Why do closed hydronic systems include pressure-relief valves, ...

[maegan_martin]

Why do closed hydronic systems include pressure-relief valves, expansion tanks, and temperature and pressure-limiting devices?
 
  A) Because the copper piping used in the system requires these measures
  B) Because freezing must be prevented and antifreeze may not be added
  C) Because building codes require certain controls on every system
  D) Because water expands and contracts as its temperature changes

Question 2

What smoke spot number represents correct combustion in newer burners?
 
  A) 1 or less B) 1 or more C) 0 D) 2 or less

[ilianabrrr]

Answer to Question 1

D

Answer to Question 2

A

[maegan_martin]

Excellent

[tranoy]

Gracias!