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Shelter HVAC

When it comes to HVAC conditioning Openchannelflow fiberglass equipment shelters there are two options:  Active and Passive.

By default, each Openchannelflow shelter is a mix of both, with the standard following HVAC equipment / features:

  • 2-inch (R~14) insulation
  • 585 CFM exhaust fan with screened hood
  • 1,500 watt heater with thermostat
  • Fiberglass intake shutter with screened hood


Heat in Openchannelflow shelters is provided by a low profile, wall mounted, line powered 1,500 wattt heater (with integral thermostat).    As an option, the heater(s) can be:  larger, redundant, baseboard style, and wash-down rated.  Let us know what you'll need and we'll provide it.


Openchannelflow provides good R-values in all our our shelters.  Our insulating core is twice as think as competing shelters and provides an R~14.  However, should greater R-values be needed, the insulation can be increased in 1 and 2-inch (R~7 and R~14) increments in the roof and / or walls.


Ventilation can be active, passive, or hybrid as needed.


Active Ventilation

exhaust fan in a fiberglass equipment shelter manufactured by OpenchannelflowEquipment shelters usually include an exhaust fan (mounted high) and intake shutter (mounted low).  The idea is to exhaust hot air (high) from the shelter while drawing in cool air (low).  Activation of the fan is typically done by an exterior mounted switch or thermostat (or a combination of the two).

This arrangement works fine for most application, but for chemical (gas) feed / storage applications where the gas is heavier than air, the fan / shutter need to be swapped (fan low / shutter high) or the operation of the fan and shutter need to be reversed (intake fan / exhaust shutter).

Where the environment / gas is corrosive it's common to have the fan operate as an intake mode (mounted high) and the shutter as an exhaust mode (mounted low).  This keeps the electrical components of the fan protected as much as is practical – although it may still need to be of a corrosion resistant design.

In addition to fan / shutter systems, Openchannelflow also offers air conditioners and heat pumps.  These units are available in sizes from 5,000 BtuH to 3 tons and can be either open or closed looped systems.  For hash environments, the units can have protective coating applied to their coils or can be fabricated from stainless steel.

Passive Ventilation

Where heat load is not as great a factor – or where chemicals are not being stored – passive ventilation may be desired.  Passive ventilation is less expensive than active ventilation and it's suitable for sites where power isn't available or expensive to bring to the site.

adjustable ventilation louver mounted in Openchannelflow fiberglass equipment shelter

A typical setup for passive ventilation is to mount two adjustable louvers on the gable ends of the shelter to allow heat to escape the shelter.  Adjustable shutter are preferred over fixed louvers as they can be closed off during colder months.

Fixed or adjustable, most louvers are designed in such a way that the rain should shed off them under most conditions.  Coast installations may, however, require dedicated rain hoods over the louvers.  In these cases the louvers are usually mounted on the eve sides of the shelter as there is typically not enough room at the gable ends to accommodate a rain hood (particularly above the shelter door which is also typically mounted on a gable end).

Hybrid Ventilation

hybrid ventilation on an Openchannelflow fiberglass equipment shelter

Falling between active and passive ventilation is hybrid ventilation. Here ventilation is provided by wind action over a specially designed louver.

While unpowered, with wind the louver draws air out of the shelter (up to 350 ft3/hr with 6 mph wind).  The amount of ventilation is directly related to the wind speed over the shutter.

No power is needed - however, without wind, there is no active ventilation with this option.

With wind, the amount of ventilation is controlled by a plunger system on the inside of the shelter.

  • Push the plunger in and the amount of ventilation is reduced (or stopped altogether)
  • Pull the plunger out and the wind-powered ventilation is maximized (as is the passive ventilation if no wind is present)

Air Conditioning

thru-wall air conditioner mounted on a fiberglass equipment shelter buildingWhen additional cooling is need, a variety of air conditioners can be integrated into the shelter.

Depending upon the cooling requirement, the unit can be a simple thru-wall unit or a large, on-wall unit.  Note that normally when an air conditioner is added, the standard exhaust fan and vent are removed to avoid the possibility of the fan coming on and evacuating all the conditioned air.

Thru-wall air conditioners usually range in size from 5,000 to 25,000 Btu and each unit includes on-unit digital controls and thermostat.  Each unit is powered by its own dedicated 120 or 240 VAC outlet.

1 ton Bard air conditioner mounted on an Openchannelflow fiberglass equipment shelter

On-wall units are available in sizes from 1 ton to 4 tons. These units can incorporate heat strips, coil corrosion protection for harsh / corrosive environments, and customizable climate controls.  Unlike thru-wall units, the on-wall air conditioners are line powered.