The math of tankless water heaters

[BSS]

I think so too.

[Todds]

I got a $2000+ quote to add a tank to my furnace. This would use the furnace to heat the water and store it in an insulated tank instead of having a separate hot water heater. Is this what you are asking about?

Another type of product is "hot water on demand system". It heats the water as you use it and has no storage. Is this the type of product you are talking about? I don't know what things should cost, but I imagine cost is a function of how much water you need to heat at a time (gallons per minute).

[RootSkier]

Tankless = on demand. They are synonymous.

[BSS]

Not exactly. While they are both tankless, it is generally understood that an "on demand" unit is a point of use type rather than a whole house unit. And they're usually 110vac. Either way.

Potato, potatoe.

[Shredhead]

I am living on borrowed time on my water heater, it's 21+ years old, and I'm thinking I should replace it before it demands replacement in a catastrophic incident. So here's the math.

Replacement water heater: $900-1000, lasts ~10 yrs
Tankless water heater: $2850, lasts 20 yrs.

Most water heaters last a lot more than 10 years. Tankless save the most in applications that have big variations in usage, ie. vacation homes.

[Bart T]

I bought a tankless (gas model) for about $600, and then yeah I paid another $100-$200 for some help putting it in.

me too.
bought a takagi. installing them is really easy. the only catch is that you need to vent them to the outside with class III pipes (stainless steel) that cost about $10 per foot. so hopefully your water heater is close to an exterior wall.

[Tippster]

You might also need to upgrade the city gas pressure in your home, if you're using NG on various appliances. Our plumber told us that should we be running the stove and the dryer simultaneously we wouldn't get many therms out of the in-line water heater with the pressure as is. We have two kids - ergo seemingly constant laundry - and there always seems to be showering going on while I make dinner, so this was a concern. In our house that wasn't cost effective (along with the double walled vent) compared to a new tank system which is very very efficient these days, especially compared to the ones from a decade ago...

That said we actually also have gas-fired radiant heat in the house, so our plumber recommended a new dual-use system that incorporates both loops into one unit, with a storage tank for the shower water.

[ANON-505]

my tankless (Rinnai) water heater is the bomb. uses wayyy less energy and is endless. Ours is LP (propane) and is tits.

if you can swing it you should. the payback on the thing is like 5 years or less.

[Danno]

man, I am still torn on this. I now have a friend who can help me install a tank heater, so the tank becomes probably $600 (with tank, tax, miscellaneous parts, and I would buy him a tool he needs as payment). Compared to $2800 for tankless, that is hard to swallow. But I do like the idea of tankless.

[Adolf Allerbush]

man, I am still torn on this. I now have a friend who can help me install a tank heater, so the tank becomes probably $600 (with tank, tax, miscellaneous parts, and I would buy him a tool he needs as payment). Compared to $2800 for tankless, that is hard to swallow. But I do like the idea of tankless.

I don't know much about the installation of a tankless system but I"m thinking of replacing the old (15 yr/old) tank system in my house too. I've been looking online at models and will probably attempt the switch out myself with the help of some friends that are a little more skilled at such things. Regardless, I'm not seeing where you're coming up with $2800. How much of that is labor vs parts/tankless system? Just curious. I was thinking of dropping about $700 on a tankless unit to replace what I have now. is the labor really $2100? BTW I'm just looking online at some general estimates and they claim labor costs would range form $500-$1200 due in large part to getting a power supply to the unit adequate enough run it. In my case our electrical box is situated right next to the existing water heater so I'm assuming the switch over would be relatively easy. In this case I'd be switching out a electric tank system with an electric tankless system. Anyhow, I'm a JONG about such things too but $2800 seems steep. Just saying.

[mcsquared]

Yea, $2800 seems high. Its going in the same general location right? So routing the gas line shouldn't be too involved and you said it was on an outside wall so venting should be a relatively short run and pretty straight forward. Ask the plumber what they would just charge for labor alone if you supplied all the parts. And in Boulder I think you might be able to squeeze out a little more benefit on resale that a new tank heater.

[Danno]

The $2800 estimate is the lowest one. And my impression is that is the going rate in Boulder, nobody other than people on the web from other places has given me the impression that the estimates are high. The unit is a Rinnai 75, which retails for $1100, the $2800 is with a sale of $200, so tax, labor and other parts is ~$1900, I guess.

[Adolf Allerbush]

The $2800 estimate is the lowest one. And my impression is that is the going rate in Boulder, nobody other than people on the web from other places has given me the impression that the estimates are high. The unit is a Rinnai 75, which retails for $1100, the $2800 is with a sale of $200, so tax, labor and other parts is ~$1900, I guess.

