Tank vs Tankless hot water heater.

[gtu160]

I'm in the process of trying to get off the oil. Not to bad last year, I used 460 gallons of oil. Alot of that wasted. Im looking at a N-G hot water heater. I'm really stuck on the http://www.boschhotwater.com/BoschHotWatercomHome/GasProducts/BoschModel2700ES/tabid/1234/Default.aspx

Im looking at a cost of 999.00+ vs the tank one at 350+. Given time in a week maybe 4 hours of hot water use, is how I can look at the tankless one, or go with the tank and progam or run a switch to turn it off and on. What do you guys think?? I searched, but found nothing I was looking for. Thanks.

 

[HUSKYMAN]

The on demand hot water heater really shines when you have long periods without needing hot water. My parents have one and it works great for them since they live alone and go away a lot.

If you have teenage kids that take 50 showers a week you will lose your a$$ on an on demand setup. I think they can be found for around $700 if you shop around.

Going down to a 30 gal tank and getting extra insulation for it, along with a timer, can help save money too. I used to have a thirty gallon tank in my last house, I didnt like it because I had to wait for 45 minutes after the washing machine was done before I could take a shower. Now I have a high efficiency washing machine, so I dont think it would be as much of a problem

 

[lt1nut]

I BELIEVE they must be mounted on an outside wall.

I tried to get one to pencil out (make sense) but couldn't until I got to ridiculously high NG prices. I went with a power vented 40 gallon NG unit and plumbed in old-style heat traps on the hot and cold side (pipe up from tank at least 18 inches, horizontal run of 6 to 12 inches, then pipe down from that for another 18 inches and finally hook up to existing plumbing system). In essence, any heat that travels past the heat traps built into modern heaters will now be "trapped" at the top horizontal run of pipe. Insulate as many pipes as you can with foam tube insulation, slit at the bottom, and tape all of the corners and joints.

There are some tricks to plumbing a tankless system if you refuse to get a cold water blast. I would do a search on "tankless water heater plumbing" or so, feel free to check out the "fine home building" website too.

 

[myzamboni]

The on demand hot water heater really shines when you have long periods without needing hot water. My parents have one and it works great for them since they live alone and go away a lot.

If you have teenage kids that take 50 showers a week you will lose your a$$ on an on demand setup. I think they can be found for around $700 if you shop around.

Going down to a 30 gal tank and getting extra insulation for it, along with a timer, can help save money too. I used to have a thirty gallon tank in my last house, I didnt like it because I had to wait for 45 minutes after the washing machine was done before I could take a shower. Now I have a high efficiency washing machine, so I dont think it would be as much of a problem

The newer hot water heaters are already so well insulated the getting an external insulation blanket is just a waste of money.

 

[pickwood]

On demand water heaters

As a custom home builder we use on demand heaters in most of our homes -the on demand are much more efficient then any typical electric heater. The electric on demand heaters are not used much- the gas models are the only ones we use. There are a couple of different sizes and they make units for outside and inside mounting-hope this helps.

 

[A. Stanton]

I'm no plumber, but those new tankless jobs look pretty impressive.

 

[bassman]

I have a bosch gas unit and it replaced a gas unit that never made 4 years as a result of my hard water and high amount of sediment.
It has been almost 10 years and not 1 problem .
I also have an OWB that I will use to heat my hot water if I feel like plumbing in a tank and exchanger but I like the fact that it uses nothing unless I need hot water unlike my old gas eating leakers.
I also question every tank type gas water heater out there !!!
its a tank with a 3 inch tube and a flame .....

my bosch unit has just warm air coming out the top when it's heating.

they are good .
buy it.

 

[lwalper]

Electric Usage Gone Crazy

The tankless units are nice, and save $$ regardless of type of usage -- and there's always hot water, even when those teenagers take 50 showers a week.

You might want to consider a possible drawback -- available Kw coming into the house. For typical temperature rise needs from what comes in out of the ground (usually 40-50 degrees or so) to the 120-130 that you'll typically want on the "hot" side, you'll need to hook up three units in series (start thinking $$$). When they're operating, each of those units will draw somewhere in the neighborhood of 40 amps of current (120 amps total). Most conventional homes only have a total of 200 amps coming in from the street (check your breaker box - mine has 200 amps). That means you'll need a new power drop from the street (more $$$) and a new curcuit box to handle that new service ($$$$).

Sure, a retrofit is possible, but you'll need to bring a few more of those greenbacks than most of us are willing to cough up. Cost and energy savings will occur, guaranteed, and over about 100 years the system will pay for itself.

Check this link for a nice electric tankless three "tank" system.

 

[BlueRidgeMark]

the electric on demand units draw their power at a bad time......usually when the electric utility is seeing peak demand on the grid. This is a very serious drawback if the electric on demand units were to be in wide spread usage.

Right on the money. One of the major challenges for any utility, be it electric, phone, or cellular phone, is those pesky customers - we can't get everyone to spread out the usage evenly around the clock. It comes in huge spikes, so we have to way overbuild the infrastructure. Most of the capacity for any of these systems sits pretty much idle most of the time, and it just isn't practical to size it for the worst of the spikes. The electrical industry has done the best job of this, I think, followed by Ma Bell.

 

[Patrick62]

Bro' has one

NG fired, and works like a charm.
With 1 demand (shower), unlimited hot water.

The electric models are completely bananas. You take 3 40A breakers and parallel them. It will draw 18-24 KW Let us re-state that :jawdrop:

18,000 watts!!!
24,000 watts!!!

3 times as much power as my Arc welder.

-Pat

 

[lwalper]

WOW!! That sounds like a terrible lot of watts. On the other hand, it's only on for a few minutes at a time -- the tank heater stays on for hours (granted, at a lower heat input rate). BTU for BTU they're the same except for radiation loss from the tank which makes the tank more expensive to operate over the long haul.

