Why Install a Noritz Combination Boiler 1: Variable Flow Control
The new CB Combination boiler/tankless water heater (CB Combi) from Noritz has a number of installer and homeowner advantages, not only over traditional, stand-alone boilers and tank-type water heaters, but also over other combination units on the market.
In this new blog series, we will explore some of these user-installer advantages. First on the list—the CB Combi’s unique flow control valve.
Why it’s there
To understand what the flow control valve does, you need to recognize the problem that it solves. If multiple fixtures are generating simultaneous demand for hot water, more energy may be required than the water heater can provide.
In such a scenario, the water emerging from the various fixtures would be colder than the desired setpoint temperature, because heat is not being transferred quickly enough due to the high volume.
What it does
The CB’s flow control valve acts to ensure that the domestic hot water (DHW) supply always emerges at the desired temperature by slowing down the water flow through the unit during periods of multiple fixture demand. Reducing the flow rate ensures enough time for the DHW to reach the setpoint temperature for all fixtures. 
Randy Oshiro, Lead Engineer at Noritz America, explains that one consequence of slowing down the flow rate could be slightly reduced water pressure from the fixtures. “The reduced pressure is so slight that it’s practically unnoticeable,” assures Oshiro. “The flow control valve sacrifices this tiny amount of water pressure to ensure the far more important and noticeable ability to meet desired hot water temperatures across multiple fixtures.”
Conversely, if there is a sharp change in hot-water demand, the flow control valve helps prevent scalding by adjusting the flow accordingly. “The goal of any domestic hot water heater is to deliver water at the desired temperature as quickly as possible,” explains Oshiro. “The flow control valve accomplishes this by either restricting or expanding water flow, depending on demand.”
Why it’s unique
Most other combination boilers on the market lack a flow control valve, meaning they either accept the fact of colder water in high-volume scenarios or require an add-on, flow-limiting device. Only the flow control valve inside the CB Combi by Noritz allows the user to enjoy desired water temperature for as long as needed, fulfilling the tankless promise.
To learn more about the CB Combi, please visit https://www.noritz.com/combi/