My Tankless Experiment

Users who are viewing this thread

Master Plumber Mark

Sensitivity trainer and plumber of mens souls
Messages
5,533
Reaction score
354
Points
83
Location
indianapolis indiana - land of the free, home of
Website
www.weilhammerplumbing.com
SO it begins....Sept 16, 07



Submitted for your viewing approval ....and consideration....

one over-weight plumber with nothing else better to do today
while being stuck baby- sitting two 6 year old girls untill 7 pm tonight


on a beautiful Sunday morning in indianapois indiana....

one new gas meter bought off e-b// for 89.00.

the meter is pre-tested and pre-set at 6.2 btus ....

One 2 year old 75 gallon gas Bradford White heater already hot
and the unit is covered by a blanket.......



now how many cubic feet of gas will it take to heat the water
for one week to two months.....????


inquireing minds want to know... sept 16,, 2007

(I dont get out very much....)


Now after about 4 months....I plan to switch to a tankless water
heater Probably a TAKAGI or Rheem just to see how it performs in
basically the same conditions.......


started experiment with 6.6 btu at high noon.

I am curious as to how much this thing will spin in an hour.....

how much the piolit light actually uses per day

as you can see it goes by 10ths of a btu......

probably wont come on today to re-heat till tonight.......
 
Last edited by a moderator:

Bob NH

In the Trades
Messages
3,310
Reaction score
9
Points
0
Location
New Hampshire
Mark,
You need to figure out what that calibration is, and compare it with your regular gas meter. 6.2 and 6.6 BTUs on the meter are not correct.

It is probably calibrated in Cubic feet, or maybe 1000's of cubic feet. One cubic foot is about 1000 BTUs.

Your gas company probably bills you in Therms. One Therm is 100,000 BTUs, which is about 100 cubic feet. One Therm may cost $1.50 to $2.00.
 

Master Plumber Mark

Sensitivity trainer and plumber of mens souls
Messages
5,533
Reaction score
354
Points
83
Location
indianapolis indiana - land of the free, home of
Website
www.weilhammerplumbing.com
meter reading

Bob...thank you for the informaion

I will find out more about the meter from the
person I bought it from...

and I will get out my gas bill, or call the gas compnay

when it came out of the box it was factory tested
and run through its paces to 6.2


So after I installed it and blew out the meter itself and
fired up the gas heater it moved to 6.6


it is now at about 7.6

I wonder how much that piolit light
actually cost me over the last 3 hours....???


any advice on how to calculate it is appreciated...

just because I can rig up a gas meter dont mean
I know what the hell I am talking about...lol


Brand New Warehouse Stock. Note:
All meters show 4-8 cu ft of useage right out of the box.
This is from the factory calibration run performed just prior to packaging at the factory.
 
Last edited:

Bob NH

In the Trades
Messages
3,310
Reaction score
9
Points
0
Location
New Hampshire
master plumber mark said:
Brand New Warehouse Stock. Note:
All meters show 4-8 cu ft of useage right out of the box.
This is from the factory calibration run performed just prior to packaging at the factory.

EDIT: I just looked closely at the picture and it says that it is rated in Cubic Ft.

From the quoted statement, if that is from where you got it, then I suspect that the 6.2 was cubic ft. Since there are about 100 cubic ft in a Therm, and the price of one Therm is about $2.00, each cubic ft of gas (as from 6.2 to 7.2 on the meter, would be about $0.02.

If you have a 30,000 BTU per hour water heater, then I suspect that it will use about 1 cubic ft in 2 minutes when it is firing. You could check that by running enough hot water to get it firing for a short time.
 
Last edited:

Master Plumber Mark

Sensitivity trainer and plumber of mens souls
Messages
5,533
Reaction score
354
Points
83
Location
indianapolis indiana - land of the free, home of
Website
www.weilhammerplumbing.com
Last edited:

GrumpyPlumber

Licensed Grump
Messages
1,521
Reaction score
57
Points
48
Location
Licensed Grump
Mark, geesh...lets simplify this!!!!

Make sure NOTHING else in the house is running on the gas, check your houses gas meter reading and write it down, then check the tankless's.
Start the tankless and run it for a few.
Check both meters, subtract the reading you get on your main and cross referrence to the tankless meter.
Your houses meter will read CF (cubic feet), do some simple math if the two readings don't jive.
 
Last edited:

GrumpyPlumber

Licensed Grump
Messages
1,521
Reaction score
57
Points
48
Location
Licensed Grump
"Meet Mr. MasterPlumberMark....
Ordinary disgruntled plumber by day....Super-cyber Plumber by night.
He's about to embark on a mission, not some ordinary mission, but one of utmost importance that even he doesn't know what will bring him to...
He's about to embark on a mission in ....THE TWILIGHT ZONE!"
 

Dunbar Plumbing

Master Plumber
Messages
2,920
Reaction score
10
Points
0
Location
Northern Kentucky/Greater Cincinnati Area
Website
www.KoldBreeze.com
This might end up on Montel.......better yet, Oprah.

MPM is goin 1.gif
 

Master Plumber Mark

Sensitivity trainer and plumber of mens souls
Messages
5,533
Reaction score
354
Points
83
Location
indianapolis indiana - land of the free, home of
Website
www.weilhammerplumbing.com
Had a lot of time on my hands today

Grumpy, read the posts closer....

I dont think I can make it any simpler...
now its all just figuring the math on the btus



Yes....I had a lot of time on my hands today...

baby sitting 2 ..6 year old girls...
that was pretty dull , but I took them for a walk to
the local store down a few blocks for candy ...your basic parenting

from 12 till 6 with not much else to do....


did a little boookwork, faxed some bills ect.....



anyway.....the meter is in the pic.... you can see
at what point it started reading my gas to only
the 75 gallon 75,000btu brad white heater....
at 6.6



you can see my laundry room..the water heater and
how I installed the meter on the floor

and nothing else is on that 3/4 line

with only the piolit light going it went from 6.6
to 8.4 at from 12 to 6 this evening.....


I am trying to keep this simple and it seems fairley easy

so once I figure out the math its no big deal to
know what a 75 gal heater average costs are per month.

bob newhart seems to have a handle on that already for me.
 
Last edited:

GrumpyPlumber

Licensed Grump
Messages
1,521
Reaction score
57
Points
48
Location
Licensed Grump
<---Nerd.

Mark, this is where our approaches would differ....
BTU = energy to heat 1 lb water one degree, assume incoming water is 40
1 gallon of water is 8.33 lbs X 90 (to 130 hot) = 749.7 BTU
Surface area of a 75 gal cylinder = 27.9936 (28 sq feet)
Code requires WH to have a min of no greater than 15btu heat loss per hour
per sq foot of surface area so -

-28 X 15= 420 BTU per hour on a 75 gal tank @ stand-by = 10,080 BTU/day

-KS faucet = 1.5 gpm (hot alone) Used lets say 1/2 hour/day for dishes etc
= approximately 45 gal/day

-Shower 2.5 gpm (1.25 for hot) with a family of 4 @ 15 min apiece
= 75 gal/day
-Tub, ok, lets toss in a 60 gal bath each day for the mrs
-Laundry, say one load/day uses 30 gal hot
-Lav/misc. Lav's flow @ 1.25 gpm lets say it's used 8 times/day @ a minute
each .63 gpm X 8 = 5 gal/day

thats 45 gal + 75 + 60 + 30 + 5 = 215 gal/day
215 gallons take 161,185.5 btu to heat to 130 from 40,
tank heater is 60% efficient so it takes an actual 268,642.5 btu house/day
add 10,080 BTU for stand-by with the 60% effiiciency offset for
16,800 btu/day.
Thats 285,442.5 BTU per day used for a tank type
Tankless is 85% efficient which means it uses 189,630 BTU /day for 215 gal.
In other words:
a tank uses 8,563,275 btu or 85.63275 therms/month (30 day)
tankless ~~5,688,900 btu or 56.88900 therms/month

