pturo
New member
Our 30 year old hot water tank finally S.T.B. Are the high efficiency ones worth it? Any way to measure the payback?
Phil
Phil
Hot Water Tanks
- Thread starter pturo
- Start date
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Phil,
There are so many factors which need to be figured in that there are no clear yes or no answers.
Regardless of what system you chose, there are a few basic rules of thumb you can apply:
Divide the cost of the new installation by the number of years you expect to have it serve you. If you know you're selling your place in five years, for example, then you would divide the $600 for a cheap unit by five and add that to the average expected running cost per year. That is your base line. Any unit which costs less to run per year will have a higher installation cost than those $600.
Example:
Cost per year for $600 conventional over five years = $120
Running costs per year $360
Total cost each year for five years $480
Total cost in five years $2,400
So if the installation of a high-efficiency costs $2,000 then you will need to save $280 each year in fuel costs to just break even.
OK, now, you can argue that fuel will go up and up and up, no doubt it will. And you can extend that baseline for the high-efficiency system if you intend to keep your house longer than five years. Still, the break even point on high-efficiency units is much further down the road than many people think.
(Modern conventional water-heaters tend to last only five or six years. Sigh.)
Most utility companies will offer you a free energy audit and can give you projections which are relevant to your area. Some utilities offer sufficiently deep discounts or financing for high-efficiency systems as to make them competitive.
Personally, living in Europe it took me exactly one shower to fall in love with endless hot water. That tipped the scales for me regardless of other arguments towards the high efficiency units.
There are so many factors which need to be figured in that there are no clear yes or no answers.
Regardless of what system you chose, there are a few basic rules of thumb you can apply:
Divide the cost of the new installation by the number of years you expect to have it serve you. If you know you're selling your place in five years, for example, then you would divide the $600 for a cheap unit by five and add that to the average expected running cost per year. That is your base line. Any unit which costs less to run per year will have a higher installation cost than those $600.
Example:
Cost per year for $600 conventional over five years = $120
Running costs per year $360
Total cost each year for five years $480
Total cost in five years $2,400
So if the installation of a high-efficiency costs $2,000 then you will need to save $280 each year in fuel costs to just break even.
OK, now, you can argue that fuel will go up and up and up, no doubt it will. And you can extend that baseline for the high-efficiency system if you intend to keep your house longer than five years. Still, the break even point on high-efficiency units is much further down the road than many people think.
(Modern conventional water-heaters tend to last only five or six years. Sigh.)
Most utility companies will offer you a free energy audit and can give you projections which are relevant to your area. Some utilities offer sufficiently deep discounts or financing for high-efficiency systems as to make them competitive.
Personally, living in Europe it took me exactly one shower to fall in love with endless hot water. That tipped the scales for me regardless of other arguments towards the high efficiency units.
pturo
New member
Thanks. In NY State, we get rebates for energy star as well.
jasonl
New member
I'm trying to find a bigger tank to be able to fill my Jacuzzi tub. Problem is, the closet that houses the water tank accommodates an 18" diameter tank and the biggest I can find of those is a 40 gallon, which is 10 gallons more than my current 30 gallon.
Should I go tankless? Which electric tankless should I look for?
Should I go tankless? Which electric tankless should I look for?
The only thnk I can say is that I love my tankless gas water heater.
It's very compact and I have very hot water forever. It heats only the water I'll use, no matter if I'm going to fill my affinity washer (with 2 spoons of water) or my bathtub or stay 2 hours+ in the shower with my future husband.
mine is a low capacity model, because our water is naturaly warm. i just use it to elevate the temperature by 3 or 4°C.
I think you should ask an engineer to calculate the hot water consumption based on your weather, water pressure, and number of showers and faucets open at same time.
It's very compact and I have very hot water forever. It heats only the water I'll use, no matter if I'm going to fill my affinity washer (with 2 spoons of water) or my bathtub or stay 2 hours+ in the shower with my future husband.
mine is a low capacity model, because our water is naturaly warm. i just use it to elevate the temperature by 3 or 4°C.
