favorite electric on demand water heater?

archibald tuttle · July 7

I put in several Bosch units thinking that buying the brand name got me something. It did, lots of headaches. The flow switch is so sensitive in these things. Don't know if that is characteristic of the many brands where the footprint is so much smaller than gas on demand but to say i'm dissatisfied wouldn't do justice to dissatisfied.

first failure wasnot noticing that they said don't use pipe dope. who ever heard of that, or am i the last to know and everyone else is getting a good laugh? so the first time I had to disassemble and clean out the flow switch was my bad I guess. But I never have this problem on a gas takagi and the flow switch is much more facile and tempers the water while the bosch (3000C US9 40 amp nom.-32 amp measured) is strictly on-off. then a year later it started the same bull again and I had to dismember it (real PIA, be one thing if this needing regular cleaning and service and they made it easy). then a year after that again. now it's gone 3 years and started again with running hot, running on, vapor locking and kicking out the temperature reset. i'm ready to move on but not until i bad mouth the thing up one side and down the other.

it's discontinued, maybe they improved this with later design?

or what flavors do you like.

been very happy with this idea if not with this instantiation. It really doesn't draw more than a 40 gallon tank when you've used enough to trigger both elements and it's small and can locate near the load reducing waste to feed up to the fixture. And it keeps up with my modest flow shower. thoughts?

Intplm. · July 7

Rinnai has been great. No issues. So far so good.

Larry Weingarten · July 7

Hi, Seisco made good units, but was bought by AO Smith in 2017. Not sure if Smith is using that technology now.🤔

Yours, Larry

Intplm. · July 8

Stiebel Eltron makes an all-electric that I have used for an entire house and performance superbly.

With this type of water heater, they tend to need a lot of electricity. The whole house models can use up to three double pole breakers.

My apologies as I misread the original post. (They all plug into the wall). I'm not sure that Rinnai makes an electric model. They make great products. Maybe a trip to their website will show an electric model. If they do have one I would surely go for it.

https://forum.heatinghelp.com/discussion/comment/1805618#Comment_1805618

Jamie Hall · July 8

There are really three distinct types of electric water heaters: tank type (including heat pump types), very small tanks suitable for a single lavatory or maybe, just maybe, a small kitchen sink, and instant on full flow types.

Don't get them confused.

If you want an instant on, point of use electric water heater suitable for a single bathroom group, which is sort of what I think you are after (it really isn't clear), they require dedicated wiring and circuit breakers; how large depends on just how big a unit you need. There are a number of makes and models of varying capacity out there. A nice small one for a single bathroom group — 2.5 gpm capacity — will require about 20 to 60 amps, 240 volts (two breakers).

Small — up to 7 gallon tank — electric water heaters are also available, some of which can run on 15 or 20 amp 110 volt circuits. Not really suitable for a shower unless you take Navy style showers, but can do the job nicely for a half bath.

GGross · July 8

I have used the eemax units I believe they are a Rheem brand. They work well for what they are, its a lot of electricity to do a whole house, they have a pretty wide range. they always suggest a flow restrictor when comfort is concerned, or else you may exceed the flow rate and the water temp will drop.

https://www.eemax.com/

PRR · July 8

…what flavors do you like.

Cheapest DUMB STORAGE electric WH in Lowe-Depot's fathers day flier. 40g, 60g, whatever.

I recognize the potential in heat-pumps but not for our small needs. I recognize the advantage in on-demand designs but, especially on electric, over-over-insulation holds the heat-leakage down.

I had a Rinaldi propane on-demand from the 1980s (no electricity except a piezo spark) and while the endless hot water is wonderful for flushing a frozen sewer, as it aged it was scalding worse and worse, and descaling is a chore which didn't solve anything. I asked my GAS guy and he said his customers went to electric storage and were happy. At our consumption we hardly noticed the increased electric bill, but the comfort was better right away. (Later I added a tempering mix-valve so I have lots of HOT water in storage but only slow-scalding at any tap.)

archibald tuttle · July 9

@Jamie Hall

i thought "on demand" is the way to say flow heater, but I guess if you want hot water when you want it, it is always on demand in a sense but there is no storage.

already have a bosch US-9 40 amp flow heater. i'm disgusted with the flow control. constant problems. never had any issue with the flow controls on any takagi on-demand gas. I have ones that are 20 years in and never had a hiccup. i've had this friggin bosch broke down 4 times and it wants another in 5 years (well it breaks down and then i have to break it down, if you will)

I can see that Bosch has changed their design and seem to provide a different kind of temperature control that appears to suggest that the newer models are not strictly on-off but vary amperage/load according to flow. that is a nice feature which the virtually failproof (in my experience with maybe 2 dozen installed) takagi's have had since i started using them. but what i care about more is that I don't have to service the damn flow switch time after time after time, or if the small form factor creates more likelihood of failure that serviced access is more modular.

so i am looking for recommendations for an "instant" or "on demand" or "flow" style water heater 40 amp electric that folks have had success with. that is the minimum nominal amperage i've found can handle a shower.

archibald tuttle · July 9

@PRR I have never had a performance problem with the propane or natural gas on demand units, scale or no scale. I understand the idea of scale problems and impact on temperature delivery related to flow, but I have never had this happen in 20 years of installing those. color me perplexed, maybe, but i'm a believer.

