# Tank or tankless water heater



## 1980z28 (Mar 4, 2010)

Have to choose between a tank and tankless water heater in the next week for new house,with hydro at 14 cents per kw,is anyone using a tankless water heater,can you share the pros and cons


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## bgc_fan (Apr 5, 2009)

Pros: less energy to maintain temperature for a large amount of water
Takes up less floor space
Hot water never runs out

Cons: can take some time to heat up water, although it isn't very long
Servicing may be an issue as not all repairmen are familiar with them

That being said, I prefer tankless.


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## bass player (Jan 27, 2016)

I've read that the true standby heat loss of a regular hot water tank is as low as $40 per year. If that's true, then the difference in cost will never be made up over the life of the system. In addition, if you live in an area where you heat the house, for a portion of the year the "lost" heat is used to warm your house, which further reduces any loss.

Tankless units are complicated and many of them require yearly maintenance, which will be an ongoing cost that likely exceeds any savings.


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## 1980z28 (Mar 4, 2010)

A tank it is


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## janus10 (Nov 7, 2013)

bgc_fan said:


> Pros: less energy to maintain temperature for a large amount of water
> Takes up less floor space
> Hot water never runs out
> 
> ...


It's a tankless job, but somebody has to do it.


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## bass player (Jan 27, 2016)

Here's a link to a study:

http://www.greenbuildingadvisor.com/blogs/dept/musings/are-tankless-water-heaters-waste-money


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## Spudd (Oct 11, 2011)

If you're doing electricity then definitely go for the tank. I hear tankless electric units are not reliable in our climate.


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## cashinstinct (Apr 4, 2009)

For your info, Hydro-Quebec says to go with a tank.

http://welcome.hydroquebec.com/ques...hydro-quebec-recommend-tankless-water-heaters

"Due to the inconvenience of connecting it, the reduced comfort and the small potential energy savings, Hydro-Québec does not recommend using this type of water heater"

They don't sell tank or tankless...


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## Koogie (Dec 15, 2014)

I had an HVAC guy tell me a few weeks ago that they are also not recommended in any area that has hard water. He also debated their energy saving value over newer, efficient tanked models. Practically useless unless you live in a small home tight on space, was his overall assessment.


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## My Own Advisor (Sep 24, 2012)

Tank here.


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## DigginDoc (Sep 17, 2015)

I guess I'm going to find out. I moved in to a new townhouse last week. Seems to be ok so far with heating water for three levels. It heats the infloor heating as well so we will see how winter goes. They tell me I will save about 20 /25 % over a year here in lower mainland. Hope so.
Cheers
Doc


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## carverman (Nov 8, 2010)

1980z28 said:


> A tank it is


Same for me. 
I will have to replace my 14 year HWT at some point soon (maybe) and after investigating the costs involved in a retrofit from a tank HWT to Tankless (about a couple thousand, never mind the copper pipe plumbing changes required), it is definitely a lot cheaper per year on average, to stay with the standard low efficiency tank with nat gas operating costs of about $273 per year. Electric storage tanks are far more expensive to operate in Ontario where recent hydro rates have been jacked up to 14cents per kwh during peak hours. Average cost about $557 per year.

I have owned my own nat gas HWT since 2000 and in the 14 years so far , I have had ZERO problems with it and never had to call a serviceman to repair it.

Now if money was no object and I could afford one of those condensing tankless water heater (around $2200) + installation costs (say $3200 with HST), it would be a lot more efficient at $171 per year,, but then with the cost of the tank +installation of about $3200 (that would negate any savings on fuel efficiency with these new technology tanks. $3200/15 years = 180 months. about $18 per month average cost (no maintenance service plan) + $15 per month nat gas costs = *$33 a month loaded cost.
*
Again, *assuming no major changes to the cold or hot water pipes* for the 9.4 gal per
minute flow rate of these heaters.

Now with the standard 50 US gal tank..cost around $900 + $250 to install, (which I will buy to own)..that's about $1150 spread out over 15 yrs (180 months) = $6.38 per month.

Even if nat gas consumption is higher with the standard tank ($273 per year), that still works out to about $23 a month + cost of tank = $29 a month..around the same per month long term and no matter how much
you try to save on energy costs..Enbridge will ensure that they still get around $25 a month to keep your
account active..so what are you really saving with the more expensive tankless heater?