I think you should ask an engineer to calculate the hot water consumption based on your weather, water pressure, and number of showers and faucets open at same time.
Jason,
Tankless is sized by the desired/required temperature rise (incoming water of X°F, outgoing of Y°F) at the flow-rate (gallons per minute) needed to support the number of simultaneous hot-water tasks the household wants/needs to run. Cold-climate areas require larger capacity. Winter-time incoming water 35°F, outgoing 130°F, temperature rise of 95°F.
Not all hot water tasks need full output temp. A typical human can't shower in 130°F water without being damaged. But still, 35°F -> 105°F is a rise of 70°.
And not all hot water tasks need the faucet running full-blast. If the unit can't produce enough temp-rise at a high flow-rate, turn the faucet slower. Filling a Jacuzzi tub at 2 gallons per minute may take a while, but is doable if there's patience and planning involved.
Tankless would certainly solve your problem. The trick about retrofitting electric tank with tankless is getting enough electric capacity on the circuit. A large-capacity electric tankless can require 100 amps or more.
Tankless is sized by the desired/required temperature rise (incoming water of X°F, outgoing of Y°F) at the flow-rate (gallons per minute) needed to support the number of simultaneous hot-water tasks the household wants/needs to run. Cold-climate areas require larger capacity. Winter-time incoming water 35°F, outgoing 130°F, temperature rise of 95°F.
Not all hot water tasks need full output temp. A typical human can't shower in 130°F water without being damaged. But still, 35°F -> 105°F is a rise of 70°.
And not all hot water tasks need the faucet running full-blast. If the unit can't produce enough temp-rise at a high flow-rate, turn the faucet slower. Filling a Jacuzzi tub at 2 gallons per minute may take a while, but is doable if there's patience and planning involved.
Tankless would certainly solve your problem. The trick about retrofitting electric tank with tankless is getting enough electric capacity on the circuit. A large-capacity electric tankless can require 100 amps or more.
toggleswitch2
Well-known member
- Joined
- May 23, 2008
- Messages
- 5,000
Jason:
If you really need huge capacties of hot water water, one could put a tankless heater inline with a regular hot water storage-type hot-water heater.
If one has a regular elctric storage-type hot-water heater, check to see whether you have a 20a or 30a circuit. A 20a unit (3,800w, usually) on a 30a line means you can swap out the less powerful hot-water heater for one with a quicker recovery (i.e. one with 5,000w elements)
Alternately, if you can have an electrician bring a second electrical line to the hot-water heater, there is a way to put each heating element on a separate line which cuts in half recovery time (time it takes to heat water). Of course one must heed local and national codes and it can't hurt to ensure each element has a fail-safe emergency thermal cutoff. (There is one in each electric hot-water heater already, but it is used to protect both elecements which are never (in 99% of domestic/residetnial installtions) energized simutlaneously.
Some of the better Sears brand storage-type hot-water heaters have a 3,800w (20a line) and 5,000w (30a line) switchable element and also accept two power-source lines, ostensibly for time-of-day metereing.
So as you can see, there are many ways to get more hot water.
If you really need huge capacties of hot water water, one could put a tankless heater inline with a regular hot water storage-type hot-water heater.
If one has a regular elctric storage-type hot-water heater, check to see whether you have a 20a or 30a circuit. A 20a unit (3,800w, usually) on a 30a line means you can swap out the less powerful hot-water heater for one with a quicker recovery (i.e. one with 5,000w elements)
Alternately, if you can have an electrician bring a second electrical line to the hot-water heater, there is a way to put each heating element on a separate line which cuts in half recovery time (time it takes to heat water). Of course one must heed local and national codes and it can't hurt to ensure each element has a fail-safe emergency thermal cutoff. (There is one in each electric hot-water heater already, but it is used to protect both elecements which are never (in 99% of domestic/residetnial installtions) energized simutlaneously.
Some of the better Sears brand storage-type hot-water heaters have a 3,800w (20a line) and 5,000w (30a line) switchable element and also accept two power-source lines, ostensibly for time-of-day metereing.
