Should I get a tankless water heater?

RandomJoe · December 2009

I realize this isn't completely on-topic for the forum, but I don't know who/where else to ask right off, and know some of you use tankless heaters, so...

Trying to keep this short and sweet while getting all the pertinent details in has been tough for me... Sorry about that! :roll:

The basic question is, for my situation is it worthwhile to go tankless? (I'm in a suburban area, grid power and natural gas.)

Most reviews I read say it's not all that great of a deal - upfront costs outweigh the energy cost savings over time. But then the reviews are also based on a typical usage pattern that is *not* mine, typically lots of water used over the course of the day while I use very little. I take a shower in the morning (NOT with a low-flow shower head!) and occasionally wash dishes by hand (I use very few, and typically just rinse then stack them in the sink, washing a batch every few days). Clothes washer is cold only, dish washer is broken from disuse and unlikely to be replaced! So for the most part my water heater sits idle all day.

I don't think mineral buildup (another of their concerns - one review even mentioned needing special taps to fairly often clean the unit with vinegar?!?) will be an issue now. My city uses well water, and for a long time it was HARD water. Had to clean the strainers on the faucets monthly to keep good flow. (This has also left a bunch of sediment in the current tank - and completely plugged the drain valve.) But they recently put a new treatment plant online that has greatly reduced that - it's been months since I cleaned a strainer. Of course, that means they are using a supersize water softening system, which I understand can mean other potential issues.

The reviews also said installation could be quite costly, as the gas line and flue has to be upsized. But - again - they tended to cover heavy usage patterns, perhaps I could use a smaller size unit? (Then again, maybe my high-flow shower head would be "heavy use"?!?

)

Another issue, of course, is being able to have hot water in a power failure. I'd definitely want to be able to plug the unit into my generator or even inverter on the battery bank, if possible. Not sure how much power these things pull, I wouldn't expect much but then another thread indicates some of these have electric heaters in them for when it gets cold...! (Mine would be in the garage, so hopefully that would never kick in...) This is where a simple tank heater sure does shine, mine was the one ray of happiness during an otherwise dismal outage two years ago - I had all the hot water I could stand! :cool:

I haven't gone looking at the current models, are any using electronic ignition? I noticed many references to a standing pilot - that surprised me, that's probably most of my summer gas bill right now is the pilot on my current water heater. (Furnace and clothes dryer are electronic ignition.)

So, any thoughts? Any recommendations on a particular brand / model?

icarus · December 2009

Re: Should I get a tankless water heater?

My answer would be a qualified yes. Most especially if you are going to need to replace a tanked type anytime soon.

There are some up front cost issues that are more expensive, especially venting. That said, demand water heaters can be located nearly anywhere, and with PEX plumbing, major relocations are not hard to do. IF you can locate a unit on an outside wall, you will be in clover, as direct vent out the wall is very easy and quite cheap.

All "modern" demand" water heater vent through fairly expensive stainless steel pipe, rather than the cheap "B" vent that conventional heater use. Modern units have fan forced combustion and vents so power is required, both for the fan, but also for the control board. The total draw of most units is ~75 watts max, so they are not big loads on inverters.

As for gas pipe sizing. Code requires a certain size pipe for certain input BTU ratings. I think that most units that I know of spec a 3/4" line unless it is a very short (or long) pipe run. I know from considerable experience that gas pipe that is too small almost always works just fine (within reason). Piping specs are there to prevent low pressure and it's associated problems if every gas burner in the house is turned on full bore, so some of your concern would be an issue you might wish to talk to an installer/inspector over.

There are few standing pilot units available any more, as they are not as efficient. They have all gone to electronic control/ignition. (too bad, IMHO, since the Paloma PH6/12 were great units for off gridders, as they vented through "b" vents and required no power).

As for brands. Personally I really like Takagis (especially the TKjr) Well built, flawless performance. I also know folks who swear by Rinnais. I know less about the new generation Palomas, but I haven't heard anything bad. On the other hand I know lots of folks that swear AT Bosches. I have know a few, and they have had chronic, unsolveable problems. Working fine, then quitting in the middle of a shower, so I wouldn't buy one.

Depending on where you are located, there are outdoor units that vent very easily, but freeze protection is an issue. Also, of you are ever going to entertain solar hot water, a new modern demand is perfect to supplement solar hot water.

I think that is enough for now,

Tony

Ps Garage location would be perfect. If venting out through the roof is spendy, then move to the outside wall with some PEX Tubing. Even if your gas line is undersized, assuming the meter is near the garage/front of the house as well, then upsizing the gas line isn't going to be very difficult.

hillbilly · December 2009

Re: Should I get a tankless water heater?

