Reheats - The Forgotten Coil

I published this last year and due to the amount of reheat coils we are cleaning currently, i thought this was relevant.

Often trapped in the dark air duct, with little to no access, reheat coils can get clogged and impede air flow to the entire supply air system.

These coils whether they are hot water, steam or electric get dirty, often out of sight and out of mind. Many clean the evaporator/cooling coils but do not think about the reheat coils. Reheat coils control the final temperature and humidity to a selected space, when dirty they affect the measured amount of air flow to that space. They can also affect the overall hygiene of the hvac system - i have viewed suspected microbial growth on these coils.

Pictured above: 1970's hospital air handlers with steam reheats after the supply air fan. I asked have they ever been cleaned? Reply: they are cleanable? Terrible access with no provisions to wet clean is the problem. Client complaint - temperature, humidity and air flow problems.

Solution: Deep clean and treat the fan assembly, water cooling coil sets, create access to the outgoing side of the reheat coils, crawl inside the supply air duct to gain access to the incoming side of the reheats, deep clean reheats with surfactant, power rinse, mastic and close openings, new stick pin fasteners, re-insulate and tape.

Proper installation is part of the battle, operations and maintenance is a huge part of the system.

Your telling me that in 40 years of operation nobody thought to clean the reheats?

It comes down to knowledge and devising a way to clean them, the coils had some visible dirt, but where mostly covered with grease from the supply air fan bearings. The return air side of this unit is pre and hepa filtered, cooling coil was dirty, fan set dirty as well.

The results: proper air flow and pressurization to the space! They gained better temperature and humidity control resulting in slowing down of the fan speeds.

Does your hospital or facility have hidden reheat coils

Lets have a conversation about cleaning them.

Robert Rizen