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Radiant Heat Install Pt 4/5 | Fill + Purge + Start Up | MAD County Build

Part four of our radiant heating system installation journey. Today, we're delving deep into the process of filling our system and purging any stubborn air pockets. Before you can take this step, you have to decide whether you want to use water or glycol. The decision between using water or glycol to fill the system isn’t always an easy one. In my setup, I've opted for water, and in an upcoming episode, we'll dedicate some time to dissecting the comparison between water and glycol, exploring the benefits and considerations of each choice.


Installing four zones of radiant heat

Our heating system is divided into four zones: Zone 1, Zone 2, Zone 3, and Zone 4. Starting with the in-floor components, our approach to the filling process is a careful process. A supply hose is strategically connected to the manifold's supply, while a return hose is positioned to lead any residual air into a bucket for careful observation.


Before we initiate the filling, it's imperative to shut off all manifold lines, isolating each zone. Utilizing a simple key, we systematically close off each line, ensuring water won't escape when the system is pressurized. This calculated step enables us to open one loop at a time, facilitating a controlled flow of water and the efficient purging of air.


Fill and purge radiant heat system

Next, the hose is connected to the supply, and the loop is gradually opened to allow water in. Observing the reduction of air bubbles, the loop is promptly closed to maintain pressure. This process is repeated for each zone until the entire system is charged, and we achieve a state free of air bubbles.


To ensure the thorough elimination of air pockets, our attention shifts to the main manifolds. Here, a purge valve, cleverly connected to the fill line, guides water through one pump return circuit at a time, effectively purging any lingering air in the system.


Radiant heat control board

One note: If you opt for glycol instead of water, additional equipment, such as a pump, is required for the process. However, with water, a straightforward hose connection is all that's needed.


With all circuits charged, it's time to connect the end switch—a critical step for signaling the boiler when any zone requires heating. Ensuring correct wiring establishes seamless communication between the control panel and the boiler.


Once everything is set up, we can shift to programming the boiler. Keep in mind that programming steps may vary, so consulting your manual or seeking technical support is very important and can be helpful throughout this process. In my case, with a closed-loop system, I needed a simple range for temperature selection. To fine-tune the system, I demonstrate how to adjust the flow valves on each circuit. Keeping them open initially, we gradually close them until they hit resistance, ensuring equal flow across all zones.


Adjusting valves for radiant heat

And there you have it—the successful filling and purging of our hydronic heating system. Join us in the next installment, part five, where we'll provide a comprehensive walkthrough of the system's operation and break down the costs involved.



Thank you,

MR Post Frame



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