I replaced my 12 year old Goodman packaged heat pump, coil leaks, last March with a Coleman 3 ½ ton PHE4 packaged heat pump. This winter only during the defrost cycles, for ~5 minutes, it puts out a foul odor, the “Dirty Sock Syndrome”. We live in middle east TN and have had a cold winter. Temps getting down in the teens.
I have waded through most of the threads on DSS on this forum and from the posts it appears that the consensus of opinions to cure it are:
1. Get the inner coil coated with an epoxy polymer. Costly and since the coil would have to be sent out could take several weeks.
2. Install UV lights close to the coil. Opinions differ if these are effective. Also costly.
3. Run the blower fan 24/7. On a packaged unit the blower fan is outside. Packaged units are not completely air tight and have sparse insulation. I tried it but my wife was complaining about cold air blowing when the heat was off.
4. Clean your filters. We have 2 - 20”x 20” Air-Care washable electrostatic, MERV 8, return vent filters. I wash them ~every 2 months. Should we be using a filter with a higher MERV rating? We used these filters with the Goodman HP and did not have DSS.
5. Treat the inner coil with disinfectant chemicals to kill the bacteria, fungus/mold on the inner coil.
In my former life, now retired, I worked as a research chemist for Bayer for 33 years.
I contacted my Coleman HP installer about the DSS smell and he came out and sprayed the coil with ComStar 90-655 Dirty SOX Odor Eliminator Aerosol, $14.50 for a 14 oz. can from Amazon. The coil was clean with no signs of fungus/mold on it. My inner coil is all aluminum. The Comstar product had a paint thinner smell that was extremely obnoxious. We had to open several windows to get rid of it and it lasted for several days. It did not work. The DSS smell was back within a week. I should have checked the MSDS (Material Safety Data Sheet) before I let him use it. It contains >10% dipropylene glycol monomethyl ether. It has an OSHA TWA (Time Weighed Average over 8 hours) of 100 ppm.
Another product that contains this chemical is Nu-Calgon Evap-Fresh No Rinse. According to its MSDS it contains 5-10% and lists it as a class 3 (severe) safety hazard. I personally would not use either of these products.
This product also contains ~0.1 - 0.2% (1000-2000 ppm) dimethyl (ethyl)benzyl ammonium chlorides, the main disinfectant component. It is not listed on its MSDS but I suspect the Comstar product contains ~the same amount.
A few posters here have stated that they had good results from using Lysol Disinfectant spray on the coil. I checked the MSDS on it to find out what chemicals were in it and compared it to Walmart’s Great Value Disinfectant Spray’s MSDS. The effective chemicals and amounts were almost identical, 50-60% ethanol and ~0.1% -0.2% dimethyl (ethyl)benzyl ammonium chlorides. The Great Value brand is about half the price of Lysol. Since we were invaded by the Covid-19 virus these products are almost impossible to find in stock.
I did find the Great Value Linen scent disinfectant spray in stock at our local Walmart for $2.97/19 oz. can. I purchased a few cans and sprayed both sides of the inner coil and drip tray with ~ 1 ½ cans; and let it dry with the panels off for a few hours. The problem with these spray cans is that they put out a fine mist so you have to get close to the coil to saturate it.
The smell was pleasant but the DSS smell came back after 1-2 weeks when the temps got colder. My guess is that the concentration of the quaternary ammonium chlorides was too low.
So, what about other disinfectants. You can check on the EPA site for approved Covid-19 disinfectants. cfpub.epa.gov/giwiz/disinfectants/index.cfm They should also be effective on mold and mildew.
You could use a dilute solution of bleach (sodium hypochlorite), 3 oz. household bleach/1 gal. water, let it sit for a while on the coil and then rinse the coil with water to remove it. Bleach though is very alkaline, high pH, and this may be only a short fix. Limited exposure to bleach should not affect aluminum.
What about using rubbing alcohol, a.k.a, isopropyl alcohol, isopropanol? You can buy the 70% or 91% strength at Walmart. It’s cheap. If you try it spray the 70% on undiluted, or dilute the 91% to 70%, give it a few hours to dry before turning your HP on. Will it work? May be, but again it could be just a short term fix. It reacts very slowly with aluminum to form an oxide but I don’t think that this is a concern with short exposure.
