(206) 949-5683, Top Rated Plumber, Seattle
Results 1 to 15 of 21

Thread: Water Heater Questions

Hybrid View

  1. #1
    DIY Junior Member GoldMaple's Avatar
    Join Date
    Jul 2009
    Location
    Canada
    Posts
    26

    Default Water Heater Questions

    I'm looking for a new tank style water heater and I have a few questions.

    1. The R factor of the insulation varies from heater to heater. Do water heater insulation blankets work very well?

    2. My 27 year old James Woods heater has legs but most of the new heaters do not. Is there a reason why most new water heaters do not have legs?

    3. What should I be looking for in a good water heater?

    Thanks.

  2. #2
    DIY Senior Member Runs with bison's Avatar
    Join Date
    Aug 2009
    Location
    Midwest
    Posts
    892

    Default

    Quote Originally Posted by GoldMaple View Post
    I'm looking for a new tank style water heater and I have a few questions.
    Electric, natural gas, or propane?

    1. The R factor of the insulation varies from heater to heater. Do water heater insulation blankets work very well?
    Yes, the blankets can help considerably, particularly on tanks with only an inch or so of insulation. My current 50 gallon gas water heater is only R8 with 1" of insulation. I added an R6.7 blanket. This reduced tank losses by about 10-15 therms/year. So it will pay out in less than 18 months.

    If I purchased an R24 insulated water heater, I might not even add the blanket as the payback would be over 10 years. (The numbers might seem odd, but I accounted for the head and base of the tank in my calcs which cannot be blanketed.) I wanted an R10 blanket for my less insulated heater, but none were in stock locally at the time. It would have added condiserably to the circumference, so the R6.7 was probably a better fit (literally.)

    2. My 27 year old James Woods heater has legs but most of the new heaters do not. Is there a reason why most new water heaters do not have legs?
    I don't know with respect to the legs. Mine has short legs. The negative of legs and other projections from a tank is that they conduct heat away from the vessel, increasing storage thermal losses.

    Since your water heater is so old, you must have pretty mild corrosion/sedimentation conditions in your hot water. That's good and suggests that it might make sense to invest in a long life tank, because you might double it.

    3. What should I be looking for in a good water heater?
    Assuming that you aren't wanting to do power venting/sealed combustion or higher efficiency condensing types, I suspect you want to invest in one with known high reliability, well insulated, and with good overall efficiency. I suspect something like this would last you a very long time.

    For gas the Bradford Whites/Rheems/GE's are generally well liked because they have a better air induction system for the FVIR regs. They draw air from openings in the sides. The Whirlpool/State/A.O. Smith/American Water Heater types have small openings for air, located on the bottom of the tank. This can result in inadequate draft with associated thermocouple failure as well as a failing gas valve/thermostat.

  3. #3
    DIY Junior Member GoldMaple's Avatar
    Join Date
    Jul 2009
    Location
    Canada
    Posts
    26

    Default Gas Heater

    Thanks! I'm looking for a 40 gallon natural gas water heater. All of the big box stores here in Canada sell tanks with very little insulation and I've been reading blogs suggesting that the big box stores sell a cheaper line so they can fit a price point. I'm willing to spend a little more to get something that might last another 27 years..... Rheem and Bradford White keep coming up as preferred water heaters so I'm already leaning in that direction.

    As for the legs on the heater I'm just a bit concerned that if I get a heater without legs and my floor is not perfectly flat that it could rock. With 3 legs it will not rock at all. The basement floors in my house are not flat.

    Also, what do they make the flat bottom tanks with? Will they rust? My basement floor does not have a vapor barrier under the concrete so moisture could collect under something that is directly on the floor.

  4. #4
    Plumber Cass's Avatar
    Join Date
    Nov 2005
    Location
    Ohio
    Posts
    5,984

    Default

    One other thing...don't expect your new heater to last 27 years...Brad White first then Rheem...

  5. #5
    Moderator & Master Plumber hj's Avatar
    Join Date
    Aug 2004
    Location
    Cave Creek, Arizona
    Posts
    25,633

    Default heater

    1. Many manufacturers specify NOT to use a blanket.
    2. Unless your heater is hot to the touch, there is almost no heat loss throught the jacket, and definitely not enough to be affected by a blanket.
    3. Gas heaters get most of their standby loss up the center flue where a jacket does absolutely no good.

