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Should you buy a tankless water heater?

Tankless Water HeaterToday I want to talk to you about water heaters. Specifically comparing a standard tank type gas with that of a tankless water heater.. A standard tank type water heater has 50 gallons of storage that is maintained by a regulator at a constant temperature that is predetermined. The water is kept at this temperature no matter if it’s 3 am or 3 pm. It’s easy to see why this type might be a little inefficient- very few people need to have hot water ready to use at 3 am. Most 50 gallon gas water heaters are approximately 60% efficient. That means that they burn 60% of the gas that they require.

A tankless water heater on the other hand is more efficient. Not only does it only heat water when you actually need it, but also it’s much more efficient. On average tankless water heaters are 40% more efficient, and depending on the particular make and model they can have efficiency ratings as high as 97%, which means they’re burning 97% of the gas they draw in. A tankless water heater only runs when you are actually calling for hot water, not in the middle of the night when there isn’t a need. Overall, they can save you approximately $90 per year. It would take approximately 10 years to pay for the difference between a tankless and standard tank type water heater. Although this seems like a long time, most people spend a longer length of time in one house.

I highly recommend switching today to a tankless water heater. The savings realized over time can be substantial, not to mention that you’re using less energy.

Should you buy a tankless water heater? was last modified: by
By |2016-05-17T17:50:14+00:00January 24th, 2012|Water Heaters|6 Comments


  1. Ali April 17, 2012 at 6:56 pm - Reply

    They work with all houses, but there is a lot you need to know. Be narwed most plumbers will do their best to convince you to return a tankless and install a tank based system. Very few of them have installed them into houses and don’t like the change. Hard water issues:If you don’t have natural soft water then you need a water softener. Or you don’t get a tankless water heater. The minerals in water will leave buildup inside your water heater. If you get too much buildup, it will damage the heater. Not to mention the water heater won’t produce much hot water with a modest amount of buildup. Second the harder the water the more often you should flush the water heater with vinegar or similar solution. This removes the buildup and only takes about 30 minutes of your time if it is setup to do so. If your water is really hard you should flush it every two weeks, but for most areas with hard water can do every 1 or 2 months. It is inexpensive to do so. Even if you have natural soft water you should flush the water heater at least every year. You should flush a tank based water heater every year too. Venting:If getting a gas tankless water heater then you need to buy venting separately. There are two types on tankless units: Direct Vent and Power Vent.Direct Vent is a double layer steel venting that will never wear out, and it is very expensive. If you mount directly to the external wall, the venting will cost 150 to 300 dollars. If you need to run 10 feet away, then you are looking at the 400 to 1000 dollar range. A direct vent is a more common type of a tankless water heater.Tankless water heaters setup for power vents are often more expensive and larger units. But the venting to run 10 feet to an external wall can be less than 100 dollars. Performance:You need to size a tankless water heater for two factors: Minimum flow rate and flow rate a desired temperatures.Minimum flow rate is the downside of not having a tank. The water flow has to reach a certain rate before a tankless will kick in. A slow trickle at a sink is not enough to activate most. Some facet setups won’t cause a high enough flow at all for some tankless heaters. The lower the flow rate for which it will start heating the better.The other big difference is a tankless can’t heat water up to 200 degrees like a tank based water heater can. Instead the reality is a target a 110 to 130 degrees. The water flow a tankless can produce goes down for the amount of heat you want. If your water is 40 degrees then you want to buy based on what the flow rate will be at for a 70 degree rise to get 110 degrees. The flow rate will be much less if you want 90 degree rise so you would want a larger unit. Fuel:After you have figured out all thee above, if you get a gas tankless water heater you need a gas line. A large tankless heater uses 3 to 8 times the gas flow of a gas furnace. You may need to have a separate gas line installed just for the tankless water heater. Or it might work on your current setup. You will have to ask your utility company after you have selected the equipment.For electric you need to made sure you have a large enough service in to the house. Many old houses don’t.

    • Daniel May 16, 2012 at 2:48 am - Reply

      I would have somebody check the extinsig tank first. Unless it is very small or you are a whole lot of water in that 15 minutes it should give you more hot water than that. In fear of scalding they do tend to set them very low these days. It may only need to be turned up. A hotter tank lasts longer because you use less. But you can’t turn it up too high if you have young children or elderly that scald easily. If it is a large tank you lower element that does most of the heating normally could be out and you are only getting a half of tank of hot water from the upper element. Or bad thermostat can do it also. First check the temp at the faucet. But a service call would be much cheaper. A tankless electric I recently saw requires three 40 amp circuits. Your extinsig probably has only one 30 amp to it so you would need extensive wiring work as well as plumbing. It would be an expensive proposition unless your tank is very close to the panel and you have enough spare capacity on the panel. Still costly though. Well worth trying to fix the extinsig. I am not sure the small savings would ever cover the cost of installing the tankless. I wouldn’t do it unless it was changed to gas. Maybe a larger tank would suit you better. But start with a service call. Good Luck.

    • Karl June 20, 2012 at 11:26 pm - Reply


      Some of what you say is true, but some is not. There are indeed lots of plumbers that are stuck in their ways and resist change at all costs. This however, is not true of all plumbers: such as myself. Tankless heaters are more effecient and in the long-run are cheaper than a tank water heater. One point that you made about flow-rates is not exactly true. Most, and I say most, tankless water heaters will kick on at .6 of a gallon per minute. Even a bathroom sink or kitchen sink is pushing close to 1.5 gallons per minutes, so this is not an issue. Also, a tankless can heat water to 200* if you use manual overrides combined with the control panels. Not all manufacturers allow this, but some do. Concerning hard or soft water, it doesn’t matter what the plumbing fixture is, hard and soft water will do damage and tankless heaters are not excluded. The flow sensors are very sensitive and need cleaned approximately once a year to take off all the calcium buildups. I just wanted to clear a few things up. Thanks for leaving your comment! I appreciate it.

  2. Ash August 23, 2012 at 9:56 pm - Reply

    Tankless are much better.Only thing is more frequent flushing is required.

  3. plumbing supplies Cork October 23, 2012 at 8:17 am - Reply

    Tank less water heater is a great concept, this is one the latest technology.
    This post about these heaters is really very useful and attractive.

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