A common question I’m asked by homeowners is whether or not a Nordic air to water heat pump will work with their current HVAC system. If their home has existing radiant in-floor heat installed, the answer is usually yes, an air to water heat pump can act as a direct replacement to their current system.
But if your home has hot water baseboards or radiators, the answer is not a simple one, and depends on the output temperature of your current heating system. Let’s look at the important factors to consider when deciding whether to replace your current system with an air to water heat pump.
How Output Temperatures Vary from System to System
First of all, let’s establish a definition for a residential hydronic heating system: A system that uses hot water to heat your home. The water is first heated by a geothermal heat pumpg, an air to water heat pump, or a boiler that is powered by either wood, oil, natural gas, or electricity. The heated water is circulated through a heat distribution system (radiant in-floor piping, hot water baseboards, or radiators) before returning to your heat pump or boiler to be reheated.
Depending on what system you have in place, the output temperature of the hot water that heats your home will vary. If you have an oil-fired boiler feeding hot water baseboards or radiators, your output temperature is probably around 180°F (82°C). This higher output temperature means you’ll need less surface area to radiate enough heat to keep your home warm.
In contrast, other heat distribution systems like radiant in-floor heating require much lower output temperatures and radiate their heat over a much larger surface area (a whole floor vs. a small radiator). Our air to water heat pump is built for those lower temperatures, and has a maximum output temperature of 120°F (48°C).
So, can you use a low-temperature air to water heat pump to heat a home with a heat distribution system that is designed for higher temperatures?
The answer is: Maybe.
How to Test if 120°F Water Will Heat Your Home
The truth is, it may work, it may not. There’s an easy way to determine whether or not 120°F water is hot enough to keep your home warm.
Simply turn down your heating system’s output temperature to 120°F. This will circulate water that is only 120°F to your home’s baseboards or radiators. If you do this for a winter and your heating system maintains your desired room temperature (the setpoint), then you know that it will work. If the lower temperature water isn’t enough to keep your home warm, you’ll know because your home won’t reach its desired setpoint or may have trouble maintaining the setpoint on the coldest days of the year.
Using this method, you can determine whether or not our low-temperature air to water heat pump will work with your high-temperature heat distribution system.
Generally, the air to water heat pump will work with radiators, but is less reliable with hot water baseboards, but again, it depends on each individual home. Our product engineer Dan Rheault offers this insight:
“I have a heat pump paired with hot water baseboards and they work, but our home is not at the desired set point all of the time.”
Dan Rheault, Product Engineer
Again, our recommendation is to test your home’s heating system at the lower temperature for one heating season, and then you can determine if you can switch to an air to water heat pump.
Interested in learning more about the Nordic ATW Series? Download our FREE Ebook:
Photo Credit: jasonpier