    Therefore, it you want the most efficiency, you need a heater with a mechanical damper on the flue that closes when the burner is not operating.

  6. #6
    Homeowner geniescience's Avatar
    Join Date
    Nov 2005
    Location
    humid summers hot, humid winters cold
    Posts
    2,152

    Default

    Quote Originally Posted by hj View Post
    1. Many manufacturers specify NOT to use a blanket.
    2. Unless your heater is hot to the touch, there is almost no heat loss throught the jacket, and definitely not enough to be affected by a blanket.
    ....
    No blanket, they haven't tested it out and they have no product to sell as an add-on. To limit liability they won't comment except to say "it's fine without any more insulation." To limit time wasted, they won't allow any discussion either.

    This has been my experience with _Electrical_ HW tank manufacturers.
    About gas, no comment.

    It IS possible that someone will overinsulate something.
    Not likely in the average household, but it's still a possibility.
    Extra Insulating an electric water heater is certainly possible, and you might like the result.
    Or, you might find you are not satisfied after doing the exercise.


    Heat is transferred in all directions to all surrounding objects. Just like the sun sending heat out to all the planets. We get heat radiated from the sun. HW tanks are a permanent source of heat energy for their surroundings. There IS some heat lost (transferred). The tank does warm its surroundings a little bit.

    Insulation that covers most of the HW tank will have an impact, reducing the amount of energy that is radiated out to the surroundings.

    Whether it's worth your while is another question, and the answer is not easy to calculate: formulas purported to justify payback are not the whole picture. Don't expect a big change. Get a good heater to start with.

  7. #7
    Plumber jimbo's Avatar
    Join Date
    Aug 2004
    Location
    San Diego
    Posts
    9,001

    Default

    On a gas heater, you cannot put any blanket on the top area at all.

    In 2003, WH companies had to make significant changes in the burner area to comply with FVIR, and invariably that tended to make the water heater taller. Since 4 extra inches of height can cause signigicant install issues for a large population of existings, they usually opted to remove the legs, to keep the overall height about the same as the old ones.

  8. #8
    DIY Senior Member Runs with bison's Avatar
    Join Date
    Aug 2009
    Location
    Midwest
    Posts
    892

    Default

    Quote Originally Posted by hj View Post
    1. Many manufacturers specify NOT to use a blanket.
    Wouldn't mean much as they do what gives THEM the fewest problems, consumer be damned. The most likely problem from insulating is that some will not notice small leaks as quickly with an extra layer.

    2. Unless your heater is hot to the touch, there is almost no heat loss throught the jacket, and definitely not enough to be affected by a blanket.
    That is completely wrong, a common layman's misperception of heat transfer. One could make the same claim about home walls and ceilings and be equally wrong.

    Double the effective R value, cut the wall losses in half. Doesn't matter whether it feels hot or not. If you drop the outer surface from 76 F to 73 F in a 70 F room, you've still reduced the wall losses by roughly half. Once you get to an R value in the neighborhood of 16+ there is much less incentive for a blanket or additional insulation. But in the R8 range the payback is rapid.

    Yes, there are other sources of loss, such as the chimney/flue, relief valve & discharge piping, and thermosiphon/conduction in the inlet/outlet lines.

    There is definitely some waste from draw up the chimney, but from what I can tell on mine, the pilot roughly balances this. Haven't had a power vent for comparison. With a power vent you can expect higher maintenance and/or earlier replacement for the efficiency gain of the damper. They cost considerably more but they tend to have more insulation to begin with.

    Quote Originally Posted by jimbo View Post
    On a gas heater, you cannot put any blanket on the top area at all.
    That is misleading though. It is already insulated so it is not insulation that is the problem, but adding additional layers there could interfere with the draft or cause other issues. (I doubt that this applies to sealed flues other than needing some offset.)

    And the area of the top is about 10% of the wall area. So while you can't cut it's losses, it is a small portion of the total.

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •