AC System Cleaning

[eze2bme]

I have just returned from the Hatteras Owner's School this week and one topic of discussion concerning the AC system pertained to cleaning the water circulation side of the system on a regular basis (every two years) to remove calcium and other deposits. I wanted to express their thoughts for all to consider and get any feedback.

I hope I got all this correct: Even though you may be getting what you perceive to be good water flow as evidenced by the water exiting the system overboard, there may be deposits inside the plumbing that can cause lower water flow than what is desirable which can lead to the pump overheating, higher electrical usage and possibly eventually causing the pump to fail. They recommended running a cleaning solution through the system in a closed loop for at least 30 minutes. This can be accomplished using a five gallon bucket with a suction hose hooked to the pump and a discharge hose hooked to the discharge side of your system. MAKE SURE TO CLOSE THE SEA COCK FIRST! Turn on the system to the pump or fan setting (not heating or cooling) and let it run for 30 minutes. Your cleaning water solution will get increasingly dirty. Afterwards the system needs to be flushed with vinegar water to neutralize it.

This is important in salt water and fresh water.

If I have any of this wrong please make corrections!!!

[MikeP]

Totally agree that it should be done occasionally. OTOH, I did mine last year and there was no difference in cooling that I could tell. Very little "stuff" came out of the pipes. As far as I know, it had not been done in at least 5-6 years and maybe much longer. So as far as doing it every 2 years, maybe it depends on the local water.

[Pascal]

"This can be accomplished using a five gallon bucket with a suction hose hooked to the pump and a discharge hose hooked to the discharge side of your system"

"Turn on the system to the pump or fan setting (not heating or cooling)"

well that's rarely going to work since it depends on where the pump is installed... remember that the AC pumps are NOT self priming and installed below the water line. in the typical install, it doens't leave you much room to put the bucket in a position where the pump will be able to prime.

also, in most systems (depending on the controls) turning it on to fan will not start the pump... it shoudl only come one when a compressor calls for flow

a much more practical solution is to get a small bilge pump and use that in the bucket as circulation pump.

what did they recommend as a cleaning solution? Ospho is pretty good, many folks use acid but that's a pain to dispose of and nasty to use.

Tehre is a FAQ written up by Genesis descripbing the procedure.

[ppat324]

"This can be accomplished using a five gallon bucket with a suction hose hooked to the pump and a discharge hose hooked to the discharge side of your system"

"Turn on the system to the pump or fan setting (not heating or cooling)"

well that's rarely going to work since it depends on where the pump is installed... remember that the AC pumps are NOT self priming and installed below the water line. in the typical install, it doens't leave you much room to put the bucket in a position where the pump will be able to prime.

also, in most systems (depending on the controls) turning it on to fan will not start the pump... it shoudl only come one when a compressor calls for flow

a much more practical solution is to get a small bilge pump and use that in the bucket as circulation pump.

what did they recommend as a cleaning solution? Ospho is pretty good, many folks use acid but that's a pain to dispose of and nasty to use.

Tehre is a FAQ written up by Genesis descripbing the procedure.

HUH????? ppat

[MikeP]

I did mine with a small bilge pump as Pascal describes and muriatic acid. If you do it with a bilge pump, be sure that the pump/bucket is above the compressors to ensure that the cleaner totally fills the tubing. I did each compressor separately with the bucket on the side deck and extension hoses running through the engine room air intake to the compressors.

[SKYCHENEY]

I am going to clean mine with the bilge pump method. You may not see any difference in flow or in the cooling but it was mentioned that you may see lower amp draw as the units will be more efficient after a good cleaning. I figure it can't hurt and I'll give it a try.

[Walter P]

I have had very good success using a closed loop setup and a material called TRAC Barnacle Buster. It is very effective and is absolutely safe to discharge overboard which is not recommended with any of the acids. The stuff gets really dirty after just a few minutes of circulation and I usually let it run for about an hour. After cleaning just reconnect the suction and return hoses and run your system. Depending on how dirty and whether it is run in salt water or fresh, you will note an improvement with lower power draw and better transfer of heat/cold which makes sense since any kind of crud build up in the system serves as an insulator and if it's constricted at all, the power draw is also higher before cleaning. Try it, you'll like it......

Walt

P.S. I used a clean 30 gallon trash can between the engines to do mine. I also do the engines every few years...no more overheating issues.

[REBrueckner]

"You may not see any difference in flow or in the cooling but it was mentioned that you may see lower amp draw as the units will be more efficient after a good cleaning. I figure it can't hurt and I'll give it a try."

That's a great solution for the guy doing the cleaning work for pay; much less so for the guy paying the bill.

It's also just about impossible...the unit will perhaps run longer if the heat transfer is impeded, but the compressor just keeps running and if the refrigerant is a tad warmer I don't think the compressor runs any 'harder'...just longer. So it's a lot more likely you'll save some POWER because the unit may run for less time.

Likely it won't hurt anything, but cleaning with harsh acids every two years without any cooling issues is unwise and unnecessary:

I'd be a LOT more inclined to use an infrared temperature sensor and monitor the water temperature in and out. Record your results after some fixed operating time, say 15 minutes, and ambient air temperature at start. That way you can compare year over year, perhaps best to do the same month each year, and if the circulating water temperature difference remains the same, why subject the copper cooling system to harsh cleaners and waste your time.

Don't fix it if it ain't broke.

[MikeP]

"I'd be a LOT more inclined to use an infrared temperature sensor and monitor the water temperature in and out."

That's WAY too scientific. We don't do "scientific" here, we do "I heard somewhere that some guy said..."

[krush]

It's also just about impossible...the unit will perhaps run longer if the heat transfer is impeded, but the compressor just keeps running and if the refrigerant is a tad warmer I don't think the compressor runs any 'harder'...just longer. So it's a lot more likely you'll save some POWER because the unit may run for less time.

Lowering head (high side) pressure results in lower amps from the compressor. This pressure is lowered by better cooling on the heat exchanger--meaning if you reducing the fouling on the condenser and allow better heat transfer, the compressor will "work less" and draw less amps, which reduces energy consumption.

Here's some technical talk about it, but it's beyond most here: http://www.hvacfun.com/a-understandi...ss-control.htm