Domestic coil hot water systems, often referred to as “tankless coil water heaters” or “boiler coil systems,” are an efficient way to supply hot water for your home. This system works in conjunction with a home’s existing boiler, heating water on demand without the need for a separate water heater tank. As more homeowners seek energy-efficient alternatives, domestic coil systems have grown in popularity due to their simplicity, space-saving design, and energy-saving potential.
In this article, we’ll explore how domestic coil hot water systems work, their benefits, and some important considerations to keep in mind when deciding whether they are right for your home.
What is a Domestic Coil Hot Water System?
A domestic coil hot water system is an indirect water heating solution that utilizes the heat produced by a home’s boiler to heat domestic water. The system includes a heat exchanger coil, typically made of copper, which is installed inside the boiler. When hot water is needed in the home, cold water flows through this coil, where it is heated by the surrounding boiler water. The heated water is then sent to the faucets, showerheads, or appliances as needed.
Key Components:
Boiler: The primary heating source for both home heating and domestic hot water production.
Tankless Coil: A coil of tubing inside the boiler where water is heated indirectly.
Aquastat: A device that controls the water temperature to ensure the coil provides water at a consistent temperature.
How Does a Domestic Coil Hot Water System Work?
Domestic coil systems are often installed in homes with steam or hydronic (hot water) boilers. Here’s a breakdown of the process:
Demand for Hot Water: When a hot water tap is turned on, cold water enters the tankless coil within the boiler.
Heat Exchange: The boiler, which is already running to heat the home, transfers heat to the water through the coil.
Hot Water Delivery: The now-hot water exits the coil and is delivered to faucets, showers, or appliances in the house.
Boiler Cycling: The boiler does not need to heat a separate tank of water, so it only heats water as needed, reducing standby energy loss.
Since the system doesn’t store hot water, the boiler heats it as needed, making it more energy-efficient than a conventional water heater that continuously maintains a tank of hot water.
Benefits of a Domestic Coil Hot Water System
Energy Efficiency
The domestic coil system can be energy-efficient, especially when the boiler is already running to heat the home. Since it only heats water when it’s needed, there is no energy wasted in keeping water hot in a tank.
Space-Saving
Unlike traditional water heaters that take up significant space, the domestic coil system integrates with the existing boiler, reducing the need for a separate hot water tank and saving valuable space in basements or utility closets.
Lower Installation Costs
If you already have a boiler for home heating, installing a tankless coil system can be more cost-effective than installing a standalone water heater. You avoid the cost of an additional appliance, and installation is simpler and cheaper.
Unlimited Hot Water
As long as your boiler is correctly sized and in good working condition, the system can provide a continuous supply of hot water on demand. There’s no waiting for a tank to refill, as with traditional storage water heaters.
Reduced Maintenance
Since there is no water storage tank, there is less risk of tank corrosion or sediment buildup, which are common maintenance issues with traditional water heaters.
Considerations for Domestic Coil Systems
While domestic coil systems offer several advantages, there are a few factors to keep in mind:
Boiler Operation Year-Round
The boiler needs to run to provide hot water, even in warmer months when space heating isn’t required. This can reduce energy savings in warmer climates, as the boiler must fire up exclusively for hot water production.
Water Flow Limitations
Tankless coil systems can sometimes struggle to meet the hot water demand of larger households with multiple simultaneous hot water needs (e.g., multiple showers running). It’s important to ensure that the boiler and coil system are properly sized to meet your household’s peak water demand.
Hard Water Concerns
If your home has hard water, mineral buildup inside the coil can reduce efficiency and shorten the lifespan of the system. Regular maintenance, such as descaling, is essential to maintain optimal performance.
Inconsistent Temperature
Some systems may have difficulty maintaining a consistent water temperature, especially when the boiler isn’t running frequently in milder weather. Installing a mixing valve can help regulate water temperature and prevent scalding.
Installation and Maintenance
Installation
For homes with an existing boiler system, adding a tankless coil is typically straightforward. A qualified HVAC technician can integrate the coil into the boiler system, ensuring proper connections and settings to ensure optimal water heating performance.
Maintenance
To keep the system running efficiently:
Descale the Coil: Hard water can cause mineral buildup inside the coil, reducing efficiency. Regular descaling will prevent this buildup.
Check the Boiler: Regular boiler maintenance, including cleaning and inspection, will ensure the coil system continues to perform well.
Monitor Water Pressure: Ensure that the water pressure in the boiler is correct. Low pressure can reduce the system’s ability to heat water effectively.
Domestic coil hot water systems provide an efficient, space-saving, and cost-effective solution for homeowners with existing boilers. By utilizing the heat generated from home heating systems, they offer on-demand hot water without the need for a bulky water heater. However, proper system sizing and regular maintenance are crucial to ensure consistent performance and maximize the system’s lifespan.
If you’re looking for an efficient and seamless way to produce hot water, especially if you already have a boiler for home heating, a domestic coil hot water system could be the perfect choice.
