How to Make Air Conditioning Systems Flushing and Descaling Easy

ttmott

ttmott

PhD in OCD
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TECHNICAL Contributor
Apr 3, 2012
8,131
Space Coast Florida
Boat Info
2006 52 Sedan Bridge
Engines
Cummins QSM11
Keeping a boat in the warm waters of the Southeast US requires routine flushing and descaling of the boat's HVAC systems; twice a year for my boat. I paid someone to do it one time and they not only did a poor job but broke things and basically trashed the boat all for close to $2K. I put together a "kit" with the pump, bucket, hoses, fittings and hose clamps and started to do the flushing myself. Doing this job is, to say the least, hot and miserable; I had to do a week long psych job just to start and it usually took a full weekend to do all four of the systems on my boat. Most of the torture is getting to, disconnecting, and hooking up the circulating system hoses. Hose clamps in impossible access locations, pulling hoses off barbed fittings, and skinned knuckles made the job almost impossible.
So, I installed these nylon garden hose fittings in locations where it was easier to access and simply connect the circulating equipment at these locations. 20 minutes and I'm circulating the chemistry. One of the big benefits is it's set up so all of the other AC systems can remain running while one is down for cleaning.... Sometimes it's the simple things.... Some photos -
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As always, thanks Tom! Even in FW, after two years since my last descaling, I just got HI PS on the fwd stateroom unit, so it's time to do it again.
 
ttmott said:
Keeping a boat in the warm waters of the Southeast US requires routine flushing and descaling of the boat's HVAC systems; twice a year for my boat. I paid someone to do it one time and they not only did a poor job but broke things and basically trashed the boat all for close to $2K. I put together a "kit" with the pump, bucket, hoses, fittings and hose clamps and started to do the flushing myself. Doing this job is, to say the least, hot and miserable; I had to do a week long psych job just to start and it usually took a full weekend to do all four of the systems on my boat. Most of the torture is getting to, disconnecting, and hooking up the circulating system hoses. Hose clamps in impossible access locations, pulling hoses off barbed fittings, and skinned knuckles made the job almost impossible.
So, I installed these nylon garden hose fittings in locations where it was easier to access and simply connect the circulating equipment at these locations. 20 minutes and I'm circulating the chemistry. One of the big benefits is it's set up so all of the other AC systems can remain running while one is down for cleaning.... Sometimes it's the simple things.... Some photos -
View attachment 91965View attachment 91961 View attachment 91962View attachment 91966 View attachment 91963
Click to expand...

Tom,
Great idea that I will put on the to do list. What was the chemistry you used?
I recently used a "coil cleaner" on the a.c. coils, and it made huge difference in the humidity level in the boat that the a.c.coils can now pull out the air. Lots of junk came out.
 
The SW Fla waters have been extra green this year. Not lumpy algae per se, but just "blech" enough to double the service of raw water components.
 
DB360 said:
Tom,
Great idea that I will put on the to do list. What was the chemistry you used?
I recently used a "coil cleaner" on the a.c. coils, and it made huge difference in the humidity level in the boat that the a.c.coils can now pull out the air. Lots of junk came out.
Click to expand...
Barnacle Buster - It's at our local WM....
 
I use Barnacle Buster (BB) (a friend recommends Rydlyme). However my procedure is a little different.

1) Close the seacock for the three A/C's (same procedure for the bridge)
2) Open the strainer and pour 5 gallons of BB into the strainer and pump into the entire system until the mix comes out all ends (similar to winterizing the A/C's). This adds BB into all 3 Units and requires a second person to turn the pump circuit breaker on/off.
3) Shut the A/C Pump off and let the chemical sit in the system and do its work for a few hours or more
4) Turn ON the A/C Pump and pour 5 Gallon Bucket of fresh water into the strainer to flush the system.
5) Shut the A/c pump off, close your strainer, Open Seacock and Turn System back on...and your done
 
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Tom,

For how long do you let the solution run and do you let it sit for any period?

Also, what are your thoughts and experience on running BB in AC lines? There are comments that BB is too aggressive on the copper tubes.
 
Alex F said:
Tom,

For how long do you let the solution run and do you let it sit for any period?

Also, what are your thoughts and experience on running BB in AC lines? There are comments that BB is too aggressive on the copper tubes.
Click to expand...
First, I connect the dock water supply and flush/blow out the AC raw water circuit (a lot of mud and gunk usually comes out) then connect up my Barnacle Buster circulation system (a 1/3hp cheapo sump pump and 5 gallon bucket). I continuously circulate the Barnacle Buster for around two hours then return it all to the bucket and move on to the next circuit. I mix the concentration per their literature. In ten years of doing this I've never seen any negative results.... Now if you use phosphoric or hydrochloric (muiratic) acids or even chlorine and bromine tablets then you will promote damage to any metals containing copper. Barnacle Buster and Rydlyme are specific products for heat exchanger descaling and as a result probably the best product for copper containing alloys. I will say that in the past when I had brass fittings on the hoses they always turned red in color when exposed for any length of time to the products which is indicative of some cuprous transfer. This is a very good technical discussion of Rydlyme and it's impact to metals https://www.apexengineeringproducts...ds/2019/12/Rydlyme_Specifications_19JUN18.pdf . The products however will readily attack and dissolve zinc so when you descale the engines or generator the zinc's must be removed (you probably already knew that).
Here is an excellent chart on compatibility of chemicals with copper alloys https://www.justmfg.com/images/pub-106.pdf
Recently there are some chlorine generators on the market for marine raw water circuits which are essentially the same principal as used in salt water swimming pools. These systems generate very low levels of free chlorine which is more of a preventative prescription to barnacles forming than a descaling process to remove barnacles. After looking closely at these systems and talking to the rep's at the boat shows I don't believe they will last long in my area's waters that have a lot of turbidity. My thoughts....
Tom
 
