Tankless water heaters vs HW tanks

[John Raabe]

This report from Consumer Reports discusses some of the problems that can be associated with tankless water heaters. Thanks to AdironDoc for sharing this information.

http://www.consumerreports.org/cro/appliances/heating-cooling-and-air/water-heaters/tankless-water-heaters/overview/tankless-water-heaters-ov.htm

Here's a few lines from consumer reports:
"they [on demand] cost much more than storage water heaters, it can take up to 22 years to break even—longer than the 20-year life of many models"

"We didn't test electric tankless heaters because many can't deliver hot water fast enough to replace a conventional water heater if ground­water is cold". Yes, like the 33 degree water in my storage tank.

"inconsistent water temperatures were a common complaint among our poll respondents", "you'll receive a momentary "cold-water sandwich" between the old and new hot water." Don't I know it.. Try showering in 45 degree bathroom only to get doused with ice water for a moment. "Adding a storage tank can resolve some of these problems, but most people go with tankless because they want to get rid of tanks."

"a tankless water heater's burner might not ignite when you try to get just a trickle of hot water for, say, shaving".

[John Raabe]

Here is one option by a person who used this small (6 gal) electric heater to smooth out the surges and sandwiches of the tankless heater. Click on the customer reviews.


http://www.amazon.com/Reliance-SOMS-Gallon-Compact-Electric/dp/B000W6AVMY/ref=sr_1_9?ie=UTF8&qid=1323014028&sr=8-9

Several people have installed this tiny heater in smaller spaces as the primary heater. You probably can't take long back-to-back showers but 6 gallons of hot water can do a lot of what you need the heater for.

[Windpower]

I installed an AquaStar (now Bosch) 10 years ago

IIRC it was about 2 times the cost of a propane 40 gallon

So far it is has been very good

For a unfrequently used cabin or house there are advantages

Before it was an electric heater that cost a fortune to leave on all the time -- and if you just turned it on when you got to the place it took a couple hours to get hot water

the tankless does a good job -- hot showers as soon as you get to the house --

no problems with poor temp control and even with very hard water no calcification problems (admittedly it has not seen alot of use in the last 10 years)

   

[MountainDon]

I have read somewhere that some of the tankless are difficult to simply drain water from the heating coils. I think bl;owing out with compressed air works better, more assured of getting the system clear.

I would like to find a small (6 to 10 gallon) tank style propane fired water heater. A home style tank like that would operate more efficiently than an RV water heater. However, all the small tank types I find are electric.

[Native_NM]

One important thing to remember is that manufacturers almost always recommend 3/4" or  greater pipe for both gas supply and water supply.  Many newer homes have 1/2" or 5/8" Pex.  If your house is designed and plumbed for a tankless heater, they can work great.   The test results they achieve at the factory are under ideal conditions.  If I was building a new house again, I wouldn't hesitate to plumb it for tankless.  In retrofit situations, you really have to make sure your lines are adequate.

[glenn kangiser]

We put ours in to get away from the standing pilot and not waste propane on that.

Scale is not usually a problem if temp settings are not too high.  We have ours set about almost scalding hot if not mixed with a bit of cold due to regulation problems if it is set cooler, but no hotter than that.

[MountainDon]

I like the water heater set up Dave Sparks has. If a person has a good solar exposure on the cabin/house I think it is great. He has a propane fueled tank heater that is factory equipped with a solar heater coil. The solar water heater collector supplies all their hot water needs in the summer IIRC. Propane is only needed in the less sunny, colder periods.

[Bob S.]

Does any one have any input on a elictric tankless water heater mounted under a bathroom or kitchen sink? Would it work better if it was only servicing one close sink?

