Opinions on tankless vs tank water heaters

Ok been researching and looking for the good and bad about a tankless water heater vs good ole' tank heaters. Anyone have one or had one? Thoughts? I came across what looks like a good deal on this one http://www.eccotemp.com/eccotemp-40h-ng-tankless-water-heater/

Thanks Paul

We installed a RInnai about a year ago. Pros-big savings on Propane bill (hot water is our only use and a tank lasts 3-4 times longer YMMV), endless supply of hot water and a tax credit for having it installed. Cons- takes longer to get the hot water flowing.

We are really happy with it but I dont think I would see the dramatic savings if we were on natural gas like our old house.

We saw some savings with NG.

I made the decision because I had a 16-year-old tanked water heater. If I replaced it I had to also put a stainless flue liner in the masonry chimney. Between the two, that made the Rinnai was a cheaper option.

It does use less gas. However, it takes me 90 seconds of running water on the second floor to get its attention, and get hot water. Plus, when doing dishes, you need to keep the water running instead of on/off, or it will go cold.

Overall, though, I like the idea of the tankless, and I am glad I got it.

Duke wrote: Plus, when doing dishes, you need to keep the water running instead of on/off, or it will go cold. Overall, though, I like the idea of the tankless, and I am glad I got it.

Duke, could you explain that a bit more? Is it your dishwasher does not heat the water and relies strictly on the water heater or ???

Thanks for all the other replies Paul

I have heard (on this board) that the tankless heaters are not very long lived. Given that they cost the same or more - if they only last 3-5yrs then they really cost a LOT more.

I ended up with an NG 60 gallon tank.

My plumber and several people I know who have had tankless for a long time would disagree with your statement that they don't last very long.

I've got it and LOVE it!

One thing, you don't have a reservoir of already hot water (that you're paying to keep hot the 23 hours out of the day you don't need it) so the systems work better when they are designed with a tankless in mind.

You don't just replace a tanked heater and expect comparable results.

I have 2, one on each end of the house. This gives short runs. You know how when the HWH is in the garage and you want to take your bath in the master Br at the other end of the house and it takes a while to flush all the cold water out of the line? I don't have that problem. I turn the low flow shower on (which means there's less water flowing so it should take longer to clear the lines), take off my underwear, drop it in the dirty clothes and jump into a nice hot, steamy shower. It takes much less time than it did at the old house with the above garage/mbr scenario.

We never run out of hot water, even when the family of 23 is over, like this last weekend. My wife fills her 80-90 gallon tub AND I can take my shower at the same time.

I have yet to find a downside.

Did I mention it's cheap to operate?

carguy123 wrote: take off my underwear,

TMI.

It's a mixture of plusses and minuses. It saves energy (and thus money) but it'll probably take a long time to pay off the difference in price. You get an unlimited supply of hot water, but it takes longer to get hot water because the burner needs to get the heat exchanger up to temperature in addition to the wait for the hot water to get to you. It requires a small amount of electricity to run, so no hot water when the power is out (unless you put it on a UPS) (assuming a gas-fired unit here). It requires a better flue than a traditional hot water heater, but if you live somewhere that it doesn't freeze very much (like California) then you can mount it outside, which doesn't require a flue.

They require annual descaling if you have hard water -- the plumber wants $400 to do it around here, but you can DIY with 5 gallons of vinegar, some hose, and a $75 pond pump from the hardware store.

For me the biggest win was that it got me enough space back in the garage to store the engine hoist. SInce we were doing a copper repipe at the same time, the extra cost required to reroute the plumbing lines and mount it outside was minimal.

codrus wrote: They require annual descaling if you have hard water -- the plumber wants $400 to do it around here, but you can DIY with 5 gallons of vinegar, some hose, and a $75 pond pump from the hardware store.

I worked in plumbing for two years (18-20) and then in Water Distribution for the City of Red Deer for 3 years. Because of what you posted, NOBODY installs instant-on hot water heaters anymore.

