Noritz tankless conversion


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Old 02-06-13, 09:19 PM
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Noritz tankless conversion

Hello, I hope someone can help me.
my 50 gal tank heater was dying so I took this opportunity to install a tankless noritz nr98.

Originalky Cold water to the tank is 1/2" and hot water out is 1/2". Gas line originally 1/2"

the original tank sat in the garage and was about 20 feet from the nearest sink. I took the opportunity to change to tankless and bought an outdoor model nr98OD. This was because I did not want to change the vent to stainless, did not have a drain to catch the condensation in the models that can be vented PVC, and wanted some additional garage room.

the only mountable location was outside the garage, about 25 feet away from the original location. I changed the gas line to 3/4" and kept hot and cold at 1/2".

thus the new tank sits about 50 feet from the nearest sink, 90 feet from farthest sink. It sits 80-90 feet from the gas main. Gas line is 3/4" all the way to the meter and hot/cold lines are 1/2". Hot water is all copper.

im finding it takes a LONG time to get hot water. Maybe 90-120 seconds to get to full temp 105 to the furthest fixture. Before the change it was on the order of 20-30 seconds

This is much worse than I imagined. My question is, is this due to the increased distance on the water lines or due to inadequate gas delivery so the tank is not heating fully or is this normal for tankless.


Thanks for all your help!!


collin
 
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Old 02-06-13, 10:04 PM
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Actually retiming shows 2.5 minutes to get to full water out of a vanity sink 90 feet away from the tank!
 
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Old 02-06-13, 10:09 PM
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That is normal for a tank-less. Installing a buffer tank will help with what you describe.
 
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Old 02-07-13, 12:20 AM
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You have almost a full gallon of water in that 90 feet of piping IF it is all 1/2 inch nominal AND is indeed 90 feet long. Your vanity faucet, by law, only passes a maximum of 1-1/2 gallons per minute so having to wait a full minute before getting any noticeable temperature increase is entirely normal. If the length of the piping counting all bends is more than 90 feet then of course it will take longer.

Also, with some 90 feet of 3/4 inch gas pipe it is possible that you are "starving" the unit for gas.
 
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Old 02-07-13, 08:50 AM
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Oh yeah I missed that. Its a 199K btu unit. 90 ft of 3/4" will only net you about 110k btu.

Yep starving for gas most likely.... You can damage the unit and carbon it up in no time and/or have CO issues that cause safety concerns...
 
 

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