What is a differential bypass valve in HVAC systems?

A differential bypass valve automatically regulates pressure and flow in variable flow HVAC systems. It helps maintain a minimum differential pressure when control valves are closed, ensuring flow continuity and protecting pumps.

How does a non-dead-leg T valve work?

A non-dead-leg T-valve ensures continuous flow at branch ends, eliminating stagnant water zones known as dead legs. These valves are ideal for maintaining water hygiene and preventing temperature imbalances.

What is an end-of-line PRV used for in a hydronic system?

An end-of-line PRV (pressure relief valve) is used to manage excess pressure and flow when terminal units close. It acts as a safeguard in closed-loop systems, preventing pressure spikes and vibrations.

Why are non-dead-leg valves important in HVAC design?

Non-dead-leg valves eliminate the risks associated with stagnant water in closed pipe branches. In systems like fan coils or over-door heaters, these valves support better hygiene and more responsive temperature control.

What is the role of an end-of-line valve in PICV systems?

An end-of-line valve provides a bypass route for water when terminal unit PICVs are nearly closed. This ensures continuous flow, maintains branch temperature, and reduces system vibration risks.

How does a CFR valve function in a variable flow system?

A Constant Flow Regulator (CFR) valve maintains a preset flow rate in dynamic systems. When used as an end-of-line bypass valve, it helps balance the system while reducing the risk of dead legs and pump damage.

What is a dead leg valve, and how is it different from standard valves?

A dead leg valve is designed to eliminate stagnant sections in pipelines. Unlike standard valves, it promotes flow through normally idle branches, ensuring water turnover and reducing bacterial growth risks.

Why is end-of-line bypass important in modern HVAC design?

End-of-line bypass maintains flow when demand is low or terminal units shut down. It helps avoid dead legs, ensures a consistent return temperature, and prevents system vibration — all crucial for efficiency.

Can a differential bypass valve replace other balancing components?

Yes, in some cases a differential bypass valve can reduce the need for traditional balancing valves, especially when paired with PICVs and non-dead-leg designs, streamlining the hydronic balancing process.

What are the different types of bypass valves and their uses in HVAC systems?

Common bypass valves include differential bypass valves, automatic balancing valves, and constant flow regulators (CFRs). Each type serves to stabilise flow, prevent dead legs, and ensure efficient operation under varying loads.

Data Sheet Downloads

+44 1282 564425

NEWS - Category System Design Considerations

Keep up to date with the latest news from FloControl.

Minimum-Flow-Circulation-in-Variable-Flow-Systems-Post-Image-2_780x520_acf_cropped_780x520_acf_cropped

End-Of-Line By-pass prevents branch dead leg and system vibrations

26 April 2020

Which design strategies will ensure minimal flow circulation in HVAC systems addressing branch dead leg, pump protection and the prevention of potential system vibration?

Privacy Overview

This website uses cookies to improve your experience while you navigate through the website. Out of these, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities of the website. We also use third-party cookies that help us analyze and understand how you use this website. These cookies will be stored in your browser only with your consent. You also have the option to opt-out of these cookies. But opting out of some of these cookies may affect your browsing experience.

Necessary

Always Enabled

Necessary cookies are absolutely essential for the website to function properly. These cookies ensure basic functionalities and security features of the website, anonymously.

Cookie	Duration	Description
cookielawinfo-checkbox-advertisement	1 year	The cookie is set by GDPR cookie consent to record the user consent for the cookies in the category "Advertisement".
cookielawinfo-checkbox-analytics	11 months	This cookie is set by GDPR Cookie Consent plugin. The cookie is used to store the user consent for the cookies in the category "Analytics".
cookielawinfo-checkbox-functional	11 months	The cookie is set by GDPR cookie consent to record the user consent for the cookies in the category "Functional".
cookielawinfo-checkbox-necessary	11 months	This cookie is set by GDPR Cookie Consent plugin. The cookies is used to store the user consent for the cookies in the category "Necessary".
cookielawinfo-checkbox-others	11 months	This cookie is set by GDPR Cookie Consent plugin. The cookie is used to store the user consent for the cookies in the category "Other.
cookielawinfo-checkbox-performance	11 months	This cookie is set by GDPR Cookie Consent plugin. The cookie is used to store the user consent for the cookies in the category "Performance".
viewed_cookie_policy	11 months	The cookie is set by the GDPR Cookie Consent plugin and is used to store whether or not user has consented to the use of cookies. It does not store any personal data.

Functional

Performance

Analytics

Analytical cookies are used to understand how visitors interact with the website. These cookies help provide information on metrics the number of visitors, bounce rate, traffic source, etc.

Cookie	Duration	Description
_ga	2 years	This cookie is installed by Google Analytics. The cookie is used to calculate visitor, session, campaign data and keep track of site usage for the site's analytics report. The cookies store information anonymously and assign a randomly generated number to identify unique visitors.
_gat_UA-67984577-10	1 minute	This is a pattern type cookie set by Google Analytics, where the pattern element on the name contains the unique identity number of the account or website it relates to. It appears to be a variation of the _gat cookie which is used to limit the amount of data recorded by Google on high traffic volume websites.
_gcl_au	3 months	This cookie is used by Google Analytics to understand user interaction with the website.
_gid	1 day	This cookie is installed by Google Analytics. The cookie is used to store information of how visitors use a website and helps in creating an analytics report of how the website is doing. The data collected including the number visitors, the source where they have come from, and the pages visted in an anonymous form.

Advertisement cookies are used to provide visitors with relevant ads and marketing campaigns. These cookies track visitors across websites and collect information to provide customized ads.

Cookie	Duration	Description
_fbp	3 months	This cookie is set by Facebook to deliver advertisement when they are on Facebook or a digital platform powered by Facebook advertising after visiting this website.
fr	3 months	The cookie is set by Facebook to show relevant advertisments to the users and measure and improve the advertisements. The cookie also tracks the behavior of the user across the web on sites that have Facebook pixel or Facebook social plugin.
test_cookie	15 minutes	This cookie is set by doubleclick.net. The purpose of the cookie is to determine if the user's browser supports cookies.

Others