My Tankless Experiment

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Dunbar Plumbing

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True....but that's not the point I'm making

The point I'm making is a slow flow of unheated water through that unit in standby mode cools down the heated compartment.....it's lines travelling out of that unit..instead of time reducing thermal loss. That is harvested heat energy that a leak will wipe out instantly. I bet the testing on those tankless ASSUME those lines don't have to be constantly reheated between uses as the test was accelerated knowing that the numbers inflate in that scenario when the heating compartment is hot along with the feeds coming out. Thermal loss is gradual with no leaks, thermal loss is great when there is a leak.


Too bad they didn't design a flow switch to catch that energy robbing situation. :cool:

RUGGED <<< Understanding the long term effects of people on plumbing since 1984...
 
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ultgar01

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Any comments on outdoor tankless units

We just purchased a new house in Charlotte NC with a detached garage. Since the garage is not part of the house and there are few basements in NC, the builder put the hot water heaters (AO Smith 40gal units) in the attic.

Even with the expansion tank and plumbed drain pans, I'm really nervous about having these in the attic and would consider replacing these with an outdoor tankless unit. Anything to look out for here (besides the usual mfg suggested clearances for venting)? SD
 

GrumpyPlumber

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Yes, frost.
Not familiar with Charlotte winters, but if it gets below freezing at any time this would be a serious note to consider.
I usually just mount them inside the foundation wall, they're generally about the size of a large suitcase.
 

Bob NH

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If you are replacing tank-type heaters in the attic, what is wrong with putting the tankless heater in the attic? The gas and water lines are already available and it is a short run through the roof for the stack.

I would use copper piping instead of PEX because the drain pans won't do anything for leaks away from the heater.

If it were mine I would check my insurance policy and leave the tank-type heaters alone.
 

ultgar01

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Bob NH said:
If you are replacing tank-type heaters in the attic, what is wrong with putting the tankless heater in the attic? The gas and water lines are already available and it is a short run through the roof for the stack.

I would use copper piping instead of PEX because the drain pans won't do anything for leaks away from the heater.

If it were mine I would check my insurance policy and leave the tank-type heaters alone.

Because the builder put a scuttle hole access to the attic instead of a pull down stairs. I dread the day, especially when I'm older, that I have to go up and replace those units.
 

Jadnashua

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Most pull-down stairs aren't rated with very heavy duty ladders, either...you can hardly carry anything up with you.
 

GrumpyPlumber

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jadnashua said:
Most pull-down stairs aren't rated with very heavy duty ladders, either...you can hardly carry anything up with you.

Oh what humorous memories that statement conjures...
Clunking up one with my trusty right angle, tool bucket & cord as homeowner grimaces.
 

Nate R

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GrumpyPlumber said:
What? And ruin all the fun?!?!?



Also, I didn't factor in the fed tax credit of $300 (which means $75-$100 in real money for most tax brackets)

No, that would be $75-100 in real money if it was a tax DEDUCTION. A tax CREDIT is far more valuable. It's money in your pocket dollar for dollar. A tax deduction lowers your taxable income. (Thus a $1000 deduction off of your income amount saves you about $250 in taxes.) A credit is subtracted directly from your tax OWED, not the # the tax is calculated from. Doesn't mean it will make the difference in savings in this case enough to be worth it, but I had an urge to point out the difference.
 

GrumpyPlumber

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Nate R said:
No, that would be $75-100 in real money if it was a tax DEDUCTION. A tax CREDIT is far more valuable. It's money in your pocket dollar for dollar. A tax deduction lowers your taxable income. (Thus a $1000 deduction off of your income amount saves you about $250 in taxes.) A credit is subtracted directly from your tax OWED, not the # the tax is calculated from. Doesn't mean it will make the difference in savings in this case enough to be worth it, but I had an urge to point out the difference.

"I'm a plumber Jim, not an accountant"
Thank you for differentiating that, I think it could well tip the scales at game point.
 

Master Plumber Mark

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reminds me of the Solar tax credits....

I remember when their was a final date for the solar tax credits back in 85?,, and after that point the solar industry was on its own....

One person I knew had invested all his money in NOVAN
a very good solar company....

but the writeing was on the wall and he still held onto the stock till it tanked to zero..

----------------------------------------------------------------------
I installed the gas meter last Sunday at 11.00 and its
mid morning now... So one week has passed.

