Tankless Water Heater Setup


Old 08-12-05, 08:38 AM
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Tankless Water Heater Setup

Currently, I am remodeling a recently purchased condo. I have to replace the old rusted water heater and I am considering purchasing a tankless system because i cannot find anything that will fit underneath my cabinets that is bigger than 28 gallons. The tankless water heaters require 220 Volt - 54 Amp. My first question is, can i tell by looking at my panel whether or not my place can handle this and if so, what type of setup is required? By no means do I plan on doing this myself, but I would like to have an idea of how much work must be done before I purchase the system. Thank you in advance for any comments received!

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Old 08-12-05, 09:45 AM
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Join Date: Feb 2005
Location: Near Lansing, Michigan
Posts: 10,535
First, you need to know the size of your current service. It should be a number imprinted on the handle of the main breaker in your panel. I would guess it's 60, 100, or 150A. If you have fuses instead of breakers, then your serivce is almost certainly too small.

Next, you need to do a "demand load calculation" for your residence to determine your current electrical requirements. Google for that phrase, and you will find a tutorial on how to perform this calculation.

Finally, you need to add [email protected] (12,960W) to your present requirements and see if it's less than your service size. If so, then you can add the tankless heater without a serivce upgrade. Otherwise, you would need to upgrade your service and main breaker panel to handle the additional power. This is rather expensive: usually $1,000 - $2,000.
Old 08-12-05, 09:06 PM
Join Date: Nov 2004
Location: CA
Posts: 2,041
I am assuming the old water heater is electric ( not gas) . Even at that, it is probably a 30 amp breaker and at the outside a 40. The wiring is definitly not adequate for that tankless. The next thing is: a tankless running on 54 amps is very small. At the very outside, one person could take a shower with a very good LOW FLOW shower head installed. Try to run another faucet at the same time and it will go cold. What is the gallon per minute rating of the tankless you are looking at?
Old 08-12-05, 11:00 PM
Join Date: Sep 2000
Location: United States
Posts: 18,497
For most people, an electric tankless water heater is not usually a good choice. It makes sense to me only if the family size is quite small, and the electrical service has lots of extra capacity in both power and space (which is usually only true in fairly new homes). Even then, the installation cost can be quite high unless the electrical panel is near the installation site.

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