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Questions tagged [hvac]

Questions about air heating, ventilation, and conditioning, including indoor air quality (IAQ).

139 questions
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What is the most efficient means of warming a building with a high ceiling?

Consider a large auditorium, a church, or some other very large, essentially one roomed building with a high ceiling. Suppose that the building has many entrances which enable cold air in/hot air out and traffic in and out of the building is…
Paul
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Why does moving air feel cold?

I'm taking a thermodynamics class and had the following question. I was going to ask my professor directly, but it seems like a stupid question with a simple answer, so I thought I'd try my luck here in fear of embarrassment. When air flows through…
user01101001
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How do heat pumps output more heat kW than the electrical kW used to run the heat pump?

I understand that a 2 kW electric heater will use 2 kW of electricity and output 2 kW of heat (apart from small losses of energy as infra red, vibration etc.. but let's exclude those for this example as they are negligible). A 2 kW air source heat…
sam
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Why isn't heatpump technology used for solar collector panels and boiler tanks?

All solar collector and boiler tank systems that I can find on the market use a liquid to circulate the heat between solar collector panels (or PVT panels) and boiler tanks. Is there a reason why they do not use expandable gas and a compressor…
Louis Somers
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9
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Can air conditioners/dehumidifiers exhaust their waste heat in their exhaust water?

If I understand correctly, both air conditioners and dehumidifiers conventionally exhaust waste heat through their exhaust air, though both also produce exhaust water. I'd like to know, Are air conditioners or dehumidifiers currently being produced…
TomRoche
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Humidity in home is much higher than outside

We have a two year-old, two-story town house with: fiberglass insulation in the walls; a Tyvek vapor barrier under foam board on the exterior walls; blown cellulose insulation in the attic; stucco outside; and a refrigeration cycle air…
user13416
8
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1 answer

Air Conditioning Modes of Failure

I have a question about air conditioning and the probable modes of failure. I recently installed a Nest thermostat in my home. I've noticed that it seems to prefer to have the air conditioner's compressor on for multiple short durations instead of…
iAdjunct
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Is a 3 Hz beat frequency from my neighbor's HVAC a sign of a malfunction?

I'm being annoyed by a pulsating hum which comes from my neighbor's HVAC system. I read up a little on the design of HVAC systems and I came to a tentative conclusion that what I'm hearing is a compressor being driven by an AC induction motor. A…
Metamorphic
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How does a compressor know to lower condensing pressure in chiller?

I am working on an indirect ammonia chiller that is used to cool the ice in an arena. The system consists of 3 reciprocating compressors, an evaporative condenser with a vfd on the fan, a float throttling valve and a plate heat exchanger acting as…
Prevost
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Why do boiler exhaust stacks use tapered transitions?

We have a boiler exhaust stack with a base dimension of 120" ID and an overall height of 84'. 21' up, the stack begins a slow transition to 7'6" ID. The transition takes approximately 35' to reach its smallest diameter in the stack. In designing…
Lawrence
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Dead Load / Self Weight for ceilings & HVAC

I need to design the roof structure for a sports facility. I have no information with regard to HVAC design at this stage. Also, the HVAC may change in future. Thus I don't know what load to apply to the structure. I intend to give the HVAC and…
SlydeRule
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Where to insulate Underfloor air distribution system in a temperate climate

I have a proposed underfloor air distribution system (UFAD) for a one level office in a temperate climate. Typically the demand for heating and cooling in this climate is about even for offices. However the building is well insulated and has a fair…
pandita
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How do dry storage cabinets work?

In my lab we use a number of materials which are hygroscopic and must therefore be stored in a dry environment. For that purpose we have numerous dry cabinets very similar to the one shown below (Amazon link here). These cabinets run on…
Chris Mueller
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Why home Air Conditioning AC compressor insulated

Compressor is hot due to gas compression, and the gas then cooled in condenser. AC installed in tropical climate. Why compressor have insulation barrier?
RainerJ
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Is it feasible to build a pedal-powered air conditioning booth?

Imagine it's hot and humid outside. You see a pedal-powered air conditioning booth. You get in the booth, close the door, and start pedaling. The pedals are connected to a shaft-driven (automotive-style) air conditioning compressor via chain and…
Chris Martin
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