At present my 75 gallon Gas Water heater has
used approx 650 cubic feet of gas for one week
with the temp set on 130.

If that is an average for the month, it should work out to 2600 cubic feet..
now all I got to do is read my gas bill and determine what a cubic foot of gas equals in therms and what it is costing me...


will I have sticker shock and run out and get a tankless water heater....???




 

GrumpyPlumber

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1 cf of gas = 1,000 BTU x 650 = 650,000 or 6.5 therms /week
A therm In my area runs about $1.40, in Furds $1.24, I assume IN has lower avg rates, so for sake of argument, until you check your bill, lets say $1.10.
That comes to $7.15 for that week, and I assume it's been a warm week for you guys like it has been here, meaning you're not looking at temperature increases of 90 degree's to heat the water.

The tankless is 84% efficient as opposed to the tanks 60%.
With a difference of 24% the tank "should" use 9.1 therms in a week for a cost of $10.01 NOT including standby.
A difference in cost of $2.86 /week - $11.44 /month - $137.28 /year.

The cost difference to install a tankless as opposed to a draft vent 75gal
Runs from 1K to 1.5K, more for expensive units.
In other words, it roughly evens out over ten years for a family, not retire3e's or single folks...excluding potential rebates or soon to be moot tax credits and unincluded standby losses.
The major factor that most people are inquiring over is the endless hot water, when you have several teens at home and you're outta luck for a shower before work, even a higher price is fine.
You're gonna want to get that guage on your tank heater asap, before the weather gets much colder, the colder it gets the worse it'll effect the tanks readings vs the tankless.
 

Master Plumber Mark

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dont sound like much $$ at all

Grumpy, if your calcualtions are correct,
that is not too bad an expence for
a 75 gallon with the standby piolit light included...
sounds like about 10 bucks a week + about 40 per month
for the BIG BOY 75....

which for all pratical purposes, is very close to endless hot water
for the average family....

Personally I thought the bill would be much higher than that...


I will check out the gas bill..

I will check out the incomming water temp tomorow..

and I will certainly check out the actual temp of the
water comming out of the heater....


you stated
The tankless is 84% efficient as opposed to the tanks 60%.
With a difference of 24% the tank "should" use 9.1 therms in a week for a cost of $10.01 NOT including standby.
A difference in cost of $2.86 /week - $11.44 /month - $137.28 /year.


judgeing by your calcualtions,
it appears that we are really splitting hairs here,
mighty, mighty fine hairs.........

and the cost saveings between them seems to be more symbolic than realistic...

can you think of anything I should be considering in this test...????
 
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Master Plumber Mark

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week #2 has passed

Another beautiful Sunday Morning Indiana week #2
Temps are now starting to drop in the area

My 75 gallon Brad white gas how water heater
has now consumed a total of 1235 cub feet

looks to be averageing about 618 cub feet per week..

still need to look up my cost......per therm.
 
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GrumpyPlumber

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Mark, I'd figured you connected the tankless by now.
A difference of temperature as little as 10 degree's makes a difference in btu consumption.
 

Master Plumber Mark

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I dont have it yet...

At this point of this experiment I am lucky to
have gotten this much done...


Thought I would give the 75 gallon a month or two
of readings....


I realize that this means that the Tankless will be comming
on line in the winter and the readings would
be at their absolute worst...


.


Or I can wait till around x mas and do the change out...


Ideally it would have been more fair to have done
this during the summer...

but we have winters here and the tankelss will
still have to perform every year through that season...

gas consumption and performance are both on my mind here

the incomming water temp is now 69 degrees....e




I am hopeing to get a Large Takagi tankless in a few weeks


to be perfectly fair they should be both running at the same time..
.through the exact same season

but I am doing what I can with what I got...


if you have a spare takegi that will handle 3 bathrooms
for dirt cheap or free......send it my way
 
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Master Plumber Mark

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Week #3 Sunday Morning

The temp of the incoming water is holding at 69 degrees

We have had company come into town this week since friday....the big sister in law is
in town staying with us...

takes a lot af water to hose her down........

presently the amount of CUBIC FEET used by the 75 gal gas is at 2065. cub feet


this messes up my esperiment a little but I suppose
I can use the figures for the first two weeks an be ok
 
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