My area a therm is approximately $1.50 ...
tank = $128.45/month
tankless = $ 85.34 A family of four saves $ 43.11/month
$ 517.32 /year
$ 5,173.20 /10 years (warranty)

Tankless installed = $3000.00 - $5173.20 = -$2173.20 (saved money)
50 gal Tank installed = $ 850.00 (draft) + 5,173.20 = +$6023.20 (10 year)
50 gal powervented = $1250.00 (still 60%) = +$6423.00 (10 year)
 
Last edited by a moderator:

Old Dog

G.C. 22+ years(in 3 states)
Messages
82
Reaction score
0
Points
0
Location
Hawaii
Tankless...

FWIW,demand heaters are very popular here.Many people live off grid.
Most are using rainwater catchment systems so there is not a hard water problem.Propane gas is what is used for the most part.People tell me they like the fact that it only uses gas when they use hot water.I do hear the complaint about temp problems if they are using water at a couple of fixtures.
I know of one new house that had 3 demand heaters installed.One in each bathroom and one to take care of the kitchen and laundry.The owner said his gas bill for propane was less than half what it was on his previous house.
Electric is very expensive here so people have gravitated toward these heaters.I"m changing over to a gas stove and heater in the very near future myself...
 

Master Plumber Mark

Sensitivity trainer and plumber of mens souls
Messages
5,533
Reaction score
354
Points
83
Location
indianapolis indiana - land of the free, home of
Website
www.weilhammerplumbing.com
did you do your own experiment?

Grumpy wrote
My area a therm is approximately $1.50 ...
tank = $128.45/month
tankless = $ 85.34 A family of four saves $ 43.11/month
$ 517.32 /year
$ 5,173.20 /10 years (warranty)

Tankless installed = $3000.00 - $5173.20 = -$2173.20 (saved money)
50 gal Tank installed = $ 850.00 (draft) + 5,173.20 = +$6023.20 (10 year)
50 gal powervented = $1250.00 (still 60%) = +$6423.00 (10 year)



Grumpy....
If you had it all figured out, why didnt you tell me this before I went and bought the gas meter???

your figures sound like "fuzzy math " to me....
but of course that is why I am fooling with
the whole thing in the first place.....

I got to prove it to myself.... what a 75 gal
gas water heater costs per month to run

I will test the temp of my hot water tonight,
and the incomming water temp for kicks too...

if the tankless save 45 bucks a month ok, great

I suppose that means I got another 45 bucks to pour into my gas tank...

I will run out and buy one tomorrow
 

GrumpyPlumber

Licensed Grump
Messages
1,521
Reaction score
57
Points
48
Location
Licensed Grump
master plumber mark said:
Grumpy....
If you had it all figured out, why didnt you tell me this before I went and bought the gas meter???

What? And ruin all the fun?!?!?
master plumber mark said:
your figures sound like "fuzzy math " to me....
but of course that is why I am fooling with
[/SIZE][/B]

Absolutely fuzzy!
I might be a nerd, but I never said I was a smart one.
one example, I knowingly over-estimated the cost of a therm for my area @ 1.50...it's slightly less and I'm pretty sure my area is more expensive relative to the norm.
If one figure in my whole scenario is off, it's multiplied by 3,653...however the rough savings should be right on in terms of percentages.
The actual figures I typed are just for an example of what you'd save @ 215 gallons of hot per day, most likely even your family uses less.
Duly note though, even half that amount would break the cost of a tankless vs tank type within the warranty period.
Also, I didn't factor in the fed tax credit of $300 (which means $75-$100 in real money for most tax brackets) and local gas companies offer a $300 cash rebate for installing them here in New England.
Bottom line is YOUR method will be the most accurate.
 

Bob NH

In the Trades
Messages
3,310
Reaction score
9
Points
0
Location
New Hampshire
Your summer gas bill should be almost all water heating. The amount used for cooking should be negligable.

