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How Does a Tankless Water Heater Work?

Learn how a tankless water heater works in this Howcast plumbing repair video with expert Tim Flynn.


I'm Tim Flynn and I'm the owner of Winters Plumbing and Heating in Cambridge, Massachusetts. Winters Company offers plumbing, heating, cooling. If you need service today; we're the business to call. My website is I'll be talking to you today about plumbing. The tankless water heater, all digital. We can raise the temperature of the water just by dialing up and dialing down. This water heater won't run until cold water runs through it, or when there's a demand, like a shower turns on. So basically, what happens is, on demand, this water heater starts to operate. This water heater...the tank type water heater would turn on and off throughout the day to maintain its temperature. This guy here has a vent that goes up and out the building. This guy here has a vent that goes into a chimney. So chimney vent, directly outside. This tankless water heater runs around in the high 90s of efficiency. This tank type water heater runs in the low 60's of efficiency. So there's a 30% difference between the two. Components within the tankless system is that it has a heat exchanger inside here that's made out of aluminum, and water passes through. We have a very significant heat source underneath this tankless water heater, that, it's like a jet engine inside this little box. As opposed to a small torch in the tank type water heater. So this guy here is very efficient, very fast, very quick, instantaneous. This guy is low and slow.

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