Tankless water heaters

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wrote:

first

We have had a Paloma tank less water heaters for over 17 years. It runs on propane. We had to replace one that was over 20 years old and the current one is abut 8 years old and working beautifully. They are expensive BUT they work perfectly. We have as much hot water as we want. We do tend to run only one hot water thing at a time but in a family of two, we have no more need than that.
We are not handy people and once we got it installed and connected to our pump we have had no trouble. We do live in the sub tropics so we do not have temperatures below 45 degrees.
Saying they don't work well is not my opinion and is just plain silly. We do not keep hot water sitting around for no reason. All our water runs through the Paloma and gets hot ...as we need it.
aloha, Thunder smithfarms.com Farmers of 100% Kona Coffee & other Great Stuff
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You actually took the advice of a HD employee to heart. I guess some are allright, just never ask another customer, that always leads me astray.
Some HD stores (like the HD Contractors Supply kind) stock some small capacity tankless heaters but these are not for a whole house but good for a small shop or similar. (perfect for an outhouse)
Like any other heating/cooling device if it is properly sized for the usage and you buy a reputable brand you should be OK. I think (my opinion here) that some people buy undersized units (they are cheap or do not want to upgrade gas or electrical lines) or underestimate their capacity requirements then complain about the quality of the unit when it can't keep up to demand.
In my case, it would require replacement of my 1/2" gas line with a 3/4" pipe all the way back to the meter. Not the extra expense I am prepared to pay
Unless you really need the space, you could buy 3-4 tank units before you pay for a tankless WH.
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wrote:

I looked into them as an alternative to the 6 gallon tank type I use for my kitchen sink. To get anywhere near the same capacity it would have cost at least twice as much for the unit plus I would have had to run a 220v line to it. They might last a lot longer then the 6 gallon water heater though since those only last me about 5 years. So a lot depends on whether you want to invest a lot of money up front and then not mess with it for a long time (assuming it doesn't break).
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Edward Grant wrote:

I've got a Bosch 250sx, and when I lived in an RV, I had a Precision Temp RV500. I have been absolutly satisfied with both.
I've never heard that they are undependable. There is some temperature variation under certain conditions (read "Loop Control" below). They tend not to scale up as badly as tanked heaters, and can be descaled easily. I suppose the parts would be expensive; the whole unit is expensive. They're a hell of a lot easier to install, and they have the potential to be more efficient. I say they CAN be more efficient because people who can take 30 minute showers sometimes do. Especially in winter ;).
Here's some things I've noticed:
Calibration: It needs to be adjusted (calibrated) when you install it. There's a procedure to follow, and the CEC folks are very helpful if you don't understand.
Output: While it will provide hot water forever, it has a finite power output. The particular model I have restricts flow to maintain temperature.
Cycling: Don't take Navy showers. Turn the water and leave it on until you're done. When you turn the water off, the flame goes out. When you turn it on again, there will be a slug of cold water in the line.
Loop Control: All tankless water heaters use loop controllers. They measure some input values (inlet temp, flow rate, and outlet temp), control some control values (fuel flow and on my heater, water flow), and thus produce a desired output value (water temp). Go look it up in Wikipedia; this is not the place for an engineering lecture.
Limitations of Loop Control: A loop controller must balance stability and response. If the controller instantly responds to changes in input values, the output will not be stable. The compromise in the 250FX means that the temp will vary (3-5 degrees) for a short period of time (5-10s) when the input parameters suddenly change (somebody abruptly opens or closes a hot water valve). Then it will stay at setpoint again. IF THIS BOTHERS YOU, DO NOT BUY ONE OF THESE DEVICES; YOU WILL NOT BE HAPPY.
Version 1.0 of ANYTHING... Ain't gonna be so great. When I ordered by Bosch 240fx, (an old proven model of the product), it was being phased out. I wound up with the Bosch GWH635ES, which is now called the Controlled Energy Corp 250FX. This product was just being released at the time, and IMO, they released it too soon. After about 4 firmware upgrades, it's operated quietly, effeciently, and reliably for almost 1 year. CEC was very helpful with the firmware upgrades, though I did the work myself. If you buy one today, you should get the current firmware.
This particular unit has very high output and costs about a grand.
Oh, yeah--set the temperature for the comfortable temp in your shower. Take your shower with hot water only; it'll be the perfect temp every time. And flushing the toilet won't fry/freeze you. (But you will get the temp variations)
Have fun!
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thrugoodmarshall wrote:

