Quick basic advice on a dripping gas 40-gal hot-water heater

Are you sure?

Look at what this energy page says about the Efficiency Factor:

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The "energy factor [is the] number of cycles that can be completed w/ one kilowatt-hour of electricity".

If that's true, then it's independent of the VOLUME of the water heater.

So, if I read that correctly, a 40-gallon water heater with an EF of .58 takes roughly about 2 KWH of power to heat once while a 50-gallon water heater with the same EF would take EXACTLY the same amount of power to heat all 50 gallons.

Can someone check my math on that web page and report back if I understand incorrectly? If we turn off our brains, of course 40 gallons would cost less to heat than 50 gallons; but if we think, it might not be so.

Can you help me think about this properly? What does the Efficiency Factor say about costs for two different sized tanks with the same efficiency factor?

Donna

Reply to
Donna Ohl, Grady Volunteer Coo
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The only number that really matters to you is the capacity, get one close to the original capacity and assuming you were happy with the performance before, you should be with the new one. I recently replaced the water heater in my mom's house with the last one on the list there, it was 20 bucks more for double the warranty, seems like a no brainer. Can't advise much on the labor cost as I've always done all that stuff myself.

Reply to
James Sweet

Call around and ask, there's only a few different companies that make these things, others just stick their name on them. As far as I know, the efficiency of gas water heaters doesn't vary much from one to the next unless you go tankless.

Reply to
James Sweet

Earthquake straps? In the Bronx? What a rip-off. I haven't been able to find an earthquake in that area larger than a 2.6 (roughly equivalent to closing a drawer). You have to get to 4.0 before there's any damage that's even noticable. (The WTC collapse registered 2.3.)

$50 permit? Call city hall and see if a permit is required.

As for charging you to haul the old one off, forget it. Just put the defunct heater on the curb and the urban faries will scoop it up during the night (they sell them to scrap metal places or make hinges for the doors on their little Leprechaun houses, I forget which.).

Reply to
HeyBub

"Donna Ohl, Grady Volunteer Coordinator" wrote in message

If you have galvanized water pipes you may run into additional cost. You may want to consider re-plumbing the house too if that is what you have.

Reply to
Edwin Pawlowski

Rheem should have a few models that qualify, and they're a pretty common brand. Also see if any State or Craftmaster models meet your needs; AFAICT those three make up the vast majority of the water heater market; many other brands are just relabels of those three. There's another one that you can't buy direct (only sold to pros) but I can't recall the name now.

BTW, you're getting all obsessive compulsive about this. I like you :)

nate

Reply to
Nate Nagel

I'm not sure that the FHR is really all that essential. The hot water available in the first hour is going to depend upon the following - inlet water temp, burner BTU/hr input and efficiency, tank size, outlet temp. Once you set a certain outlet temp (using the dial in the front), you can get an idea of the FHR with the efficiency and burner input. I see however that your table only has efficiency for only 1 model, although it has burner BTU for all. I have the 9 yr 40 gal model, its efficiency rating is 0.59 per the label. I was able to find a little more info on the net using the model number (not UPC). The model number on mine is PG40T09AVH00. I believe the 12 yr model's number starts with 'S'.

Oh, I just saw that you can get the efficiency and burner BTU numbers at the HD web site. Put in your zip code, then it shows more models.

If you are getting the thing installed, and by HD, I wasn't aware you could pick the model; they only offered me the 12 yr. IIRC, the warranty lengths increase if they install it?

Oh, just to muddy things up a bit, I remember once I has bought and installed the heater from HD, I had looked at the Sears site, and found a minor advantage to buying there. I can't remember why. However, models, etc. change quite often, so I don't think that difference would be still valid.

Reply to
Nexus7

Good point ... dead capacity vs active usage!

Darn. I wish I understood this EF thing better, especially given two identical situations where the *only* difference is the CAPACITY.

Based on what you implied, if I inferred correctly, if the USAGE was exactly the same for two water heaters with the same EF, then the costs to operate a 50-gallon water heater would be EXACTLY the same as the costs to operate a 100-gallon water heater (if the Efficiency Factor were the same for both).

Did I understand the math (and your point) correctly?

Donna

Reply to
Donna Ohl, Grady Volunteer Coo

Another good point.

Does the Efficiency Factor take this heat leakage into account? Or is the ONLY way to research the insulation thickness (which doesn't seem to be on the energy star label).

What's the easiest way to compare heat leakage between two water heaters?

Donna

Reply to
Donna Ohl, Grady Volunteer Coo

I think it was MY MISTAKE to call it an efficiency factor. It's actually an ENERGY FACTOR. And, it seems to be independent of the capacity of the tank. It's dependent on the "cycles".

