Covering AC Condensers in the Winter

[Nick Ostrowski]

I sometimes see AC condenser units covered in the winter months but most of the time I see then left exposed. It seems the main benefit of the covers is they keep debris and tree litter from getting inside the unit. Are there any negatives to these covers (ie - trapping and holding moisture inside the unit)?

[Joseph Hagarty]

What winter?
Penn Dot was mowing the Medial Strip on US Route 1 yesterday at Route 41.
LOL

[John Arnold]

Covers encourage critters to take shelter and store acorns, etc. there? Can't remember where I heard that.

[Joseph Hagarty]

similar to covers on grilles
encourages mice to nest within...

I do not see any benefit at all to covering an AC unit (except for those that sell the covers).

[William Kievit]

A cover that protects the top of the unit, fan can be a good thing but The sides should not be covered so that you don't encourage rodents to make homes.
An old plastic trash can lid makes a good cover.

[Scott Patterson]

I have been told by a couple HVAC contractors that they love to see folks wrap and cover their units with plastic. Why? They both said that they know the fan will need to be replaced that summer or sooner than normal!

They both said that it is best to place a piece of plywood on top to cover the top of the unit. Weight it down with a brick or two but it is important to leave the sides open. This will keep stuff out of the unit and also keep snow and ice from sitting on/in the fan motor.

[Kerry Staudt]

Yesterdays inspection had two covered units. I told my client to remove the covers for all the reasons others mentioned.

This past spring my neighbor was running his AC with the cover on for almost a month. The ironic part is I'm the guy that replaced my eight year old compressor.

[Rod Butler]

Yesterdays inspection had two covered units. I told my client to remove the covers for all the reasons others mentioned.

This past spring my neighbor was running his AC with the cover on for almost a month. The ironic part is I'm the guy that replaced my eight year old compressor.

YES cover the condensing unit for the same reason you cover your BBQ grille and you put your car in the garage. Keep it clean and reduce damage potential from flying debris in winter storms.

If someone runs the AC without removing the cover then Darwin theory comes into play. For crying out loud, take care of your stuff.

[Mr. Duct]

I have been told by a couple HVAC contractors that they love to see folks wrap and cover their units with plastic. Why? They both said that they know the fan will need to be replaced that summer or sooner than normal!

They both said that it is best to place a piece of plywood on top to cover the top of the unit. Weight it down with a brick or two but it is important to leave the sides open. This will keep stuff out of the unit and also keep snow and ice from sitting on/in the fan motor.

Great advice, Scott. We're based in Chicago A/C (http://www.mrductcleaning.com/air-conditioner-cleaning.html) market, so the winters are pretty tough here. Covering the top of the condenser will certainly keep a majority of the debris out of your unit, but as long as yearly maintenance is being performed in the unit, this shouldn't even be a concern since the debris will be removed anyway! We've even seen cages around the AC units, though we're pretty sure it's to prevent copper theft, not animal nesting. :)


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Mr. Duct Inc.
Chicago duct cleaning (http://www.mrductcleaning.com) & HVAC services

[Galen L. Beasley]

We've even seen cages around the AC units, though we're pretty sure it's to prevent copper theft, not animal nesting. :)


----
Mr. Duct Inc.
Chicago duct cleaning (http://www.mrductcleaning.com) & HVAC services

The theft of A/C condensers here in KC has spawned several new businesses which make and sell cages for them so it is more difficult for the thieves to remove or disassemble them.

[Mr. Duct]

The theft of A/C condensers here in KC has spawned several new businesses which make and sell cages for them so it is more difficult for the thieves to remove or disassemble them.

That's what we thought; thanks for the confirmation!

----
Mr. Duct Inc.
Chicago duct cleaning (http://www.mrductcleaning.com)& HVAC services

[Rich Goeken]

YES cover the condensing unit for the same reason you cover your BBQ grille....

Rod, I guess you don't grill in the winter. :D
My grill is used all year around, and having to take a stiff and/or brittle cover off or trying to get the snow off without damaging the grill cover just doesn't hack it. I have not seen any issues within the grill, and a spray can of black fixes the looks on the outside.
The reason that I heard NOT to cover your condensing unit in the winter, is that a cover over the unit causes condensation to continuously build up in within the unit causing rust or oxidation on the respective metals, as well as premature paint failure.
From a HVAC person that loves people covering their units.;)

[Binford Tools]

If somebody uses a cover, just pull the service disconnect. This way they have to plug it in and will see the cover is still on. ;)

[Rod Butler]

Rod, I guess you don't grill in the winter. :D
My grill is used all year around, and having to take a stiff and/or brittle cover off or trying to get the snow off without damaging the grill cover just doesn't hack it. I have not seen any issues within the grill, and a spray can of black fixes the looks on the outside.
The reason that I heard NOT to cover your condensing unit in the winter, is that a cover over the unit causes condensation to continuously build up in within the unit causing rust or oxidation on the respective metals, as well as premature paint failure.
From a HVAC person that loves people covering their units.;)

I too grill all year long but I still cover my grill and I don't need to spray it to keep it looking new. But then I keep it covered year round.

But to address your main point, which is condensation: why would condensation occur when the outside temp is the same as the inside temp (of the condensing unit)?

And more to the point, if condensation were to occur would it be any less damaging than three feet of snow and ice? Consider water getting between the condenser fins and then going thru multiple freeze-thaw cycles, or ice building up inside of the cabinet.

Not trying to be confrontational Rich, I just don't understand the logic of not covering during the winter.

[Eric Barker]

Seems to me that condensers are designed to be out in the weather year round. Manufacturer's are pretty specific about how their equipment is to be maintained and I don't recall ever seeing a spec requiring protection from the elements. Sounds more like some A/C cover manufacturer's marketing worked quite well.

