That would depend on your local cost structure. I would guess that in
some situations you would recover the investment cost quicker than you
think. In others it might not be worth it.
You also need to consider the recovery rate. Not all water heaters can
re-heat water at the same speed. A high recovery 40 may be enough if your
current model does not have a high recovery rate. I would also add that
having one 60 gallon heater will result in far less standby losses than two
" Would going from 40 to 60 and then dropping the temp from 150 to 125
I did run some numbers. Assuming the incoming cold water is 50
degrees, mixing 150 with it 3:1 gives you the 125 temp. So, a 40
gallon tank of 150 water could be mixed with 13.3 gallons of 50 degree
water to yield 53.3 gallons of 125 water.
So, going to the 60 gives you 60 gallons at 125, vs 53.3 by the mixing
approach. The other factor to consider is the heat loss through the
tank is also proportional to the temp difference. Assuming an ambient
of 55 degrees, with water at 125, you have a delta of 70 deg. At 150,
the delta is now 95, an increase of 36%. So, your gonna lose 35% more
energy through the tank with the higher temp. I think these two
together mean that unless there is some other issue, like space, the
bigger tank is going to be the better solution.
I got to thinking. Since the only time you seem to have a problem is
when you have company from out of town, it may be better to have put the
electric first so most of the time you can have it turned off and you will
not use any electricity and will not have any standby losses (heat loss from
the tank). Then when expecting company you can crank up the electric unit.
You might even set it up to heat just a little to temper the water rather
than heat it so the gas unit can do the real work.
in series that wouldnt work although he could do it by adding some
although I would leave the tank full of non moving water for a extended
the best thing he can do is monitor his electric bill if it spikes then
try something else
With the electric tank LAST in series, only turning on the electric
tank during periods of peak use will not work, since the water after
being heated by the gas tank would cool and never be heated in the
electric last tank. espically is they didnt use hot water for a couple
if his electric bills spike he could add some valves, during normal use
water would enter electric tank first, and not be heated, going to gas
tank for heating. this way water wouldnt sit stagnant in the electric
tank. //// during peak use he would reverse this by changing valve
position to gas tank first and turning on electric tank. valves are
cheap, with 2 tanks of differing ages I would altering valving to
isolate one tank or the other, that way when one fails as it certinally
will one day he moves some valves and has hot water from the remaining
good tank till the bad one is replaced.
I certainly could do that. Or I thought I could just use a couple of valves
to bypass the electric water heater all together and take the gas heated
water straight into the house, but, I am concerned about what happens to a
full tank of un-heated water sitting for days. I also thought about putting
in a power-vented gas model in series ahead of my existing model. With it
there is no pilot light so I could put a switch to kill the power to the
heater, no power = no heating, but this idea became somewhat cost
prohibitive and again I would have the problem of water sitting in a tank
un-heated. Would you guys (gals?) mind giving me some feedback on my second
post about the insulation blankets. I really appreciate all the ideas so
far. I do think I will take the advice and raise the temp on the gas heater
a bit in an effort to keep the electric one from running at all.
No matter what you do, be sure to put a drain pan under each of these water
heaters in your attic and pipe the drain down to someplace in the living
space where you will see it right away. It's easier than having to replace
half your ceiling.
the more insulation the better! Just DONT block venting or burner
access on the gas heater! or wiring access on the electric
if you can insulate hot water line between and leaving tanks, that will
save a little, and save running water till it gets hot too. insulated
lines are a save save save!!
They have premaid hot water tank insulating blankets. safe convenient
and pretty cheap.
just for the record I wouldnt leave any tank sit with stagnant water
hot or not for a extended time. if were on vacation for a week I make a
habit of running water espically hot but both when we get home, its
cheap and seems a good precaution...
I already took the liberty of insulating the pipes. To their credit, the
original plumbing was insulated as well, I just had to add to it when I ran
some extra lines to tie the water heaters together. I have seen these
pre-made insulation blankets at Lowes for I believe $14. Lastly I don't
think that leaving a tank of water sit is a good idea either, therefore I
will just try to keep the use of the electric heater to a minimum.
Thanks for the feedback...
There is a drip pan under each heater. Code requires 6 inches deep (which
they are). The are both connected to a 1" PVC drain line which exits the
attic and dumps the water outside the house should they leak.
That's good, but make sure you can see any water from a window you look out
a lot. I've seen people run them into rain gutter and never know they were
leaking until the water heater bursts. Then they say "I guess that's where
all the water on my lawn was coming from."
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