And let me tell you, I installed/saw installed a couple thousand units (I installed water meters in every home built during the boom). It was the thing to do. Unfortunately, none of the home builders informed their customers of such a need, and a lot of units burnt out/essentially were wrecked due to scale buildup.

Having said that, they are the bees knees IMO. Only better system is a boiler, but that only works if you use water/coolant to heat your whole house.

I did a bunch of research on this subject and can give you two absolute pieces of advice:

1.) Don't buy a cheap under-sink tankless Bosch. There is no 'warm' water. Even after adjustment, you still have to turn Hot nearly full-on before the heater kicks on. Oh, and the first unit we bought was defective - it didn't turn off and melted all the CPVC lines under the sink.

2.) For our remodel this year I bought an A.O. Smith 50-gallon unit. This Thing Rocks! Seriously, we can have 2-showers running at once and/or have multiple consecutive showers(family of 6, plus the kids' friends on weekends) and the water never goes cold. At $1500-shipped it wasn't cheap, and the exhaust fan is loud(it operates like a furnace), in fact it came with a muffler for the exhaust flue. But overall we've been very satisfied with it.

About descaling: if you run a whole house filtration system, does that help?

con: if you are in a house without gas

whole house electric tankless units require 3 dedicated 40amp breakers. so upgrade to 200amp service is a must if you do not have it already.

most of my customers that love theirs and rave about them have the unit mounted as close to the kitchen/bathroom as possible.

As mentioned previously, don't overlook the turn on rate for instantaneous water heaters. Some will actually use the water pressure to turn on so not all require electricity to operate.

It actually takes a little bit of thought to correctly size a tankless water heater compared to just tossing in the standard sizes of domestic tank water heaters.

paulmpetrun wrote:

Duke wrote: Plus, when doing dishes, you need to keep the water running instead of on/off, or it will go cold. Overall, though, I like the idea of the tankless, and I am glad I got it.

Duke, could you explain that a bit more? Is it your dishwasher does not heat the water and relies strictly on the water heater or ???

No, I mean when hand washing pots and things. It works fine with the automatic dishwasher. But when hand washing, I was in the habit of running water to wet the pot, then turning it off while I scrubbed, then rinsing. But doing that won't keep the tankless heater's attention, so it goes cold.

Most single-lever faucets in the default middle position are drawing from the hot and cold side. In order to prevent the water heater from kicking on every time you briefly rinse your hands or something, the tankless units are programmed to ignore hot water demand below a certain volume or duration. That means if you really want hot water, you have to run enough continuous volume to keep it awake.

I used to work with them, and I recall that they require a special exhaust pipe. (Type B?) It is a double-walled unit that allows air to enter while the gas exists? The point is that you cannot just unhook your water tank and swap in the tankless. You need more gas supply (that 1/4" line isn't going to work) and you need a new vent to the outside.

The company I used to work for developed nice kits that allowed for backflushing. (http://www.dormont.com)

We live in a relatively hard water area and descaling hasn't been an issue for any of the 200+ homes that have it.

Scaling is the same issue as with a traditional HWH so if it isn't a problem where you live now it won't be a problem on the tankless.

Codrus just exactly how do you descale a HWH with the equipment you described? You'd have to completely unhook all the water lines on the HWH wouldn't you? I don't have a bypass valve on mine.

My underwear comment earlier was to illustrate just how quickly I get hot water.

And they are classified as boilers due to the amount of heat they put out which is why the double walled exhaust pipe. Mine is on the outside wall so I don't need that. That's one of the concerns I mentioned earlier when I said you didn't want to just replace an existing heater with one, you wanted to design your system for the tankless. They don't work as well on a retrofit.

Anyone doing solar water heaters that use a big tank with NG/Propane as a backup in the storage tank?

carguy123 wrote: Codrus just exactly how do you descale a HWH with the equipment you described? You'd have to completely unhook all the water lines on the HWH wouldn't you? I don't have a bypass valve on mine.

