HVAC evaporator coil cleaning

Reply

  #1  
Old 04-01-19, 10:55 PM
XSleeper's Avatar
Group Moderator
Thread Starter
Join Date: Dec 2004
Location: USA
Posts: 26,788
Received 847 Votes on 776 Posts
HVAC evaporator coil cleaning

I thought I would run this up the flagpole and see what suggestions might come back.

There are 3 large residential sized furnaces in our congregation, (around 20 yrs old) and I have been tasked with giving them some love. I've already done a preliminary inspection, so I know what I'm in for. They are slightly filthy, but not nightmarish. All 3 are configured the same way. Sorry, I don't recall the brand and I don't think that's too important for this discussion anyway.

One strange problem is that these are up flow units... with what I would best describe as an upside down A-coil. When you remove the 22x22 filter below the coil and look up at it, you are looking up at the V. So the upper sides are a little hard to get to. (I plan to have several brushes duct taped to a dowel as a way to have a longer handle... brushing only "with" the fin direction as needed.) But since this area underneath is maybe only 22 wide x 18 tall, laying on my back under there doesn't sound pleasant.

Instead, when you remove the furnace side panel that surrounds the breaker box, there is nice access to the top of the coil, which looks like an open V from above. Due to that, my plan of attack is to use a garden sprayer to apply the cleaner (using Nu-Calgon 4168-08 Evap Pow'r No Rinse Coil Cleaner) to both sides of the coil, allowing it to soak as directed. Then I plan to use compressed air to see if I can blow the cleaner down through the coil (this is the correct way since this is an upflow). I assume I will have to do this at least twice to get it clean enough. And even though it says it's no rinse, I plan to rinse it as best as I can with another garden sprayer and clean water... followed by another shot of compressed air. I'm aware I need to keep the nozzle several inches away from the fins so as to avoid damaging them.

There is insulation on the sides which is also dirty, dusty, so I suppose I will try to vacuum that first with a shop vac and an upholstery brush. Then switch to wet vac mode to suck up the gunk and drippings that I will be blowing out the bottom. I'm just assuming this will overwhelm the condensate tube and I will be blowing a lot of it down the sides of the furnace. (I also thought about bringing a couple large pieces of aluminum trim coil that I could coil up then unroll and slip up the sides to keep that insulation from getting completely soaked.) I will likely have a second person to assist me in sucking up any water that finds its way to the bottom of the unit. (All electronics are above, so no worries there, and the breakers will be off plus we will be using lockout tagout.)

Does this sound like a reasonable approach?

Removing the coils to take them outside to clean is not an option. There is also not good drainage in the furnace room as space is tight and the floor is not really sloped to the drain where the furnaces sit... so a hose is out of the question.

I know there are foaming aerosol products you can spray on but I really don't think they will do as good as what I have mentioned above.

Good news is that all 3 of these units are scheduled to be replaced this winter. So this is mainly just for air quality concerns and to get us by for one more cooling season.

Looking forward to any comments or suggestions.
 
  #2  
Old 04-02-19, 05:07 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 61,398
Received 1,399 Votes on 1,296 Posts
I would nix the brush idea. I like the foaming spray cleaner but the type you mix and spray on are fine too. Two applications are usually needed for a through cleaning. Put a screen over the drain line to catch the lint but let the water drain thru. It'll clean out the drain lines. I don't use and don't usually recommend using compressed air. Too easy to bend the fins. I use a hose with a controlled spray nozzle straight at the coil rinsing from the supply side of the coil to the return side. Basically blowing the lint thru from the opposite direction of the normal air flow.
 
  #3  
Old 04-02-19, 05:18 PM
XSleeper's Avatar
Group Moderator
Thread Starter
Join Date: Dec 2004
Location: USA
Posts: 26,788
Received 847 Votes on 776 Posts
Yeah, I would use the hose sprayer if it was possible but since it's not I feel like I have to use compressed air. I can set the regulator to 40 or 50 lbs to prevent any damage from high pressure.
 
  #4  
Old 04-02-19, 05:44 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 61,398
Received 1,399 Votes on 1,296 Posts
The important thing is to blow straight into the coil. Blowing on an angle will fold the fins over.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: