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WCohn
WCohn, Construction Worker
Category: HVAC
Satisfied Customers: 1099
Experience:  Been in contruction 18+years
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I have a Rheem RTG 74XN2 tankless water heater, about 8

Customer Question

Hi, My name is***** have a Rheem RTG 74XN2 tankless water heater, about 8 years old. It takes forever to get hotwater in the house, and sometimes, once it is hot, it goes cold after about 5 min. We have a 2 story, 1800' house. What can I do to get hot water quicker and longer?
JA: How long has this been going on? And how severe is the problem?
Customer: About a year. Bad
JA: Do you plan on doing the work yourself?
Customer: Is it something I can do myself with guidance, or should I have a plumber or specialized Rheem person work on it?
JA: Anything else we should know to help you best?
Customer: That is the issue
Submitted: 8 months ago.
Category: HVAC
Expert:  WCohn replied 8 months ago.

Hello, my name is ***** ***** I look forward to helping you!

Expert:  WCohn replied 8 months ago.

This is due to the way tankless water heaters work

Expert:  WCohn replied 8 months ago.

They take quite a bit of time to fire up. About 8 seconds and then they slow down the flow to a rate that it can heat to the desired set temperature.

Expert:  WCohn replied 8 months ago.

Depending on you house pressure and how it is plumbed hot water will flow through the system at a rate as low as a foot a second.

Expert:  WCohn replied 8 months ago.

There are some things that can be done to help with the issue. What is the set temperature?

Customer: replied 8 months ago.
140
Expert:  WCohn replied 8 months ago.

Lower it down to 120. 120is more than hot enough to sterilize your dishes and we humans only shower in 104 so lowering the set temp will allow it to go through the system faster. Next would be to install a recirc pump and a thermal bypass valve.

http://www.homedepot.com/p/Hot-Water-Recirculating-System-with-Built-In-Timer-500800/100426993

Expert:  WCohn replied 8 months ago.

Any questions? I'd appreciate a positive rating for my time.