Author Topic: Tankless Hot water heater  (Read 6767 times)

HiItsMe

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Tankless Hot water heater
« on: December 26, 2013, 09:48:51 PM »
OK. I didn't install it myself, but I do have some numbers to report for those of you considering making this switch to tankless hot water.

-- Installed both the propane and a tankless hot water tank. (Nat gas not avail at our location) at the end of 2011. Taking "tanked" hot water heater off reduced our electric bill by something like 200 KwH per month. (yes, we might have taken shorter showers, we know better now.)
--Propane, averaged over the year has cost about $ 30-40 per month, including tank rental, tax delivery fee, etc.
--Electricity in the Puget Sound, WA area costs about .10 per KwH. (your costs may vary!) 
--This means that instead of the Water Heater "paying for itself", it's costing us about $10-20 more per month.(Might be a different story if it was electric, not propane.)

--In addition, a centralized  tankless water heater doesn't keep residual hot water in the pipes, so must evacuate all the cold water before the hot water reaches the tap. Even if someone just got out of the shower, you gotta wait. This "cold water sandwich" means a higher water bill and water waste. Some tankless heaters are located right under the sink. This solution would help. 

--Here's a bit of support in Michael Bluejay's post here http://michaelbluejay.com/electricity/tankless.html

« Last Edit: December 26, 2013, 10:03:36 PM by HiItsMe »

schimt

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Re: Tankless Hot water heater
« Reply #1 on: December 27, 2013, 06:58:49 AM »
A standard water heater with a tank does not keep the water hot between the tank and the faucets either. It may put hotter water in the lines, so it will stay warm longer, but if both units are filling the lines with the same temperature water, it will get cold at the same time. You may also want to consider insulating any easy to reach hot water lines.

Spork

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Re: Tankless Hot water heater
« Reply #2 on: December 27, 2013, 07:15:17 AM »
A standard water heater with a tank does not keep the water hot between the tank and the faucets either. It may put hotter water in the lines, so it will stay warm longer, but if both units are filling the lines with the same temperature water, it will get cold at the same time. You may also want to consider insulating any easy to reach hot water lines.

The cold water sandwich he is talking about isn't really the filled lines getting cold...  If you run full hot, then turn it off for 30 seconds, the manifold gets cold very quickly from the cold water sitting in it.  When you turn it back on, there is a definite burst of cold in the center.  I doubt it seriously impacts the water bill, though.  You're more likely to up the water bill from the nice, long, endless hot shower.  (Or by watering the lawn.)

I heat water with propane/tankless as well...  I was advised by a plumber friend NOT to do electric with a tankless.  He said it would normally require a panel upgrade to 400amp to handle the heater.

bacchi

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Re: Tankless Hot water heater
« Reply #3 on: December 27, 2013, 10:57:51 AM »
I like Bluejay but his reasons are mostly wrong in this case even though his conclusion is still sound. For example, the study he refers to shows a "37% savings of water heating energy per household," which is far from "meager."

If finances are your number one priority and you can't do it yourself, the financial payback is the most important reason to not replace a tank with a tankless: "However, this savings was not enough to offset the high incremental cost resulting in paybacks from 20 to 40 years."

If the retrofit is easy and you can install it yourself, the payback is a lot faster.*


*This is true with NG and not propane, at least in the OP's case.

"Even with these positives of tankless water heaters the low cost of natural gas and the high installed cost of TWHs limits
their feasibility."
« Last Edit: December 27, 2013, 11:02:07 AM by bacchi »

HiItsMe

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Re: Tankless Hot water heater
« Reply #4 on: December 27, 2013, 02:37:07 PM »
Thanks all for weighing in on this, and to Spork for explaining the "Sandwich" nicely.

Definitely, the TWH would work well and save money for many home situations, and it does have that unlimited long shower benefit!
Agreed. water bill is not expensive, so the cost of extra water is not a great added expense. You gave me an idea...Maybe I could collect it to water the lawn?

I was researching the tankless purchase, sources overwhelmingly stated it would be a HUGE money saver. We even got a  federal tax credit to offset the install cost. But it just hasn't turned out to be a money saver for us, it has in fact cost more in monthly energy bills.

My hope is that potential renovators will learn from my error, and crunch their numbers carefully before deciding to make an investment in big stuff.   

NinetyFour

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Re: Tankless Hot water heater
« Reply #5 on: December 27, 2013, 02:47:17 PM »
FWIW, I love my tankless (NG) water heater.  I live alone, have a very small (600 sq ft) home, and use hot water only to shower and to hand wash dishes in the winter.  Plus, I rarely shower at home, since I commute to work by bicycle and shower there.

I can't say whether this water heater has saved me money, because I have nothing to compare it to.  (Before I renovated this space, there was no running water, and hence no water heater.)  But since I use such a small amount of hot water, it just didn't make sense to me to have constantly heated water in a storage tank.

TomTX

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Re: Tankless Hot water heater
« Reply #6 on: December 27, 2013, 07:43:19 PM »
Propane is expensive.

Natural gas is cheap.

b4u2

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Re: Tankless Hot water heater
« Reply #7 on: January 14, 2014, 10:48:22 AM »
I have a tankless electric water with a household of 5. I am starting to look into our energy consumption and this heater may be a huge draw. I installed this myself about 7 years ago when I was single and rented a few rooms out. Now with way more people (got remarried) living in the house I have a feeling that the electric tankless is a bad idea. I am going to be testing and monitoring my power usage here soon but I would need a way to figure cost and compare to replacing with a natural gas tankless.

ksfrank

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Re: Tankless Hot water heater
« Reply #8 on: January 14, 2014, 05:54:13 PM »
Has anyone figured out the difference in cost - propane vs. electric?  Is there some way to match it up?  Those are our two options. 

We have to purchase a new water heater soon.  The electric 50 gallon one we currently have was here when we purchased the house 28 years ago.  It works fine - but it has developed a steady slow leak. 

My husband can install either replacement (tankless or tank, electric or propane) himself using some trade off with the contractors he works with for the specific plumbing aspects.  So the installation should only cost us in supplies.

Propane is about $2 a gallon.  We use $1000 to $1200 a year in propane currently for our central heat. 

We use 1350 KWH per month ($135 or so) right now.  We suspect the deteriorating hot water heater is why we never get a $70 bill anymore like we used to regularly.  The rise happened a couple of years ago and its never went back to the old levels. 

Is there a standard way to compare propane to electricity? 


LowER

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Re: Tankless Hot water heater
« Reply #9 on: January 14, 2014, 07:34:19 PM »
If you have 3 or more teenage daughters, you may not want endless hot water.  Just saying'.

Spork

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Re: Tankless Hot water heater
« Reply #10 on: January 15, 2014, 07:53:06 AM »
Has anyone figured out the difference in cost - propane vs. electric?  Is there some way to match it up?  Those are our two options. 


Try this calculator (there are others out there... I grabbed the first I found.)
http://suhresgas.com/propane_vs_electric.htm

It's funny.  If you start googling, you'll find electric companies that show their way is cheapest and propane companies that show their way is cheapest.

It seriously depends on the efficiency factor and the unit price.  A little wiggle on each and you can tip the scale.  The only way to really sort it out is to go find the actual units you are interested in and calculate it.

We went with propane/tankless.  And, while I really love it, the calculations we did were narrowly close... and the ROI was many years out.  I find that I probably take slightly longer showers (because... it's nice...) and I suspect that it comes out even or possibly tips towards electric/tank.   (Now... if I could get natural gas... I think that would sway it back a little.)

Longwaytogo

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Re: Tankless Hot water heater
« Reply #11 on: January 15, 2014, 01:13:25 PM »
I think the new Electric/Heat pump hybrids are the way to go. I love mine, was actually thinking of writing a post/review now that I've had it for 6 months. I have heard a lot of horror stories on the tank-less in maintenance costs/issues from some of the plumbers I work with.

TheDude

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Re: Tankless Hot water heater
« Reply #12 on: January 15, 2014, 04:07:03 PM »
I dont like thankless. The upfront cost is crazy, They take more maintenance.  They make great sense if its you and you can get by with really small one but for family I dont think its worth it.

Instead I say but a quality water heater with a tank. Either gas or propane. Change out the valve so its easy to drain once ever 6 months or so. Also before its installed take out the anode rod and wrap it with tefflon tape so you can replace it in 5 year or so.  Then I would add a second anode rod. The once its installed wrap some insulation around it. I bet you can get 30 years out of it if you drain it and changes the rods. 

Here is a good sources that talks about water heaters. http://www.waterheaterrescue.com/pages/WHRpages/English/Longevity/water-heater-anodes.html