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  • Jeremy Cook

Tank vs. Tankless Water Heaters

Are you thinking about upgrading to a tankless water heater?  Here's what you need to know.

Conventional Hot Water Tanks:

     -You can see a conventional tank on the left of the image.  This is likely the type of hot water tank you currently have.  Let's go over some pros and cons:

Pros:

          -Low Cost ($800-$1500 depending on size and efficiency)

          -No Maintenance Required.

          -I can set very high water temperatures, and achieve them.

          -Gas or Electrical Units are Available.

          -Electric Tanks are available with a lifetime warranty on the outer shell (that holds the water) and elements are easily replaced as needed.

          -Hot water starts its journey to the tap as soon as the tap is opened because there is hot water just waiting in the tank to be used.

          -Capability about 40,000 BTU/hr (on-demand systems are about 160,000 BTU/hr)

Cons:

          -Increased Utility Costs. Water heater is trying to keep the water warm all day and night.

          -Prone to Leaking.

          -Calcium Buildup Reduced Efficiency Over Time.

          -Short Life Expectancy of 8-12 years.

There are 4 types of conventional tanks

          1) Conventional Efficiency: natural draft is used to vent off gases.

          2) Mid Efficiency: an induced draft fan pulls air through the heat exchanger and vents it directly to the exterior.  Fresh air is gathered from the basement for combustion.

          3) High Efficiency: sealed combustion brings fresh air from the exterior for combustion and send the off gases back outside after they are burned.  This increases efficiency because you are not using air that you have already paid to heat for combustion. 

          4) Electric:  these tanks are becoming more popular due to lower electricity costs in YYC as compared to natural gas.  They also sometimes only use one of the two elements for heating (when less water is used, for example running a dishwasher).  Having both elements only firing when you would say, run a bath, reduces the energy consumed.  In addition, electrical tanks are easier to service.  Electrical tanks are available with a lifetime warranty on the outer shell (that holds the water) and the elements can be easily replaced as needed, extending the useful life.

There are several sizes available













Tankless or On-Demand Hot Water Systems:

   -The tankless version is on the right hand side of the illustration.  Let's examine some of the pros and cons, yes there are some cons.

Pros:

          -Longer Life of 15-20 Years with proper maintenance.

          -Unlimited Hot Water.  This can be useful for large households.

          -Takes up less space in the utility room.

          -Lower Utility Costs as it only turns on when needed.

          -Adjustable Temperature.  There are limits, see Cons below.

Cons:

          -High Upfront Cost of $3,000-$5,000 

          -Hot water takes longer to get to the taps.  The system needs a certain flow of water before it knows it is safe to turn on.  This increases the wait before hot water arrives at the tap by around 10-30 seconds depending on the distance.         

          -Regular Maintenance of $100-$200 per year for cleaning is needed.

          -It is difficult to run a small amount of hot water.  If you wanted to wash your hands with a trickle of hot water, you can't.  The system needs a minimum volume of flow before it will fire.

          -Alberta ground water temperatures are very low.  Getting the water from that low temperature up to 120°C to 140°C is incredibly difficult.  Not to mention the heater is trying to do that in only a second or two.  The result is most people feel the water isn't warm enough for their liking. Ground water enters at 50°F and if the system can increase that by a maximum of 55°F then your highest water temperature can only be 105°F no matter how high you set the desired temperature. https://learn.compactappliance.com/tankless-water-heater-sizing/

          -More BTU's are required to heat the water that quickly, around 160,000 BTU/hr or more.

The Short Answer:

On-Demand systems are expensive upfront and in ongoing maintenance.  The water, in the opinion of most, does not get hot enough and takes longer to get to the tap.  Unless you require unlimited amounts of how water, I recommend staying with a conventional tank system. 

A lot of people would consider that the conventional tank system is far less efficient.  Is it?  If you are using lots of hot water then I would say no.  If you are using hot water you are using energy to heat it, science.  The inefficient times for the conventional system are the times when the tank fires just to keep the temperature even though you are not using hot water, this happens about 2 times during an 8 hour period.***  If you are using lots of hot water, then the tank is likely only being fired when you are actually using hot water which is unavoidable.  

          Example:  If someone is home during the day or if you are washing dishes or doing laundry late at night, you likely wouldn't see much of a savings from a tankless system as you might think because there are fewer times when the hot water tank would turn on just to keep the temperature. 

Cost Breakdown:  Imagine you have the $5K needed for the tankless system, what should you do?***











Tankless or On-Demand Hot Water Systems:    -The tankless version is on the right hand side of the illustration.  Let's examine some of the pros and cons, yes there are some cons. Pros:          -Longer Life of 15-20 Years with proper maintenance.          -Unlimited Hot Water.  This can be useful for large households.          -Takes up less space in the utility room.          -Lower Utility Costs as it only turns on when needed.          -Adjustable Temperature.  There are limits, see Cons below. Cons:           -High Upfront Cost of $3,000-$5,000           -Hot water takes longer to get to the taps.  The system needs a certain flow of water before it knows it is safe to turn on.  This increases the wait before hot water arrives at the tap by around 10-30 seconds depending on the distance.                   -Regular Maintenance of $100-$200 per year for cleaning is needed.          -It is difficult to run a small amount of hot water.  If you wanted to wash your hands with a trickle of hot water, you can't.  The system needs a minimum volume of flow before it will fire.          -Alberta ground water temperatures are very low.  Getting the water from that low temperature up to 120°C to 140°C is incredibly difficult.  Not to mention the heater is trying to do that in only a second or two.  The result is most people feel the water isn't warm enough for their liking. Ground water enters at 50°F and if the system can increase that by a maximum of 55°F then your highest water temperature can only be 105°F no matter how high you set the desired temperature. https://learn.compactappliance.com/tankless-water-heater-sizing/           -More BTU's are required to heat the water that quickly, around 160,000 BTU/hr or more. The Short Answer: On-Demand systems are expensive upfront and in ongoing maintenance.  The water, in the opinion of most, does not get hot enough and takes longer to get to the tap.  Unless you require unlimited amounts of how water, I recommend staying with a conventional tank system.  A lot of people would consider that the conventional tank system is far less efficient.  Is it?  If you are using lots of hot water then I would say no.  If you are using hot water you are using energy to heat it, science.  The inefficient times for the conventional system are the times when the tank fires just to keep the temperature even though you are not using hot water, this happens about 2 times during an 8 hour period.***  If you are using lots of hot water, then the tank is likely only being fired when you are actually using hot water which is unavoidable.             Example:  If someone is home during the day or if you are washing dishes or doing laundry late at night, you likely wouldn't see much of a savings from a tankless system as you might think because there are fewer times when the hot water tank would turn on just to keep the temperature.  Cost Breakdown:  Imagine you have the $5K needed for the tankless system, what should you do?***​










The average use of natural gas is 110 GJ/yr in Alberta. A Gj of natural gas costs $3.80 at its high point. Over 10 years your total natural gas use is only about $4,180 according to these studies. 

http://www.gasalberta.com/gas-market/market-prices?p=pricing-market.htm

http://www.statcan.gc.ca/pub/11-526-s/2010001/part-partie1-eng.htm

***Notice I didn't add any savings for utilities.  The utilities savings would be based on how much water you would use and I don't have that info.  Just consider you probably wouldn't save $8,018 is natural gas, LOL. 

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