Thanks for your "consumer review", I found it interesting. It's the first detailed discussion of some of the "side effects" of tankless water heaters that I have seen.
You say the output is limited to maintaint temperature. Are you able to take a shower and run the dishwasher and run the washing machine all at the same time, or does this result in inadequte flow at the shower?
If you set the control point temperature for what you like in the shower, doesn't this make the water too cold for the washing machine and dishwasher?
How do you descale it?
Finally, do you (or anyone) know if they make these things in electric versions with reasonable capacity for a whole house? We live where there is no gas avaialable, and electricity is cheap (so we heat with all electric -- heat pump and electric backup furnace). We would need an electric version of the tankless water heater.
Thanks,
Terry
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Terry wrote:

I don't know. Typically, we wash everything in cold water, so it's rare that the washing machine would need the hot. The dishwasher, also, is plumbed to the cold water line, and heats it own water; it's got a heating element in the bottom (I think all dishwashers are like that).
Alright, I'll go check it. Turning on 2 showers, 1 washing machine (hot), 1 kitchen faucet (hot), 1 bathroom faucet (hot), and dishwasher (I don't think it'll make a difference, but you asked...). Yes, the flow in the showers is weakened. But it's still usable, and most importantly, it's still HOT! OK, now turning on the fill faucet in the jacuzzi tub. (at full flow, that faucet moves about 13-15 gpm--10 or so showers.) Now, there's almost NO hot water on the upper floor, and the ground floor is weak, too. And what's there is still at the correct temperature.

See above re: washing machine & dishwasher. You can best answer that question by filling in "what you like", "what temp you want in the w. mach", and "what temp you want in the dishwahser". But check your dishwasher first before worrying about it; it may not even be connected to the hot supply.

Short answers (2): 1. Don't. Instead, get a decent water softener and feed the heater good water. 2. Google for "descaling kit". Follow nose.
Long answer (hey, I warned you):
About water heaters and how they handle scale: Note that tanked and tankless water heaters both produce scale, and both can be descaled by pretty much the same process. In a tanked heater, it's not that noticeable until the heater is FUBAR. Also, newer tanked heaters try to cause the water flow to flush out the scale before the heater turns into a block of limestone. Tankless heaters do this because of their fundamental design (high velocity water flow).
My experiences: What follows is my experience, along with some guesses as to why and how these things happen. I'll try to make it clear when I'm speculating and when I'm reporting what I actually saw.
Three types of water: You get scale from stuff already in your water: My wife and I lived in an RV (I'm a consulting Engineer; travel a lot), and saw two kinds of water go through our RV-500: In Michigan, we saw orange/red stain everywhere the water touched, and black scale from the hot water system. Super Iron-Out cleaned up the stain. Conclusion: Iron-rich water. In Ohio, the scale was white and crusty. Fizzed when mixed with vinegar. I'm thinking calcium in the water.
Scale is not magically created; it comes from your water. So, if your water doesn't have dissolved solids in it you won't get any scale. My wife and I now live in a house (much gratitude to her infinite patience putting up with living in a RV for 3 years!!). We got an appropriate water softener for our well supply and we have no scale.
How the scale appears: Water heater scale is produced when dissolved solids precipitate as the water is heated. Talk to a chemist or industrial pipefitter (not plumber) if you want more detail. With a tankless heater, the water flushes *most* of the scale right out with the hot water. "Scaleless" tanked heaters do the same thing by designing high-velocity water flow in the places where scale is likely to accumulate. So, the scale come out of the heater along with the hot water. And then promptly clogs up every &^%^$##!! screen in your water system. Typically there are screens in the water feeds to your washing machine, shower hot water, and sink sprayer. Well, that's where the grit wound up in our RV.
Avoiding the problem altogether: I'll say this again, even though it's implied above. The best solution is to get a good water softener from Home Depot/Lowes/Sears, etc. That's what my wife and I did in our house. It works great, and we have not had a single speck of scale. Also, our showers & bathtubs are clean and shiny, and we don't have to use Comet on them. When shopping for a softener, I do NOT suggest you consult one of the hard-sell triple-overpriced used-car salesmen that work for a company whose name begins with "C"!! You will NOT need to deal with the scale if you never get any.
Dealing with suspended scale in the hot water lines: Use a filter. You'll be glad you did. (Remember those screens? It's a lot easier to clean out ONE filter than a dozen screens. Which are buried in your appliances) In our RV, I installed an ordinary water filter & used spun yarn filter cartridges. Every month or so, I'd replace the filter and pour out the quarter pound of "sand" that accumulated in the housing. If you want a proper filter, you can get a hot-water rated one from McMaster-Carr.
Descaling the heater:
Well, you can look up instructions on the internet, but here's what I did to descale my RV500. I have never had to descale the 250SX. As the scale forms, some of it will stick to the hot surfaces of the heater, and it will build up. To descale the heater, first shut off the gas and power. Then disconnect the heater from the water system and connect hoses to the inlet and outlet. If you plan on doing this, put in the appropriate valves during installation. You'll be glad you did! Next, you mix up the appropriate concentration of acid (I used 10% sulfamic acid by weight. That's ~1/2 5-gal bucket of water + 2 lbs of sulfamic acid). Use hot water and dissolve it all. Stick the pump and the other hose into a second bucket. Use ty-wraps to secure the hoses to the bucket handle so they don't fall out! Pour the acid solution into the bucket. Plug in the pump. Acid now flows round and round, and the solution in the bucket fizzes like crazy. (That's why you only make HALF a bucket of solution!). After a while, the fizzing peters out. When there's no more fizzy bubbles coming back from the return hose, the reaction has stopped. At this point, you have either run out of acid or you have run out of scale. Throw some baking soda into the bucket. If it fizzes, you have run out of scale. Otherwise you have run out of acid. If you're not out of scale, mix up another batch of acid and do it again. When the scale is all gone, connect up the heater again, and flush the remaining acid out of the lines by opening up the hot water faucet nearest the heater.
Dealing with scale is a major PITA. Most people don't do it at all, and just throw out their water heater when it gets ruined. The best solution is to get your water analyzed and install the appropriate softener or iron remover.

