Water heater – adding insulation
edwardh1
| Posted in Energy, Heating & Insulation on
How much insulation is too much around a water heater. I have a 47 gal new Rheem electric- Rheem has no insulation R factor listing but it has insulation and the outside does not feel warm. I have wrapped about 2 inches of insulation around it , cept on the top- am thinking of putting a piece of HVAC ductboard on parts of the top. But I read that the yearly standby costs was about $90 a year which does not seem like a lot of money. Where does the law of diminishing returns set in on more insulation?
Replies
Generally, with a newer electric unit there's no advantage in adding insulation unless it's free. No harm in adding the insulation, though, and no real limit on how much you can add.
Agree with DanH.
Be sure to cut openings around the access panels (all three of them).
Speaking of diminishing returns, remember that, if your water heater is in an inhabited part of the house, you only 'lose' heat when you're not heating your house.
So a lot depends on where you're located.
under the house
Too much would be if it blocks the mech room door!! ;)
Diminishing returns ... yes ... after the first 2 inches (which has eliminated 90% of the heat loss), it drops off radically.
$90/year sounds really high for standby tank loss. Where did you get that? What energy type and rate are we talking about here? What size tank? I'm thinking maybe it should be $20-$30/yr ... actually I calc'd that for 7 cents/kwh and $1.20/therm for a 40 gallon tank. 80 gallon would be $30-40 per year.
Slide your hand under the 2" insulation and see how hot it is in there.
my plumber told me not to insulate directly on the tank in the basement because of condensation and rust. i built an insualted box around mine probably not worth it .
A box? Sounds difficult in terms of any maintenance you might have to do on the heater.
Condensation?? ... you wrap a hot tank w/ insulation. Any moist air getting in through the insulation (from the room) ... the RH drops dramatically ... therefore no condensation. I could be missing another point, though. But that is the only humidity scenario I can think of w/ what you said. There really is no moisture generation at the tank.
Since most my wood and insulation i get free, built a box around mine with a door and have an extra 4" of closed cell polyfoam insulation. Also have heat stop siphon traps on both input and output.
Dont know how much it saves me but sure makes me feel all warm and fuzzy that i'm being PC green - <G>
"nother advantage is that now 3 vertical walls of the box can now be used to hang stuff on and build shelves against.
> "nother advantage is that now 3 vertical walls of the box can now be used to hang stuff on and build shelves against.Though that may be a bit of a problem when it comes time to change out the water heater.
The modern conservative is engaged in one of man's oldest exercises in moral philosophy; that is, the search for a superior moral justification for selfishness. -John Kenneth Galbraith
"...it has insulation and the outside does not feel warm."
So why would you add insulation then?
Of course, if it were "perfectly" insulated it would feel a bit on the cool side.
The modern conservative is engaged in one of man's oldest exercises in moral philosophy; that is, the search for a superior moral justification for selfishness. -John Kenneth Galbraith
I heat my water with propane and spend probably $100/month on hot water (2 teenagers), My basement ceiling is insulated (8") so the basement gets down to 50 in the winter. I wrapped my Rheem 40 gal tank with R13 fiberglass insulation, sides and top. I covered the whole thing with sheet of vinyl around the outside (Velcro holds it together) to keep the whole thing together. If you put your hand under the insulation (on the outside of the tank) it is really hot so I know I am saving gas. Key cautions: do not cover the overpressure valve (can't test otherwise) or the controls. Do not block airflow at the top around the vent pipe. Add brackets at the bottom to keep the whole thing from slipping down and covering the combustion air intake slots. (Don't rely on tape or tightness of insulation -- over a year or two the insulation will slowly slip down.)