September 3, 2020

Difficulties Getting Hot Water to Upper Floors


Many multistory homes throughout the country experience something called the “cold water sandwich” effect. This phenomenon is most common on upper floors of homes with tankless water heater systems. While these systems are incredibly efficient and effectively provide hot water on demand, they may struggle to provide consistent hot water after first turning on, especially when sending hot water to upper floors.

The “cold water sandwich” refers to a tankless system engaging and supplying hot water initially, then a small amount of cold water, and then hot water again. This happens because the water in the system takes some time to heat up on the system’s heat exchanger, resulting in a small gap in hot water as the system catches up to the water usage.

Stopping the Cold Water Sandwich Effect

If you have experienced the cold water sandwich with your tankless system, this may not be so bad when it comes to short uses of hot water such as washing your hands, but it can be pretty bothersome when taking showers. Homeowners can solve the cold water sandwich problem and ensure effective delivery of hot water to upper floors with two main solutions:

  1. Create a Hybrid System.
    A tankless water heater system comes with the advantage of saving the space typically occupied by a tank, but a hybrid system with a small reservoir effectively provides the best of both worlds. A tankless unit with a small hot water reservoir provides a steady stream of evenly heated water. Instead of a large tank storing your hot water, the smaller reservoir effectively acts as a buffer and prevents the cold water sandwich effect when you need hot water for an extended draw. If you’re having trouble maintaining steady streams of hot water on your second or third floor, installing a hot water reservoir could offer a relatively easy solution.
  2. Install Multiple On-Demand Water Heaters.
    If you install an additional tankless water heater on your second or third floor dedicated to the upper floors’ bathroom, you can enjoy steady streams of hot water with little to no delay and reduce the cold water sandwich effect. Tankless water heaters are small enough to fit inside most small closets. You could potentially add a second water heater to an upper floor bathroom without sacrificing valuable storage space.

Either of these solutions should lead to diminished cold water sandwich experiences. However, either option will come at some initial expense. Think carefully about whether diminishing this effect is worth the extra expense, but keep in mind that an efficient tankless water heater system can provide consistent energy savings for many years. You will also encounter fewer issues that demand repairs, and any repairs you do end up needing will be much more affordable than they would be with a tank-based traditional water heating system.

Every home is different, and every homeowner has different goals when it comes to heating their water. Whether you’re more concerned with energy savings or simply never want to worry about running out of hot water when you need it, we can help.

Contact Applewood today to learn more about the potential solutions to the cold water sandwich effect in your home, and our team will walk you through the potential solutions and the long-term value they might provide to your home.

Resources: https://www.efficientsystems.net/blog/cold-water-sandwich-effect-solution/ (reference only)

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