CHILLER COMPRESSORS

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 CHILLER COMPRESSORS In HVAC industry, the refrigeration machine that produces chilled water is referred to as a “Chiller”. A chiller package operates either on the principles of vapor compression or vapor absorption. The vapor compression system uses mechanical energy in the form of electric motor to drive the cooling cycle whereas absorption chillers use heat to drive the process. The vapor compression chiller system, which is far more prominent in commercial buildings, consists of four major components: the compressor, evaporator, condenser and expansion device all packaged as a single unit. The classification of vapor compression chiller packages is generally by the type of compressor: centrifugal, reciprocating, and screw being the major ones.                                                        Chillers are the largest consumer of energy in a commercial building and it is therefore important to understand the relative benefits and limitations of various types in order to make t
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Heat Recovery Ventilation

 

HEAT RECOVERY VENTILATION

Introduction of Heat Recovery Ventilation(HVR) :-

            An HRV is a mechanical ventilation device that helps make your home healthier, cleaner and more comfortable. It does  by continuously replacing the indoor air with fresh outdoor air. Their ability to exchange heat between the supply and exhaust air reduces the cost of heating or cooling of fresh air circulating through the home. HRVs are sometimes called air-to-air heat exchangers because they preheat or cool incoming air using exhaust air.
                                                                    There are many types of HRVs on the market, as well as different installation strategies. That depends on the size of your house, type of heating system and geographical location.

Mechanical Ventilation:-

The new homes are built to be airtight. This limits the uncontrolled flow of air in and out of the home and reduces heat loss and moisture damage to the building structure.

To complement this airtightness and ensure a healthy living environment, modern homes use a mechanical ventilation system to remove pollutants from the home by replacing indoor air with fresh outdoor air.

In most homes, the mechanical ventilation system is an HRV. This system allows fresh air to be distributed throughout the house. A properly installed, operated and maintained HRV exhausts indoor air pollutants and excess humidity to the outdoors while distributing fresh air throughout the house. During the heating season, the HRV captures heat from the outgoing air and uses it to preheat the incoming fresh air. During the cooling season, an HRV can reverse this heat-exchange process, removing some of the heat from the incoming air and transferring it to the outgoing air.

Component of Heat Recovery Ventilation System(HRV):-

  1. Insulated ducts for incoming (fresh) and outgoing (stale) air, with exterior hoods.
  2. Ductwork to distribute fresh air throughout the home and to return stale air to the HRV
  3. Fans to circulate air throughout the home and to exhaust stale air to the outdoors.
  4. A heat-exchange core, where heat is transferred from one air stream to the other.
  5. Filters to keep dirt out of the heat-exchange core.
  6. A drain to remove any condensation from inside the HRV (may not be required with all models)
  7. Operating controls to regulate the HRV according to ventilation needs.

Need of Balanced System:-

HRVs are designed to operate in a balanced state – the same amount of air should be drawn into the home as the amount being exhausted. An unbalanced system results in poor airflow and poor heat recovery. It can also lead to other problems, including an undesirable, continuous air-pressure difference between the inside of your home and outside.





Operation of Your HRV:-

The operating controls include the following functions, depending on the installation and HRV model.

  1. Speed controls for the ventilation rate.
  2. A circulation mode setting, which circulates air inside the home but does not exchange indoor and outdoor air.
  3. A de-humidistat that will trigger the HRV into high-speed operation when the humidity level in your home reaches a pre-set level.
  4. A timer, which can be set to run the HRV at high speed for specified intervals.
  5. An intermittent exchange mode setting that automatically turns on the HRV at low speed for specified intervals.
  6. Pollutant sensors that increase the ventilation rate when pollutant levels in the home rise.
  7. A maintenance light, which comes on automatically when the filters, and possibly other components, need to be cleaned or serviced.

Low Speed Operation:-

To ensure the removal of indoor pollutants and the supply of fresh outdoor air, an HRV should be operated on low speed.

High Speed Operation:-

Under certain conditions, the ventilation rate in your home may need to be increased from low-speed operation. High-speed operation is often needed in the kitchen and bathrooms.

Heating Season Operation:-

Most HRVs feature an automatic defrost mode that activates when the temperature of the incoming fresh outdoor air is below -5°C. A defrosting mechanism is required in cold climates because, as the heat is extracted from the home’s outgoing moist air (to warm the incoming fresh air), the temperature of the outgoing air drops to the point at which moisture or frost can form on the surfaces of the heat-exchange core. A build-up of frost can block airflow through the HRV.

Non-Heating Season Operation:-

The best strategy is to operate your HRV continuously year-round, even during the non-heating season. Except for adjusting the de-humidistat setting, operation should be essentially the same as during the heating season.

Maintenance Steps :-



DISCONNECT THE ELECTRICAL POWER BEFORE SERVICING YOUR SYSTEM.
  1. Clean or replace air filters.
  2. Clear the exterior intake and exhaust vents of obstructions.
  3. Clean the heat-exchange core.
  4. Clean the condensate drain and pan
  5. Service the fans
  6. Clean the grilles and inspect the ductwork
  7. Arrange for annual servicing.


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