Intersting...I have no idea what it should cost. I was looking at buying this one: http://www.heater-store.com/bosch-po..._1615_prd1.htm But it sounds like a better idea would be to go with Euro or Japanese models instead?

[jon turner]

Intersting...I have no idea what it should cost. I was looking at buying this one: http://www.heater-store.com/bosch-po..._1615_prd1.htm But it sounds like a better idea would be to go with Euro or Japanese models instead?

isn't bosch a german company?

[Adolf Allerbush]

isn't bosch a german company?

Might be...or are they out of Belgium? I guess that would fit the bill of a Euro company though.

[jon turner]

I know they supply VW car parts.

[Danno]

Intersting...I have no idea what it should cost. I was looking at buying this one: http://www.heater-store.com/bosch-po..._1615_prd1.htm But it sounds like a better idea would be to go with Euro or Japanese models instead?

FWIW, all 3 estimates I got are for the Rinnai 75 (and I didn't ask for it, it's just what they would install). I don't know about any of this, but if for some reason I were to buy it on my own and install, I'd buy a Rinnai.

[Adolf Allerbush]

FWIW, all 3 estimates I got are for the Rinnai 75 (and I didn't ask for it, it's just what they would install). I don't know about any of this, but if for some reason I were to buy it on my own and install, I'd buy a Rinnai.

From what I read on their website (Rinnai) they do not make an electric version. I'm trying to get my house off the grid as much as possible and we don't have Nat Gas running to the house currently...so I'd like to keep it electric if possible. Plus I don't want to have to worry about venting the F'er since mine will be inside.

[ILAP]

I had the larger Rinnai 98 model replace my electric water heater. We don't hve natural gas in my area, so we use propane to fire it up. Works great and we love it, because there is nothing like taking a really long hot shower and never running out of hot water. There is a little longer delay before getting hot water coming out of the tap, but once it comes out you are good to go. You should also have a dishwasher that preheats the water because of the longer delay before hot water gets to the dishwasher. One more thought - the colder the water coming into your house, the longer it takes to get the temp to where you want and the less flow you have so I went with the max-size. We love our Rinnai.....

[strawjack]

i have a rinnai tankless in my garage and its bitchin'!

[ILAP]

Mine is mounted on the exterior wall of my house - no carbon monoxide and venting issues this way.

[TeleHoar]

You might also need to upgrade the city gas pressure in your home, if you're using NG on various appliances. Our plumber told us that should we be running the stove and the dryer simultaneously we wouldn't get many therms out of the in-line water heater with the pressure as is. We have two kids - ergo seemingly constant laundry - and there always seems to be showering going on while I make dinner, so this was a concern. In our house that wasn't cost effective (along with the double walled vent) compared to a new tank system which is very very efficient these days, especially compared to the ones from a decade ago...

That said we actually also have gas-fired radiant heat in the house, so our plumber recommended a new dual-use system that incorporates both loops into one unit, with a storage tank for the shower water.

Up-grade gas pressure?
Ha ha ha...this sounds like a plumber trying to sell you something you don't need. I would get a second opinion.

city gas pressure can run million BTU boilers in hotels without any problems, I think your house can run a water heater, stove, fire place and anything else no problem.

I am not sure how you would "up" the pressure of a gas line. Regulators step it down usually

[SchralphMacchio]

Did you call your utility to ask if they have any detailed information on rebates, incentives, and tax credits? That might help you get more information than your contractors would know.

[Tippster]

Up-grade gas pressure?
Ha ha ha...this sounds like a plumber trying to sell you something you don't need. I would get a second opinion.

city gas pressure can run million BTU boilers in hotels without any problems, I think your house can run a water heater, stove, fire place and anything else no problem.

I am not sure how you would "up" the pressure of a gas line. Regulators step it down usually

You need to not have the regulators choked down to 4 inches of water in the pressure gauge from 7... but I'm just parroting what our contractor friends tell me. The standard pressure in a house is not sufficient to run all gas appliances simultaneously if you have a tankless system, because those systems need a lot of available pressure to run efficiently.

[moose pit]

Looks like I am going to enter the market for a new hot water tank...

I currently have a 40gal gas Rheem tank that is in need of replacement. Right now I have just lost hot water pressure. I have drained and filled hoping it was a sediment issue but it looks like the tank is just slowly dieing.

After reading the threads I was wondering if anyone has any other ideas floating around?

I'm looking into the on-demand systems, which I know is a more expensive option, and the tank option will be a self installed deal since all the piping and venting is in place.

There seem to be a lot of options cropping up brand wise and I'm wondering if there are some that are better than others.

Just looking for thoughts and opinions.