Yeah, you can get electric ones, too. I think CEC sells them. The 250FX outputs (at most) 142,968 Btu/h (41.8 kW). Efficiency is 86.5%, making maximum input 175,000 Btu/h (51.2kW). For electric with the same efficiency and output you'd need a little over 230A(RMS) at 220V(RMS).

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thrugoodmarshall wrote:

They all have heaters, but I thought they heated the incoming hot water to be even hotter. I'll have to look at ours.

Interesting, sounds pretty good.
Thanks for the info, and the further info on descaling.

230A is a lot of current! I got curious and did some googling, and found electric versions with about 1/2 that wattage (28KW). They require a 120A breaker, twice the size of my electric furnace. I guess you'd need to check out your electrical service to see if you have enough capacity to install this.
Thanks,
Terry
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Correct Terry. To plumb to cold water is truly dumb. Most hot water heaters are set at about 120 degrees. To sanitize, a dishwasher heats the water to something like 160 or 180 on one or two of the cycles. In most cases, it is cheaper and more efficient to heat the water with gas or oil as opposed to the electric in the DW. Dishwasher detergents are not designed for cold water use and will not clean as well or rinse as well.
Quoted from a major appliance company DW installation guide Water Supply Requirements
.. A hot water line with 20-120 psi (138-862 kPa) water
pressure.
.. 120F (49C) water at dishwasher.
.. 3/8" O.D. copper tubing with compression fitting
This is from their Use and Care guide
Hot water dissolves and activates the dishwashing detergent. Hot
water also dissolves grease on dishes and helps glasses dry spotfree.
Is the water temperature too low? For best dishwashing
results, water should be 120F (49C) as it enters the dishwasher.
Loads may not wash as well if the water temperature is too low.
Water that is too hot can make some soils harder to remove and
cause certain detergent ingredients not to function. If your water
heater is located far from the dishwasher, it may be necessary to
run the hot water at the faucet closest to the dishwasher to
minimize the amount of cold water in the water line
From the Troubleshooting tips:
Spots and stains on dishes
 Spotting and filming on dishes
Is the water temperature too low? For best dishwashing
results, water should be 120F (49C) as it enters the
dishwasher. Refer to the "Performance Tips" section.
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I can't speak to the quality of any single brand, but I'm just to checking to see if you thought about all the other factors involved with tankless water heaters:
The flow rate, the electrical/gas upgrade costs, the maintenance costs, etc.
I only mention this because we often hear of people extolling the "cost savings" of these devices until someone points out the cost of installation, flow rates, etc.
You can't always just rip out your old tank, pipe one of these bad boys in and go. There are often many other factors to consider.
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On Wed, 3 Feb 2010 09:43:04 -0800 (PST), DerbyDad03

