SHI Solar Thermal System Design & Components 5

Question 1

Which SRCC (Solar Rating and Certification Corporation) document certifies the thermal performance of individual solar collectors?

Accepted Answer

OG-100

Answer

SRCC OG-100 certifies the thermal performance of individual solar collectors based on ASHRAE 93 test protocols, while OG-300 certifies complete solar water heating systems.

Question 2

What effect does increased propylene glycol concentration in a solar collector loop fluid have on system performance?

Accepted Answer

It lowers freeze point but also reduces specific heat capacity and increases viscosity, slightly reducing heat transfer

Answer

Higher glycol concentrations lower the freeze point but also reduce the fluid's heat capacity and increase pumping resistance, so concentration should be no higher than necessary for the local climate.

Question 3

In a solar thermal system serving a radiant floor heating application, why is a low-temperature collector configuration preferred?

Accepted Answer

Radiant floors operate at 85–120°F (29–49°C), allowing collectors to run at low temperatures with higher efficiency

Answer

Since radiant floor systems use relatively low supply temperatures (85–120°F), solar collectors can operate near this range, keeping collector efficiency high because heat loss to the environment is minimized.

Question 4

What is the purpose of an automatic air vent installed at the high point of a solar thermal collector loop?

Accepted Answer

To automatically release trapped air that accumulates at the system high point

Answer

Air naturally migrates to high points in a hydronic loop; an automatic air vent releases it before it can form an airlock that stops circulation.

Question 5

According to ASHRAE 93 testing, what two collector parameters define the linear efficiency curve?

Accepted Answer

Optical efficiency (y-intercept) and first-order heat loss coefficient (slope)

Answer

The ASHRAE 93 linear model characterizes a collector by its zero-loss optical efficiency (η₀) and its first-order heat loss coefficient (a₁), which together define efficiency at any operating condition.

(SHI) Solar Heating Installer Certification Practice Test

(SHI) Solar Heating Installer Certification Practice Test

SHI Solar Thermal System Design & Components 5