We have an outside Tankless water heater (made from Paloma), and I overall like it a lot. My main reason for buying an outside unit was to try to save some money and time and hassle with plumbing and venting. This was probably a mistake, due to the increased power consumption while idle on cold nights (this might not be as big of a concern if we were not off the grid). As far as power consumption while operating, it's quite low typically <100watts, and LP gas consumption is modest as well (depending on how long and how hot you like your showers). Regarding gas piping and mineral deposits, we've not had any real issues with either but we used 3/4" gas line and have fairly nice soft water from our well.
If this is for a single person and you were looking at absolute minimal power and gas use, I think that a small RV tank that was only turned on just before you needed a shower or to do the dishes is quite a lot more efficient. I've done that for years, and it works to a degree: light the pilot and fire up the hot water heater about a half an hour or so before each shower and you get a short shower and then the water starts to go cold if you dawdle too long. Call it forced conservation, but it does work.
I would say the big plusses for a tankless over a more standard sized hot water tank would be: more efficient, no shortage of hot water ever, and a much smaller footprint in terms of space needed. For us the biggest downside has been waiting for the hot water to reach the tap, which can be a while depending on how far the heater is from that tap; if I were to do it all over I'd be sure to put the heater as close as I could to the kitchen sink as that's where we most frequently desire hot water for a short burst, less waste waiting a bit longer for the hot water to reach the shower as that is usually only turned on about 5-10 times a week instead of 5-10 times a day. Still this is a pretty minor issue overall in my opinion.
Sorry I cannot really comment about specific brands and models because I really don't have lot of experience with other brands.

icarus · December 2009

Re: Should I get a tankless water heater?

HB does make a good point about being as close to the fixture as possible. One unmentioned down side to demand hot water is lag. When you first turn on the tap, it takes a couple of seconds to fire the burner. This really isn't any more of a problem than a conventional, in that you also have to wait for the hot water to flow, but with demand, it is hard to (but not impossible) to install a circ system to keep hot water at the tap.

The other lag issue is, if you turn off the tap momentarily, (or even turn it down too far) the water heater will stop firing, and then have to re-fire, causing a potential burst of cold coming through. This can be quite irksome in the shower until you learn to manage your shower valves. With the older non modulating units, they would throw out the heat full bore as long as the water was flowing, so if you slowed down the flow by turning the hot water valve down, the temperature might (and did) actually go up! Or you might turn it down too far and the fire would go out, resulting in a surprising cold snap!

We have been able to get around this problem by installing two handle shower valves, such that you never adjust the hot by reducing the hot, but rather by adjusting the cold up or down.

With the new modern modulating units, the preset temp comes out, regardless of flow rate, so that a single hand faucet works fine, unless you turn it down far enough fot the fire to go out.

For me it is a bigger issue doing dishes. We tend to partially fill the sink, wash, then do some rinsing using hot water to add to the water in the sink, shutting off the water in between. Once in a while we can get a blast of cold because of the couple of second lag time between the water flowing and the heater firing. Not a big deal, but certainly one that folks should be aware of.

Tony

If you only use it for showers/dishes and small laundry, it is pretty hard to beat a PH6 Paloma. They are out of production but spares are still abundant, and they are very reliable. You see them every now and again on Ebay, but you often have to bid against me for them LOL!

BB. · December 2009

Re: Should I get a tankless water heater?

I will vote on the no side and stick with a tanked heater for now...

For the average home, I think Solar Guppy said, that one could expect a 20% reduction in their hot water costs.

We use a fair amount of hot water (two kids who like to shower, a lot). With a low flow shower head (+ two adults), our hot water is probably well under $20 per month (includes a gas stove and drier--which don't get that much use in the summer).

I get a good 12 years on a tanked heater (currently around $550 or so) and I can replace them myself pretty easily. No issues with minimum water flow for turn on and no issues with the balance valve (sort of anti-scaled valve) on the shower/tube (can cause issues with unstable water temperature/flow). With low flow shower head and sink faucets (in California, you cannot buy any other type)--a 40-50 gallon natural gas hot water heater never runs cold for us. Also, some folks have reported that their tankless hot water heaters are pretty noisy (flame roar).

