Tankless water heater breaker/wire/etc

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Old 07-14-09, 08:00 AM
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Tankless water heater breaker/wire/etc

I'm in south florida and I'm thinking about installing a new tankless water heater (Titan SCR-2, Model N-120) The installation requires #6 wire and a double pole 60 amp breaker. I currently have a tank water heater with a double pole 25 amp breaker. I haven't looked at the existing wire, but I'm guessing it isn't #6, so would my approach be to just replace the 25 amp breaker with the 60 amp breaker and then pull the old wire out and run the new wire where the old wire was? Or would it make sense to leave the existing breaker and wire in place in case a future owner ever goes back to a tank water heater. I would appreciate any advice with this, and any other issues you think I might encounter with this installation.
Thanks!
 
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Old 07-14-09, 08:38 AM
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Is the old wire in conduit? If so what size conduit? What size main breaker do you have. Florida + Air Conditioning means if the main breaker is100 amps or less and have an electric stove and clothes dryer you may have to increase your service.

Also note if you use cable to install the heater you may need #4 not #6. #6 is ok for individual wires in conduit.
 
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Old 07-14-09, 09:31 AM
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Originally Posted by Titan Website FAQ
For instance, the SCR2 N-120 draws a maximum of 54 amps. Meaning, it will consume a maximum of 54 amps at peak power output, only as necessary. Our local codes (Miami, FL) call for the use of a 60 amp breaker, and a #6 AWG wire gauge.
The manufacturer's interpretation of the code in Miami is not necessarily the same as you might find in other jurisdictions. There are plenty of areas that would require #6 in conduit or #4 in cable for this heater. Verification with your local building department would be a good idea when you get your permit, before purchasing the supplies.

Ray's point about the service size is an important one, especially if you have air conditioning. You may want to perform a demand load calculation before proceeding down this potentially very expensive path.
 
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Old 07-14-09, 10:52 AM
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The service was upgraded when we put in a pool. I forget what size, but I think it is more than sufficient. I will definitely verify before proceeding. The old wire isn't in conduit, it is just romex run through the walls and attic.
 
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Old 07-14-09, 11:25 AM
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The service was upgraded when we put in a pool.
Does the pool have electric heat or was it just to give more juice for the pump?
The old wire isn't in conduit, it is just romex run through the walls and attic
You would just disconnect at the service panel and tag with an explanation.

What I'm about to say is just an idea not a suggestion. A 60 amp instant water hearer is borderline depending on the temperature of the incoming water. If down the road you found there were times it wasn't adequate you cold leave the old heater to act as a supplement. In fact on the instructions of one tankless I remember
reading it suggested that in colder climates you may need to use a second heater to preheat the water.
 
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Old 07-14-09, 11:29 AM
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Originally Posted by ray2047 View Post
more juice for the pimp?
I'll fix that one for you.
 
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Old 07-14-09, 12:46 PM
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Originally Posted by ibpooks View Post
I'll fix that one for you.
Thanks.

.....................
 
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Old 07-14-09, 04:15 PM
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Ray,

I am shocked! You know we try to keep things PG around here.
 
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Old 07-15-09, 08:00 AM
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The service was upgraded to 150A because of the electric heater for the pool which uses a 60A dual pole breaker.

I can't imagine I would ever have everything running at once (pool heater, tankless heater, stove, washing machines, air conditioner, etc) but I guess it's possible.
 
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Old 07-15-09, 08:58 AM
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You need to rethink that model. Note that at a very modest 64 rise, you get a MAXIMUM 1.5 GPM. That doesn't even give you a hot shower.

It means if the ground water is 55, you can get 1.5 GPM at 119. If someone tries to wash their hands in the kitchen sink at the same time, your shower will shut down.

In my opinion, that model is too small for any application which includes a shower ( totally FORGET it for a tub). It would be OK for a couple of small sinks, maybe a dishwasher, but not a washing machine at all.
 
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Old 07-15-09, 09:29 AM
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Originally Posted by floridagator View Post
The service was upgraded to 150A because of the electric heater for the pool which uses a 60A dual pole breaker.

I can't imagine I would ever have everything running at once (pool heater, tankless heater, stove, washing machines, air conditioner, etc) but I guess it's possible.
200a service would probably be minimum given a pool heater also.
 
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Old 07-17-09, 09:08 AM
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I'm in south florida and I think the ground water temp is something like 72, so if I want to heat to 112, it would give me about 2.0 GPM, do you think that is not sufficient?
Thanks for the advice everyone!
 
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Old 07-17-09, 09:30 AM
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A 60A water heater should give you a 50-55-deg temp rise @ 2.0GPM. On a cold winter morning in FL, that'll give you around 105deg. Average Florida weather, You'll be at 125deg.

Most shower heads flow 2.5-3GPM, at a 50/50 mix, that's 1.5GPM max coming off the hot water line, which would be around a 70-deg rise. You shouldn't have any problem if you're using 1 major appliance or shower+sink. 60A tankless heaters are good for a 2-3 person household.
 
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Old 07-17-09, 11:00 AM
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My locale climate is somewhat similar. I installed a 60a in a one person household and that person was happy when I asked several months later.

If you remember in my first post I suggested leaving the tank water heater you have. You could use it as a preheater for those times you need more hot water and turn it off when not needed. Just hook the output of the tank to the input of the tankless.

Gas may be another option especially given the limited capacity of your main panel but may be more expensive to install because of gas pipe size and special high temp stainless steel venting.
 
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Old 07-17-09, 11:23 AM
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gas is supposedly superior to electric in tankless designs, I would probably go gas if I had the service.
 
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