, same scenario, same ending.

You see, there was easy access to the roof, via windows over a porch roof from one of the units, and that units renters used the easy access to extend their living space (to the obviously dangerous roof).

I believe both men were wearing leather sole dress shoes on a pitched roof, when gravity took them on that final ride.

A couple of owners later the house burned and was a total loss, which solved the roof problem.

So where I'm going with this, is if there is an easy access point to the roof, you may get sunbathers, partiers, adventurous teens up there monkeying around with the HVAC equipment (in addition to the droning humming noise).

Good Luck!

Mario Morales · Answer

I am no expert but I like the central air units, especially when its a in an "A" or "C+" neighborhood as it attracts higher quality tenants. It allows me to charge a premium rent. It is highly recommended , I've been told that it's a really good idea, I heard it on the Straight Up Chicago Investor podcast, that a basement in chicago, should have central air. I can't recall the BTU, but depending on the sq. footage I think it's measured by tonnage. There are a lot of Youtube videos that help explain.

Jay Garrison · Answer

The quote was $8700 for everything, including a crane to get the units on the roof (the roof hatch is too small to put them through). My neighborhood is challenged/promising, just south of Back of the Yards... that may be why he recommended cages.

Paul De Luca · Answer

What was the quote amount? For my units (~1000 sf) a few years back we had 2 ton condensers installed. I think where the condensers are installed depends on (1) code and (2) practicality/convenience. Most commonly I see them installed in the rear of the property on the ground without cages. I think cages are typically installed around condensers in D class neighborhoods.

Mario Morales · Answer

Good question!!! I have a few, one mounted on a roof, one on a wall, as the cage was just too expensive for me, looking to see what others think

Lesa McComber · Answer

Hi Jay,

I put in two mini splits. BUT they have mini split units that can support up to 6 inside blowers. (That is what I originally wanted) but the two units were less.

I use cielo breeze to lock the settings so it cannot go below 73 degrees.

I can see the settings on my phone so I know what's going on.

I use Two Nest for the main units "Best upgrade I ever made"

The two main air handler units are used very little now,, where they use to run almost constantly. Also I added ceiling fans in the hot areas to circulate the mini split air. The mini's are way more efficient than the big units.

The next project is blowing insulation into the two car garage, because it has no insulation and I am sure the hot air is getting sucked into the rest of the home.

P.S. I put the mini splits in the tenants rooms. The main house unit on that side gets set to 79automatically at 10pm

If the tenants are watching tv one will open a bedroom door and the ceiling fan cools the media room, without running the 3 ton unit.

Hope I explained okay.

Oh...we call the window units "window shakers😄"

Lesa McComber · Answer

Hi I am new here.but I have 1 3ton and 1 2 and 1/2 tonwhich is supposed to cover 4500sft single story.

The rear addition which faces south in south florida was ridiculously hot.

wound up putting in two mini splits.

cost mini split x 2 840.00

Parts and labor which included 2 30 amp fuses, wire and breaker box 1600 installed.

way more efficient than my two condenser/ handler units.

I saw the electric bill drop and tenants are happy.

look up McCool mini splits on YouTube.

I figure if it can keep a house Ice Cold in the Caribbean why not Florida.

Scott Mac · Answer

Why do you lock them at 73 degrees?

That seems warm to me (???)

Jerry V. · Answer

Hey Jay, a Roofer here ...

No one has mentioned, you may want to look into what the roof actually IS on top there.  I.e. What material, condition, color ... On most units like you describe, you could have Mod Bit (Modified Bitumen) with colored granules, or it could be smooth; could be the white TPO material, but if aging it needs attention.  Even if newer, if it is 'not' a whit-ish color to reflect the heat and solar gain... then COAT it!  What is there (material and type) will determine on what type of coating may be best.  Good quality Silicone coatings are common, but a high-solids acrylic may work just as well.  You may need a Base coat for adhesion or cover-up, then the top coat... etc etc etc.  (Really need a local and HONEST Roofer to look at/evaluate if things are possible)

But again, the roof may be something to think about looking into (or it may be fine, who knows).  Send me a message if I/we can be of help on any "Roofing" or skylight questions.  Oh!  I know that for mini-splits, Daikin is a GREAT brand (look into D itself, not their other brands).

(w/ J's Roofing - Richardson, TX )

Jay Garrison · Answer

Mario, how satisfied are you with the central air units, what is their BTU and what size space do they need to cool?

Central Air Condenser on the roof or in a cage?

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