No pilot light seems to not save much energy--since the pilot does keep up with some of the heat loss. If there was a better way of preventing heat loss through the stack--it seems that would be a better solution--but I have not seen any reasonably priced natural gas water heaters that do anything like that--unless you go for the few (one?) condensing model hot water heater AO Smith Vortex 50 gallon (which does require AC power for the controller and draft fan). That guy is really efficient (seems to be more efficient than a tankless unit)--but is not cheap itself and comes with a 6 year guarantee.

I like the Vortex because it requires a standard gas line (not a huge burner like the tankless--units just a 100,000 BTU burner). But at around $2,000, it is not cheap.

If I can save $2-$4 per month on my hot water bill (at current prices)--it just is not cost effective for me to use it. Perhaps, it makes sense for somebody with a restaurant or hydronic heating... But not for me.

Maybe, it does last longer than 6 years--but even at 12 years, the cost of the Vortex minus the money saved on gas ($4*12mn*12yr=$576 savings) is still twice the costs of a standard hot water heater replacement plus "extra" gas use...

If I lived in an area using propane, I would probably have a different opinion.

A low flow shower head can really save lots of money on your gas (and water) bill. It has for us. Also, our standard tub type clothes washer just uses a few gallons of hot water for a "pre-wash" kind of action--so the rest is cold water fill. Another big savings. I believe those simple conservation measures have saved us more than a straight conversion to tankless would ever save in energy costs.

-Bill

Cariboocoot · December 2009

Re: Should I get a tankless water heater?

My two cents (CDN) worth:

The more hot water you use the less viable an instant water heater is.
Their main fuel savings comes from not having to repeatedly re-heat a tank full of water that's just sitting around not being used. Tank-types 'fire' whenever the water inside drops below a pre-set level, whether due to introduction of fresh, cold water or from radiant heat loss. A well-insulated tank unit with the temp set relatively low (it doesn't have to be 180 F!) can offer long-term savings over the instant type.

That said, I have instant at the cabin and will be installing one in the new house when I remove the electric monster that's there.

Oh yeah; we bought a new house and will be saying good-bye to the all-electric valley home.

BB. · December 2009

Re: Should I get a tankless water heater?

I do keep our hot water heater fairly cool.. Basically, if it has been sitting over night, the hot water in it is just hot enough to take a shower with little cold water needed for tempering.

My wife keeps wanting to turn it down more, but I don't like to wash dishes in luke warm water in the morning (typical tanked hot water heater does not accurately hold its temperature set point--in my experience).

I also worry a bit if I keep it too cool...:

B]Legionnaires' disease[/B

Legionella will grow in water at temperatures from 20 to 50 °C (68 to 122 °F). However, the bacteria reproduce at the greatest rate in stagnant water at temperatures of 35 to 46 °C (95 to 115 °F).

-Bill

Cariboocoot · December 2009

Re: Should I get a tankless water heater?

Bill you are spot-on, as usual. For sanitary reasons the temp should be 140 F or more. All tank-type heaters have a 'range': burner/element comes on at one temp, shuts off at another. Has to cool down a bit before it starts heating again (almost all thermostatically controlled devices have this characteristic). If you need really hot water you can 'trick' it into firing by opening the hot tap in advance and letting some cold water in 'til the heating comes on. Then make use of it once it reaches its maximum temp. Takes a bit of guess work to figure out just the right amount for your particular heater. Tankless heaters have less variation, but still have a little even though the flame fires all the time water is running.

Oh; never buy an electric tankless! They're horrible things.

chevenstein · December 2009

Re: Should I get a tankless water heater?

I used to live exactly as the OP describes - one long hot shower in the morning every day then virtually no additional HW use (I was a bachelor - no dishes because I got pizza or chinese all the time, minimal clothes washing, etc). This was while living in a house with a 40 gallon electric water heater. After a few months of high electric bills I put a 10KW Intermatic brand mechanical timer on the heater, setting it to run the thing for one hour ever morning before I got up. The timer was $40 and paid for itself in about two months.

LucMan · December 2009

Re: Should I get a tankless water heater?

Sounds to me like you could get away with a 40-50 gal solar one or two panel HW system. If you are handy you can install it yourself for about the same cost as a tank less system. The most important thing is to get a storage tank with a low standby loss. Tanks range from about 2 degrees per hr to 1/4 degree per hr standby losses, that makes a big difference the next morning in water temps for that early morning shower.
Up to $1500 Tax credits available may make it the least expensive option.:D

RandomJoe · December 2009

Re: Should I get a tankless water heater?

Well, that was certainly a nice dose of information! Thanks!

