Heat Pump Coil Coatings
Heat Pump Coil Coatings
Heat Pump Coil Coatings & Corrosion Protection.
Heat pump coil coatings come as either pre or post manufacture for evaporator coils that are used in the HVAC & Heat Pump markets.
Heat pump coil coatings all provide a degree of protection covering different potential uses. The most common coatings used in today’s heat pump systems standard gloss cover and the blue coating (also known as Blue Fin Coating). However more advanced heat pumps now use hydrophilic coatings or Epoxy coatings (sprayed on or for best performance dipped).
Toyesi heat pumps have used the “Baked on Dipped Epoxy Coating” as its preferred coating for over 10 years now. Best suited to any project where saltwater spray may be common, such as by the ocean, or for projects that use salt water such as in aquaculture.
Coil Coating Guide
Low End Corrosion Protection
Natural or Standard Finish: A natural finish is an uncoated coil, where a standard coils has a clear water-based gloss clear finish, which is sprayed onto the coil after manufacture.
It prolongs the life of heat exchange coils in general working environments. Better suited for office environments or high humidity environments.
Blue Fin Coating: Blue Fin is a high performance aluminium foil manufacturers gloss finish that is specifically designed for application to aluminium. Blue Fin appears as an anodized finish with a gloss blue tone that remains flexible.
The manufacturer applies Blue Fin to the raw aluminium fin stock. Therefore, only the fins of the coil are coated. All other parts of the coil are natural finish. Thus, open to environmental conditions.
Also during the stamping process of the coils there is a chance that the edges of the fin cuts are still exposed and can corrode the coil from the inside. Often an additional cleat spray coat is advised to prevent this from occurring.
Blue Fin is ideal for refrigeration heat exchange coils where they might be exposed to mild coastal conditions or mild hazardous industrial or commercial environments.
It is also the main coil protection used for heat pumps in today’s marketplace due to its low-cost verses level of protection.
Blue Fin coatings are not suitable in mining, industrial applications or any highly salty or coastal application. It is recommended no loser than 2 km from the coastline, or where contaminants are > 100ppm or Where pollution is over 125ug/m3 (especially SO2 levels.) Blue Fin coats do not pass the ASTM B117 Natural salt spray test for exposures over 500 hours.
High End Corrosion Protection
Hydrophilic Coating: A hydrophilic substance is a polar substance that attracts water molecules and has a strong affinity for water. The term hydrophilic means any substance that loves water, and is the opposite of hydrophobic, which is a substance that is water fearing, i.e., repels water in a practical sense.
The coating is usually applied after the coils manufacture, giving a superior overall protection over blue-fin coatings. Thus may not require additional coatings
The advantages with this coating is that is spreads condensate evenly all over the coil surface, enabling better heat transfer and unimpaired air movement. Creating highly efficient coils.
However, when in a corrosive environment with high salt or acid content or high turbulent air flow, it is far better to move to an epoxy coating. This is because the acidic or salty water is held onto the coils for prolonged periods increasing corrosion potential.
Other issues associated with a hydrophilic coat is that any moisture held onto the surface can increase the likelihood of mould and bacteria growth. All hydrophilic coatings should have anti-bacterial additives added into the mixture or added as an extra topcoat. Thus these types of coats are not suitable in food or medical applications.
Epoxy Coating: the Epoxy Coat is a high-performance two-part epoxy-based finish, that is designed for application to aluminium, copper, and other non-ferrous metals. Epoxy coats are usually blue, blue-green or green in colour.
Unlike Blue Fin Coating protection, Epoxy coats are usually applied after construction of the evaporator coil. The advantage of this coating is that there are no exposed or natural areas in the fins or pipework. Significantly reducing corrosion potential over most other corrosion protection forms.
Epoxy coatings can be applied cheaply as a sprayed on coat, or as an immersed (dipped) coat. Dipped epoxy coating is far superior as it will fill any gaps and give a complete coil protection. Epoxy coats can be air dried or baked on. Baked on coats have additional impact and corrosion protection.
Toyesi has been using Baked On Epoxy Coated Coils, for 10 plus years, due to the superior handling of salty environmental conditions and that it cannot be scratched off or chipped. A little dearer but a great investment.
Advanced Corrosion Protection
Toyesi’s New E-Coated Coil Range. Hydrophobic Coating Technology
E-Coat: The E-Coat provides superior protection against many corrosive environments. The coils have an extremely durable and flexible epoxy coating uniformly applied all over the coils’ surface for complete isolation from the contaminated environment and is one of the most effective means of corrosion protection available and is considered the benchmark for corrosion resistance. Passing over 6,000+ hours during ASTM B117 salt fog testing.
A consistent coating is achieved through a controlled electro-coating process that bonds a thin impermeable epoxy coating to all the coils surfaces. Comes with all the benefits of our dipped baked on epoxy coated coils, with the additional UV top-coating on its surface.
Offering a superior corrosion protection and increased thermal conductivity.
It is a treatment particularly important for extremely corrosive environments, like highly polluted urban areas and highly corrosive coastal and industrial areas.
E-Coat is not cheap to due to the extensive application process, however in highly corrosive environments the investment more than pays for itself.
Toyesi can offer this solution, whoever is currently as a special order situation.
Other Coating Types & Brands
D-Coat: Is a treatment that is slightly hydrophobic and also contains anti-bacterial properties. Which makes the coat an ideal additive for HVAC systems.
Blygold (brand name): is a polyurethane coating sprayed onto the coil after manufacture. Ideal for chemical & UV resistance. Or a water based hydrophobic coating. Great as additional aftermarket coil coatings, often used by superior air-condition companies as a value add product.
Technicoat (brand name) – is an air-dried resin based thermoplastic top coat over a phenolic coating. Ideal for salt water environments holding up to 1500 hours in testing.
Heresite: is a baked on phenolic coating and dark brown in colour.
Blue Coat Epoxy or Thermoguard (brand name): is a blue epoxy coat that is exceptional at resisting the adhesion of dirt and dust. Similar to epoxy coating mentioned above. Sits between Blue Fin and Epoxy for rating purposes. Easy to tell that the coil will look coated right to the tube ends, where blue fin is just the coil fins coated.
Esgard (brand name): is a general base coating and is a wax-alkyd coating. Very general purpose type of coating.
Coatings Make The Difference
Assorted images taken from the web to serve as examples only.
Coil Coating Summary
There are many choices in Heat pump coil coatings and each comes with a benefit to cost ratio.
Blue coat is a low cost and provides protection for most domestic and low end commercial applications. However, as soon as you move into commercial grade applications, coastal, or corrosive conditions, they may just not stack up to the level of protection required. Providing many expensive repair bills.
High end heat pump coil coatings just may be the best way to go from the get go. A little dearer to start with, but well and truly pay for them selves long term.
Toyesi produces a premium quality heat pump solution and thus invested in the Backed on Epoxy option. Knowing that our systems can be installed in most situations from salt water and coastal locations through to plant room applications.
Sample collection of Toyesi & Trident Heat Pumps and Chillers..
If you want to now how Toyesi can help you and your water or pool heating project increase energy efficiency, reduce running costs or minimise your waste energy then give us a call.