[AdironDoc]

I was using the propane Eccotemp L5, and later the L10, to service a single low flow shower. Water from a rain-barrel varied greatly in temperature, as did the pressure at any given moment. A high pressure shur-flo primed itself from the barrel, some 10 ft away. Low flow caused ignition failure so the shower had to run fairly strongly to kick in. To prevent the incessant rattling of the system, I installed a 5 gallon pressure tank, but that only led to pressure variation between cut-in and cut-out pressures. The pressure variation resulted in wild temperature swings. Since both units were outdoor models, a change to the temp of the shower to allow for the different temps of the incoming water meant a walk around back to turn the knobs again..and again..

The on-demand systems have their advantages, to be sure, but be aware that they may not be as easy as the ads tout. I've spoken with many who find them finicky, inflexible to plumbing modifications, and not worth the savings in the short run. I've seen premium models that have internal thermostats to avoid temperature swings, but that requires line voltage. Ignition is not a problem for the electric models, but they have more difficulty with cold climates due to a narrower rise rating. Moreover, their high electrical demand mean rewiring for many. The amperage of the recommended breaker for one I looked at exceeds the rating of my entire service entrance.

Having opened the drain plug as per manufacturers instructions on my own unit was apparently not enough to prevent damage from cold. Alas, another unit and couple hundred dollars in the trash. I'd be very careful in areas where the fall temperatures are in the 40-50's and night-times in the 20's. You may find your morning shower and unit are a memory. After two bad experiences, I'm reluctant to return for a third round.

[Squirl]

I had signed up for consumer reports because I was in the market for a new water heater a few months ago.  Because of their poor information on tank water heaters and this article I canceled the very next day.

This article has some glaring mistakes that the author should be ashamed to publish.  They compare the two based on initial cost and energy consumption alone.  They mention in the article that their's is a 20 year warranty on the tankless water heaters.  What they don't mention in the average tank water heater in the $300-$450 range has a 6-9 year warranty.  Do the math and they did not factor in the cost of replacing the tanked model, or the cost of the plumber for most people. 

I have seen many tanked models fail.  It is fairly unpredictable.  Everyone pushes it or doesn't pay attention. The failures are spectacular and almost always cause damage.  I have seen an entire subfloor have to be replaced.  Nobody wants to go out and spend $350 and two days labor to replace a water heater that is working, until it fails.

Also they "We also ran more than 45,000 gallons of very hard water through a tanked model and a Rinnai tankless model to simulate about 11 years of regular use."  The real energy loss of a tank heater are when those times that it goes unused.  10 hours at work 10 hours over night.  It adds up over time, just running 45,000 gallons doesn't equate to letting it sit unused and on for 20 hours a day in a cold house or basement.  I don't think their calculation of energy usage of tanked water heater was accurate.

They also didn't factor in the average rise in energy prices usually outstrips inflation.


When I added up the cost of replacement every 6-12 years, my time and effort, along with possibility of damage the tankless was the clear winner.  The fact that they are more energy efficient is just icing on the cake.

[MountainDon]

Code in most places now requires a catch pan under a tank type water heater. It's an excellent idea even if code didn't require one. Depending on the installation a drain pipe can be run to dispose of any water in a safe manner or the drain is plugged and a sump pump installed in the pan. With all the insulation around the tank pretty much all tank failures will drip into the pan.

We have one under our tank and I have added an alarm bell that goes off if and when the pump starts. The pump has no trouble keeping up with the flow when the tank drain valve is opened.



We have a "12 year" tank. I replaced the original after 16 years only because it seemed like a good idea to do it when it was convenient for me.

[Squirl]

I'm not saying they aren't a good idea, but a  pan wouldn't have done any good in most of the failures I had seen.  They would rust usually at the connectors.  This would spray 4-5 ft up or around the tank. 40 psi and a small hole can really shoot some water.  Luckily, on the last one, I was home at the time and it was in a basement.  It only got the first floor above it wet and ruined some decorations.

The worst one I had seen was in the first floor of a 1 story with crawl space.  It shot the water around it.  The person wasn't home.  It flooded the first floor and ruined the flooring right down to the subfloor.  Pennywise pound foolish.  The owner bought one of those nice 12 year glass lined ones, but didn't replace it after 12 years and put it off until it failed.  It ended up costing him thousands.

