I am currently in the design phase of a 2400 sq ft house just outside of Houston, TX. I will have a 3 ton Bosch installed with a desuperheater. There will be 4 people living in the house. I am thinking of using a 80 gallon Marathon as a buffer tank with a 50 gallon electric water heater. Is the Marathon worth the extra money or would a std tank suffice? I had always planned to go with tankless, propane, but I don't see that as the best fit for this application. Do you agree? Thanks, Michael

Correct, tankless gas heaters aren't a good match for water that may be almost fully preheated. You might look into combination heat pumps that can provide 100% of hot water with a single tank and no additional heater.

From all my research, I thought that a buffer tank was required. How does a heat pump water heater eliminate that need?

I think what jonr is talking about is a hybrid or combination heat pump, Waterfurnace has one called the synergy 3d, It can heat air and water.

I have one made by Hydro-Temp, but I use it for radiant floor heating, DHW, warm and cool air.

In your case, you may just get away with two 50 gal. electric tanks, the first one as a buffer non-powered. Look for the ones with 3" of insulation.

ChrisJ

Posted By munch74 on 17 Jul 2013 08:07 AM
I am currently in the design phase of a 2400 sq ft house just outside of Houston, TX. I will have a 3 ton Bosch installed with a desuperheater. There will be 4 people living in the house. I am thinking of using a 80 gallon Marathon as a buffer tank with a 50 gallon electric water heater. Is the Marathon worth the extra money or would a std tank suffice? I had always planned to go with tankless, propane, but I don't see that as the best fit for this application. Do you agree? Thanks, Michael

The Marathon tank is a great tank, but not worth the money. Takes a very long time to pay back. Especially as a buffer tank. Save the money, and use a regular tank if you are on some kind of budget!