[rockman413]

Hi there,
I'm in the south of U.S., thinking about those citys in Los Angeles, Arizona Desert... It's really really hot and easily get to over 113 degree outside, with burning Sunshine.
Is it safe to put the Outdoor unit of a Mini split system onto the roof? I think it will have more air flow than on ground, but it will suffer way more hot burning sunshine in hot summer.
Check this video

the outdoor unit condenser explode...
Would the burning sunshine and hot weather some how makes the outdoor unit more dangerous and easier to explode? If explode no matter what reason, do you think it's powerful enough to penetrate the Roofing Shingles and hurt people underneath?

We're only talking about the mini-split systems here.
The reason of exploding in this video is not because of sunshine, but this topic is to discuss the burning hot sunshine/hot temprature on the roof's effect on the condenser.
Thanks

 

[user_12345a]

It's safe, as long as the roof can support it.

Makes it harder to service and clean though.

Most condensing units move well over one thousand cubic feed per minute (mant - 2000++ cfm) so the sun has a minimal impact on performance. The incoming air temperature has a huge impact.

Compressors have a plug/seal where the wire terminals are and that can blow, spraying refrigerant and flammable oil everywhere; electrical arching can ignite the oil. Has nothing to do with whether the unit is on a roof or not.

 

[rockman413]

It's safe, as long as the roof can support it.

Makes it harder to service and clean though.

Most condensing units move well over one thousand cubic feed per minute (mant - 2000++ cfm) so the sun has a minimal impact on performance. The incoming air temperature has a huge impact.

Compressors have a plug/seal where the wire terminals are and that can blow, spraying refrigerant and flammable oil everywhere; electrical arching can ignite the oil. Has nothing to do with whether the unit is on a roof or not.

I see some people talked that it's best to have the outdoor unit to be lower than the indoor unit so there's less possibility for the condenser to run without oil. Is this true?

 

[user_12345a]

A little bit of oil always get picked up by the refrigerant from the compressor, it's impossible to avoid.

The refrigerant and oil are mixable and flow together. The oil picked up gets brought back to the compressor.

If the manufacturer's instructions are followed you won't have a problem.

There may be specific instructions which need to be followed when it comes to long vertical runs.

 

[COLDIRON]

Millions of Condo units in Florida with condensers on the roof. Lined up and numbered to which Condo they go to.

 

[beenthere]

It is better for the condenser to be on the ground as far as oil return is concerned. But proper piping makes it that units on the roof have no trouble with oil return.

 

[rockman413]

It is better for the condenser to be on the ground as far as oil return is concerned. But proper piping makes it that units on the roof have no trouble with oil return.

This is the best answer I saw so far! Very objective and I believe both way works. But in my case, as my current AC installer does not communicate with me very well, I have no confidence that he will do proper piping since it's on the roof or does he even care to know about the special piping to make the oil return.

Considering my other post about:
"Unit 1 24K unit:
In the manual it says:
Back of outdoor unit cleaearance should be 12 in
Front of outdoor unit clearance should be 78in
The real life is:
Back of outdoor unit to the exterior wall is 6.5 in (with lineset/cables in the middle)
Front of outdoor unit to the side fence is 40in

Unit 2 36K unit:
In the manual it says:
Back of outdoor unit clearance should be 12 in
Front of outdoor unit clearance should be 78in
The real life is:
Back of outdoor unit to the exterior wall is 12 in
Front of outdoor unit to side fence is 41in

Do you think in real life this is good? Specially the Unit 1 back has only 6.5 inc with some lineset/cables at the back of it close to the exterior wall. Would this cause any safety hazards issues?"
Should I risk to move the outdoor units to the roof that they may or may not do the piping correctly (I don't know how to check it either), or should I just put them stay where they are?

Thanks a lot!

 

[beenthere]

The 6" clearance to the back isn't good, but unfortunately its a very common thing to see.


Fenced in units seldom have proper clearance on all sides like they should have. But often it seems to have little to no effect on life span. Unless the clearance is reduced to less than 12" all the way around. And its not a lattice fence.


On a mini, clearance is a bit more important then on a conventional. So if they can't get the full 12" for the back clearance, I would recommend moving it to the roof.


As for the front clearance, that depends on the wind direction. If they are on the windward side, moving them is a good idea, so they don't recirculate their own air.

 

[COLDIRON]

Contractor's installing equipment should always follow manufacturer's instructions and specifications as to distance and clearance. A couple reasons. Proper airflow though the unit and service clearance. Many times we arrive and have difficulty repairing the equipment because the installer didn't care about long range service problems. The Contractor just wanted to sell and install the equipment and move on. Not all Contractor's.

 

[rockman413]

The 6" clearance to the back isn't good, but unfortunately its a very common thing to see.


Fenced in units seldom have proper clearance on all sides like they should have. But often it seems to have little to no effect on life span. Unless the clearance is reduced to less than 12" all the way around. And its not a lattice fence.


On a mini, clearance is a bit more important then on a conventional. So if they can't get the full 12" for the back clearance, I would recommend moving it to the roof.


As for the front clearance, that depends on the wind direction. If they are on the windward side, moving them is a good idea, so they don't recirculate their own air.

What I care the most is, would the "not enough clearance as manual", for the numbers of clearance I have listed for both unit, cause any damage to the condenser and cause any safety issue such as the possibility to explode in the long run?

 

[user_12345a]

What I care the most is, would the "not enough clearance as manual", for the numbers of clearance I have listed for both unit, cause any damage to the condenser and cause any safety issue such as the possibility to explode in the long run?

that question has already been answered!

 

[rockman413]

that question has already been answered!

Well I think the question has changed in this thread to "cause any damage to the condenser and cause any safety issue such as the possibility to explode in the long run?"
Should I start a new topic?

 

[user_12345a]

No safety issues as previously stated - if the compressor's terminal plug blows, it's due to an inherent defect and not the installation location.

 

[rockman413]

No safety issues as previously stated - if the compressor's terminal plug blows, it's due to an inherent defect and not the installation location.

Thanks for the clarification.

 

[rockman413]

Just to help me understand, if it affect reliability, longevity does it lead to affect safety?

 

[user_12345a]

If heat discharged by the unit gets recirculated back into the unit due to poor installation placement it uses more electricity to do the same job and capacity can be reduced.

Compressor lifespan may be shortened. Compressor and fan motor both have thermal overload that will cut power if a severe overheating condition develops.

Some better units have a high pressure cutout as well.

 

[beenthere]

What I care the most is, would the "not enough clearance as manual", for the numbers of clearance I have listed for both unit, cause any damage to the condenser and cause any safety issue such as the possibility to explode in the long run?

It won't cause it to explode.


6" clearance may cause a shortened life span. But no one can say that it will for sure.

 

[rockman413]

Thanks!

So in the front of the minisplit outdoor unit, the manual says 72'', but I only have 40'', is this still good and will not cause any issues for the outdoor unit?

 

[beenthere]

Does the wind blow toward that area or a way from it.

 

[rockman413]

Does the wind blow toward that area or a way from it.

The front faces the side fence, so it's facing a way and then the side fence.