Replacing a Oil Hot Water with gas

Discussion in 'Water Heater Forum, Tanks' started by keano016, Feb 14, 2011.

  1. keano016

    keano016 New Member

    Messages:
    35
    Location:
    Mass
    I want to replace my 9 year old oil tank with a gas one. Can you tell me why a plumber thinks I should re-line the chimney when the current oil one is going through the chimney. If I do not want to use the chimney, what are my options? Power venting? Does Home Depot sell any power venting ones? I think my plumber quoted me around $950 to buy a 50 gal direct vent gas HW heater.

    Also can the venting occur under a deck? Can the venting be done using a flex pipe?
  2. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,245
    Location:
    Cave Creek, Arizona
    Condensation is a bigger factor with gas than oil, and if the flue is too large, it loses it drafting capacity.
  3. keano016

    keano016 New Member

    Messages:
    35
    Location:
    Mass
    Thanks for the input few more questions.

    How do you rate the quality of a Rheem, A.O. Smith or GE that is sold in Home depot? The GE I am looking at is model Model # GG40T06PVT. What is the difference with the GG40T06PVK that is the same price?

    Also, how difficult is to install one (apart from the gas). I am comfortable with my water supply plumbing skills but have not done the exhaust plumbing before.
    Last edited: Feb 16, 2011
  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,802
    Location:
    New England
    In most places in Massachusetts, it is illegal for a homeowner to replace a WH...

    There is no great concensus, but the brand that seems to get the most votes is Bradford White. Rheem is probably second. Rheem makes the GE unit to a price for HD. The biggest difference is in the burner design. My personal preference would be to put AO Smith in third place one that behind BW and Rheem. Maybe 3-4 years ago (don't remember exactly), the Feds mandated most sizes of WH must provide protection against igniting combustable vapors that may be present around the burner such as paint fumes, solvents, etc. The design of that took different directions between the manufacturers. BW seems to have the fewest problems with Rheem a close second.

    Longer warranty doesn't necessarily buy a better tank, but a longer insurance policy as any tank could last that long. Sometimes, it buys you an extra anode rod, which you can replace yourself for a lot less (if you think of it!).
  5. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,298
    Location:
    Yakima WA
    I have a GE/Rheem Power Vent that I got at HD. It performs well. This is my second power vent, and this one is improved over the first one although in my case, it didn't make much difference. The vent piping can be smaller and go for a longer distance. I just continued to use the original 4" ABS because there was no reason to replace it. It would be a good idea even if not required to have it professionally installed to make certain everything is properly connected.
  6. keano016

    keano016 New Member

    Messages:
    35
    Location:
    Mass
    Thanks for all the feedback. You are right, having a plumber install the heater and get the proper permit is definitely worth it.

    Now, my questions is, what happens if the tank fails? What is the service company that you would call to get the tank replaced? Is that the advantage over getting one from the supply house?

    Also, will I regret putting a 40 gallon tank in a house with 3 full bathrooms (family of 4). I see how it is valuable to have a larger one, but in the end, if there is no hot water, wait for it to warm up :). Would a washer, a dishwasher and a shower empty the tank so that a second person can not take a shower right afterward or at the same time?
    Last edited: Feb 22, 2011
  7. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,802
    Location:
    New England
    In a typical tank, you can draw off somewhere between 70-80% of the stored water before you notice it is cooling off. On a 40-gallon tank, say 30-gallons. Now, because it is typically hotter than you would use in a shower, and depending on whether it is winter or summer, you might use 75% hot, and 25% cold, so you're back to maybe 40-gallons of shower temp water. A typical showerhead uses 2-2.5 gpm, so maybe 16-minutes. A typical teenager will easily exhaust the WH, and depending on the recovery rate, most people would then have to wait.

    Depending on the type of washing machine, and the cycle you use, some don't use any hot water, and if warm, it could vary from 20-gallons to maybe only 3-4 (top loader on warm verses a front-loader).

    One way to make a tank 'look' bigger, is to raise the storage temperature. Then, you normally mix in more cold to get the desired temp. But, it is more dangerous. Where I live, ALL WH need a tempering valve, that limits the outlet temperature of the WH, regardless of how hot you make it in the tank, tempered water comes out (can be adjusted, but most come preset to 120-degrees F). If you have the flexibility, sometimes people will tap off the hot water before the tempering valve to feed things like the washing machine and dishwasher, where that hotter water can make a difference, but the rest of the house only gets the 'safer' cooler water.
  8. keano016

    keano016 New Member

    Messages:
    35
    Location:
    Mass
    Thank you for that analytical analysis. As an engineer I appreciate the data you presented and helps me better understand the issue. I know that I have one of those eco freindly water flow reducing shower heads which should decrease the amount of water flowing during a shower, but thinking that somebody may use 30 gallons of water during shower is just crazy and wasteful :).

    Now, I need to mention that my current tank is only 30 gallons and I have not noticed any water shortage. Maybe because my kids are small and don't take 20 min showers, yet.
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