So you could compare your demand (Therms) with Grumpy's 85 Therms per month.

I think the hot water demands are excessive. The kitchen faucet (45), laundry (30), and Mrs bath (60) in addition to shower are probably 2 times what the those uses would be in a real family.
 

Statjunk

DIY Senior Member
Messages
540
Reaction score
0
Points
0
Bob,

Grumpy is simply thorough. He over engineers most things. He also likes the ladies clean!

Tom
 

Jadnashua

Retired Defense Industry Engineer xxx
Messages
32,771
Reaction score
1,191
Points
113
Location
New England
As a reference, I used 15 therms last month of gas with an indirect, gas dryer, stove, barbeque. The previous year, I used 18 therms for the same month. The heat was from a Trianco Heatmaker that is a hybrid tankless (87% efficient boiler). I've used my new barbeque more than the older one, letting it run for at least an hour baking potatoes, that I didn't do last year.
 

Furd

Engineer
Messages
448
Reaction score
1
Points
16
Location
Wet side of Washington State
I use about ten therms a month for water heating. I live alone, like long showers, occasionally use a 6-foot long whirlpool tub, and have a 50 gallon Kenmore Power Miser 6 water heater with a continuous pilot.

I did remove the restrictor from my shower head but I also use the volume adjustment of my Moen shower valve.
 

Master Plumber Mark

Sensitivity trainer and plumber of mens souls
Messages
5,533
Reaction score
354
Points
83
Location
indianapolis indiana - land of the free, home of
Website
www.weilhammerplumbing.com
Bob NH said:
Your summer gas bill should be almost all water heating. The amount used for cooking should be negligable.

So you could compare your demand (Therms) with Grumpy's 85 Therms per month.


you are not accounting for the GAS DRYER in the home like I got....

my wife runs the gas dryer sometimes for 5 ++ hours per day.... lots of laundry to do

that is why I got the meter...to monitor the heater only

now all I got to do is wait for the fellow I bought it from to answer my questions...


as far as factoring in a 300 dolllar credit, you also got to factor in
yearly maintaince on a tankless heater.....

what is that worth???






 
Last edited:

GrumpyPlumber

Licensed Grump
Messages
1,521
Reaction score
57
Points
48
Location
Licensed Grump
Bob NH said:
yearly maintaince on a tankless heater.....
what is that worth???
How much is a bottle of vinegar, a small pump & a double ender going for these days?
About as difficult and time consuming as flushing a tank type.

Bob NH said:
I think the hot water demands are excessive. The kitchen faucet (45), laundry (30), and Mrs bath (60) in addition to shower are probably 2 times what the those uses would be in a real family.
Fine, then let's modify my original "equation" by going to the opposite extreme and cutting it all in half...
GrumpyPlumber said:
a tank uses 8,563,275 btu or 85.63275 therms/month (30 day)
tankless ~~5,688,900 btu or 56.88900 therms/month
My area a therm is approximately $1.50 ...
tank = $128.45/month
tankless = $ 85.34 A family of four saves $ 43.11/month
$ 517.32 /year
$ 5,173.20 /10 years (warranty)
[/B]
Ok, now lets say the family saves $20 a month - 240/yr - 2400 for ten years.
The tankless cost 3K to install, you're in for $600 after saving over ten.
Tank (75 gal draft NOT PV) costs at least 1000 with ten year warranty PLUS the extra 2400 not saved. You're in for $3400 over ten, make it $3200 for a 50.
As for maintanence, here's a foolproof way to guage.
I've seen one inquiry here regarding a tankless misfiring, with probes that were gummed in over 3 months.
Would this forum be an excellent way to guage that?
 
Top
Hey, wait a minute.

This is awkward, but...

It looks like you're using an ad blocker. We get it, but (1) terrylove.com can't live without ads, and (2) ad blockers can cause issues with videos and comments. If you'd like to support the site, please allow ads.

If any particular ad is your REASON for blocking ads, please let us know. We might be able to do something about it. Thanks.
I've Disabled AdBlock    No Thanks