different between warm air and fresh air
Answers
Answer:
Warm-Air Heating
Because of its low density, air carries less heat for shorter distances than do hot water or steam. The use of air as the primary heat conveyor is nevertheless the rule in American homes and offices, though there has been a growing preference for hot-water systems, which have been used in European countries for some time. The heat of the furnace is transferred to the air in ducts, which rise to rooms above where the hot air is emitted through registers. The warm air from a furnace, being lighter than the cooler air around it, can be carried by gravity in ducts to the rooms, and until about 1930 this was the usual method employed. But a gravity system requires ducts of rather large diameter (20–36 cm [8–14 inches]) in order to reduce air friction, and this resulted in the basement’s being filled with ductwork. Moreover, rooms distant from the furnace tended to be underheated, owing to the small pressure difference between the heated supply air and cooler air returning to the furnace. These difficulties were solved by the use of motor-driven fans, which can force the heated air through small, compact, rectangular ducts to the most distant rooms in a building. The heated air is introduced into individual rooms through registers, grilles, or diffusers of various types, including arrangements resembling baseboards along walls. Air currents through open doors and return air vents help distribute the heat evenly. The warm air, after giving up its heat to the room, is returned to the furnace. The entire system is controlled by thermostats that sample temperatures and then activate the gas burner and the blowers that circulate the warm air through ducts. An advantage of forced warm-air heating is that the air can be passed through filters and cleaned as it circulates through the system. And if the ductwork is propery sized, the addition of a cooling coil connected to suitable refrigeration machinery easily converts the system to a year-round air-conditioning system.
Explanation: fresh air
the air outside, esp when considered good for you because it does not contain dirt or dangerous substances
You should go outside and get some fresh air.
'Let's take the baby outside,' I suggested. 'We all need some fresh air.'
I need some fresh air.
Take exercise, preferably in the fresh air.
This campaign they remain a breath of fresh air due to the honesty of their manager.
Times, Sunday Times (2016)
Keep calm and get some fresh air.
Times, Sunday Times (2016)
She did her work there in ondon near her the fresh air.
The Sun (2016)
Remember the healing qualities of fresh air.
The Sun (2016)
Take the short walk down to the beach or a stroll out into the country for a breath of fresh air.
The Sun (2017)
The fresh air is good for you too.
The Sun (2009)
You talk about needing to stretch your legs and get some fresh air.
Times, Sunday Times (2015)
We went outside for a bit of fresh air before going to bed.
The Sun (2014)
It was very hot in the club so we decided to go outside for some fresh air.
The Sun (2014)
You need some fresh air in this relationship.
The Sun (2009)