Also, with the simpler technology AND less things to fail on the storage type HWT, you don't have to have that expensive maintenance plan of another $100 or more per year that you may need for the tankless heater.

The only real savings maybe is that 1) you should never run out of hot water and 2) the tankless mounts
on the wall and takes up less floor space in your basement..or apt.


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## coptzr (Jan 18, 2013)

Good thread, we had a similar discussion at home when considering upsizing our current tank or adding a 2nd tank. Had quote for propane tankless(on demand) setup. When quotes started coming in at $3-$5k, we stuck with what we have and just worked on efficiency.


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## carverman (Nov 8, 2010)

While the tankless heaters are great idea..hot water on demand with no wasted energy from the heated water in a large 40 to 60 US gal storage tank, there is a point of diminishing returns..cost of the tank vs reliabilty, additional retrofit costs and with gas heaters it will be SIGNIFICANT COSTS because most gas heaters these days require special venting through the basement wall. 

Now if you have a condensing furnace and its vented through the basement wall, it's not so bad then, because its just the labour cost of drilling a 2 inch hole in the cement foundation..but if that can't be done easily, installation will depend on the layout of your basement.

If your house is an older model with 1/2 inch copper pipes from the water meter..and 5/8 inch flexible pipe from the utility shut off valve....the copper pipe inside diameter (less than 1/2 inch) may not be able to keep up with the FLOW RATE of the tankless heater and * it's burner will go on/off , on/off* because the water coming is not enough to
satisfy the settings of the thermostat, even if adjusted.

If you happen to live in an older house where you don't have 3/4 inch inside copper pipe distribution, to washer, taps, showers and toilets and outside taps, it could be a problem, because more than likely having two places that water is coming out at ONCE restricts the pressure in the pipes and affects the flow rate, making the heater far less efficient than first believed or sold by the tank sales people.

In that case, running a BRAND NEW WATER LINE all the way to the shut off valve on the street or your driveway may be the only solution. For that to happen, a 6 foot deep trough has to be dug from the inside water meter and (which may require changing as well) and through the foundation to the water shut off valve somewheres deep in your front lawn or driveway...

...and if its located on your driveway,...consider another $1000 to dig up and repair the asphalt driveway, as well as running new 3/4 inch flex copper plumbing ($2K to 3k or more) to the water meter.

Then running a new 3/4 inch water distribution trunk line to all the 1/2inch taps that go upstairs or through out the house.

It's not just the hot water pipes affected in this case, the cold water supply main is very much affected.
Something the sales dudes don't tell you until the unit is installed at already great cost to the homeowner.


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## OhGreatGuru (May 24, 2009)

Are we talking about a tankless *electric* water heater here? I was surprised to find them even considered for whole-home water heating, because of the power demand. I see there are such models being advertised, in sizes from 10KW to 35 KW or larger. But 10KW is more than the average stove uses. For anything bigger you probably need to increase the mains supply to the house. The Quebec hydro link mentioned above use a 24 KW as an example (which I assume is for an average house.) This requires 100 amps @ 240 Volts just for the water heater. (Actually I think it would be 120 amps because usually heating appliances require a 20% overload factor.) 

An NRCan site says tankless electric water heaters don't generally have enough delivery capacity for whole-house applications. Presumably because they didn't think it economical to put a big enough electrical system in the average home to power one of the bigger models.

Storage water heaters vary in size, but peak demand is usually limited to 3KW. (Product labeling is confusing because a 6KW storage water heater has two 3KW heating coils in it, but only one can come on at a time, so the electrical demand is only 3KW)


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## carverman (Nov 8, 2010)

OhGreatGuru said:


> Are we talking about a tankless *electric* water heater here?


NO. I was referring to nat gas fired tankless heaters that are expensive enough to buy and install, electric tankless will use a lot more expensive electric power because the heaters have to be on during demand. 



> I was surprised to find them even considered for whole-home water heating, because of the power demand. I see there are such models being advertised, in sizes from 10KW to 35 KW or larger. But 10KW is more than the average stove uses.


Yes, even with the oven bake element on (2.5kw) and one or two top burners on high (1.5Kw x 2)= 3kw, the average stove will only use about 4.5 to 6Kw. Over an hour that's 5 to 6 kwh. With the loaded electricity rate in Ontario now (during peak times) stove would cost around $1.90 to run for an hour.