The airlines and other industries are now using electrostatic fog machines for disinfecting. I’m not sure exactly what chemicals they are using but hydrogen peroxide, quaternary ammonium chlorides, and chlorine dioxide (ClO2 gas is considered environmentally friendly as it rapidly breaks down into sodium salts) are used in fog machines. There is a concern now that these chemicals, especially the chlorides, are getting into the electronics and could cause corrosion.
Another product that hospitals, and you can purchase it (500 ppm solution) from Amazon, are using as a disinfectant is hypochlorous acid. hypochlorousacid.com/ It’s a weak acid and 70-80 times more efficient at killing microbial pathogens than chlorine bleach. It’s made by the electrolysis of NaCl, table salt. It though has a short shelf life and can contain a high percent of unreacted salt. Not good for HP coils, so I would not use it.
I am going to try spraying the coil again using a solution with a higher concentration of quaternary ammonium chlorides.
There are hospital disinfectant products that have higher concentrations of quaternary ammonium chlorides. Lucasol One-Step Concentrate contains 4.5% quaternary ammonium chlorides, $27.93/gal. at Amazon.
There is also a product called Wet and Forget 10587 that contains 9.9% quaternary ammonium chlorides, $29.94/gal. at Amazon and Lowes (get 10% off with a military discount). It’s advertised primarily as a moss, mold and mildew stain remover for concrete, brick, stucco, aluminum, painted surfaces, siding, decking, roofs and more. It’s MSDS lists quaternary ammonium chlorides as its only component. I don’t see any reason why it could not be diluted and used on an inside coil. I contacted the company and asked them. They replied to check with your HP manufacturer. I doubt if Coleman would know.
I purchased a gallon of it from Lowes for $26.98 and a $1.00 32 oz. plastic spray bottle. They suggest to cut it 1 to 6, but IMO that’s too strong for a coil. I made up a 32 oz. 5000 ppm solution. I used distilled water for the solution. I sprayed it on some green mold on my deck. In about an hour the mold was gone. The pH of the solution is 6.8, almost neutral. I submerged a piece of aluminum foil in the solution for 5 days. It had no effect on the foil. The product has a pleasant odor to it. Yesterday it was 68F here so I sprayed my inside coil and let it dry for 5 hours, HP off. The temps are supposed to drop down to the mid 20s next week so my HP should go through a few defrost cycles. I’ll post back if this works or if the DSS comes back.
If interested, here’s the calculation for 32 ounces of a 5000 ppm solution
1 gallon = 128 oz. @ 9.9% quaternary ammonium chlorides
128 oz. x 0.099 = 12.67 oz. total quaternary ammonium chlorides
12.67 oz./128 oz. = 0.1 per ounce quaternary ammonium chlorides
1% = 10000 ppm
Convert to percentage
5000 ppm/10000 = 0.5%
Convert percentage to a decimal number
0.5%/100 = 0.005
32 oz. solution x 0.005 = 0.16 oz. quaternary ammonium chlorides
0.16 oz./0.1 per oz. quaternary ammonium chlorides = 1.6 oz. concentrate
1 ounce = ~30 ml
1.6 oz. concentrate x 30ml = 48 ml concentrate needed for 32 oz. to make a 5000 ppm solution
If you round this off to 2 oz. (60 ml.) of concentrate it will give you a 6188 ppm solution.
Another product that looks interesting is Vindex Ultra. vindexultra.com
I searched the forum and found a few members that have used it successfully. Can you purchase this directly from them or do you have to go through one of their distributors? There’s none in my area.
From their website: Properly applied Vindex Ultra will kill the bacteria that causes the odor and the elastomeric polymer coating will protect from reoccurrence of odors for years.
According to its MSDS it contains 16% polyurethane copolymer, 75% acetone, and 9% methyl ethyl ketone. If you use this indoors wear a respirator.
When using any chemical, ALWAYS wear PPE, safety glasses, a respirator if you have one or a mask, and adequate ventilation, and take proper precautions with products that contain chemicals that are flammable.
