HVAC & Hydronic Piping.

Class A VA Contractor License #2705147099
DMBE VA SWAM # 684641

HVAC & Hydronic Piping

What is Hydronic and HVAC piping?

HVAC & Hydronic Piping

HVAC and Hydronic pipelines run vertically and horizontally. The piping runs along walls or columns from the roof of a commercial or residential building all the way down to the ground surface level or sub surface level. Hydronic pipelines can have extreme high and low effluent temperatures. Most HVAC pipelines operate under pressure or suction. HVAC lines can have multiple cross connecting horizontal pipes that supply heating or cooling effluent to each room or floor of a commercial building. It is not uncommon to observe several bends or turns as the piping travels through a facility. Common HVAC piping can range from 2”- 15” in diameter. HVAC piping usually is made from Cast Iron, Ductile Iron, or PVC.

What happens over time to HVAC piping?

Pipe problems shownMuch like other building or facility assets, hydronic piping ages and the material surface becomes thinner and rougher overtime. Metallic based piping such as ductile iron, which is the most common HVAC pipe material, can be vulnerable to surface corrosion from years of chemical and detergent use. As chemical corrosion matures the pipe surface thins and begins to form linear and longitudinal cracks. During the corrosion process the pipe walls become increasingly rough. Surface roughness causes the walls to constrict the HVAC piping’s flow capacity. HVAC pipe problems can cause: surface and wall damage, mold or mildew, heating and cooling service disruptions, excessive internal flooding, personal property damage, and high heating or cooling expenses.

At Dynamic Drain Technologies, we use a design first philosophy. Due to the complex nature of HVAC piping it is vital that we understand and observe all construction, operational maintenance, and structural related details of a buildings HVAC piping system. The design process starts with a site survey in which all HVAC components and effluent features are accounted for. Our team of specialists then tag and title any access points needed. These access points provide entry to the HVAC piping system. Access is vital and must be considered when moving forward into the video inspection and pipe cleaning phases.

Pipe inspection and location.

Site plan for hot water loop

Pipe inspections allow us to do several very important things. First and foremost, they allow us to locate and map the piping system. We trace the piping system via a sonde transmitter located in our camera heads. We often place painters tape on the wall or flooring surface to mark the locations of the HVAC piping. Digital site plans or riser diagrams are also generated during this process. Pipe inspections also allow us to observe and collect conditional data points of the HVAC piping system. This data consists of structural, operational, and maintenance related observations that determine the HVAC piping’s current structural deterioration level.


All hydronic or HVAC piping systems operate under pressure and can produce extreme temperature ranges for combined heating and cooling purposes. Most HVAC systems also use various corrosive chemicals to maintain heating or cooling effluents. It is highly critical that the survey and design team collect accurate levels of temperature, internal pressure, and chemical concentrations of HVAC pipe systems. This information, in conjunction with the HVAC pipelines current deterioration level, will allow our engineering team to determine a pressure class and proper CIPP design equation. A design equation will determine how thick our liner needs to be and what epoxies will be used to guarantee long term chemical and physical resistance.

At this point we have all the information needed to present the data and layout the action or pipe lining design. Design will cover the following areas: scope of works, approximate pricing, working hours, project durations, pipe cleaning, diversion or bypass pumping options, water shutdown, CIPP liner design calculations, and finally project management requirements and responsibilities.

Pipe Cleaning

The pipe cleaning process requires a remarkable amount of labor and technical expertise. A typical HVAC pipe cleaning scenario may call for heavy amounts of mechanical chain knocking or scouring of the internal pipe surface. This process removes years of rust deposits from the pipe walls and surfaces. The dislodged debris are then washed out with forced air or high pressure water jetting. The desired result of this process is to achieve a clean pipe surface, free of any deposits or roughness that could interfere or interrupt the bonding of the cured in place pipe liner.

Pipe cleaning workers

Cured in Place Pipe Lining of HVAC Piping.

Once the pipe is completely cleaned, technicians then perform another video pipe inspection to record the pipeline before the pipe liner is installed. This is done to show that the pipe was properly prepped and cleaned prior to installing the liner. All lining materials are fabricated onsite using our turnkey job-ready mobile trailer units. Our mobile lining trailers are outfitted with state-of-the-art electric vacuum assisted wet out tables. The liner material is loaded onto the roller table and the epoxy resin is introduced to the liner and passed through the electric roller until the liner has reached 100 percent saturation. In addition to using 100% solids epoxy resin we also will install hydrophilic rubber ends seal for extra long term protection for higher pressure applications.

Now the liner is ready to be loaded into one of our inversion devices and inverted into the pipeline using compressed air. This process is called inversion. For single access installations, a bladder or calibration tube is inserted after the liner and inflated to press the liner against the pipe walls. Once inversion is complete a curing method is implemented. Depending on the application the liner can be cured using 2 methods. The most time-consuming method is an ambient cure. During an ambient cure epoxy resins are combined with an accelerator that will encourage a natural air cure within 3-4 hours of installation. Faster cure times can be achieved by using external heat sources. The quickest external heat source is steam. Forced steam is passed through the liner until the epoxy reaches its desired exothermic flash point. Depending on the diameter and length, using steam can reduce cure times to 1-2 hours.

After a proper cure time is reached, air pressure can be released and the calibration tube can be removed. At this point the liner is now fully cured and bonded to existing pipe walls. A post liner video inspection is then conducted verifying the quality of the install.

At the finale of our process we have achieved an internal pipe repair without the need of and demolition. This pipe liner will have 50-year design life and will improve flow capacity. HVAC pipe lining is one of the most cost effective pipe repair options a facility will encounter. Downtime can be limited by using this trenchless technology.

Let's talk about your hydronic pipe problems