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Rinnai’s new RH180 Water Heater VS “Standard” Rheem 50 Gallon Gas WH


  Water heaters are boring to most people, but if you’re reading my blog you aren’t like most people!  You are like me, you are a researcher.  Most likely you’re a male, between the age of 45-55, possibly an Engineer or Physician, and you are most likely handsome (guessing here).  No offence ladies, but my blog stats show this profile fits 80% of the people reading here.  Ok back to the water heaters…
   Most houses in America that have access to Natural Gas use a standard 50 gallon gas water heater like this one.  Rheem makes a pretty good unit, and I’ve used this model for a few houses over the years. 

Rheem Fury 50 Gallon Gas Water Heater

  I’ve got three issues with these “standard” tank units.

  1. Low capacity.  They are typically 40,000 BTU inputs and deliver 70-90 gallons of hot water in the first hour of use.  That is enough hot water for small 1-2 person households, but once you fill a bathtub the person showering after that might get cut short on hot water.  
  2. Low efficiency.  These standard gas tanks are between 55-62% efficient in their use of gas.  That means for every dollar of gas I spend I’m only getting 55 cents back, the other 45 cents is lost to inefficiency.  
  3. Venting.  This doesn’t affect you if you are reading this for tank replacement advice, but if you are building a new house you might have this tank inside your conditioned space and the standard metal “B” vents are terrible for combustion safety, and for air leakage. 

Finally there is a competitor to the standard tank!
I was reading one of my trade journals last night and came across this really cool new product from Rinnai!  I’m a big fan of this company, and have used their tankless units for years (including my house with an outside mounted tankless unit) so this really stood out to me.

Rinnai RH180 Hybrid Tank-Tankless Water Heater

It appears to be a smallish tankless unit that’s married to a standard 40 gallon storage tank.  Here’s a link to the Rinnai website if you want to check the details, but here’s what I like about this unit.

  • It would make a great replacement to an existing 40-50-75 gallon gas unit.  Same 1/2″ gas line, same connections, and roughly the same space needed.  It also uses a standard 4″ metal B-vent like 99% of the homes in America have currently.  Any plumber should be able to install this without special training. 
  • Their stats show double the hot water capacity of a 50 gallon gas unit.  First Hour Rating of this unit is 180 Gallons compared to that Rheem I cited above that has 90 Gallons FHR. 
  • Efficiency.  This unit is 80% efficient compared to the Rheem which is 62% efficient.  Less waste is a good thing! 

Overall this unit shows alot of promise.  I’m sure I will have a house in future that will be a good fit for this unit so hopefully I’ll have a future Post-Install review to share.  Please comment if you have any direct experience with this new unit.
UPDATE DEC 2, 2013:
I had my supplier price this for me to see how it compares and it’s about $500-600 more than a standard Rinnai tankless unit.  That isn’t “cheap” but I think for a well built unit that should last 20+ years that’s not a bad price for the performance.  If you are thinking of swapping out your standard tank and going tankless you will easily make up that $500 in extra costs for labor/gas lines/venting.  This unit is well priced and I can’t wait to install one on 2014.

 Best,
Matt Risinger
Risinger Homes in Austin, TX

Risinger Homes is a custom builder and whole house remodeling contractor that specializes in Architect driven and fine craftsmanship work. We utilize an in-house carpentry staff and the latest building science research to build dramatically more efficient, healthy and durable homes.
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