I have waded through most of the threads on DSS on this forum and from the posts it appears that the consensus of opinions to cure it are:
1. Get the inner coil coated with an epoxy polymer. Costly and since the coil would have to be sent out could take several weeks.
2. Install UV lights close to the coil. Opinions differ if these are effective. Also costly.
3. Run the blower fan 24/7. On a packaged unit the blower fan is outside. Packaged units are not completely air tight and have sparse insulation. I tried it but my wife was complaining about cold air blowing when the heat was off.
4. Clean your filters. We have 2 - 20”x 20” Air-Care washable electrostatic, MERV 8, return vent filters. I wash them ~every 2 months. Should we be using a filter with a higher MERV rating? We used these filters with the Goodman HP and did not have DSS.
5. Treat the inner coil with disinfectant chemicals to kill the bacteria, fungus/mold on the inner coil.
In my former life, now retired, I worked as a research chemist for Bayer for 33 years.
I contacted my Coleman HP installer about the DSS smell and he came out and sprayed the coil with ComStar 90-655 Dirty SOX Odor Eliminator Aerosol, $14.50 for a 14 oz. can from Amazon. The coil was clean with no signs of fungus/mold on it. My inner coil is all aluminum. The Comstar product had a paint thinner smell that was extremely obnoxious. We had to open several windows to get rid of it and it lasted for several days. It did not work. The DSS smell was back within a week. I should have checked the MSDS (Material Safety Data Sheet) before I let him use it. It contains >10% dipropylene glycol monomethyl ether. It has an OSHA TWA (Time Weighed Average over 8 hours) of 100 ppm.
Another product that contains this chemical is Nu-Calgon Evap-Fresh No Rinse. According to its MSDS it contains 5-10% and lists it as a class 3 (severe) safety hazard. I personally would not use either of these products.
This product also contains ~0.1 - 0.2% (1000-2000 ppm) dimethyl (ethyl)benzyl ammonium chlorides, the main disinfectant component. It is not listed on its MSDS but I suspect the Comstar product contains ~the same amount.
A few posters here have stated that they had good results from using Lysol Disinfectant spray on the coil. I checked the MSDS on it to find out what chemicals were in it and compared it to Walmart’s Great Value Disinfectant Spray’s MSDS. The effective chemicals and amounts were almost identical, 50-60% ethanol and ~0.1% -0.2% dimethyl (ethyl)benzyl ammonium chlorides. The Great Value brand is about half the price of Lysol. Since we were invaded by the Covid-19 virus these products are almost impossible to find in stock.
I did find the Great Value Linen scent disinfectant spray in stock at our local Walmart for $2.97/19 oz. can. I purchased a few cans and sprayed both sides of the inner coil and drip tray with ~ 1 ½ cans; and let it dry with the panels off for a few hours. The problem with these spray cans is that they put out a fine mist so you have to get close to the coil to saturate it.
The smell was pleasant but the DSS smell came back after 1-2 weeks when the temps got colder. My guess is that the concentration of the quaternary ammonium chlorides was too low.
So, what about other disinfectants. You can check on the EPA site for approved Covid-19 disinfectants. cfpub.epa.gov/giwiz/disinfectants/index.cfm They should also be effective on mold and mildew.
You could use a dilute solution of bleach (sodium hypochlorite), 3 oz. household bleach/1 gal. water, let it sit for a while on the coil and then rinse the coil with water to remove it. Bleach though is very alkaline, high pH, and this may be only a short fix. Limited exposure to bleach should not affect aluminum.
What about using rubbing alcohol, a.k.a, isopropyl alcohol, isopropanol? You can buy the 70% or 91% strength at Walmart. It’s cheap. If you try it spray the 70% on undiluted, or dilute the 91% to 70%, give it a few hours to dry before turning your HP on. Will it work? May be, but again it could be just a short term fix. It reacts very slowly with aluminum to form an oxide but I don’t think that this is a concern with short exposure.