Yes, you need to unhook the water lines. Mine has the service kit installed, which gives a bypass valve on both the supply & output lines. I used a 5 gallon bucket, a submersible pond pump, a 20' hose remnant, and a hose end (cut the hose in half and put the end on it so that both pieces have a female screw fitting on them).

Here's the procedure given by the manufacturer (nortiz descale) but basically you just fill the bucket with vinegar, hook the pump up to the inlet, run the outlet back to the bucket, open the valves, disable the burner, and turn the pump on for an hour or so. Then you flush it with water for 5 minutes and turn everything back to normal.

The pond pump isn't exactly rated for pumping vinegar, but even if I had to buy a new one every year it's still way cheaper than paying a plumber to do it.

I had a semi-tankless in a house I was living in for a while, it had a smallish (like 2-3 gallon) reserve tank, just enough to make up for the dealy from the heater warming up and doing its thing. I miss the hell out of that thing, infinite hot water was awesome for taking baths.

while in europe and central we stayed in a few places with them... in spain we had one that ran on just a BBQ style propane tank... it was a small flat and we only where there for a week so no idea on economy... but it worked well

stayed in another flat in germany that had the tankless heater setup in the bathroom, took a little bit to get hot water to the kitchen sink but in the bathroom it was awesome... I also recall seeing some point of source water heaters... basically they attached to the inline pipe of the faucet right under the sink

in costa rica we had one in just the bathroom, that one had a switch to turn it on... worked great as long as you remembered to hit the switch before you got in the shower...

we had a hole house unit in Panama... it was on an island so the house was run completely on solar power and all water was from a rain water reclamation system... because of how many people we had in the house we took the on/off type showers, on long enough to wet your hair then off to soap up, back on only long enough to rinse off... because of the on/off nature of the shower the water rarely ran long enough to actually have warm water...

the neatest stuff was in costa rica the "widow maker" shower head... it's a shower head with an electric line ran to it to heat the water a bit as it flows though... it was enough to knock the harsh cold edge off the water, but thats about it...

when I was looking into buying a house I had looked into a DIY solar water heater running into a tankless heater, the solar does most of the work but the tankless would make things heat up a smidge if you'd had a few cloudy days or something... so it would cost less but not have all the dependence on the solar heat.

donalson wrote: the neatest stuff was in costa rica the "widow maker" shower head... it's a shower head with an electric line ran to it to heat the water a bit as it flows though... it was enough to knock the harsh cold edge off the water, but thats about it...

They have a whole different view of 'lectricity south of the border.

There were lots of houses in Mexico with black solar water heater tanks on the roof. These things were big, probably 75 gallons or so, some were even bigger.

You find those big black tanks all over. Caribbean, Israel, sunny places. Hard to beat the operating costs. (zero)

I know the tanks on the roof are pretty common everywhere down that way... but I don't think it's really for heat... a lot of that has to do more with the fact that they don't know when the water will be flowing...

while there is a water system it may only run 3 days a week... and you didn't know what days those would be... so the tanks would fill and provide water on the days the water didn't flow... they where on the roof to let gravity let the water flow... we had a few 750 gallon tanks at one place we where at and sat uphill of where we where

When we needed a new water heater a few months ago I did a lot of investigating and getting prices and info. Unfortunately our only choices were electric (what we currently had) or propane(very expensive around here).

In addition, I had 2 different plumbers tell me that due to the layout of our house we should put in 2 tankless heaters for efficient operation.

Ended up putting in a large electric fiberglass tank type for less than half the tankless would have cost me.

the cost savings is supposed to be from only using power/gas when the water starts to flow... not the electric always keeping the water in the heater warm...

but as I understand it the electric can't keep up with more then one big appliance... maybe 2 (shower, washing machine, etc)...