Flushing growth from your AC system can be easy and environmentally friendly.
By Capt. Vincent Daniello
Follow our tips for flushing your AC system.
For cool sheets in the heat of summer, air conditioning is essential cruising equipment, but to remain troublefree, modern marine air conditioners require regular maintenance. Cleaning sea strainers and cabin air filters top the list, but one maintenance routine often overlooked is periodic flushing of the condenser coils. To understand its importance, let's start with a brief look at how the system works.
A marine air conditioner cools by rapidly depressurizing a refrigerant inside an evaporator, changing it from liquid to gas and capitalizing on the cold this process creates. A fan moves air over the cold evaporator, distributing it throughout the cabin, and the cool gas then flows to a condenser unit, which is typically located in the engine room. Each condenser uses a compressor and a cooling coil to turn the gas back into a liquid, transferring the heat created in the process to seawater that is circulated through the unit.
Over time marine growth can coat the inside of those condenser coils with algae and calcium, which reduces the effectiveness of that heat transfer. Fortunately, cleaning the coils is now an easy job for the do-it-yourselfer and is also safe for the environment.
When condenser coils are too hot to touch, or if a condenser's liquid discharge valve exceeds 15 degrees above seawater temperature, buildup within the cooling coils or blocking water lines feeding those coils will keep air conditioners from cooling efficiently. Professionals circulate inhibited hydrochloric acid through the system to dissolve growth. With a few plumbing fittings, some hose and a bucket they'll use the ship's air conditioner seawater pump to do the work.
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But today's air conditioners won't run the seawater pump without also operating a condenser. Air conditioner technicians know how to bypass this feature to run only the pump, but a simpler and safer solution comes from Trac Ecological in Fort Lauderdale (trac-online.com). Its Port-OFlush Jr. kit includes a submersible pump plumbed to fittings in the side of a bucket, along with hoses and fittings to connect to a boat's AC system. By using its own pump, Port-O-Flush Jr. cleans condensers without powering any of the ship's air conditioner system.
"We use a light, food-grade phosphoric acid, the same thing you'd have in Coke or Pepsi," says Patrick Leclerc, president of Trac Ecological. The acid dissolves calcium but is biodegradable and safe for the environment and ship's systems. The company's Barnacle Buster product also contains environmentally friendly corrosion inhibitors and penetrating agents. "If you've got barnacles covered in algae, plain acid won't do its job," Leclerc says. Barnacle Buster is nontoxic, but rinse your eyes if splashed and don't drink it. It will tarnish polished aluminum and also slowly dissolves zinc.
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One gallon of Barnacle Buster dilutes to make five gallons of cleaner. Most boat air conditioners take five to 10 gallons of circulating cleaner, but can require more if there are long hose runs from the seawater pump to condensers. (This is common on small boats where self-contained air conditioners include both the evaporator and condenser in the cabin, while keeping the sea strainer and pump in the engine room.) Trac Ecological's website offers guidance for calculating the approximate seawater capacity of a boat's AC system.
Port-O-Flush Jr. includes valves on the bucket and easy-to-connect garden-hose fittings. Two 10-foot hoses are adequate for most boats, but might not reach if the strainer and pump are located far from the air conditioner condensers or overboard discharge. The company includes both three-quarter-inch and half-inch pipe fittings that attach to their hoses, but you'll need to adapt from those fittings to hose barbs that fit your seawater intake and discharge hoses.
Other Boatkeeper tips featured this month:
- More Electronics from past issues.
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