Unit 11: Building Environmental Systems & Controls

Question 1

Hygroscopic

Answer 1

Hygroscopic refers to a matter’s ability to adsorb and absorb water from the surrounding environment.

Question 2

Why do hydronic systems need expansion tanks?

Answer 2

1) As water is heated it expands. To prevent excess pressure buildup, the hot water expands into the expansion tank
2) As the water cools down it contracts. The expansion tanks keeps the system properly filled.
3) Prevents wasting making up water to account for the expansion and contraction

Question 3

Hot Water Heating Systems use these chemicals to remove corrosive inducing substances? These alkaline solutions can be circulated through the system for serval hours to lower acidity.

Answer 3

1) Trisodium Phosphate
2) Sodium Carbonate (Soda ash)
3) Sodium Hydroxide (Caustic Soda)

Question 4

Hydronic System Filling and Startup

Answer 4

1) Vent all air/open vents
2) Close drains
3) Admit Water at the required pressure for the highest points in the systems
4) Make sure expansion tank level is 1/2 full or less on gauge glass
5) Startup power to circulating pumps and boiler
6) As the system warms up more air is vented
7) Put into Automode

Question 5

Considerations When using Antifreeze with Hydronic Systems

Answer 5

1) Make sure antifreeze is not corrosive to system piping material
2) Antifreeze expands more requiring a larger expansion tank
3) Antifreeze is sending then water, so requires more power to pump
4) Antifreeze does not carry as much heat as water so it requires higher operating temps to achieve the desired outcome
5) Antifreeze should not be directly circulated through the boiler, instead, a heat exchanger should be used

Question 6

What is the purpose of ventilation?

Answer 6

its to remove contaminants from the building air such as dust, CO, CO2, odors and high humidity.

Question 7

Air changes per hour?

Answer 7

This is defined by how many times per hours the total volume of air in the building is replaced or exchanged.