Condenser location challenge


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Old 04-15-21, 03:13 PM
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Condenser location challenge

I'm trying to get my 30+ years old central heating/cooling system replaced. The existing condenser unit sits in a deck "well" or cut-out (42" x 42" with a 2' drop-down) next to an exterior wall. The cut-out is enclosed by a box-like structure with a removable cover. See attached pics. The proposed replacement condenser is much bigger H 29", W 29", D 26" than the existing condenser. The issue is that putting a new condenser in place would leave very little working room in the well nor provide enough space around it as required by the manufacturer. In addition, I'm constrained by homeowner's association rules as well as township building codes. After several discussions with them, it appears that I am compelled to locate the condenser in the same location but elevated to the deck floor level. One obvious means is to close up the cut-out and locate the condenser on top of the deck. The issue I see here is that when running, the condenser might set up vibrations in the deck. Are there other solutions like using some free standing structure that sits in the well but is not mechanically attached to the deck so that no vibrations are transmitted to the deck?




 
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Old 04-16-21, 04:32 AM
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Wall brackets attached to the house?
 
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Old 04-16-21, 05:11 AM
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Along the coast many of the homes have their condensers mounted on platforms attached to the side of the house to keep them above flood waters. It works but it does put some vibration into the house.

As you mentioned you can build a freestanding platform within the well and not touching the deck. This is probably the best solution but you've got a few things going on in your "well" and a platform would severely reduce access. I don't know the height of the disconnect box but it looks a bit low and probably will need to be relocated which will further complicate things.

Or, just put it on the deck. Since I don't see any flashing or anything done where the deck meets the house I assume the deck is freestanding. The deck will vibrate a bit but I think it's better than mounting it to the house and shaking the house.

I think the best albeit possibly the most expensive option is to modify the deck to make the well opening bigger.

Since your new condenser is larger it is also probably more efficient than your old one. It could be more susceptible to poor airflow. I'm sure the HVAC contractor will recommend to not enclose the unit. If you do you really should do the math and find out how much open area you have around the condenser. The current one looks like the boards are blocking 60-70% of the area. The enclosure is larger in size and it looks like there is open space under the deck but I would do some math to make sure I was providing enough free airflow for the unit.

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I know you didn't ask but you really need to give your house a good inspection where the deck meets. It doesn't look like any work was done to the house when the deck was built. We often see that decks like yours cause rot problems where it meets the house.
 
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Old 04-16-21, 01:42 PM
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Pilot Dane, thanks for a detailed response. In answer to your questions, the HVAC contractor can move the disconnect box as necessary. However, he's reluctant to seat the condenser on the ground due to air-flow reasons and service space required, as you've mentioned. The only places I see a connection between the deck and where it meets the house are huge screws or bolts or nails securing the corner pillars of the box structure (and the deck perimeter pillars) to the wall.

Here's one simple minded, low tech idea that came to mind. Can I lower into the well an "outdoor furniture quality" table of the right size and have the condenser placed on the table?
 
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Old 04-17-21, 04:54 AM
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I don't know of any "table" I would use. I mean if I welded one up out of steel or made it out of pressure treated timbers with the legs attached to footers it could work.
 
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Old 04-17-21, 05:09 AM
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Cinder blocks.

Fill to get minimum word word count for posting.
 
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Old 04-22-21, 06:57 PM
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I've been discussing this issue with a contractor. He prefers that a carpenter (which could be me) close out the deck by installing additional planks and he would place the new condenser on top of it. I mentioned the vibration issue. He contacted the Trane tech rep who suggested using cork/rubber vibration pads. He added that there could be slight vibration during start-up or shut down (implying no vibration in the steady state). Does this sound plausible? Will the condenser produce more noise on the deck as opposed to being placed on the ground? As you can understand, it won't be any fun relaxing or dining on the deck when it's vibrating and/or the condenser noise is excessive.
 
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Old 04-23-21, 05:24 AM
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There are many vibration isolating feet, pads and mounts available. They are often used in industry for mounting motors or machinery. And you can reinforce the deck with diagonal bracing to really stiffen it up against side to side vibrations.
 
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Old 05-04-21, 12:48 PM
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I was proceeding to move ahead with closing out the deck and went to Home Depot (HD) to buy lumber. A conversation ensued with the HD associate, who asked me about the details. I said I plan to lay planks side to side and screw them into the shoulder boards. He said that may not be a very stable structure and suggested an alternate solution. Looking at my pictures, he suggested that I could remove the fence boards and cut the front two pillars at slightly above the deck floor. Then I could place the cut-out cover right at the floor level. The condenser can then be placed on top of this cover (with intervening pads). This scheme would avoid any major deck alterations. You may not be able to discern the cover via the pics above so I'm attaching a new pic showing the cover lying on the deck floor. Any comments?


 
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Old 05-04-21, 01:04 PM
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I don't know. In my opinion I'd rather see the floor even without the cover sitting on top.
The guys opinion is valid but you could add additional framing under the floor.

On the other hand.... the cover could also be sitting on a foam or rubber bed further reducing vibration.
 
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Old 05-04-21, 06:28 PM
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PJmax, additional framing under the floor is not required. The cover is a sturdy structure on its own. There exist 2 bracing bars on the underside of the cover planks. See pic of the cover turned upside down.


 
 

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