Hi all,
We're in the beginning stages of considering one.
I'm soliciting 'real world experience' comments concerning these heaters... good, bad, un-expected surprise/s, maintenance issue/s, gotchas, and/or any other stories or suggestions would be greatly appreciated.
Thanks!
Erik
It depends GREATLY on your use profile.
I have one, Bosch 2400 and I LOVE it, but it does have a few small drawbacks.
It isn't so great for a quick hand wash at the far faucets, you get used to washing in cold water.
It needs a certain flow rate to stay on, if you throttle back the shower, it can go cold on you. This seems to be partly caused by having a low-flow shower head too, I'm probably just over the cut-off running full out.
Probably the best deal would be the tankless passing through a very small, well insulated 3-6 gallon electric unit near the sinks.
It seems to me that if your heater is really a hot water holding tank, tankless makes sense. If you run frequent, small amounts of hot water all day a regular heater might be better. The other beauty is that when we had guests, we had 4 or 5 consecutive showers without any loss in heat. And for us, 23 hours a day, we don't have water just sitting there, cooling off.
Stuart
Black Dragon (amc) installed one. Haven't seen him around lately, tho.
Gas or electric? I think electric makes much more thermodynamic sense -- like electric ovens, esp. convection.
One way to go is to have small ones installed at each location. But the electric ones are quite a jolt to the wiring, about 4,000 W each (like a dryer). If you have, like 3 or 4 sep. locations, and they are all used simultaneously, wow.... poss. demand charges from yer local rapacious utility. This, plus a dryer, central A/C, and mebbe shop stuff, Big Wow.....
Post to alt.home.repair as well.
I have a Rinnai unit and I second most of that. With the water saving faucette it's hard to get a stream of washing hands water to stay warm. The flow is too low to keep the sensor knowing you want hot water.
Most experienced people will tell ou they probably don't save any money on water heating.
...and the one biggie they **NEVER*** tell about is:
You have to flush the thing out every few months with two or more gallons of vinegar and a small pump and hoses to keep the thing from liming up so bad it will make you kettle look like polished metal inside.
I have 17 grains of hardness in my water, going through a water softener ( sodium Ion exchange type) a potassium permanganate filter to remove other minerals and a sand filter. If the thing isn't flushed in a year you got troubles with it being bunged up almost permanently. Then you run vinegar through it for hours to get working again.
Your gas service **may** need to be increased for the 185,000 BTU demand without extinguishing your furnace flame. BTW: A regular water tank will run about 30,000-60,000 BTU
Check things out before you jump on that one. Don't let anybody fool you about "Adjusting the temp at the faucets or tub". It's crap. You never will in order to kill Legionella bacteria. Your inspection code may not allow you to do that, either.
As mentioned by Stu there are benefits, too, if you will ever get to notice them.
It isn't so great for a quick hand wash at the far faucets, you get used to washing in cold water.
It needs a certain flow rate to stay on, if you throttle back the shower, it can go cold on you. This seems to be partly caused by having a low-flow shower head too, I'm probably just over the cut-off running full out.
Probably the best deal would be the tankless passing through a very small, well insulated 3-6 gallon electric unit near the sinks.
It seems to me that if your heater is really a hot water holding tank, tankless makes sense. If you run frequent, small amounts of hot water all day a regular heater might be better. The other beauty is that when we had guests, we had 4 or 5 consecutive showers without any loss in heat. And for us, 23 hours a day, we don't have water just sitting there, cooling off.
Stuart
What's a "hot water heater?" Why do you want to heat hot water?
Thanks, Rich
OK, notwithstanding my lame joke about heating hot water, the only time I've ever used one was the shower in the apartment in Ubon Rachatani, Thailand, and I was perfectly satisfied with it - you could run a hot shower indefinitely or until the propane runs out, but that might not be a fair comparison, considering the ambient temp averaged about 95°F. ;-)
Cheers! Rich
I assume that you are talking about the thingies which attach to the bathroom wall - cold water in and warm/hot bath water out?
They are probably more common then the U.S. tank type water heaters in Asia. I've got three of them.
Firstly they are not "tankless", they actually have a small - about a cupfull - tank where the heater is installed. They have low pressure and (most of them) over temp safety switches and work well, within their designed operating parameters.
They generally have reducers in the outlet line as heating ability depends on heater size and residence time (in the tiny tanks) and I've seen at least one that warned about NOT using the hand spray,i.e., an open discharge line.