So as you can see, there are many ways to get more hot water.
While I'm not in the market for a new water heater at the moment I will be in a few years. I like the sound of a tankless setup, but from all indications none will give me 150+ degree water that I like. Is that true?
I keep my current tank at as hot as I can, I like steamy showers and clean dishes and clothes, 130 doesn't cut it for me. Add the fact I use hot water for my furnace humidifier and I think that rules out tankless. Unless I could use a small storage tank just for the humidifier.
I keep my current tank at as hot as I can, I like steamy showers and clean dishes and clothes, 130 doesn't cut it for me. Add the fact I use hot water for my furnace humidifier and I think that rules out tankless. Unless I could use a small storage tank just for the humidifier.
Surely you're not standing under a stream of 150°F water in your shower? If you're running a high tank setting just to get sufficient capacity to stay in the shower for hours at a time, that's not necessary with tankless. If you're actually mixing a shower temp of 110°F for example, a tankless unit can produce water at 110°F as long as the faucet runs, assuming the gas or electric supply doesn't fail, or the unit itself.
Tankless units are limited in maximum output temp for safety reasons. Household units typically max-out at between 125°F and 140°F depending on the manufacturer and model. Some intended for commercial use can go higher.
As has been discussed in previous threads, I keep my tankless set at 100°F to 105°F as normal operating temp for showering (100°F in summertime, 102°F to 105°F in winter). I raise it temporarily to ~112°F for a Jacuzzi tub soak, and for washing some loads of clothes (115°F to 140°F). Actually, what I typically do for washing clothes (depending on which machine I'm using) is set the machine temp on hot and set the tankless on the exact temp I want for the load. No need to raise it for my dishwasher which heats the main wash and final rinse to specific temps per the selected cycle.
Tankless units are limited in maximum output temp for safety reasons. Household units typically max-out at between 125°F and 140°F depending on the manufacturer and model. Some intended for commercial use can go higher.
As has been discussed in previous threads, I keep my tankless set at 100°F to 105°F as normal operating temp for showering (100°F in summertime, 102°F to 105°F in winter). I raise it temporarily to ~112°F for a Jacuzzi tub soak, and for washing some loads of clothes (115°F to 140°F). Actually, what I typically do for washing clothes (depending on which machine I'm using) is set the machine temp on hot and set the tankless on the exact temp I want for the load. No need to raise it for my dishwasher which heats the main wash and final rinse to specific temps per the selected cycle.
The biggest mistake people make with the tankless H.W. heaters is setting the temperature. When the typical person uses a tank water heater, they set the temp fairly high, usually about 130 - 150. When that person takes a shower, they temper that hot water with cold water to make a shower or bath of around 95-100 degrees or so. This allows one to bathe using less water out of the hot water tank, and thus allowing the hot water to last longer during the bathing period.
The proper way to use a tankless water heater however is totally opposite. Since a tankless water heater heats the water as it travels through, it won't ever "run out" of hot water. Because of this, the best way for both maximum efficiency, and proper temperature balance is to set the tankless WH to the exact temp you desire to take your bath or shower at, and then turn on ONLY the hot valve when you bathe. If this method is used, the best efficiency and comfort is attained.
If the "tanked" method of setting the temperature is used, one will find the tankless water heater "cycling" like it is on a thermostat. This can especially be a problem with the automatic single-handle faucets frequently used in newer homes. The problem stems from the amount of flow needed to trigger the water heater to come on. If the hot water is tempered with cold water, then there will not be enough flow through the heater to turn it on. The result is that the user, or the automatic faucet will open up the hot side until the flow is high enough to turn on the heater. After this happens though, the water gets too hot and the user, or the faucet closes the hot valve, then the flow drops off through the heater, and it shuts off...the cycle continues as the bather gets more annoyed and angry, and eventually makes an angry phone call to the plumber to remove the infernal appliance because it doesn't work properly!