Insulate your tank -- it's a cheap investment with a quick payback.

 

[BlueRidgeMark]

WOW!! That sounds like a terrible lot of watts. On the other hand, it's only on for a few minutes at a time -- the tank heater stays on for hours (granted, at a lower heat input rate).

But it's not just about watts - it's also about amps. What can YOUR house service support? Can your house's system handle that much load while you're also running your AC/ refridgerator, extra freezer, TVs, computers, etc., etc., etc....

Insulate your tank -- it's a cheap investment with a quick payback.

You got that right. New tank or not!

 

[bassman]

I will aslo say that we are installing a titan electric unit out at my father in laws cottage.
Anyone looking at the massive power consumption that the bigger or multiple units require will find that they are just nut the answer for high demand homes with kids and wifes and ocd hand washers as that will require alot of power.
but a cottage that gets used on weekends and holidays with 1 shower and a few dishes to wash is just where a small tankless will shine.

 

[pickwood]

The electric units are not worth the change over from typical HW units- we had problems with them and they are not as efficent as the gas units. My next will be a gas on demand unit- we typically spend about 1200.00 on the larger unit.

 

[wildbio]

I'm getting geared up to start making an outbuilding into an in-law cabin and been researching this for a while.
The gas tankless can be mounted inside or out but does need to be vented. There are direct vent models (sealed combustion) which still have to be vented but with a different set up. becuase it's so windy here and can be very cold I would have to go with a backdraft suppressor.

I have no natural gas to my home just propane which is expensive and getting more so everyday. I'm going to be switching my hot water and back up heat to electric because it's more efficient than propane and my utility company offers a "heat rate" at 4.5 cents / kw (half the normal rate. They will supply the seperate meter and box and I will do the rest. I can only tie in the heat and hot water (in my main house and the cabin) to this meter.

The electric on demand would, as others have mentioned, draw a lot of juice when in use (the one I was looking at pulled 120 amps at 240 v). I just don't want to bring that much power into the future inlaw cabin (would require an upgraded main panel and heavier (more expensive) wiring).

I'm going with a 40 gallon tank water heater and will just shut it down and drain it during the winter (the cabin won't be used then).

$350 for a 12 year warrantied electric tanked model
vs
$599 for the on-demand electric plus upgraded electrical service
vs
$485 for on-demand propane plus venting (and cutting holes, etc t vent) plus the ridiculous cost of propane.

For the use I expect (3 mths per year) the tanked model will likely be the least expensive upfront and in the long-haul.

Oh and the water from my well (drilled to 240 feet) comes out the tap at 40 degrees f....so don't forget you have to look at the specs of whatever tankless unit you're interested in and check to see that it will raise the temp to what you want at the flow rate you want (someone above mnetioned having to put three in a series....yikes)

 

[cjk]

I put in a Bosch Aquastar about 4 years ago to replace an LP tank style. Once adjusted properly no problems. It will get the water hotter than you can stand it so we turn it down some. We installed a new furnace that year also and our LP usage was cut in half. The wood stove cut that usage even more. About 1800 gal/year down to less than 500.

To me it just makes sense to heat the water when you need it.

 

[Ekka]

Dont you guys have different electricity tariffs?

Over here you get a big tank and switch to off peak power supply for it. the large storage volume means plenty of hot water but the electricity only kicks in off peak, like 9pm to 4am etc.

We have a 250L unit and never run out of hot water. Good savings with off peak power supply, check it out.

http://www.originenergy.com.au/2087/Electricity-tariffs-QLD

 

[A. Stanton]

I'm getting geared up to start making an outbuilding into an in-law cabin and been researching this for a while.
The gas tankless can be mounted inside or out but does need to be vented. There are direct vent models (sealed combustion) which still have to be vented but with a different set up. becuase it's so windy here and can be very cold I would have to go with a backdraft suppressor.

I have no natural gas to my home just propane which is expensive and getting more so everyday. I'm going to be switching my hot water and back up heat to electric because it's more efficient than propane and my utility company offers a "heat rate" at 4.5 cents / kw (half the normal rate. They will supply the seperate meter and box and I will do the rest. I can only tie in the heat and hot water (in my main house and the cabin) to this meter.

The electric on demand would, as others have mentioned, draw a lot of juice when in use (the one I was looking at pulled 120 amps at 240 v). I just don't want to bring that much power into the future inlaw cabin (would require an upgraded main panel and heavier (more expensive) wiring).

I'm going with a 40 gallon tank water heater and will just shut it down and drain it during the winter (the cabin won't be used then).

$350 for a 12 year warrantied electric tanked model
vs
$599 for the on-demand electric plus upgraded electrical service
vs
$485 for on-demand propane plus venting (and cutting holes, etc t vent) plus the ridiculous cost of propane.

For the use I expect (3 mths per year) the tanked model will likely be the least expensive upfront and in the long-haul.

Oh and the water from my well (drilled to 240 feet) comes out the tap at 40 degrees f....so don't forget you have to look at the specs of whatever tankless unit you're interested in and check to see that it will raise the temp to what you want at the flow rate you want (someone above mnetioned having to put three in a series....yikes)

I would caution you to be careful of any special rates the electric companies offer. Forty years ago in my state, the company offered a special rate to people who used electric heat to heat their houses. You guessed it. After a time the discount went the way of the dodo bird--away. You should factor this in to any decision you make to heat your water or home.

 

[lwalper]

Solar is looking better all the time. Good quality collectors with 120gal storage -- if you're in a position to collect much of old Sol at all (south facing, even in the northern climates) there are lots of free BTUs beating down on your roof.