How to Find the Right Home Tankless Hot Water Heater

Using energy in the most efficient manner is part of the green home profile. It’s also a way to save money. Tankless water heaters are one approach to do this. 

With new home construction there is a reachable productivity focus of 90 percent. Implying that green homes, worked to guidelines, utilize 1/10 the vitality of traditional housing.  

Retro fitting older homes to this level is probably not economically rewarding at this point, but there are steps you can take, as pointed out below. 

On the off chance that you have a tank water heater that is 10 years old, you are most likely confronting an effectiveness rating of 40 to 50 percent.  

This implies that about a large portion of your fuel dollar is wasted. 

By moving up to a tankless hot water heater, or an on-demand water heater, as they are here and there called, you ought to have the option to raise this number to 80-95 percent, depending on the steps you take. 

A quick energy efficiency comparison: 

If you do nothing more than a replacement this energy efficiency you can expect, under the right conditions. This number will be reduced by some value due to heat loss in the piping. 

Gas storage  60-65 

Electric storage  90-95 

Gas tankless  80-85 

Electric tankless  95-99 

How to Choose the Right Size Home Tankless Hot Water Heater 

Rate of flow and climate are two factors that determine the horsepower of the heater you are looking for. 

The Climate Factor 

For anyone considering a tankless water heater Toronto, the climate factor will determine how powerful a heater you will need. Tankless water heaters operate on the direct relationship between climate and flow rate – if one goes up the other goes down. The colder the climate, the fewer gallons per minute. The output of a tankless model doesn’t mean much without this info. 

Smaller, less expensive electric models operate in the range of 2-3 gallons per minute (winter.) Gas and larger electric models are needed for colder climates and have higher flow rate (higher energy usage.) These offer the convenience of on-demand, unending supply of hot water but will probably not pay for themselves over the life of the unit because of the installed cost.  

Step 1 – Temperature Rise 

This is the measurement of water temperature for your climate. It is the difference between the water temperature (winter) as it enters the house and the temperature at the faucet. 

As an example: From 50 F degrees, the water entering the house is heated to 110 F degrees at the showerhead, this is the rise. The rise in this case would be 60 F degrees. 

Step 2 – Flow Rate 

You also need to calculate Flow Rate – how many gallons of water you need during peak times. If you can get by with one shower or one other outlet at a time, your usage would be 1-½ to 2-1/2 gallons per minute (GPM). This is the efficient way to use an on-demand water heater. If you need more then you can estimate. 

Or, simply use a bucket and a watch to take your own measurements, as shown above. 

As an example: 1 shower + clothes washer = 4 to 5GPM 

Step 3 – Figuring the size 

Once you have numbers for temperature rise and flow rate, you can apply them to gas and electric model tankless heaters to find the right size.  

Here is an example of max output with a 60° F rise in temperature: 

TypeSizeOutput
Electric17 kw2 gpm
Electric25 kw4 gpm
Gas1.17 therms 3.2 gpm

Here is an example of max output with an 80° F temperature rise : 

TypeSizeOutput
Electric25kw2.2 gpm
Gas1.17 therms2.4 gpm
Gas1.75 therms 3.7 gpm
Gas2 therms4.1 gpm

STEP 4 – Is it electric or natural gas? 

Now you have an idea as to how climate affects flow rate, which of course determines energy use. It’s energy you will be using for the next 10-20 years so it’s worth comparing the two. Here is an example that compares electric and a natural gas. 

A Simple Comparison of Electric and Gas Tankless Heaters

Type Power Max flow Rate Cost 
Electric 80 amp-17 kwh 2.9 gpm $0.09/ kwh 2gpm $1.53 hr 
Electric 120 amp-23 kwh 4.5 gpm $0.09/ kwh 2gpm $1.53 hr 
Gas 1.17 therms/ hr 4.3 gpm $1.65/ therm 2gpm $1.21 hr 

These are manufactures and utility numbers and do not have any adjustment for energy efficiency. 

If you want to make your own calculations, these conversions will be handy: 

1 therm = 100 cu ft of natural gas 

1 therm = 29.3 kwh 

1 kwh = .03412 therms 

Whether it is gas or electric depends on the rates in your area. 

The growing emphasis on electrical power and the decline in gas reserves point to a shift in energy use as these electrical and gas charts show. 

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