The airlines and other industries are now using electrostatic fog machines for disinfecting. I’m not sure exactly what chemicals they are using but hydrogen peroxide, quaternary ammonium chlorides, and chlorine dioxide (ClO2 gas is considered environmentally friendly as it rapidly breaks down into sodium salts) are used in fog machines. There is a concern now that these chemicals, especially the chlorides, are getting into the electronics and could cause corrosion.
Another product that hospitals, and you can purchase it (500 ppm solution) from Amazon, are using as a disinfectant is hypochlorous acid. hypochlorousacid.com/ It’s a weak acid and 70-80 times more efficient at killing microbial pathogens than chlorine bleach. It’s made by the electrolysis of NaCl, table salt. It though has a short shelf life and can contain a high percent of unreacted salt. Not good for HP coils, so I would not use it.
I am going to try spraying the coil again using a solution with a higher concentration of quaternary ammonium chlorides.
There are hospital disinfectant products that have higher concentrations of quaternary ammonium chlorides. Lucasol One-Step Concentrate contains 4.5% quaternary ammonium chlorides, $27.93/gal. at Amazon.
There is also a product called Wet and Forget 10587 that contains 9.9% quaternary ammonium chlorides, $29.94/gal. at Amazon and Lowes (get 10% off with a military discount). It’s advertised primarily as a moss, mold and mildew stain remover for concrete, brick, stucco, aluminum, painted surfaces, siding, decking, roofs and more. It’s MSDS lists quaternary ammonium chlorides as its only component. I don’t see any reason why it could not be diluted and used on an inside coil. I contacted the company and asked them. They replied to check with your HP manufacturer. I doubt if Coleman would know.
I purchased a gallon of it from Lowes for $26.98 and a $1.00 32 oz. plastic spray bottle. They suggest to cut it 1 to 6, but IMO that’s too strong for a coil. I made up a 32 oz. 5000 ppm solution. I used distilled water for the solution. I sprayed it on some green mold on my deck. In about an hour the mold was gone. The pH of the solution is 6.8, almost neutral. I submerged a piece of aluminum foil in the solution for 5 days. It had no effect on the foil. The product has a pleasant odor to it. Yesterday it was 68F here so I sprayed my inside coil and let it dry for 5 hours, HP off. The temps are supposed to drop down to the mid 20s next week so my HP should go through a few defrost cycles. I’ll post back if this works or if the DSS comes back.
If interested, here’s the calculation for 32 ounces of a 5000 ppm solution
1 gallon = 128 oz. @ 9.9% quaternary ammonium chlorides
128 oz. x 0.099 = 12.67 oz. total quaternary ammonium chlorides
12.67 oz./128 oz. = 0.1 per ounce quaternary ammonium chlorides
1% = 10000 ppm
Convert to percentage
5000 ppm/10000 = 0.5%
Convert percentage to a decimal number
0.5%/100 = 0.005
32 oz. solution x 0.005 = 0.16 oz. quaternary ammonium chlorides
0.16 oz./0.1 per oz. quaternary ammonium chlorides = 1.6 oz. concentrate
1 ounce = ~30 ml
1.6 oz. concentrate x 30ml = 48 ml concentrate needed for 32 oz. to make a 5000 ppm solution
If you round this off to 2 oz. (60 ml.) of concentrate it will give you a 6188 ppm solution.
Another product that looks interesting is Vindex Ultra. vindexultra.com
I searched the forum and found a few members that have used it successfully. Can you purchase this directly from them or do you have to go through one of their distributors? There’s none in my area.
From their website: Properly applied Vindex Ultra will kill the bacteria that causes the odor and the elastomeric polymer coating will protect from reoccurrence of odors for years.
According to its MSDS it contains 16% polyurethane copolymer, 75% acetone, and 9% methyl ethyl ketone. If you use this indoors wear a respirator.
When using any chemical, ALWAYS wear PPE, safety glasses, a respirator if you have one or a mask, and adequate ventilation, and take proper precautions with products that contain chemicals that are flammable.
source https://hvac-talk.com/vbb/showthread.php?2226574-DSS-Dirty-Sock-Syndrome-from-a-chemist-s-point-of-view&goto=newpost
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