We all know that designing an efficient heating system is essential for your clients. So, we wanted to share a recent post from one of our top product lines, Patterson Kelley where they take a stand on the debate between variable primary or primary secondary piping and even offer a third, new option with their NURO® Touch Screen Control System.

 

Hydronic Boilers Piping Arrangements

Just like we would debate over sports, music, or politics, engineers have long held strong opinions about piping arrangements for hydronic heating systems.  Which is better:  Primary-Secondary or Variable Primary?  They each have their benefits, but most boiler manufacturers tend to side with Primary-Secondary.  Wouldn’t it be nice to have a different choice?

What is a Variable Primary Piping System?

In Variable Primary piping systems, there is one set of system pumps, generally piped in parallel, that distribute water through the heating equipment and terminal units.  Heat generated by the boilers is sent directly to the terminal units.  A Variable Primary piping arrangement can result in lower initial costs due to the installation of fewer pumps, less piping, less electrical, etc.  Variable Primary systems are generally considered to be more energy efficient. This is based solely on the concept that fewer pumps use less energy.  For any given installation these assumptions may or may not be true, but they are accepted when choosing between Variable Primary and Primary-Secondary piping arrangements.

What is a Primary-Secondary Piping System?

The Primary-Secondary piping arrangement includes two sets of pumps, system pumps and boiler pumps.  The system pumps distribute water to the terminal units and the boiler pumps circulate water through a loop that serves the heating equipment only.  The two piping systems are decoupled through what is commonly referred to as a “zero pressure bridge”, which hydraulically separates the boiler from the system. Traditionally, Primary-Secondary piping arrangements have meant full flow in the boiler loop and variable flow in the system loop.  Manufacturers tend to prefer Primary-Secondary because it ensures proper flow through the boiler.  Although a few manufacturers have boasted “Zero Flow” capabilities for their boilers, engineers know that no flow means no heat transfer; this begs the question, “why is the boiler firing?”  Engineers have begun to shy away from Primary-Secondary due to the perceived excessive pumping energy; but is that really the case?

A Third Option

With the advancement of on-board boiler controls like the NURO® Touch Screen Control System, there is now an additional option: Variable Primary-Variable Secondary.  The NURO® can vary the speed of your boiler pump, equipped with either a VFD or EC motor. As the boiler firing rate varies, the pump speed and flow adjust accordingly.  It’s the best of both worlds; flow rate ensured through the boiler, and energy savings associated with variable flow.  One might argue… “what about installation cost?”  Yes, there is slightly more piping associated with a Variable Primary-Variable Secondary piping arrangement, however, the installation cost is not significantly more.  Variable primary systems require a two-way control valve on each boiler to prohibit flow through an unfired boiler.  A boiler circulator with an EC motor is marginally more expensive than the control valve.

Next Step?

Interested in more information on the Nuro system and how it might help your clients? Give us a call at 800-355-7061 and we’d be happy to answer any questions or help you with the engineering specifications.

Patterson-Kelley recently published a blog post on innovation in boiler controls that we thought would be of interest to you. They are one of our most trusted lines of heat transfer equipment like boilers and water heaters. As you will see in the blog post, Patterson-Kelley is definitely committed to making boiler control technology one of the most impressive features of your heating systems. Read on!

The Evolution of Boiler Controls

The technological innovation of boiler systems has drastically enhanced how users interact with their boilers. The industry continues to improve safety and efficiency standards to fit the game changing environment. Today, users seek features that influence the return on their investment. These notable features include increased energy efficiency, great zone controls and low operational costs; all of which can be achieved by selecting the right boiler control technology.

Boiler control systems have evolved through the years, reducing energy waste and providing the user with greater control over their equipment. Innovation helps to facilitate day to day processes, and allows boilers to better respond to the genuine requirements for comfort heat and hot water demand.

Prevent Boiler Short-Cycling

We all want our heating system to increase cost savings and reduce carbon emissions. However, the issue of boiler short-cycling is the primary reason for boiler inefficiency, generating high operational costs for building owners. Boiler short-cycling occurs when the system fires only to recover its standing heat losses, without genuine comfort heat or hot water demand.

In a previous era, “time delay” devices were introduced to attempt to prevent short-cycling. This device keeps the boiler from firing on fixed time delays. However, it does not take heat or hot water demand into consideration, limiting the end user’s ability to realize cost saving energy reductions.

The introduction of building management systems(BMS) and building optimization positively affected the heating industry by increasing efficiency and providing the end user with more control over their system. But once again these controls have resulted in the implementation of technology that can interfere with existing control strategies, compromising the comfort levels of a building.

Today, we use a modern and intelligent boiler load optimization control. The computer-based control allows for continuous monitoring of both flow and returning temperatures in real time. The control consists of both hardware and software, and engineers have even found a way to integrate the use of internet protocols.

The Patterson-Kelley Solution

The Patterson-Kelley NURO® control system constantly analyzes the boilers outlet temperature and compares it to the current comfort heat setpoint. This enables the control to identify and prevent the boiler from short-cycling. When the outlet temperature drops below the setpoint, the NURO® commands the boiler to increase its firing rate, and as it approaches the comfort heat set point, the control will command the boiler to decrease its firing rate. Both the Comfort Heat Wizard and the Domestic Hot Water Wizard in the NURO®, allow the end user to easily set up and tune the comfort parameter for optimal performance. The control also allows for remote monitoring through a desktop or mobile device, with the NURO® Connect App. Who better knows how to control the boilers than the boiler manufacturer themselves.

The success of this approach led Patterson-Kelley to engineer a NURO® Conversion Kit, which allows current MACH® boiler owners to convert their control to the latest technology.

We’d be happy to talk with you and answer any questions on the Patterson-Kelley Boiler Control options for your next project. Give us a call at 800-355-7061.

This post originally appeared here