So, it seems if a 50-gallon water heater has an EF of 0.50, then it takes two kilowatt hours of power to "cycle" that water heater. Likewise, if a

100-gallon water heater has the same EF, then it takes the same amount of power to "cycle" that water heater.

Now we have to figure out what a "cycle" is. I can presume it is to heat up a stated amount of hot water, presumably the capacity but I don't know that for sure.

If a "cycle" is the capacity, then it would actually cost LESS per gallon for a 100 gallon water heater than a 50 gallon water heater assuming the same Energy Factor.

Realistically, all the Home Depot water heaters have a 0.58 or 0.59 EF so that would indicate, if my assumptions are correct, they the larger ones (e.g., 50 or 60 gallons capacity) actually costs LESS to operate than the smaller ones (e.g., 40 gallons capacity) for any given number of gallons USEAGE.

Can my math possibly hold water?

Reply to
Donna Ohl, Grady Volunteer Coo

no larger heater costs no more to heat the same amount of water.

if you call a real plumbing store AO SMITH sells a 96% efficent condensing hot water tank but i dont know the cost.........

Reply to
hallerb

Heating less water costs less, even with equally efficient heaters.

Reply to
mc

Nope.

Yup.

The smaller heater will be cheaper to run -- but it may not provide enough hot water when you need it.

But the difference (between 40 and 50 gal) isn't going to be that great provided the heater has good insulation.

The energy factor tells you how well much of the gas is converted into hot water. A low rating on a gas heater means lots of therms (energy) are going up the flue.

If your current heater is 40gal and meets your demands, I see absolutely no reason to upgrade to a 50gal tank.

I'm in Northern CA and a 50 gal tank is just about adequate for my home -- with 2500 sq ft, two adults and three kids. We run a little low on hot water if everyone takes a shower or bath in really quick succession while doing laundry. It's a very minor problem about once a year. 99% of the time, 50 gals is just fine.

Reply to
Malcolm Hoar

For the same water use, yes. Efficiency refers to non-electric heaters (electrics are 100% efficient), and accounts for the heat loss up the vent pipe. In other words, heat that doesn't heat the water.

Not to heat the water, but over the lifetime, yes.

True.

Although both units will use the same amount of energy to heat water, the larger heater has a larger tank, which in turn means it has more surface exposed to the outside. The greater the surface area, the greater the heat loss when you aren't using water, which means the larger heater will use more energy to maintain the hot water.

Now, if you live north of the Mason Dixon line and your water heater is inside the house, then that isn't a total loss as you heat that escapes goes to warm your house. It only becomes a problem when you want to run the A/C.

OTOH, if you live south of the Mason Dixon line or your water heater is in the garage, then yes, you will pay a little more to run a 50 gal heater than a 40 gal. one. Is it significant? Look at the energy tag on the two heaters, but I suspect the difference is less than $20/year. OTOH, you may find the larger unit has better insulation, which may compensate.

Reply to
Rick Blaine

Sigh. Absolutely true and totally meaningless within the context of this discussion. Oh wait! This is usenet...

Hint: Direct energy cost is based on _use_ and efficiency, not _capacity_ and efficiency.

Reply to
Rick Blaine

At the risk of repeating myself... and the insulation.

Think about it. How many hours per day do you actually spend with the hot water faucets turned on?

The tank is "leaking" heat 24 hours per day, 7 days a week. A well insulated tank will store the energy you used and paid for. A poorly insulated tank will throw it away.

Reply to
Malcolm Hoar

Yes they do. Basic physics says that it takes the same amount of energy to heat the same water, regardless of the container size.

But not because it takes more energy to heat the water, because the heat loss from the tank is slightly higher.

Reply to
Rick Blaine

"Donna Ohl, Grady Volunteer Coordinator" wrote in message

Why a major chain? They don't give very good service. Try a local plumber and plumbing supply house for a better deal and usually better units.

Reply to
Edwin Pawlowski

Strange. Then it isn't a measure of efficiency.

Reply to
mc

Not exactly. There are two types of heat use/loss in a water heater: One is the heat used to heat the water you are actively using. The other is to reheat the water that's sitting in the tank all day when you aren't using it.

Both tanks will use the same amount of energy to heat the water you are using directly. If both tanks have the same efficiency and the same insulation, the smaller tank will lose less energy to the outside air and thus be slightly less expensive to operate over the course of a year.

The actual difference in cost is probably not that much. Look at the estimated annual cost of the two heaters on the yellow energy tag. They normalize for all that. If one say $180 and the other says $200, that's a rough idea of the difference in operating costs.

Reply to
Rick Blaine

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