Fan Coils 101 Webinar

This webinar provides a great background on fan coil products

[@eulaliorodriguez5325]

Thank you for sharing this video.

[@user-sm9hh9hz8j]

أحسنت ، Well done .

[@mohammadalshaikhhasan5091]

Thanks , well explained. What about the child water pressure drop ? How they affect the efficiency and cooling capacity?

[@TitusHVAC]

As the pressure drop increases or decreases it won’t have an effect on the coil’s cooling capacity. However if a designer were to increase the number of circuits inside the coil to lower a high internal pressure drop then the coil’s cooling capacity would decrease. This is because the cold water will spend less time inside the coil which decreases the time allowed for heat transfer between water and fin block. Note that high pressure drop levels inside coiling coils does decrease the efficiency of the overall building’s plumbing system. The reason is that as that coils with high pressure drops increase the size (therefore increasing cost and energy usage) of the building’s pumps to circulate water in the building’s water system.

[@mikes1615]

I live in a building with vertical fan cool units. In winter, the instructions are - Keep the window in the unit closed and don't keep the sliding door open, even by half an inch. The sliding door is next to the FCU. Apparently, the cold air can cause the coil to rupture, and leak uncontrollably. Coil rupture has happened on more than one occasion. Is there a solution for this apart from keeping the windows and doors closed in winter? Are coils available that can withstand these "extreme" conditions and is there a way to automatically shut off water if there is a leak?

[@TitusHVAC]

As a person might imagine the situation that is occurring is the cold air from outside the building is causing the temperature inside the Fan Coil to drop to below the freezing point. This in turn causes the water inside the coil to freeze, expand and burst the thin copper tubes inside the coil. There are water coils constructed with thicker copper tube walls that are meant for Steam applications. While using this type coil might give a little bit more strength to the coil, it wouldn’t make much of a difference when compared to the amount of force water exerts when freezing and expanding. As we can imagine the best solution is to prevent the coil from being exposed to the cold air in the first place. However this is very difficult because generally we must rely on people (occupants of the room with the Fan Coil) to not let cold air reach the coil. It sounds like this has been a problem in several situations in the past for this building installation. Another helpful strategy is to introduce a type of glycol (usually Ethylene or Propylene) to the Fan Coil water system. These glycol’s act like ‘anti-freeze’ and help reduce the chance of water freezing. Please consult a building design engineering consultation firm before doing this as adding glycol will impact every pipe and piece of equipment that comes in contact with the glycol throughout the building’s plumbing. In addition glycol cannot come in contact with any type of water that a person or animal might touch/consume as it can cause serious harm and even death. In addition not all building systems are compatible with glycol which can cause damage to equipment and the amount of glycol to be used must be precisely calculated as well. Another good strategy is to not allow the water in the coil to freeze by keeping it ‘hot’. This means always allowing hot water to flow through the water coil even when the thermostat and fan are not calling for hot air to be supplied to the room. The hot water valve must remain open at all times to keep the hot water (usually 140 to 180 degrees F) from the boiler flowing through the coil at all times. This can be accomplished by sophisticated thermostat control systems that will always command the hot valve to stay open regardless of room temperature. Also manually locking the hot water valve in the ‘open’ position will accomplish this strategy. The potential drawback of this strategy is overheating of the room (even if the fan isn’t running) or causing the sheet metal housing of the fan coil itself to heat up and cause harm to anyone or anything that touches the fan coil (i.e. a person touches the front panel of the fan coil and burns their hand). This strategy should be experimented with in one Fan Coil room for effectiveness and safety before implementing building wide.’

[@mikes1615]

@@TitusHVAC Thank you for your quick detailed response. Fan coil ruptures occurred in 2 units on 2 separate days in January. In one case, water damage extended as far down as the ground floor (6 floors below the unit with the ruptured coil). The building is only about a year old. With this very important protective function left for a human being to perform, more ruptures are likely. The sliding door opening is only about 1 foot from the fan coil unit. If the door opened from the other direction (left to right instead of right to left), the opening would have been 6 feet from the unit, providing a better level of protection. *Two Observations* According to the manufacturer's data: (a) The units are equipped with 1 kW auxiliary heaters to provide heat during the Spring and Fall when the systems are in cooling mode. (b) The units are equipped with a temperature sensor that causes the unit to enter anti-freeze mode when air entering the unit falls below 4C/40F. Anti-freeze mode circulates hot water through the coil and shuts down the fan to reduce cold air flow *Questions* (1) Shouldn't item "b" above have prevented coil rupture? (2) The temperature sensor ties into a digital controller which activates a relay that brings in the heater. Can't the temperature sensor be used to turn on the auxiliary heater when the temperature drops to 4C/40F and maybe also activate an alarm?

[@TitusHVAC]

@@mikes1615 It would be best for you to contact our fan coil specialist at [e-mail].