40 gal just not enough: Replacing water heater for 2400 sq home. Family of 2 adults + 2 children

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"ransley" wrote

Actually I didnt mention that but I'll add I 'seem' to get a *small* benefit there. It isnt much but in the garage, which is cold in winter, a small amount of heat is added by it. Being in the garage, it's effect on the AC of the house in summer is negligible.
Mine is nearing end of life cycle so I'm reading the discussion carefully and looking at replacement units. Newer ones are much better than my old one.
I note several tank types around 400$ or less which would effectively replace the existing unit with same style but more efficient, and lots of tankless systems.
Running through the web page another posted, I seem to be the 'break even' on gas price to run here with a slight edge to a tank type. The only real difference seems to be how long the units last? That and a slight residual heat generated to the garage which in winter for me, is a beneficial but minor 'nice' towards the tank type.
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Hi Mark,
The impact of standby loss with respect to added a/c demand is generally very modest for three reasons:
1) with the exception of some of the southern most states, heating degree days exceed those of cooling throughout most of North America, in some cases by a factor of ten or more (e.g., Minneapolis MN). Pittsburgh PA, a mid-eastern seaboard city, has 5,968 HDD and 654 CDD. Even in San Diego CA, heating demands exceed those of cooling, i.e., 1,256 HDD versus 984 CDD;
2) generally speaking, water heaters are located inside conditioned spaces in colder regions due to the risk of freeze damage whereas they are typically placed in non-conditioned spaces (e.g., attached garages) in warmer climates -- located outside the home's thermal envelope, there would be no impact on cooling demand;
3) for every kWh used, an air conditioner will remove three or more kWh of heat. A 10 SEER air conditioner will purge 2.93 kWh of heat for every one kWh consumed and a 13 SEER air conditioner (the current minimum standard) will eliminate 3.8 kWh of heat. Thus, each kWh of standby tank loss translates to 0.34 kWh of cooling demand at 10 SEER and 0.26 kWh at 13 SEER.
Taken together, it's pretty clear the benefits in terms of heat gain far outweigh any potential loss with respect to added cooling demand.
Cheers, Paul
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wrote:

Hi paul, I really dont see much of either heat gain winter or summer, Im just arguing against misinformed oposition. I see a flue going up the uninsulated part of the tank going outdoors. I guess im a little pissed at negatives thrown at tankless by people that never owned one, and post wrong information. I own one, I can see on my 9$ summer gas bill, I see a short payback, and I cook all food on a gas stove and have a gas dryer. Tank Energy Factor is what nobody wants to aknowlegde. Energy Factor for Tanks are about 52-60, and it simply means, in fact, if your tank is a 60 E.F., $0.40 of every dollar you pay to heat water is wasted. Tankless EF ratings are near Total efficencies, Tankless EF ratings are from 82-95 [95 for a condensing Takagi] We have all these folks here who put down tankless with bogus, stupid, bad, information. Granted tankless are not for all, but they are designed to last 30 years since the coil is thick copper pipe, they save money, they have drawbacks you must learn to live with, but I like saving money and not paying utilitie companies. I did so well with a 110 yr old house, lowering utilities from maybe 1500 a year to 550 that the gas company came out to see how was I stealing gas. I was told by Nipsco my house is the most efficent they have seen. I heat 1800sq for no more than $105 at max -14f lows. Tankless can cost alot more, but can cost the same, last longer, and save enough to pay you back, very quickly. Quickly, and that is at todays Ng gas prices, with oil over 100 a barrel, it`s going to rise real dam fast. Your payback will be sooner with every Ng price increase, and last I read, new NG field are not being opened from NIMBY bs, consumption is outpacing production, that`s why LNG dockyards are being built, so we can IMPORT gas on tankers, even though we have it in the ground. We have no energy policy, we have no education. Even England mandates only Condensing heating units, and England is an Exporter of energy. We are an Importer. Dam I should run for President and give America an Energy agenda.
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On Wed, 9 Apr 2008 12:02:29 -0700 (PDT), ransley

Hi Mark,
I don't like misinformation either and I don't have a strong opinion on this matter. I don't doubt the operational performance of natural gas tankless units is superior to that of their electric counterparts and that the efficiency gains are more impressive. I have no first-hand experience with tankless gas, but I'm familiar with the electric variant and that experience left me cold, literally! It may very well have been undersized (I don't honestly know), but the water never got what you would call "hot" even though the shower was equipped with a low-flow head and I was the only user at the time. Based on this admittedly limited experience, I would be hard pressed to recommend an electric unit, unless it was a high capacity model and that, in itself, opens up another can of worms.
If someone could tell me that a conventional gas water heater with an EF of 0.60 would use X cubic metres (or therms) of gas per year and that a state-of-the-art tankless version would use Y, it would help me to better compare these two technologies.
Cheers, Paul
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wrote:

So your views are jaundiced. Taking experience from electric and applying it to gas tankless is like comparing apples to oranges.
It may

And that has what to do with gas which has far higher output capability?