[boltpost]

Greetings...on this forum I saw an image of a tankless waterheater mounted in the outside wall of the home.  Which one of you pro's did this? and what was the reason for outside vs inside mount.  Thanks in advance - boltpost

[Squirl]

I didn't do it.

Some people do it because of the model.  Many camping tankless water heaters don't have venting and are designed to be used outdoors.  They give off carbon monoxide.  If you know you are only going to use it in the summer or you are in a mild climate, it is a low cost way to install hot water.

[MountainDon]

I think phalanx used an exterior mount tankless heater. South TX, not much freezing to worry about

[AdironDoc]

That may have been the photo I posted earlier of my $99 Ecco Temp 5 camping heater hanging on the back of my camp. I had hoped it would give an easy hot shower without much cost or fuss. In the end, it never kept a steady temperature and froze. This was likely because the 12V shurflo pump didn't keep a steady pressure seen in a home garden hose. The Ecco-10 replacement died when the night temperature fell below 30. My bath in the guest camp is very small and there's no basement. External placement is the only option I had.

I went a different route on the main cabin. I Just bought a Rheem DVP64 for around $600 in the hopes that spending a bit more than I did last time will eliminate the problems I encountered before (this unit has a temperature regulator). But to the question, I got the indoor version which requires a through wall venting kit for an added $120. The exterior versions cost roughly the same but do not require any additional equipment. If vented properly, the indoor version both gets its fresh air and rids itself of spent gases through the same vent ( a double lumen pipe). The Rheem is freeze-proof to an advertised -30F whether indoor or outdoor. In the end, most buyers guides leave it up to convenience and optimum  placement. Performance is the same. For me, putting the unit on the interior basement wall directly under the shower makes more sense than a long run to an outside wall. Of course it means a length of black pipe for propane to reach the unit vs. the exterior version.  I suppose if the bath were on a side or rear wall, I'd have chosen the outdoor version and merely punched through. In the end, it's 6 of this vs a half dozen of another.

[MountainDon]

LOOK HERE for topic

[Don_P]

Our present clients have an exterior mounted cheap camping tankless on the hut while we are building the house. Even drained, it cracked a lower pipe last winter. The homeowner fixed it and sweated on a drain in the problem area.

In the same neighborhood we had a tankless thru the wall unit. I had to put the exhaust on the west and very windward wall which meant that sometimes frigid air would be driven back towards a cold unit... the downside of no standby heat, it's easier to freeze. They had a backdraft connector that fit in the exhaust pipe to prevent those blasts of cold air. Although they claim great efficiencies that exhaust stream sure seems to contain alot of wasted heat. This has been a few years there have been advances I'm sure

[PorkChopsMmm]

That may have been the photo I posted earlier of my $99 Ecco Temp 5 camping heater hanging on the back of my camp. I had hoped it would give an easy hot shower without much cost or fuss. In the end, it never kept a steady temperature and froze. This was likely because the 12V shurflo pump didn't keep a steady pressure seen in a home garden hose. The Ecco-10 replacement died when the night temperature fell below 30. My bath in the guest camp is very small and there's no basement. External placement is the only option I had.

I went a different route on the main cabin. I Just bought a Rheem DVP64 for around $600 in the hopes that spending a bit more than I did last time will eliminate the problems I encountered before (this unit has a temperature regulator). But to the question, I got the indoor version which requires a through wall venting kit for an added $120. The exterior versions cost roughly the same but do not require any additional equipment. If vented properly, the indoor version both gets its fresh air and rids itself of spent gases through the same vent ( a double lumen pipe). The Rheem is freeze-proof to an advertised -30F whether indoor or outdoor. In the end, most buyers guides leave it up to convenience and optimum  placement. Performance is the same. For me, putting the unit on the interior basement wall directly under the shower makes more sense than a long run to an outside wall. Of course it means a length of black pipe for propane to reach the unit vs. the exterior version.  I suppose if the bath were on a side or rear wall, I'd have chosen the outdoor version and merely punched through. In the end, it's 6 of this vs a half dozen of another.