Depending on ambient temperature you may want to go for the larger sizes and do check the wattage as a big box doesn't necessarily mean a bigger heating element.
Life time? No moving parts + copper internals + limited heating cycle (while you are bathing) = long life. I've got one that was in use for fifteen, or more years, and was replaced one year, with unusually cold weather, not because it had failed but because the water wasn't warm enough.
Yeah, to quote yourself "Why would you want to heat hot water?"
Cheers! Rich
Thanks, we're looking at whole house gas fired.
Erik
Wouldn't "whole house" kind of defeat the purpose of the tankless style?
I thought the purpose was to heat the water locally so that you don't have to heat all that intervening pipe. It seems to me it'd make more sense to spend your money on insulating the pipes.
Thanks, Rich
Sorry, That is nonsense.
The tankless units have lots of moving parts / valves to adjust the different flame patterns to adapt to all flow rates and temperature outputs and inputs and to purge the flame chamber and so on and so on. Very complex mechanicals in them. Very high maintenance compared to a simple hot water tank.
...and flushing is required more critically and more frequently than your kettle.
Here is how to flush it...see page 16 for detailed instructions using your bypass valve configuration...oh yeah another hundred $$$ you weren't told about, plus the pump that rusts out after using vinegar in it each few years.
Thanks, we're looking at whole house gas fired.
Erik
Both types exist. My pipes are buried in the foundation, so insulating them isn't practical at this point.
When I looked into them a couple of years ago (our hot water heater had finally gotten so crudded up it needed to be replaced -- 20+ years!), it seemed like they would indeed be more efficient (no keeping a big tank warm), but would require a much larger exhaust than a tank. Upon reflection, putting in that big exhaust seemed like more trouble than the tankless would be worth.
Hmmmm... these things are starting to look way too Rube Goldberg like.
I'm sticking with the tank type... they're simple, reliable, work well, and cheap. I also have no issues with installing a new one myself every
10 or 15 years, and have never had need to do maintenance on one. [1]Thanks to all for the heads up!
Erik
I take that back now that I think about it... I did R&R a thermocouple maybe 25 years ago, and as I recall, the tank on that one started leaking about a month or so later...
Not as cheap as they used to be. I bought a 50 gal Sears 5 yr gas water heater for $160 about 15 years ago, and it's STILL working!! Holy shit.....
But now, these things are EASILY $1000.... wow..... I should proly hunt for one on sale, and just store it.....
An electric one should be dirt simple to make, no? Heating element/'stat in a propane tank? And a cupla plumbing fittings..... Fiberglass/styrofoam insulation? Hmmmmm......... Ahm thinkin, box the tank up in 1/2" ply, fill it with styrofoam "peanuts"? The wood itself is not a bad insulator.
Anyone make their own electric water heater?.
I have one. I am not really sure that it saves much on gas because I switched from an electric.
In the dead of winter taking a shower with the heater adjusted to max I have to reduce the flow to get a nice hot shower. In the summer I have to turn down the heat or it is too hot. This part is not too bad for me, but the wife and the daughter seem to have a hard time adjusting the shower to their liking. they will add too much cold and the flow of hot drops off enough to kick off the heater and then they get blasted with cold. They are learning slowly.
If someone is taking a shower and someone else runs the hot water in the kitchen you loose a lot of heat (I try to time my showers to be the only user of water at the time.
Cost issues.
The initial cost is very high. Installation cost might be higher than you expect if you have to increase the size of the gas line. Also they require the big gas flue. If you are changing from a tank you will need to retrofit there also. When things go wrong, there is one place in Vermont that sells parts for my unit. They are really good with help in diagnosing the problems but the parts are very pricey and then the cost or the time to ship adds up also. I, being cheap, opt for ground shipping so several times I have done without hot water for a week.
I plumbed the unit to be able to back flush, but I have never had to.
From what I understand, the newer, larger units are much better throttling up for multiple users, but they have electronic controls which are very pricy to replace when they go out.
The good thing is you never run out of hot water.
If my unit requires a replacement I will be switching back to a tank.
One more point, the big sales point is that you have no standby losses so you save on gas. If your house is cool the effect is you get the heat in the house anyway so that only is an issue if you have the AC running not really a big deal in my opinion.
The place where a tankless would really shine is at a hunting cabin or vacation house where it would really be nice to have instant hot water when you got there and didn't have to wait for a tank to heat up.