I could certainly move the water heater location to an outside wall easily enough - it's about four feet from it now, and I could wall-mount one in the corner of the garage. (And free up a nice chunk of prime space in the workbench / solar system area!

) The gas line is more problematic. It enters the house at the farthest point possible, then runs through the attic to the area over the heater. There are drops from it to the furnace, water heater and clothes dryer that are all on the same wall between garage and kitchen. I'll have to check the line size, may need to upsize anyway - the kitchen is currently all electric and I'd love to go with at least a gas range in the future... (The previous owners remodeled at one point, so maybe there already is a gas line into the kitchen somewhere...!)

An interesting if not too feasible alternative is actually relocating closer to main use. Both bathrooms - and showers - are (again!) on the opposite side of the house, with the water lines in the concrete slab. Takes a good while to get hot water even from a shower head - it's pointless to try for hot water from the sink, I'm long done with handwashing before there's any hint of warmup! But perhaps a little replumbing could get a water heater over there for the bathrooms, and perhaps a small unit under the kitchen sink. (Do they even make gas ones that small? Probably would be electric - not too keen on that...)

But I really am starting to lean back toward keeping the regular tank. I think it would be hard to cost-justify it unless I could move them right to the use point - but then that's going to involve more time / money just getting things rearranged. I might be better off to make what I have more efficient. I was just thinking that the closet the heater is in is open to the attic, so right now cold air is falling into the closet. I could put in a ceiling of some sort to slow that down. (Those two code-required air tubes would still let it fall in, but a lot slower. -- Could I put vent louvers in the door of the closet and just pull air from the garage instead?) Be nice to have a damper in the flue for when the burner wasn't on - guess with an electronic that would be feasible, not so much with my standing-pilot...

I've also wondered about anything I can do to try cleaning out the existing tank. (I was able to actually hear the loose stuff "swishing" around inside the tank while the burner was fired.) Some further searches online suggested using a "stiff wire" to try to loosen the crud, but seems like that may damage the internal lining - in which case I'm accelerating the eventual corrosion and leakage of the tank. Is the drain valve just into the side of the tank, or straight out the bottom with an elbow, or...?

The parts breakdown in the manual doesn't show that particular portion of the tank (hidden by the burner assembly). Maybe I'll go look for some pipe cleaners or something tomorrow...

Plumbing seems to be my nemesis... I generally know or can find out *what* to do, and *how* to do it, but I have yet to have a plumbing project that goes smoothly. Everything is a royal pain!

:roll:

Lots to think about, thanks!

RandomJoe · December 2009

Re: Should I get a tankless water heater?

LucMan wrote: »

Sounds to me like you could get away with a 40-50 gal solar one or two panel HW system.

I have always been interested in that option, just haven't tried anything yet. I also have a space issue - very little south-facing roof. I have plenty of west-facing, but especially in winter it gets shaded pretty quickly - the neighbor to my south has a gigantic tree at the back of their property. West-facing for summer would probably be great, not sure how well it'd do in winter...

BB. · December 2009

Re: Should I get a tankless water heater?

There is the "Heat Pump" based water heater... If you have hot/humid weather, can be pretty nice (if you have lots of cheap electricity--basically cool/dehumidify the space and 3x more efficient that a resistance based water heater--use a desuper heater if you have a regular A/C). For your area, looks like you have both hot and cold weather... So, it probably won't work well in winter.

Although, for the sinks, a small, well insulated electric hot water heater may be more efficient than pumping/recirculating hot water to distant points in the home. Add a timer to shut them off when you are not home--might be an OK solution.

Probably lots of research/work/money spent no matter what you... And the difference between the various solutions may end up being round-off error.

-Bill

icarus · December 2009

Re: Should I get a tankless water heater?

If you have AC and use it regularly to cool, then a heat pump water heater would be choice number 1 on almost any environment! Serves two purposes. First, it heats water fairly efficiently, and more importantly, it allows the AC to run way more efficiently. Then you could use a demand (or tankless) for the times of the year the heat pump isn't used. Also qualifies for tax credit I believe.

A small electric demand in the kitchen, with a relocated demand gas for the baths would be a pretty good alternative. You could also install a 2-5 gallon gas RV batch water heater under the counter in the kitchen (assuming it is on an out side wall) Not real efficient, but for small kitchen batches it might work great. Draws combustion air from outside, and vents out the side wall, with no fan or duct. Like this:http://www.atwoodmobile.com/water-heaters.asp

Tony

mike95490 · December 2009

Re: Should I get a tankless water heater?