AdironDoc, small world! I have the Rheem DV64XP external tankless propane heater -- cousin of your heater. I am having second thoughts on it being external, although there is no going back now. I got it hooked up and working this past December. I drained the heater, blew my lines out with compressed air (!), and turned off the electricity. When I came back and fired the unit back up I had major leakages; some internal plumbing had frozen. Despite being drained Rheem will not fully warantee an external tankless heater if the power has been turned off. I am on solar, like you, and I turned the unit off to conserve power. They sent me some free replacement parts that I will be installing tonight. Wish me luck!

[AdironDoc]

Yes, Good luck swapping out the parts! I suppose I'll be mounting my unit in the next month or so. The indoor unit has a small fan I had overlooked in the specs. I hope this won't drain my battery set over time. I'd rather it had no fan like your model. I guess we'll need to compare notes on how things have turned out.

Cheers,
Doc

[considerations]

"on this forum I saw an image of a tankless waterheater mounted in the outside wall of the home.  Which one of you pro's did this? and what was the reason for outside vs inside mount.  Thanks in advance - boltpost"

I don't remember posting a photo, but my tankless is mounted outside, and is designed for it.  It is a Bosch. I live here year round so winterizing is not an issue. It runs on propane, has a pilot light and there is an electric plug in for a "pipe heater" that keeps it from freezing up if the outside temps drop too low. 

The reason for an outside mount was 2 fold.  1st I did not really feel I had space for an inside tank.  2nd, tankless was the logical choice once the decision was made to heat water outside the cabin.  I think from a cost standpoint, I'm happy.

Except for some initial scrambling whilst I learned the ins and outs of feeding it enough propane, it works great and I'm happy with it through a year of use.

[AdironDoc]

I was very reluctant to buy another tankless having had poor experiences with the two eccotemps I had. They are the cheapest models on the market and it's possible I got what I paid for. What I didn't like was how finicky there were. A touch of the dial sent water from ice cold to scalding and sent me running out of the shower, back outside to turn it another click, and inside again. A major PITA. I'm planning on installing my new Rheem with temperature control in the coming month. I'm wonder, do you guys suffer the from the "ice water sandwich", when your unit kicks on and kicks off again? Have you been happy with the consistency of the temps?

[considerations]

"I'm wonder[ing], do you guys suffer the from the "ice water sandwich", when your unit kicks on and kicks off again?"

No

"Have you been happy with the consistency of the temps?"

Yes, very

I have a Bosch model

[desimulacra]

I went with a standard small tank water heater on my boat. It is 110V and I have it on a switch. Really like it and works GREAT! When turned off the water will stay hot for most of a day and warm for another. The convenience of flipping a switch and turning the heater off when leaving the boat or turning it on when arriving is great. The switch has a red light on it to remind me of the water heaters state. Whenever we leave the boat, even for a few hours, we turn the heater off.
I highly recommend this to someone who is needing part time heat. It is simple and fairly cheap. Of course a small water heater is more than a standard 40 gallon, initially, but much cheaper in the long run. It takes about an hour for it to heat up from a cold start in the winter. Another advantage is I have a valve on the lower water penetration and can drain it with a twist of that valve.
It supplies enough hot water for showers and washing dishes, for 2 people. To give an idea of energy usage until the hottest months when I run AC the electric bill is usually the minimum.

Of course this applies only if there is plenty of 110v available

[builderboy]

I have a Steibel Eltron electric tankless heater for my infloor heat in Nova Scotia. Works fine, but folks who've tried them for domestic hot water found them inadequate - can't handle the temperature rise required in winter. No propane delivery in my location so that wasn't an option.