I think the OP left town.
He can at least look here for some good information*
http://www.tanklesswaterheaterguide.com /
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Ive had the Bosch 117000 btu unit for about 7 years and no problems, its a one shower unit it, I know the larger Bosch is made by Takagi and maybe the small unit as well. You have to do your homework like using a Manometer before buying anything. It all has to be planned by the numbers to see if it even might work, even measuring winter incomming waters lows temp and temp drop to point of use, if you guess likely you wont be happy so spend the time to run numbers and do tests. I have a 4 yr payback, I installed it myself. There are quite a few brands, so to get and honest answer you need to find someone that has actualy dealt with them on a service level. If its multi use then you will need one of the big dollar near 190,000 btu units, then it gets very expensive. EF is how a water heater is rated, an AO Smith tank Cyclone or Vertex is about 82-84EF and thats about as good as you can get. You can go condensing tankless like the takagi TH1 thats over 91EF, Rinnai, Rheem and others make good units, but Rheem hasnt been in tankless long. A real good AO can for many aplications be better, I have a 190000 BTU AO Cyclone condensing tank in an apt building, the Vertex is the residential model. Gas supply is critical for tankless, you have to do a test with everything on thats takes gas, then calculate in reduced winter pressure on the coldest days of record to even get an idea if your shower will be warm on that coldest day, my 117000 btu at -15 with about 40f incomming works without being set on full high for a hot shower. Now we will hear the bs from all the folks that never owned or used one, but really know.
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I don't know how "guns" got involved, but yes they CAN "shoot around corners".
Regarding your tankless water heater: where do you live?
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Right around the corner. ;-)
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heater? Are there any

I have an AquaStar.
To install it I had to run a 3/4 inch gas line and a vent larger than for a tank water heater.
Mine is a standing pilot type and it does not throttle to well if you are trying to take a shower while doing a load of wash or dishes.
The maintenance costs in parts is very high, I have had to repair it three times in 15 years.
When I moved in I went from electric hot water to the tankless gas, so I am not too sure of the savings as I have nothing to compare.
I suspect if I was to do it all over again, I would go with a tank style. The initial cost is less and the maintenance costs are a lot less. That would probably buy a lot of gas.
The up side is that you never run out of hot water.
The newer fancier ones have a few more BTUs and a better throttling sustem, but I suspect that the initial cost and the periodic cost of parts will be a lot more than the tank style.
--

Roger Shoaf

About the time I had mastered getting the toothpaste back in the tube, then
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Thanks for the input. I've been delaying a tankless install because the volume of hot water I need is only for 2 people plus the cost of propane here in extreme north NY state is out of line with the rest of the world. On top of that I have a dual day/night electric rate and the current 120 gallon tank (now 31 years old and is not leaking !!) only heats at night.The night rate is only about 5 cents total per kw. A plus for the Takagi is it does not use a pilot light and offers an attractive warranty. I would opt for the remote temp/service status sensor. Additionally I already have propane for my generator and I can do the install myself. I'm also looking at solar now that there is a 30% tax credit on material and labor with no upper dollar limit on the amount of the 2010 tax credit but I'd probably still need a small electric backup.
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With that low electric rate, and apparently expensive propane, I don't see why you'd want to switch fuels. The largest part of the fuel bill is for actually heating the water used. With a tankless, you eliminate the standby losses, but it's likely that could not be enough to put you ahead. Also factor in that electric water heaters have a very long life, are 100% efficient, cost less, etc. and it sounds like electric could be best.
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I think if I were you I would opt to keep the electric hot water. You perhaps could opt for a smaller water heater. The tankless sucks a whole lot of gas while it is running, and your current electric rate for nighttime usage seems to be so cheap that you would never recover the cost of the tankless.
You might want to consider some preventive maintenance on the 31year old water heater. You might never need to replace it if your anode is kept in good shape and you are able to flush the sediment from the bottom of the tank. This web site explains how: http://waterheaterrescue.com /
--

Roger Shoaf

About the time I had mastered getting the toothpaste back in the tube, then
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Thanks for all the inpt.
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I wish I had 5c a kwh, im at near 0.14. A tank on a timer is what I would do, There are some super insulated electric tanks sold. At .05 kwh you may be below what you pay for propane or local Ng per BTU, you should run numbers because night time home heating may be cheaper with electric space heaters.
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On a new well insulated tank, how much do you think you're gonna save with a timer? You won't save anything until the water cools down below the point that it would have come on. And my bet is by that time, the timer will be about ready to turn it back on anyway. The bottom line is that especially with an electric tank, which is completely insulated, the water cools so slowly when it's not being used that it isn't going to make a difference big enough to make the installation of a timer worthwhile. And if you have to pay an electrician to do the install, I'd bet you come out a big loser.
As an experiment, you could measure the temp of water coming out of a tap close the heater at night. Then shut it off and measure again in the morning. I'm going to try it on my gas water heater.
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