I ran 2 tank heaters in series - mostly because I had a spa tub in the master bath, and it needed 100g of hot water for each fill (used about 3x a year).
I ran the first tank about 80F, and the 2nd 130F. These were both gas heaters, when I sold the house, one was 20years old, other was 15. I think running a lower delta from inlet to outlet, contributes to long life. (and flushing via a 3/4" ball valve installed instead of the provided hose bib) Water bill in summer for household of 4 with laundry, showers and dishwasher and cooking, would be pushing about $10 month. With 2 burners, I had a great recovery time, and for earthquakes, I had 100 gallon of stored water (2, 50's). (winter was another story, when the furnace lit up, the gas meter spun like mad.)
Then I'd compare that to my inlaws house with tankless, and the shower throttle problem. Took me 1 shower to figure it out, but they never got the knack of it, and are always swearing about the hot water and shower.

BB. · December 2009

Re: Should I get a tankless water heater?

Tony,

Does the RV hot water heater come with a Natural Gas option (I did not see one)... Also, I wonder if they are legal for a home install (RV's are probably a tougher install--so it would seem that they could be safe--if tested and listed for home/mobile home use).

-Bill

russ · December 2009

Re: Should I get a tankless water heater?

At www.aceee.org they provide the costs and estimated operating costs for varoius types of water heaters over a 13 year period.

There is a good table there but it does not copy correctly so you have to go to the aceee site.

The heat pump type of water heater is shown to the the most economical over it's life time. That is a dedicated water heater and not part of a home heating/cooling system.

LucMan · December 2009

Re: Should I get a tankless water heater?

http://www.aceee.org/consumerguide/waterheating.htm#lcc

icarus · December 2009

Re: Should I get a tankless water heater?

Two things,

The consumer link is useful, but all the ones I have seen often over estimate the installation costs.

Second, I suspect that the RV type heater doesn't come in a natural version, but it might be worth a note to Atwood.

Tony

sawmill · December 2009

Re: Should I get a tankless water heater?

It seems most discussions about tank vs tankless seem to center around cost, few dollars one way or the other.

In a home you need different temps for the job at hand. Most tank type owners have reduced the thermostat setting to save on stand by losses (120) seems to be most popular. If you are comfortable using these low temps for food prep, dish washing, certain laundry jobs I suspect the tank type is the way to go if dollars are your primary concern. Keeping in mind any restaurant using these temps in their kitchen would be shut down.

Our tankless uses a digital control in the kitchen and in the bathroom to select the temp needed. We never mix cold, just select temp needed for the job. When hand rinsing dishes, showers or shaving, when near the end you can reduce flow until unit shuts down and drain all hot water from the pipes for zero waste.

With food safety and health being a top concern only the individual can decide how "penny wise & dollar foolish" they want to be on this matter or any decision that concerns their home. In other words there is no "right answer". I leave the dollar discussions to the actuaries.

Bill

BB. · December 2009

Re: Should I get a tankless water heater?

The gas price used for the estimate is about right for us.

However, the electrical costs are quite low:

9.5¢/kWh for electricity, $1.40/therm for gas

Our (N. California) rates run from $0.115 to $0.443 per kWhr--with a "typical home" paying a marginal rate around $0.28-$0.39 per kWhr...

That would make the energy costs for the Heat Pump version 3-4x as expensive as they estimated. Makes it much more expensive than Natural Gas.

Cariboocoot · December 2009

Re: Should I get a tankless water heater?

I'm glad this discussion came up. I'd forgotten about water heater timers, for one thing. Less than $100 and it can keep the tank off all night when not needed or all day if you're away. Here in BC electric is $0.05-$0.07 kWhr, so in combination with the timer that's probably my cheapest option until the tank unit gives up. Especially as I seem to be having difficulty locating a local source for anything other than the Bosch tankless units. And $1,2000 will buy a lot of electricity in BC.

Since tankless heaters use more energy per volume than tank-type, they only pay off with very low hot water demands.

vcallaway · December 2009

Re: Should I get a tankless water heater?

What is th opinion on the Bosch Aquastar?

I've seen them pop up on craiagslist near me. The require venting, but don't require electricity.

Cariboocoot · December 2009

Re: Should I get a tankless water heater?

vcallaway wrote: »

What is th opinion on the Bosch Aquastar?

I've seen them pop up on craiagslist near me. The require venting, but don't require electricity.

I've had good luck with my Bosch, but it may be just luck; I've also heard a lot of stories of failure and lack of serviceability.

