ASHRAE Journal - September 2024 - 48

TECHNICAL FEATURE
FIGURE 5 Basic application of primary-secondary to the system shown in Figure 4.
20 Branches Total
20 ft PD
30 Branches Total
27 ft PD
20 Branches Total
20 ft PD
and minimize
early failure of
components known
as " normal wear
items. " Therefore,
a thorough
32 ft PD
(5 ft + 27 ft)
20 ft PD
Secondary
S/R Risers
Primary
Mech Room
Source
Avoiding Common Pitfalls to Ensure
Responsible System Design
With the expectation that low site energy use
intensity (EUI) building design will become mandatory,
balancing first-cost and the cost of lowering energy
use is an obstacle designers face in this emerging era of
decarbonization, electrification and sustainability.
Design errors and improper system control strategy
setup can erode the potential operating efficiency of
hydronic HVAC systems. Taking the following proactive
steps can help avoid common system design mistakes:
1. Take full advantage of a manufacturer's knowledge
base. While water is one of the most efficient fluids
for the transfer of Btus, many applications require the
use of other fluids, such as propylene and ethylene
glycol. As more and more design professionals use
manufacturer's equipment selection programs on
their own, assigning incorrect or extreme fluid
properties when selecting equipment such as pumps,
heat exchangers and heat transfer coils has led to
system performance issues that may not be identified
until the equipment has been installed. Having a
manufacturer's representative validate selections prior
to being placed in an equipment schedule is a good
practice to catch oversights at no cost.
2. Follow proper maintenance. Design professionals
must evaluate routine maintenance requirements
based on the operating environment the equipment
will be subjected to, as well as the level of expertise
of the maintenance staff tasked with system and
equipment upkeep. System fluid quality must be
considered to maintain performance, prevent fouling
48
ASHRAE JOURNAL ashrae.org S E PTEM B ER 2024
Common Pipe
20 Branches Total
25 ft PD
ASD
60 ft PD
High PD
Tertiary Zone
Common
Pipe
water treatment
and filtration
program should be
established.
3. Use industry
tools. HVAC tools
like equipment
selection and system
design software are
necessary to ensure proper piping system design.
4. Embrace industry education and training
opportunities. Learning about new and emerging
technologies and how to effectively embrace hydronic
HVAC system design is vital. This is especially
apparent as HVAC contractors struggle to attract young
professionals to address the growing skilled technician
shortage, making robust industry education and
training opportunities essential to retain and prepare
the next generation.
Making the Case for Hydronics
When it comes to achieving decarbonization goals
through retrofitting, hydronic systems can deftly
accommodate energy source upgrades due to their
flexibility and long system life. Installing hydronicfriendly
energy sources like water source heat pumps
allow for easy building upgrades and future additions
without replacing all existing equipment because of
the mandatory changes to new refrigerants on all new
equipment manufactured after Jan. 1, 2025.
As the building sector moves away from gas-fired
boilers toward water-source heat pumps, hydronic
systems provide an adaptable, efficient delivery of
heating and cooling, regardless of the source, and
are already compatible with a wide range of energy
sources, including refrigerant-based, thermal and
electric heating and cooling sources. What's more,
water can transfer heat 24.17 times faster than air,
proving itself as a far superior heat absorbing material.
Water is a natural refrigerant with a zero or near-zero
global warming potential (GWP). Additionally, water's
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