Installing A Tankless Water Heater

There are a lot of opinions about whether gas or electric tankless heaters are better. Only if you do the math, as I did, will you know the answer. Be careful of online comments, many leave out info that is essential to making a good decision.

I found that even though electric rates are 60 percent higher than natural gas where I live, I would still be ahead after 10 years of use. You can figure this out by converting KWH and Cubic Feet to therms. I also found that even though I live 500 miles above the "warm zone" shown on most tankless maps, I do fine with a smaller unit, this is due in part because I use my old tank heater as a passive heater and I have low volume needs. You can figure this out by calculating the difference between winter ground temperature and showerhead temperature. With that you need to factor in your water needs in gallons per minute.

To be sure electric tankless heater is right for you
Before you can install a tankless electric check these things:
Check panel amp capacity
Check your map
Size up your home usage
Compare energy sources

If you are confident this will be right for you then you are ready

Wiring Simplified: Based on the 2008 National Electrical Code



Remodel Plumbing (For Pros by Pros)




The Homeowner's Handbook to Energy Efficiency: A Guide to Big and Small Improvements




The Complete Guide to Reducing Energy Costs (Consumer Reports: You Need to Know)

2 adjustable wrenches
Pipe cutter
Wire cutter
Electrical tape
White plumber's tape
Green pot scrubber pad
Drill and bits
$2 circuit tester

Basic tools for soldering copper pipe
Torch
Lead-free solder
Flux
Emery paper

Also need to purchase:
New circuit breakers
Wiring as recommended by manufacturer
Wire fasteners
Copper pipe
Fittings
Cut-off valves
Mounting screws and maybe a mounting board

You should have already checked your breaker panel and noted that there is reserve capacity. Which means that the amperage of the of the breakers you are going to add plus the breakers already in place are less than the capacity of the circuit panel - usually 200 amps. In fact it should be no more than 180 amps, I've read. If in doubt, ask an electrician. A sub panel can be installed if necessary.

Step 1
Throw the main breaker to the off position before removing the cover to the panel. Use your tester to make sure the power is off.




1. Main breaker should be in off position.





Step 2
One pair of wire goes to each breaker. Carefully remove ½ inch of insulation, so as not to cut any strands, feed these ends into breaker guide holes and tighten the screws. Repeat this with each breaker and attach ground wire(s) to the common ground bar. To wire up refer to an existing breaker to see how it's done.








2. A double pole breaker will have two switches on top; each one marked with the amps.








3. Once these breakers are wired, they can be pushed into position by hand.

Leave these breakers and the main breaker in the off position.

Step 3
Replace the panel cover and string these new wires to the tankless water heater.



4. Attach these wires as shown in your manufacture's guide.





Note: Use the same model breakers as the existing ones. Use the gauge wire recommended by the manufacturer - old wiring to the tank heater is too light. If you need electric power, you can turn the main breaker on as long as the tankless breakers remain off. Be sure to turn off the breaker to old tank heater.

You can have significant savings if you leave your water tank in place. That is, if it meets two requirements: 1) it doesn't leak and 2) it's in a close to room temperature location - that is, if it's 10-20 degrees warmer than ground temperature, you will save that much in energy. Not only will it mean saving money on energy it could also mean that you can buy a smaller capacity electric tankless hot water heater.

To turn you old tank heater into a passive preheated you can remove the top and take out all the insulation. I recommend that you put a drip pan under it, if there isn't one there already. Without the heating element working its still got plenty of life left.

There are two ways to go about this. The less expensive way is to solder the copper pipes together. More expensive but quick and easy, and especially good in tight spaces are compression fittings. No tools needed, just push together. There is a useful plastic release ring tool, if you want to make changes. Or you can, as I did, slip a garden hose repair clamp over the pipe to push the release ring. All the necessary plumbing supplies can be found at HomeDepot and Ames.

Of course you can use a combination of solder fittings compression fittings and flexi-pipe.

Step 1
Start by turning on all the faucets in the house and turning off the water where it enters the house. Drain the tank and prepare it for its new role as passive storage, if you are going to use it - be sure to close the drain valve when done.

Step 2
Mount your tankless unit on the wall at a convenient level.
Assemble copper pipes to and from the tankless unit; be sure to include shutoff valves. Using flexi-pipes will make match ups much easier.




1. Measure lengths an cut with a pipe cutter.


2. Clean ends before assembly.


3. Easy-to-use need only a push and twist.






4. Use plumbers tape at all threaded connections.


5. Install both hot and cold cutoff valves. Some codes require a pressure release valve.

With the circuit breakers still off, turn main water valve on and all water faucets. This pushes any debris out of the water line and avoids vapor lock.

Now you are ready for hot water.
Close all the faucets except one hot water.
Flip tankless breakers on and watch for the red light on the heater cover. It will only light up when the heater is on.

Now you can adjust the temperature and flow rate. Most problems occur because the flow rate is greater than heating elements can handle. By reducing volume and temperature you should find something that works. This is usually more of a problem in colder months, for systems without a storage tank.

Note: I have tried to make this as accurate as I can, based on my experience installing this type of tankless heater. I am not a trained electrician; you should consult someone qualified if you have any questions about this kind of installation.