A 10kw electric tankless heater OTOH, depending on how cold the incoming water from the supply line is will always cost more in the winter time because it takes more electricity to heat the water you are using,
to proper temperature. 
10kwh x 32c per kwh (loaded rate) = $3.20 per one hour of usage.

One hour of usage is a lot of hot water, but depending on how many people live in your house and how many times a week you use the shower or bathtub, the washing machine and the dishwasher, *it can cost you a lot* more.



> For anything bigger you probably need to increase the mains supply to the house. The Quebec hydro link mentioned above use a 24 KW as an example (which I assume is for an average house.) This requires 100 amps @ 240 Volts just for the water heater. (Actually I think it would be 120 amps because usually heating appliances require a 20% overload factor.)


You must mean just the breaker amperage needs to be higher than the actual current draw because of the heating effect of the supply wire (wire guage) and the breaker itself. 

A resistive heating device that draws 12-15 amps consistently at 240v will require a heavier supply wire than 14/2 copper, and 15 amp breaker . The wire depending on the length of the run from the breaker
would have to be at least 12/2, as the lower resistance of the wire guage gives it a max current capacity of 41 amps. 
So a 20 amp breaker would be required for a safety factor, and that requires about an additional 5amps 
(15amps draw + 5 amps safety factor) to prevent thermal overheating tripping of the breaker) is about 20 percent. 

100 amp service is pretty much the standard these days in newer built homes since the early 60s. Before that, a lot of GTA older homes had only 60amp service. The old home that I bought in the GTA in the early 70s, was knob and tube mostly and 60 amp service with a special fuse/disconnect box for the rental HWT from Toronto Hydro.
I decided to retrofit with 100 amp breaker panel..that along with the standpipe and larger overhead wires to the pole mounted transformer cost me $3000 back then..I would shudder to think what it would cost in *todays dollars for the upgrade*. 



> An NRCan site says tankless electric water heaters don't generally have enough delivery capacity for whole-house applications. Presumably because they didn't think it economical to put a big enough electrical system in the average home to power one of the bigger models.


To convert a (assuming here that your home has the standard 100amp service, (which doesn't mean that you use all of that 100amp capabilty at once, your hydro bills would skyrocket at todays electricity rates.! There is also the POWER FACTOR calculation when drawing from 240 volts supply panel. 



> In AC circuits, the power factor is the ratio of the real power that is used to do work and the apparent power that is supplied to the circuit.
> The power factor can get values in the range from 0 to 1.
> When all the power is reactive power with no real power (usually inductive load) - the power factor is 0.
> When all the power is real power with no reactive power (resistive load) - the power factor is 1.


but lets assume a simple power calculation (with no power factor value) for the 35kw tankless heater on for an hour..that's 35kw @240volts (35kwh x 35c per kwh = $12.25 per hour of usage especially if it's on full blast heating cold water...OUCH! guard your wallet!


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## OhGreatGuru (May 24, 2009)

OP's original post was:

* Tank or tankless water heater*

* Have to choose between a tank and tankless water heater in the next week for new house,with hydro at 14 cents per kw,is anyone using a tankless water heater,can you share the pros and cons* 

Nothing in here about gas, which creates the confusion.

If you are choosing between a gas-fired tank and a gas-fired tankless water, the price of hydro is irrelevant.


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## carverman (Nov 8, 2010)

OhGreatGuru said:


> OP's original post was:
> 
> * Tank or tankless water heater*
> 
> ...


Nat gas is the way to go. With any plumbing changes to accommodate a tankless aside, you will be happier with the gas and it will be cheaper in the long run..but not as cheap as a HWT because these tankless units are still about double the price of the conventional, even the power vented tank heaters.


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## Brainer (Oct 8, 2015)

One more, albeit less common advantage of HWT: In a power outage, you still have hot water for a day or three. With a tankless, you're out of luck.


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## carverman (Nov 8, 2010)

Brainer said:


> One more, albeit less common advantage of HWT: In a power outage, you still have hot water for a day or three. With a tankless, you're out of luck.


That is true, but it also depends on the size of the HWT and how much use during the day. With the old pilot light burners, the HWT is independent of electricity.

The newer ones with the power vent (venting motor that requires a 120 volt plug and a small sensor board to purge the burned gases outside the basement wall are NOT, so if there is a power loss, the burner won't function.

But at least you will have some hot water at your disposal for a bit of a long duration power outages lasting more than a day, like what happened in the GTA during a December ice storm about 3 years ago.


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