The other side of this is that when hot water is tempered down, not only is the flow of hot water reduced, but the hot water is cooled down. Okay, so why are you going to pay to heat the water, then cool it back down?!?!?! With the precise temperature regulation that most tankless units have, you are best just setting the heater's temp to what you need for the usage, and not tempering, thus saving the energy needed to heat it to the hotter temp. Most tankless units have a remote thermostat so that the user can adjust the temp to the needed amount depending on what task is being performed. For example, one can turn the WH up to 140 degrees to run the dishwasher with.
The proper way to use a tankless water heater however is totally opposite. Since a tankless water heater heats the water as it travels through, it won't ever "run out" of hot water. Because of this, the best way for both maximum efficiency, and proper temperature balance is to set the tankless WH to the exact temp you desire to take your bath or shower at, and then turn on ONLY the hot valve when you bathe. If this method is used, the best efficiency and comfort is attained.
If the "tanked" method of setting the temperature is used, one will find the tankless water heater "cycling" like it is on a thermostat. This can especially be a problem with the automatic single-handle faucets frequently used in newer homes. The problem stems from the amount of flow needed to trigger the water heater to come on. If the hot water is tempered with cold water, then there will not be enough flow through the heater to turn it on. The result is that the user, or the automatic faucet will open up the hot side until the flow is high enough to turn on the heater. After this happens though, the water gets too hot and the user, or the faucet closes the hot valve, then the flow drops off through the heater, and it shuts off...the cycle continues as the bather gets more annoyed and angry, and eventually makes an angry phone call to the plumber to remove the infernal appliance because it doesn't work properly!
The other side of this is that when hot water is tempered down, not only is the flow of hot water reduced, but the hot water is cooled down. Okay, so why are you going to pay to heat the water, then cool it back down?!?!?! With the precise temperature regulation that most tankless units have, you are best just setting the heater's temp to what you need for the usage, and not tempering, thus saving the energy needed to heat it to the hotter temp. Most tankless units have a remote thermostat so that the user can adjust the temp to the needed amount depending on what task is being performed. For example, one can turn the WH up to 140 degrees to run the dishwasher with.
No, I don't stand in the 150 degree water....
But I do aim it at the tile a steam up the shower and stand a few inches from it. I do temper the water, but I can't say I've ever check the temp.
I guess like anything using tankless requires some change in usage. I would not have thought about using only hot water and not tempering it had it not been mentioned. Old habits....
But I do aim it at the tile a steam up the shower and stand a few inches from it. I do temper the water, but I can't say I've ever check the temp.
I guess like anything using tankless requires some change in usage. I would not have thought about using only hot water and not tempering it had it not been mentioned. Old habits....
About a month ago Orchard Supply Hardware (OSH) had a special sale of smallish Japanese-made tankless water heaters for $299 each. It was also a "We Pay The Sales Tax" weekend, and I was really tempted to get one of the tankless units for the workshop. That was until I read the requirements for gas piping. There is a 3/4" gas line running to the workshop, but the length is at least 100 feet, which is just too long to meet specs for even that small a heater. A 1" pipe would be just adequate, but since the gas pipe runs underground and under some concrete walkways I'm not too interested in upgrading that piece of the infrastructure. A tank unit would be ok at the end of the run in the workshop, but the whole idea of a tankless unit would be to avoid having to pay to keep water hot in an area where I use it maybe once a week.
I looked at the gas piping in the house and figured that the piping to the regular tank water heater in the enclosed patio would be sufficient to run a small tankless unit... but the tankless unit might be undersized for the main house.
So I decided to save my pennies and not put a water heater of any type in the workshop as yet. Right now I run the Miele washers back there, and they are perfectly happy to heat their own water.
I looked at the gas piping in the house and figured that the piping to the regular tank water heater in the enclosed patio would be sufficient to run a small tankless unit... but the tankless unit might be undersized for the main house.
So I decided to save my pennies and not put a water heater of any type in the workshop as yet. Right now I run the Miele washers back there, and they are perfectly happy to heat their own water.