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Just to be clear Tom do you connect your hoses to the existing in/out hoses coming from the AC’s or are you just descaling the AC unit itself? For me that would require taking apart some of the cabin to get to the hose that expels water overboard.
 
JPGator said:
Just to be clear Tom do you connect your hoses to the existing in/out hoses coming from the AC’s or are you just descaling the AC unit itself? For me that would require taking apart some of the cabin to get to the hose that expels water overboard.
Click to expand...
I connect right at where the raw water pump is; there is a manifold (see pictures) that the pump connects to. This is the entire water supply hose to the AC unit. For the discharge from the AC unit I try to get as much of the hose as possible but most is inaccessible so I find a convenient connection point as far downstream as reasonable.
 
Barnacle Buster active ingredient is Phosphoric Acid. The premixed jug has about a 20% concentration of the acid. The concentrate is 85% and when you follow their 4:1 water mixing instructions it gets it down to the 20% working concentration. This info is available on the company's data sheet for the products.
 
ttmott said:
Keeping a boat in the warm waters of the Southeast US requires routine flushing and descaling of the boat's HVAC systems; twice a year for my boat. I paid someone to do it one time and they not only did a poor job but broke things and basically trashed the boat all for close to $2K. I put together a "kit" with the pump, bucket, hoses, fittings and hose clamps and started to do the flushing myself. Doing this job is, to say the least, hot and miserable; I had to do a week long psych job just to start and it usually took a full weekend to do all four of the systems on my boat. Most of the torture is getting to, disconnecting, and hooking up the circulating system hoses. Hose clamps in impossible access locations, pulling hoses off barbed fittings, and skinned knuckles made the job almost impossible.
So, I installed these nylon garden hose fittings in locations where it was easier to access and simply connect the circulating equipment at these locations. 20 minutes and I'm circulating the chemistry. One of the big benefits is it's set up so all of the other AC systems can remain running while one is down for cleaning.... Sometimes it's the simple things.... Some photos -
View attachment 91965View attachment 91961 View attachment 91962View attachment 91966 View attachment 91963
Click to expand...
Funny...I have the exact same connector/flush set up on all 4 of my units that I installed when I got this boat. I took the time to do it this way to make it easy to do this maintenance. Great minds think alike...LOL And yes it is amazing how much muddy muck comes out when you put 10-15 psi of "shore hose water" to the loop.
 
DB360 said:
Tom,
Great idea that I will put on the to do list. What was the chemistry you used?
I recently used a "coil cleaner" on the a.c. coils, and it made huge difference in the humidity level in the boat that the a.c.coils can now pull out the air. Lots of junk came out.
Click to expand...

Hi there,
what coil cleaner product did you use? I would like to clean my condenser on the outside, there is so much junk in it and it makes the whole boat smell.
 
Juergen said:
Hi there,
what coil cleaner product did you use? I would like to clean my condenser on the outside, there is so much junk in it and it makes the whole boat smell.
Click to expand...

J. B.,
Product was from Home Depot. Can't remember the name, but believe it was a white spray can with yellow & green writing on the label. Was easy to do. Hope this helps.
D
 
Tim Fila said:
Do you just spray it on and let it go, or does it need to be rinsed off?

Tim
Click to expand...
Some says no rinse required but I always rinse the coil down with fresh water afterwards. More lint and dirt always seems to come out with the rinse.
 
Regarding the Rydlyme Flushes many of us do on our A/C units... Are your guys savings the Rydlyme in a bucket and reusing season after season? Wondering how affective it stays after use...

Thanks
 
I had a 5 gallon pail delivered and just make up fresh.
 
rlynch03 said:
I use Barnacle Buster (BB) (a friend recommends Rydlyme). However my procedure is a little different.

1) Close the seacock for the three A/C's (same procedure for the bridge)
2) Open the strainer and pour 5 gallons of BB into the strainer and pump into the entire system until the mix comes out all ends (similar to winterizing the A/C's). This adds BB into all 3 Units and requires a second person to turn the pump circuit breaker on/off.
3) Shut the A/C Pump off and let the chemical sit in the system and do its work for a few hours or more
4) Turn ON the A/C Pump and pour 5 Gallon Bucket of fresh water into the strainer to flush the system.
5) Shut the A/c pump off, close your strainer, Open Seacock and Turn System back on...and your done
Click to expand...
I was about to embark on installing fittings in my six systems to attach my circulating system to the 506 but the sytem is so spread out and difficult to reach I like the idea of just filling the system thru the strainer and pumping until the system is full and letting it sit. Ill try that this today as a matter of fact. Wife left in a frump this morning so I get the day to myself:)
 
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