The EF is a measure of how much hot water the unit produces per unit of energy. It isn't that hard to calculate. If you know the EF of your current unit, what your bills are and the EF of the other unit, the math is straightforward.
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On Wed, 9 Apr 2008 15:09:05 -0700 (PDT), snipped-for-privacy@optonline.net wrote:

Let me say this again, but this time more slowly so perhaps you might come to understand it. I said "I don't doubt the operational performance of natural gas tankless units is superior to that of their electric counterparts and that the efficiency gains are more impressive." I also explicitly stated that "I have no first-hand experience with tankless gas". I did not in any way knock gas tankless; my criticism was in regards to *ELECTRIC* units, which should have been obvious to even the most dim witted amongst us -- guess you proved me wrong.

It has absolutely nothing to do with gas, just electric. Let me spell it out for you again. *E-L-E-C-T-R-I-C*.

And if a homeowner uses natural gas for space heating, cooking, clothes drying, etc., they can isolate the DHW component from their bill how?
Cheers, Paul
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wrote:

Go to Takagi.com or www.energystar.gov , If sized right , mainly meaning NG supply, they work. I have one.
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wrote:

You need someone to check Gas Flow or supply with a Manometer. To be sure at your lowest winter temps, with all competing appliances on, and calculating winter reduced flow YOU HAVE THE BTUs most installers are to dumb to do it. .
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wrote:

No, it's not clear at all to me that is the case. Because contrary to your claim, in my experience most water heaters I've seen, from NJ through New England are NOT in conditioned spaces. Most are in an unfinished basement. That's where mine is. Some others are in garages. I would say only a minority are in conditioned living spaces. In all the condos and homes I've lived in, I have never had a water heater in the living space. I know they exist, but the point is, they are not the majority of cases. Even where you have one in a utility closet, it's not clear to me how much of that waste heat gets into the living space itself, as opposed to just raising the temp of the closet that it's in.
Now, even hallerb apparently conceeds that most of the standby loss is up the flue. And the rest of the loss, that escapes the tank sides, doesn't by some miracle all go into the living space above. In fact, I would bet that in a water heater in the basement, which is a typical case, only a small amount, probably unmeasureable makes it up there.
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On Apr 9, 5:59 pm, snipped-for-privacy@optonline.net wrote:

And even if it's in conditioned space, it most assuredly is not where you want it nor when you want it.
R
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On Wed, 9 Apr 2008 14:59:35 -0700 (PDT), snipped-for-privacy@optonline.net wrote:

As is true of most every home in my neighbourhood, my DHW tank is located in a finished basement so 100 per cent of its heat loss is usable over the course of the heating season; in this case, a span of some seven months -- eight for thermal wimps.
Even unfinished basements, unless the floor joists are well insulated, are thermally connected to the conditioned space above. In fact, according to one Ontario Hydro study, 25 per cent of a home's heat loss occurs through the basement. Until it reaches equilibrium, heat will eventually migrate throughout the building structure, regardless of its point of origin.
Cheers, Paul
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wrote:

ahh tank vs tankless, while posters get their panties in a wad, they could be getting a energy audit where they evaluate your insulation and check for air leaks.
heating water standby losses are just one of many standby things in your home eating energy.
how old and how efficent is your furnace? using LED or CF lights to save power, are all your appliances energy star rated?
how about the SUV in your driveway? or do you drive a small fuel efficent car?
theres a million ways to waste energy, hot water is just one.........
are all your hot water lines insulated?
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Yea and HW is the biggest waste for most, so what is your Point . Zero. as I see it....Zero in your attacks
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And HW waste just shows your overalll ignorance
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wrote:

This is completely wrong, most heat loss is up the chimney, a total waste of energy. Tankless only heat water when you need it, not from whatever = 7pm - 6am.. Tankless saved ME MONEY and Im happy... and dont sell or work with Tanlkess companies. Now how abourt Foam Roofing !!! A way to save $$$$
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wrote:

Heat loss, Up chimney, you calculated wrong, sorry bub, your loss is more than you think. Your loss is 24x7 and its alot of BTUs up and out, you dont know jack on saving jack.
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On Wed, 9 Apr 2008 18:01:56 -0700 (PDT), ransley

Hi Mark,
Just to be clear, there is no natural gas service in our neighbourhood -- there are perhaps 500 homes in the entire province that have access to it, if that. Consequently, our DHW tanks are electric, although a small percentage are oil-fired and with rare exception propane (at $1.25 per litre/$4.70 per gallon, propane is almost three times more costly than electric). The heat losses I speak of are in relation to electric water heaters, not gas.
Cheers, Paul
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On Apr 9, 4:59pm, snipped-for-privacy@optonline.net wrote:

A flue is a chimney, it is a heat loss, only controled by Btu input and airflow. Holes in walls waste energy.
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New tankless may last 30-40yrs +. a copper pipe, finned is the Exchanger, your answer is how long do your copper pipes last, 60 years ??
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I don't understand this criticism, we've been over this before. The energy factor of typical gas tankless is 0.80 and the energy factor of a typical gas tank is 0.60. The difference, 20% of the theoretical heat value of the gas used, is the standby losses. Most of the standby losses go up the central flue of a conventional gas tank water heater, as there can't be any insulation between the flue and the hot water.
Yours, Wayne
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