My final verdict is get a big enough tank that is well insulated.
Roger Shoaf
With gas a lot of the inefficiency is the chimney.
Think about what happens to the heat when an empty pipe goes outside from the middle of the tank when the flame isn't running. It leaks heat up the chimney constantly.
I believe in the next few years tests will emerge to show that tankless is not any more efficient than regular tank water heaters. The few dollars saved will surely be offset by the huge initial cost of tankless and the maintenance costs to flush them and replace the complex valve switching schemes to vary a gas flame.
I own a whole house unit and am debating to switch to a tank unit to heat my whole house. I have more thinking to do but am not impressed, so far. The clacking of the valves is noisy throughout the whole house but I have been informed I chose the wrong model for my application.
Another thought on your hunting cabin would be a radiator running off the tankless for 185,000 BTU of heat for quick warm-ups. Mind you a 20 lb. tank of propane would last about 5 minutes...LOL
In the dead of winter taking a shower with the heater adjusted to max I have to reduce the flow to get a nice hot shower. In the summer I have to turn down the heat or it is too hot. This part is not too bad for me, but the wife and the daughter seem to have a hard time adjusting the shower to their liking. they will add too much cold and the flow of hot drops off enough to kick off the heater and then they get blasted with cold. They are learning slowly.
If someone is taking a shower and someone else runs the hot water in the kitchen you loose a lot of heat (I try to time my showers to be the only user of water at the time.
Cost issues.
The initial cost is very high. Installation cost might be higher than you expect if you have to increase the size of the gas line. Also they require the big gas flue. If you are changing from a tank you will need to retrofit there also. When things go wrong, there is one place in Vermont that sells parts for my unit. They are really good with help in diagnosing the problems but the parts are very pricey and then the cost or the time to ship adds up also. I, being cheap, opt for ground shipping so several times I have done without hot water for a week.
I plumbed the unit to be able to back flush, but I have never had to.
From what I understand, the newer, larger units are much better throttling up for multiple users, but they have electronic controls which are very pricy to replace when they go out.
The good thing is you never run out of hot water.
If my unit requires a replacement I will be switching back to a tank.
One more point, the big sales point is that you have no standby losses so you save on gas. If your house is cool the effect is you get the heat in the house anyway so that only is an issue if you have the AC running not really a big deal in my opinion.
The place where a tankless would really shine is at a hunting cabin or vacation house where it would really be nice to have instant hot water when you got there and didn't have to wait for a tank to heat up.
My final verdict is get a big enough tank that is well insulated.
Roger Shoaf
Dats a very good point. They make 24 V "mod motors" for berlers that could be used to shut off the flue when the flame is off. This, however, would make the purely mechanical gas valve obsolete, in favor of a boiler-type control, coordinating the flue valve with the gas valve.
Electric water heaters (tank type) would obviate all this, tho.
Summer time, airconditioning = "free" hot water and "free" swinning pool heat ....
In the shop, I use a rheem hp-50.....with an additional 80 gallon storage tank attached...and during winter, I intentionally chill the building at shift end by rejecting heat into these hot water tanks. ( this is heat that would have otherwise been lost to the outside as the building naturally cools down overnight )
--next morning, the hot water is then run through hydronic fan coils in order to quickly warm the building back up, after which point the roof mounted heat pumps again take over.
Upside - as noted in the brochures.
Downside, and what's not stated - for the larger ones, they require a big electric supply or gas supply. If the house is new construction, this can be figured in at time of construction, but on a retrofit, costs a lot to run a dedicated XXX amp line and breaker. Length of run - the water can't be run for long distances to multiple bathrooms as it cools quickly. May require a recirculator, translates more money. Temperature of water - Water does not get as hot as it does from a "normal" hot water heater, thus you have a supply of warm water. Depends on what you're doing, and what you like. If doing loads of white clothes that need hot water, not so good. If you like long hot showers or a hot bath in a big tub, not so good. Replacement costs are also very high, and restrictions in pipes due to water condition are an issue.
If I did a new construction, I would not consider them. I'd have more than one hot water heater if the house was of a size to warrant it, and I'd situate it so that the runs would be short.
MHO. People who I have known who have them say that the amortization of them over the long term puts them on a par cost wise with a traditional system that's properly installed, tank blanketed, short runs, and temp set at 105.
Steve
What is nonsense?
the conversation. natural order of It screws up the Please don't top-post.
Hope This Helps! Rich
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