They're a bit tricky to install as you need the metric pipe adapters which should come with it.
Also, they do not have regulated output temp: it's whatever degrees in plus whatever the unit can add to it (+50F I think).

But this is my model which I don't think they even make any more.

Even though I'm satisfied with the one we have, I'd be wary of buying another.

mike95490 · December 2009

Re: Should I get a tankless water heater?

sawmill wrote: »

... Our tankless uses a digital control in the kitchen and in the bathroom to select the temp needed. We never mix cold, just select temp needed for the job. When hand rinsing dishes, showers or shaving, when near the end you can reduce flow until unit shuts down and drain all hot water from the pipes for zero waste.....

What type has this feature ?

icarus · December 2009

Re: Should I get a tankless water heater?

Mike: The takagi and (I think) some of the Rinnais can be had with remotes so you can have a different temp for different function. (PS I have it backwards,, I know the Rinnai can use a remote and I think the Takagi can. Don't know about the Palomas) PPS A little google search reveals that Takagi, Rinnai and Paloma all can be had with remote controls) T

As for Bosch: I have had experience with Boschs. The standing pilot units have had a pretty good track record in our service. We haven't used any of the hydro driven ignitors models. I still run a early French made Aquastar. It has been a bit finicky, but I have been using it for ~15 years.

I have had much less luck with the electronic models. The couple of units that I have had contact with have been chronically un-reliable. Mystery fault codes, shutting off in the middle of showers etc. Bosch technical and dealer support has been terrible. One guy paid for two service calls, for a unit under warrantee, and they never did solve any issue.
He finally yanked the whole thing out and put in a tank when he couldn't keep it running.

Tony

LucMan · December 2009

Re: Should I get a tankless water heater?

East - West is good. Or you could put 1 panel East & 1 panel West there are differential controllers that can accommodate this setup. You just have to oversize your array to makeup for less hours of sunlight.

RandomJoe wrote: »

I have always been interested in that option, just haven't tried anything yet. I also have a space issue - very little south-facing roof. I have plenty of west-facing, but especially in winter it gets shaded pretty quickly - the neighbor to my south has a gigantic tree at the back of their property. West-facing for summer would probably be great, not sure how well it'd do in winter...

icarus · December 2009

Re: Should I get a tankless water heater?

Water heat systems are much more forgiving of misorientation/ shading issues.

A west facing collector that gets good sun in the summer is way better than nothing.

T

System2 · May 2010

Re: Should I get a tankless water heater?

I have two tankless propane water heaters serving different parts of the house. They are three years old and work very well. I am considering putting a self built "batch" style solar water heating in front of and therefore feeding a tankless water heater in the new home I plan to build soon. This should significantly reduce the amount of propane necessary to heat the water to 120 degrees. Anyone have experience with such a set up? Any Comments?

BB. · May 2010

Re: Should I get a tankless water heater?

Are your brand/model of Propane tankless heaters able to take pre-heated/variable input tempurature water in and give stable temperature water out?

Not all tankless water heaters have variable flame / thermal control capable of doing this.

And you should also look at desuper heater type hot water heaters (attached to A/C system) and see if they make sense for your home (assume you are in/around Texas and do a fair amount of Air Conditioning).

Or there are these:

BB. wrote: »

Trying to make this thread a jumping off place to further information (links, data, etc.).

Following up on Russ' Energy Star Suggestion:

www.energystar.gov
Energy Star Hot Water Heaters

Links to a couple of manufacturers from Solar Guppy (see above links for more):

GE Heat Pump Water Heater
Ruud Heat Pump Water Heater

For a quick discussion about heat pump based hot water heaters, see this thread (starting at post #12):

Guidance for Grid-Tie

Heat Pump based hot water heaters are probably a great idea for those in warmer climates (especially if using electric power or oil for heating).

If you are in a cooler climate (below ~55-45F area where heater will be installed)--check out the details to ensure it makes sense where you live--and I may very well be overly pessimistic on my suggestions--others disagree with me.

-Bill

icarus · May 2010

Re: Should I get a tankless water heater?

Solar pre-heat works quite well with the new modern modulating demand water heaters (Takagi/Rinnai/Paloma and some Bosch units) I have built several small simple flat plat collectors that put a fair bit of heat into a pre-heat tank. Even a tank "under glass" painted black will pick up a lot of BTUs on a sunny day.

That said, a waste heat A/C unit (if you use A/C) might be a better bang for the buck as Bill suggests. Saves money two ways. First is free hot water, and second is it allows the A/C to run more efficiently. A classic win/win.

Tony

Should I get a tankless water heater?

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