I don't disagree that insulation on a tank style electric helps keep loss down , but they cost twice as much as on demands and the small form factor means i can locate the electric on-demand 4 feet from the demand meaning i get less loss in pipes. i've been happy with this setup except for the finicky flow switch on the bosch i bought. i just didn't expect that aspect to perform so poorly after never having a prob lem with the gas units.

Mad Dog_2 · July 9

Stiebel Eltron hands down. Just be prepared to feed it with MEGA power and amperage that they call for. In many cases, they are practical for a bathroom 🚻 or cottage. To supply multiple hot water fixtures, adequately, the work, cost & feasibility electrically speaking is cost-prohibitive OR the building simply doesn't have the amperage coming in off the pole or in the panel. Mad 🐕 Dog

Jamie Hall · July 9

40 amps at 240 volts is a smidge less than 1 gpm at a 70 degree rise (note there is a typo in my previous comment — 2.5 gpm requires 50 to 60 amps, not 20 to 60, and I didn't mention that it depends on the temperature rise as well).

Larry Weingarten · July 9

Hi @archibald tuttle , What are the loads you're trying to meet? I'd supply a tub or shower differently than I'd supply a lav sink. 🤔

Yours, Larry

archibald tuttle · July 9

@Jamie Hall @Larry Weingarteni worked it out emperically that 40 amp 240V models will satisfy me for a shower. (albeit the models are 40 amp breaker required but are actually like 7.3 to 7.5 kilowatts or operating at just over 30 amps depending on voltage.) then it meets the needs of all the smaller loads excepting whether it s able to actively vary current either gradually or in steps. the one I have now, you can set it high or low but it is just plain vanilla on and off, 1 or 0 according to flow.

I notice that Stiebel Eltron in that size (7.3 kw i think) is back ordered for 2 months at least my common supplier. various comments on its page suggest load matching which I presume means that it does not have self varying current supply based on flow. it does look like the new bosch's may have such a feature although i'm gunshy after the last version.

mattmia2 · July 9

On/Off is probably controlled with a flow switch and modulation is probably controlled by a supply water temp sensor. Since the entering water will vary in temp, the outlet temp tells you far more than flow ever would.

mattmia2 · July 9

Side note, have you contacted Bosch? Perhaps they have a design change that can be retrofitted to your model that is more reliable or at least can be service more easily.

archibald tuttle · September 9

https://forum.heatinghelp.com/discussion/comment/1805859#Comment_1805859

reasonable point albeit was looking for feedback on units that have been successful to weigh against anything I can get out of bosch.

archibald tuttle · September 9

back here because I went eemax (which i guess is a rheem downline).

only issue is the connections appear to 1/2" compression although adapters are provided to 1/2" IPS but no diagram or instructions relative to their installation.

like the Bosch although not in big letters on the front of the manual as it ought to be, they want teflon tape and no dope on connections (don't know what that means for downline connections or how far away that should be observed and neither do their support people have any insight on how this stuff actually works in the field.

i'm assuming because the body connection and the adapter both have tapered seat that you use the ferrule between the adapter and the body threads and because it is brass or copper it has enough internal structural resistance to provide the seal to those tapers without having a piece of pipe in it.

the other anamoly in the instructions is that this is quite clearly made to be on a wall and they give clearances above, below and to side but then say 24" from combustibles. I assume this doesn't mean the substrate on which it is installed, per se, but is meant to caution that chattel not be placed near the installed unit, e.g. filling up a cabinet where it is installed. again, first line personnel at rheem have no clue what i'm talking about.

probably would have been better off not to bother to read the instructions :-).

also, this manufacturer, unlike takagi doesn't specify a pressure relief. the takage diagrams are on the hot side. have friends in industry who think cold side is better for relief if you use one. the code citations are for "Storage heater" although some localities have just walked it across. replacing a unit that didn't have one. given the flow characteristics of operation, I feel like the operation is relief albeit you could imagine a circumstance where the thing gets stuck on without flow but then you have the resettable temp cutout. thoughts? thanks.

favorite electric on demand water heater?

Comments

Categories