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Old 11-08-2008, 09:11 AM
 
4,832 posts, read 6,565,203 times
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Quote:
Originally Posted by AndrewMensch View Post
Can you see a reduction in the amount of propane used?
Yes...and it's wonderful to never run out of hot water.
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Old 11-08-2008, 11:04 AM
 
4,832 posts, read 6,565,203 times
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Here's a good post by my husband about the cost effectiveness of tankless water heaters:
Propane Refrigerators/ Tankless Water Heaters - Homesteading Today


Join Date: Nov 2004
Location: Idaho
Posts: 92
The myth of tank vs. tankless water heaters
Quote:
Originally Posted by joken
Here are my thoughts on the tankless versus tank type water heater. The only operational saving with the tankless is that you do not have radiation loss from a tank full of hot water. The tankless units are much more expensive to purchase and install. They have huge BTU consumption generally around 250,000 per hour. Tank type is around 35,000 BTU/hr. Tank type flue is generally 3", Tankless 5"and larger. I do not think the tankless heaters make any sense from a economic standpoint. I suspect lots of folks buy them simply because it is a trendy thing to do. Ken in Oregon


Trendy? No. Efficient? Yes

A 40 gallon hotwater (Whirlpool Flame Lock) tank uses 40K BTU/Hr assuming an efficiency rating in the range of 75% and a flow rate of 66 gallons per hour. A tankless water heater uses 235,000 BTU/hr assuming a an efficiency rating of 82% and a flow rate of 300 gallons per hour. This works out to 783 BTU's per gallon for the tankless water heater and 606 BTU's for the tank based heater. So, on first look, it appears that the tank water heater uses less btu's than a tankless. However, the tank based water heater has to keep the water hot all the time rather than just when it is being used. Let's assume a duty cycle of 5 mins every 2 hours for the tank based heater to keep the water hot, that works out to 5 mins X 24hours/2hrs x 1hr/60mins = 1 hr of heating per 24 hours to keep the water hot, so we add another 40,000 BTU's just to keep the water warm. Now, lets assume that the avg family uses 100 gallons of hot water daily. In that scenario, the family would use 60,600 BTUS for heating water plus 40,000BTUS to keep it hot for a tank water heater for a grand total of 100,600 BTUS daily. For a tankless water heater, it would be 100 gallons x 783 BTUS per gallon or 78300 BTUS per day with a tankless. So, in conclusion, the tankless would save this family 22,300 BTU's per day. Considering that propane has approximately 90,000 btus in a gallon, this equates to ~157 gallons of propane per year or (at an avg. cost of 1.60 per gallon) about $251. Which means that the tankless would pay for itself in ~3yrs. This analysis does not take into account the 10yr lifespan of a tank water heater vs the tankless and it does not take into account the cost of floor space for a tank water heater vs. hanging the tankless on a wall.

Backwoods Solar is a decent group of people. Better with Steve & Elizabeth owned it but expensive. I mail order almost all of our items and put it together myself.

jim

bsee Purdue
msee MIT
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Old 11-08-2008, 12:19 PM
 
Location: USA
17,069 posts, read 8,711,398 times
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Quote:
Originally Posted by sterlinggirl View Post
If you have hard water, you may want to do some more research before you buy.

Or get a water softener, which is a good ideas in general.
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Old 11-09-2008, 05:03 PM
Status: "0-0-2 start!" (set 10 hours ago)
 
Location: The beautiful Rogue Valley, Oregon
7,262 posts, read 15,300,867 times
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Quote:
Originally Posted by mistyriverranch View Post
(at an avg. cost of 1.60 per gallon)
Except that propane, where I live, is twice that much (and more than that if you plan poorly and need a winter delivery). We looked at tankless, but because we don't have the option of natural gas, just electric or propane, we went solar thermal with an electric boiler backup for both domestic hot water and radiant flooring.
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Old 11-09-2008, 06:53 PM
 
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I have soft water and have gotten as much as 20 years out of a standard hot water heater, Most cheaper ones are guanteed for 6years minium;or replaced free. Know a frind that had a liner crack in 5 years and it was replaced free of charge.Guess prices vary but I had a 40 gallon installed about one year ago for $500 including the water heater.Thya's a liitle over $100 labor with the price I could have gotten on the same heater.I am sure he gets a discount tho.

Last edited by texdav; 11-09-2008 at 07:03 PM..
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Old 11-09-2008, 07:17 PM
Status: "0-0-2 start!" (set 10 hours ago)
 
Location: The beautiful Rogue Valley, Oregon
7,262 posts, read 15,300,867 times
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We just bought an (electric) 80 gallon tank to use as the storage tank for the solar thermal system and it was $405. Granted, we weren't looking for an expensive one, so it wasn't top-of-the-line.
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Old 11-09-2008, 07:22 PM
 
4,832 posts, read 6,565,203 times
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Quote:
Originally Posted by PNW-type-gal View Post
Except that propane, where I live, is twice that much (and more than that if you plan poorly and need a winter delivery). We looked at tankless, but because we don't have the option of natural gas, just electric or propane, we went solar thermal with an electric boiler backup for both domestic hot water and radiant flooring.
Yes...this post was made a few years ago. So you plug in the cost of propane now and do the numbers. And the comparison was being made between the tow types of propane fired water heaters.
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Old 11-10-2008, 09:10 AM
 
353 posts, read 903,771 times
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Quote:
Originally Posted by mistyriverranch View Post
Yes...this post was made a few years ago. So you plug in the cost of propane now and do the numbers. And the comparison was being made between the tow types of propane fired water heaters.
It seems to me that the higher the fuel cost, the faster the payback... every cloud has a silver lining!!!
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Old 11-10-2008, 04:49 PM
 
Location: 3814′45″N 12237′53″W
4,152 posts, read 9,821,964 times
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We purchased and LOVED our tankless heater back in 2001. When we lived in Berkeley, there were only a few plumbers at the time who knew anything about tankless heaters and they were the only ones to have any experience installing them.
NONE of them recommended anything other than the Takagi's.
We watched our natural gas bills plummet over the course of a couple of years and we never had a problem with it.
All of them ragged on the the Rinnai albiet not as much as they ripped Bosch.
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Old 04-28-2012, 08:30 PM
 
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Hi, I can only speak from one side of the question because I have experience only with the Rinnai water heaters, namely the RL75i, tankless model. This is the most common model of the Rinnai tankless water heaters, and more of an entry level, but still it handles two bathrooms the same time (with low flow shower heads). Choose Rinnai because a good friend of mine who is quite experienced in plumbing and is a guy who I call everytime I need some works done around the water system of my house also suggested Rinnai. I give on his opinion. Hope I helped. Cheers
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