Design Considerations for Hydronic Pump System Design - a PDH Online Course for Engineers

Design Considerations for Hydronic Pump System Design

Course Outline

This 5-hour course provides design considerations for hydronic pump systems. Although pumps are typically purchased as individual items, they provide service only when operating as part of a system. Pump systems are often designed and operated inefficiently. This course attempts to show the relationships between the components that make up the pumping system with generic references to air-conditioning applications so that the reader can appreciate the nuances for any application. A little extra effort in the system design can make a safe & efficient system.

This course is suitable for students, architects, system engineers, energy auditors, facility designers and O&M professionals.

This course includes a multiple-choice quiz at the end, which is designed to enhance the understanding of the course materials.

Learning Objective

At the conclusion of this course, the student will:

Be able to understand the pump system terminology;
Be aware of the various pump system design configurations; and
Be able to design the right pumping system

Course Introduction

The pumps are used everywhere may it a building, industry or a process application. In commercial buildings for instance, pumps are used to move fluids.

1. Chilled water through the chiller(s) and air-handling units
2. Cooling water through the condenser and cooling tower
3. Pumping of hot water systems for HVAC and plumbing
4. Water supply from a source to an overhead tank or pressure tank
5. Drainage from basin to the main drainage lines
6. Sewage from a sump to the main sewer lines and
7. For fire fighting applications

Procurement costs of the pumps in general amount to less than 1% of the total investment of a plant, yet the operational quality of a pump may be the decisive factor in the overall running costs. Pumping system operation is expensive. The reasons will vary from process to process and application to application, but the constant outcome is the cost to industry through wasted energy, which runs into millions of dollars every year, and the cost to the environment through the generation of this wasted energy.

According to the Hydraulic Institute:

5% of industrial energy goes to pumps.
Pumping systems account for nearly 20% of the world's electrical energy demand and range from 20% to 25% of the energy usage in certain industrial plant operations.
Energy consumption is 90% of the total cost of owning a pump.

It is important to note that an efficient system design is established more by those concerned with system design, installation, balance and operation than by the pump engineer.

Course Content

The the course content is in a PDF file Design Considerations for Hydronic Pump System Design. You need to open or download this document to study this course.

Course Summary

Pumps are not the biggest consumers of energy, but they're not the smallest either. A little extra effort in the system design and equipment selection can make a worthwhile difference. The complexity associated with selecting a pump often results in a pump that is improperly sized for its application. Selecting a pump that is either too large or too small can reduce system performance. Under sizing a pump may result inadequate flow, failing to meet system requirements. An oversized pump, while providing sufficient flow, can produce other negative consequences:

Higher purchase costs for pump and motor assembly
Higher energy costs, because oversized pumps operate less efficiently and
Higher maintenance requirements, because as pumps operate further from their BEP they experience greater stress

Ironically, many oversized pumps are purchased with the intent of increasing system reliability. Unfortunately, conservative practices often prioritize initial performance over system life cycle costs. As a result, larger than necessary pump are specified, resulting in systems that do not operate optimally. Increased awareness of the costs of specifying oversized pumps should discourage this tendency.

In systems that experience wide variations in demand, pumps are sized for the maximum anticipated flow rate and the system efficiency depends on configuring a pump or set of pumps. The most frequent means of varying the pump performance to have a line which re-circulates flow back to the suction tank. Another method is to have a valve in the discharge line, which reduces the output flow rate when throttled. Either method works well, but there is a penalty to be paid in consumption of extra power for running a system, which is oversized for the normal demand flow rate. A solution to this power waste is to use a variable speed drive (VSD), which yield good payback in majority of applications even though the capital expenditure is relatively high. The implication of the squared and cubic relationships of head and power absorbed is that relatively small changes in speed give very significant changes. VSDs provide power savings at a cubed rate.

To handle wide variation in flow, multiple pumps are often used in parallel configuration. This arrangement allows pumps to be energized and de-energized to meet system needs. One way to arrange pumps in parallel is to use two or more pumps of the same type. Alternatively, pumps with different flow rates can be installed in parallel and configured such that the small pump - often referred to as the pony pump operates during normal conditions while the larger pump operates during periods of high demand.

In general, the following should be remembered:

Match the pump type to the intended duty
Don't oversize the pump
Match the driver type to the intended duty
Specify motors to be high efficiency
Adjustable-speed pump drives provide deep energy savings, but aren't appropriate everywhere.
Incorporating primary/secondary and even tertiary piping loops facilitates load matching, increasing energy savings.
Match the power transmission equipment to the intended duty economic impacts of pipe sizing and valve selection are important. Bigger pipes and low-loss valves reduce operating costs significantly.
Evaluate system effectiveness
Monitor and sustain the pump and system to maximize benefit
Consider the energy wasted using control valves
Install and operate pumping systems on manufacturer's guidelines and established best practices.

Once you finish studying the above course content, you need to take a quiz to obtain the PDH credits.

DISCLAIMER: The materials contained in the online course are not intended as a representation or warranty on the part of PDHonline.com or any other person/organization named herein. The materials are for general information only. They are not a substitute for competent professional advice. Application of this information to a specific project should be reviewed by a registered professional engineer. Anyone making use of the information set forth herein does so at their own risk and assumes any and all resulting liability arising therefrom.