[Rich Goeken]

Seems to me that condensers are designed to be out in the weather year round. Manufacturer's are pretty specific about how their equipment is to be maintained and I don't recall ever seeing a spec requiring protection from the elements. Sounds more like some A/C cover manufacturer's marketing worked quite well.

Probably the same company makes covers for grills...... :D

[Richard Johnson]

Being a HVAC/R contractor for many years, I love to see clients that cover thier condensors in the winter. I always explain that they should not be covered for the following reasons:
1. The cover causes the condensing unit to hold moisture causing the unit to rust out.
2. The cover causes the condener fan motor bearings to sieze requiring a new motor.
3. The cover encourages rodents to make a home within; they will normally add with wiring insulation to thier diet.
The list can go on and on.
I try to explain to the clients that the A/C condensing unit is outside in the rain all summer long with no problems, it is not going to be harmed by the snow. If they insist then want to cover it, I recommend only placing a piece of plywood the same size as the unit itself on the top. The will allow the air to circulate and not hold moisture inside nor will it invite the critters from the area to make a new home.

[Rod Butler]

Being a HVAC/R contractor for many years, I love to see clients that cover thier condensors in the winter. I always explain that they should not be covered for the following reasons:
1. The cover causes the condensing unit to hold moisture causing the unit to rust out.
2. The cover causes the condener fan motor bearings to sieze requiring a new motor.
3. The cover encourages rodents to make a home within; they will normally add with wiring insulation to thier diet.
The list can go on and on.
I try to explain to the clients that the A/C condensing unit is outside in the rain all summer long with no problems, it is not going to be harmed by the snow. If they insist then want to cover it, I recommend only placing a piece of plywood the same size as the unit itself on the top. The will allow the air to circulate and not hold moisture inside nor will it invite the critters from the area to make a new home.

Richard, your argument makes no sense. Your car or truck is made to be outside in the rain and snow as well but keeping in a garage when not driving seems to extend the life. Sure the manufacturer doesn't say it has to be garaged but they are in the business of selling cars. The sooner your old one wears out the sooner you buy a new one. See any correlation here?

And I still don't understand why condensation would occur and even if it did why that is worse than snow, ice and rain.

And the list can go on and on.

[Stephen G]

You guys get lots of snow in the Philippines?:p



I agree on this terms..!
Just trying to get the snow off with less damage..
Covering A/C protects the top of it..!

[Raymond Wand]

As mentioned by others put a board on top with a brick.

Covers are a rip off. Expensive and tear eventually. Someones idea how to rip people off.

[Scott Bennett]

I checked Trane, Carrier, York, Rheem, Lennox, Goodman and Nordyne websites for User Manuals and FAQs regarding covering air conditioning units in the winter months. Rheem and Lennox were the only manufacturers who addressed the question directly. Others just mentioned keeping the outdoor unit free of dirt and debris and not draping or covering the unit during operation.

Frequently Asked Questions (http://www.rheem.com/products/heating_and_cooling/faq/)

Should outdoor units be covered in winter? No. Rheem heat pumps operate year-round and should never be covered. Similarly, air conditioners that operate seasonally are built to withstand an outdoor environment and should not be covered.


Should I cover my outdoor unit in the fall and winter? | Lennox Residential (http://www.lennox.com/resources/faqs/care-and-maintenance/outdoor-unit-care/)
Lennox Care and Maintenance

Should I cover my outdoor unit in the fall and winter?
Covering the unit is not necessary, especially if you have a heat pump that runs all year long. In fact, covering an entire unit may actually trap moisture. If you're concerned about leaves and debris getting inside the housing, short covers are available as an optional accessory and may be purchased through your local Lennox dealer (http://www.lennox.com/locate/).

[Raymond Wand]

Thanks Scott for checking this out.

[David Bell]

Richard, your argument makes no sense. Your car or truck is made to be outside in the rain and snow as well but keeping in a garage when not driving seems to extend the life. Sure the manufacturer doesn't say it has to be garaged but they are in the business of selling cars. The sooner your old one wears out the sooner you buy a new one. See any correlation here?

And I still don't understand why condensation would occur and even if it did why that is worse than snow, ice and rain.

And the list can go on and on.

Your roof may actually last longer if you cover it too! Moister from snow and rain dry faster on an uncovered unit. The rodent problem is real whether you cover or not, they actually nest quite well around the contactor.

[Rod Butler]

Your roof may actually last longer if you cover it too! .

My point exactly.

[Nate Workentine]

Richard, your argument makes no sense. Your car or truck is made to be outside in the rain and snow as well but keeping in a garage when not driving seems to extend the life. Sure the manufacturer doesn't say it has to be garaged but they are in the business of selling cars. The sooner your old one wears out the sooner you buy a new one. See any correlation here?

And I still don't understand why condensation would occur and even if it did why that is worse than snow, ice and rain.

And the list can go on and on.

1. Your automobile is used on a frequent (usually daily) basis during the winter whereas your A/C unit is not.
2. Putting your vehicle in a garage is not similar to the tightly enclosed space of an A/C cover. A more accurate analogy would be a car cover - which, from my understanding, are not recommended, either.
3. Enclosing an outdoor fixture increases radiant heat - which can cause the inner temperatures to raise above ambient temperature. This increase in temperature, even during winter, is enough to raise it above freezing, causing condensation. The restrictive airflow caused by the enclosure keeps this condensation from evaporating, and then it freezes at night at the absence of radiant heat. This cycling of solidifying and liquefying can also cause the unit's components to expand and contract making them more susceptible to breakage.