Using tankless water heaters in cold climates

Natural gas tankless systems work best under cool conditions. (Photo courtesy of Lilly Funcion)

Natural gas tankless systems work best under cool conditions. (Photo courtesy of Lilly Funcion)

Dear Angie: Is it true tankless water heaters do not work well in cold climates? The water temperature in Anchorage, Ala. is in the mid-to-high 30s. I have had several heating companies come out to collect info to build proposals to replace my boiler and hot water heater. The first three specifically didn't recommend on-demand water heaters due to the cold temperatures of our city water. The fourth company went against the grain and will be proposing an all-in-one on-demand unit for home heating and drinking water. I didn't ask him his thoughts on the others' point of view, but have been looking for an answer. What are your thoughts? – Vinny B., Anchorage, Ala.

Dear Vinny: First, I commend you for taking the time to do your research and seek out multiple service companies for advice. You’ll almost assuredly be better off because of the time you spent doing your homework on the front end. To answer your question, many tankless water heaters can work in cold weather climates, depending on the type of tankless water heater it is.

As you likely know, tankless water heaters are able to provide an almost endless stream of hot water while occupying a very small space compared to a traditional tank unit, which requires the use of fuel to maintain a hot temperature. Plus, they heat only the water you use, so you waste less energy.

Though it is true that most electric tankless heaters do not perform well in cold weather, many natural gas tankless systems do. Many manufacturers build the gas tankless units to provide freeze protection to accommodate sub-zero temperatures.

A professional with experience with tankless water heaters can address the size of the system you need to accommodate your usage to ensure the unit provides enough hot water for you and your family to be comfortable. In a cold-weather area like Alaska, it’s important that the person doing the installation insulates the pipes feeding the unit. You also need to consider power failures. Even gas tankless heaters require electrical power to work, so if you experience a lot of power outages, tankless heaters might not be the best fit for you – unless you enjoy taking cold showers. Tankless units also require proper venting and should be installed close to gas lines to operate at their highest efficiency. Most homes can be retrofitted with a tankless heater, though some homes will require modifications to accommodate a venting flue. Larger homes also sometimes need more than one unit.

Because there are so many nuances involved with the installation and use, it’s important that only a qualified, licensed plumber install tankless water heaters.

Angie’s List collects about 40,000 consumer reports each month covering more than 350 categories of home-related services. Angie Hicks compiles the best advice from the most highly rated service pros on Angie’s List to answer your questions. Ask Angie your question at askangie@angieslist.com


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Tankless water heaters provide hot water on demand

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Natural gas tankless systems work best under cool conditions. (Photo courtesy of Lilly Funcion)
Natural gas tankless systems work best under cool conditions. (Photo courtesy of Lilly Funcion)

A storage tank water heater must maintain hot water even when not in use, but a tankless water heater provides endless hot water in minimal space.

Comments

With all respect to Dennis, there are a few facts mixed up in his comment on tankless water heaters. The first is that no matter how long you run the faucet, the tankless unit providing heat will not fluctuate its temperature. It doesnt "heat up" over time. Whatever you set the temperature at, it will produce the moment you turn on the hot tap, unless the temperature rise is too great of demand. The question you need to ask yourself, and your installer is what is the temperature rise for the unit. That is, if the incoming water heater is at a chilly 33 degrees F, and the tankless unit only capable of a 60 degree F difference (the temperature rise) then the water heater is only going to produce 93 degree water (on its first go around). Yes, i know many adjustments can be made to alter that in different tankless units, but the point is that temperature rise differential is the important question to ask regarding a tankless units appropriateness for a given climate, especially a cold one. Also, if a house has hard water it can and should be both filtered, and softened to protect not only the water heater, but the piping, and fixtures as well. Electric water heaters are not more efficient because that heat IS wasted. Its wasted every second it sits there unused, cooling down in the cold weather environment it was installed in, only to kick on again in 20 minutes to regain the temperature it just lost. You dont need to insulate a tankless water heater because it doesnt store hot water. It produces it when the hot tap is turned on, and it shuts off the minute the hot tap is closed. If installed correctly by a technician who is familiar with them, they are not any more high maintenance than a standard tank type heater. Not many plumbers and HVAC technicians have taken the time to familiarize themselves with this efficient technology. As a result there is often a general and uninformed criticism with the new technology on the block from the older dogs that refuse to learn anything new.

I wouldn't go with a tankless water heater in a cold climate area. First of all, the water would have to run quite some time before heated to a desired temperature. Secondly, if you have hard water, or sediment, your tank will clog up quite fast, causing huge maintenance expense. Tankless water heaters are high maintenance and waste water. Electric water heaters are more energy efficient because nothing is wasted, and are better insulated. Tankless are expensive all around and would never save enough to pay itself off, unless it came with the house in the first place.

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