H410 Air Conditioning Seawater Lines

[sailing gal]

The seawater line for my aft air conditioner on my H410 always clogs up over time. It isn't scaled up because I acid cleaned it last year and it when back to slowly losing flow. I appears that it is just a flowrate issue and that dirt slowly settles in the line and slowly blocks it up. To clear I normally connect a dock hose to the system and shut the forward air conditioner outlet and blast it out. It isn't the pump as the forward system never seems to lose flow.

Any other H410 owners have the same problem?

 

[Don S/V ILLusion]

Presuming you have a filter on the intake, with what does it clog? If no filter, therein lies the problem.

 

[sailing gal]

it has a strainer

both forward and aft air conditioners are supplied via the same pump, they have the same size lines, only the aft lines clog up as I bet the clearance in the cooler for the aft is smaller in area and get less flowrate through it.

 

[Don S/V ILLusion]

So the filter is clean but the line gets clogged?

 

[BobH57]

Similar experience with my '99 H410. I just use my dockside water hose to blow the lines out about once a year.

 

[Don S/V ILLusion]

yes

I am interested in other H410 owners experience

Excuse me for trying.

 

[Sailgunner]

I have one intake but use a different pump for each. I also have Marsh pumps. Never have any issues.

 

[JamesG161]

My H430 does the same thing.

Read this entire thread on most methods of keeping your AC running all year long

Air Conditioning won't work after 5 day sail

A lot of tips and info by @Don S/V ILLusion and @BigEasy who have encounter this issue before.

Jim...

 

[JamesG161]

I appears that it is just a flowrate issue and that dirt slowly settles in the line and slowly blocks it up.

My Guess is this...

The AC refrigerant / sea water heat exchanger is fouled on the Water side. This fouling restricts that flow and settles stuff in that line.

In my link above , we discussed adding 1 inch Bromine spa Tabs to my inlet strainer, which is my case cleaned up the fouled exchanger. It improves slowly as the Bromine chemically reacts the Sea Water Scaling.
I checked with the manufacturer before I did this, and their heat exchanger metal is same type used in Spa/Pool heaters. Thus the Bromine will not damage the metal and only the scale.

Good luck...
Jim...

 

[DeniseO30]

It is not about the size of your boat or the particular model boat.

it is about the layout of your air conditioning systems the intake plumbing, pumps, strainers, hose, piping connections, intake locations etc

Assuming both air conditioning units are identical piped with equal lengths of hose you may get lucky and have a balanced system.

In reality, it's almost impossible to have a balanced system with one pump. As systems run at the same time
there would still be variations in flow rates through the Heat exchangers which have a high resistance to flow to begin with. When one is not running and the other is it will establish flow rate it will not be the same as when both units are running although one would think it would be equal to both

All of your operating parameters: pressures temperatures flow rates can be determined with the proper tools and equipment, most are not expensive. without knowing temperature differences flow rates etc it will remain a conversation about what have others done. "Try this, try that, this might
work"
Fortunately many people get very lucky because the solutions are usually quite simple

 

[Sailgunner]

Did you install a second pump?

Yes. Actually I installed the system so installed two pumps initially.
Hey Sailing Gal, headed to Marathon tomorrow. Plan to be there three days.

 

[flightlead404]

Similar experience with my '99 H410. I just use my dockside water hose to blow the lines out about once a year.

Where do you connect the dockside water hose? Do you disconnect AFTER the pump and connect the hose there? I presume you're not using hose pressure through the pump.

 

[flightlead404]

I connect mine before the pump so both discharge lines get flushed and have a hose fitting installed to do it. I don't turn on pump!!!!

I'm surprised you get good water pressure after the pump. Does the pump not add a restriction doing it this way?

 

[senang]

If your AC pump is a Little Giant like we have on our H38 the pump rotor is driven by a watertight magnetic coupling. Flushing it with the pressure of wall water will most probably turn the pump body at speed without any damage or major resistance because of the weak magnetic coupling.

 

[JamesG161]

The question remains as to why the aft clogs up

We have discussed this before and know how to fix that issue.

My H430 system is about the same as yours.

We use 1" Bromine Tablets in our inlet strainer for the AC Water pump inlet.

Those kill marine growth. I have used this for years and each spring flush out as you do.

I add those tablets at the start and then mid way into the season. 2 tablets each time.

See my post #11 above. [ please read that sited link again for many tips ]

Here is one of the easy ways to flush out by @BigEasy
Flushing Caps

Jim...

 

[Capt Robbie]

Bio film or slime will form within any raw water tubing either hoses or heat exchanger on your air conditioning system. Bromine or chlorine tablets will work very well when the unit is operating, however very corrosive when not in use. This could potentially case internal damage to the plumbing and to the unit. I would only use the tabs if the unit is running at all times.

what I do about once a month or two is mix a little dawn dish soap with a gallon of bleach then run it through the system until you see bubbles coming out of the discharge. Shut it down for a day or two then start up as normal. The crud that washes out is amazing. The straight 6-12 percent bleach left in the system for a short period of time is much less then bromide or chlorine tabs that are normally 56-68 percent. Pretty strong stuff if left sitting in the system for a week or so. Pool heat exchangers get damaged quickly by the high amount of the same chemicals. So be very careful when using the tablets. They work, but they may work to well

 

[JamesG161]

however very corrosive when not in use. [ ]

Not true on my AC units, by Dometic. [I called them to verify it]

They use the same metals in their heat exchanger, just like is done for Spa Heaters that use Bromine and/or Chlorine tablets.

Only thing that the tablets might hurt is the visibility of the ABS plastic on your strainer enclosure.

That is the Reason I switched to Bromine which is acceptable for ABS plastic.

Jim... aka Chemical Engineer.

 

[sailing gal]

The answer was that there was lots of scale and hard growth/shells in the aft loop. It was so much that once I started acid cleaning that it clogged up and I was lucky that dock hose pressure was able to flush it out clear. Meanwhile the forward loop had hardly any scale. Still no reason found why the aft loop has/had this issue. Maybe sometime way back in past the system was run with a low flow issue and that caused a scale up problem.

While I had the loops split at the pump I installed a valve in the aft loop so I can shut it off. Since I long ago installed a dock water flush hose fitting in the pump supply line I can fresh water flush each loop and inlet separately to get max flush. I can also shut the aft loop after with fresh water in if.