hoover1060
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Hmmmm...
What kind of energy does a tankless system use?
Electric? Gas?
What kind of energy does a tankless system use?
Electric? Gas?
1951 Westinghouse Off To The Hospital
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westyslantfront
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Hi Jeff. The tankless hot water heater can be either gas or electric. I am getting gas version. I may also have to install a small electric heater, thermostatically operated in the very cold weather to keep the room above freezing.
I am just glad to have the additional spaces for more washers.
Ross
I am just glad to have the additional spaces for more washers.
Ross
Tank vs. Tankless Water Heating
{thread tangent}
As Toggles says, tankless water heating heats the water as it flows through. There is no standing storage tank holding 40, 50, 60, 70 gallons of heated water. Hot water does not exist until a faucet is turned on and the heating unit activates. The idea is that standby heat losses are eliminated, and one heats only as much water as is needed at any point in time, for whatever is the task at hand.
Tankless is offered in both electric and gas. Various sizes are available to fit the usage needs. Small units for single usage points such as a bathroom or kitchen sink, and much larger capacity units to handle an entire household. Gas tankless is more popular. People seem to be afraid of the power requirements of electric units, although gas units need a hefty gas supply as well. Whole-house gas units typically need a 3/4" gas line or larger, may have a 200,000 BTU or larger gas burner, and special venting requirements. Whole-house electric units require a 120 amp to 160 amp circuit, but of course no venting is needed so they can be installed anywhere they'll fit (under a sink, between wall studs, in a closet).
You see, being as the water is heated on-the-fly as it flows through, a large energy input is needed. A flow of 2 gallons-per-minute or more must be *instantly* heated from input temperature (50°F to 70°F or whatever) to the target usage/output temperature (110°F, 120°F, 130°F, etc.). One BTU (British Thermal Unit) is roughly the amount of heat needed to raise the temperature of 1 pound of water by 1°F. Thus, a specific amount of energy is needed to heat a specific amount of water from a specific starting temperature to a specific target temperature. A tank unit does this slowly over a period of time with a smaller heat input, and stores the heated water in an insulated tank for later use. Tankless does it instantly with a much larger instantaneous heat input. But the end result *technically* is the same amount of energy needed in either case.
Modern tankless water heaters throttle their power usage (either gas or electric) to maintain the set temperature according to the input water temperature and the flow rate. They don't always run at full output. Even so, electric utilities typically don't like tankless because of the demand factor. If *everybody* had electric tankless, and *everybody* ran hot water at the same time, utilities couldn't supply enough instantaneous power to carry them all.
Tank capacity is limited because the cold water flowing into the tank to replace the hot water flowing out must also be heated to maintain the target tank temperature, and the energy input isn't enough to recover immediately. Run the hot water long enough, to fill a bathtub and a toploader (or two or three!) at the same time, or several successive showers, etc., and the tank will be depleated.
Tankless never runs out. Hot water is created as long as there is a water and energy flow (gas or electric).
There are many detractors to the technology, who see tankless as an attempt to fix a problem that doesn't exist. The units are more expensive than a tank water heater both for purchase and install, and have the hefty energy requirement. A common detracting point is that standby losses are actually very minimal, due to tank units nowadays being insulated very well. Electric tank water heaters are nearly 100% efficient. The heating elements are submerged IN the water tank so ALL the energy consumed goes into the water. Electric tankless is likewise efficient. Gas tank and tankless both are a little less fundamentally efficient due to some of the heat being vented. A point is often made about gas pilots light constantly using energy ... but a counterpoint is that some of the pilot energy IS going into the water.
The trick to saving energy with tankless is to use it intelligently and efficiently, and actively. By actively, I mean being conscious of hot water use. When there's a 50 gallon tank filled and waiting, one doesn't need much conscious thought in regards to hot water. Turn the tap and heated water comes out. You've *already* paid for what you've used. But on the other hand, suppose you only need 1/4 of a gallon of hot water for the task. There's a 50 gallon tank of it ALREADY HEATED. Seems a waste.
With tankless, hot water doesn't exist in advance. It's only created when a tap is turned on and the unit senses water flow. So *think* about whether you really need hot water, and how much, for the task at hand. If you only need 1/4 of a gallon, then 1/4 of a gallon is what's made (true, that doesn't include some water flow and energy use while the unit is ramping up to power, but that's still much less than 50 gallons!).
Another aspect is that since tankless creates the hot water on-the-fly, and never runs out, the water only needs to be heated to the specific temperature needed for the task, and NO HOTTER. A tank heater gets reserve capacity by heating to a higher temperature than what's actually needed. Many people may keep their water heater set at 140°F, but NOBODY could stand under a 140°F stream of water in a shower! Thus, some cold water is mixed in at the point of use, which effectively increases the tank capacity. But you're still keeping 50 gallons of water heated to 140°F 24/7. This is akin to floorboarding your car's accelerator and using the brake to maintain 30 MPH. With tankless, set the temperature to precisely what's needed, run ONLY the hot tap when showering, and you're not overheating the water needlessly. No brake needed to slow down a speeding engine. Of course, most people wouldn't bother with constantly resetting their tankless heater for various hot water tasks (showering/baths, dishes, clothes). Many tankless units, however, have remote controls for adjusting the temperature from the kitchen sink or the bathroom.
Personally, my tankless is electric. Requires a 120 amp circuit (four 7,200 watt elements). I keep it set at 102°F to 105°F for "normal" use which is my preferred showering temperature. It's installed in a broom closet in my utility room, so is EASILY accessible for raising the temperature for specific tasks. I ran my whirlpool bath a couple days ago, set it at 112°F. I checked the digital readout, and it reported running at 37% to 40% capacity (10,656 to 11,520 watts) with an input temp of 71°F and a flow rate of about 2 GPM. That sounds like a lot, but it was ONLY for the duration of filling the tub, and that was the only hot water I used for the entire day, and I rarely use the tub. 103°F at 1.2 GPM for a shower would be considerably less power needed.
As Toggles says, apologies for the logorrhea.
{/tangent}
{thread tangent}
As Toggles says, tankless water heating heats the water as it flows through. There is no standing storage tank holding 40, 50, 60, 70 gallons of heated water. Hot water does not exist until a faucet is turned on and the heating unit activates. The idea is that standby heat losses are eliminated, and one heats only as much water as is needed at any point in time, for whatever is the task at hand.
Tankless is offered in both electric and gas. Various sizes are available to fit the usage needs. Small units for single usage points such as a bathroom or kitchen sink, and much larger capacity units to handle an entire household. Gas tankless is more popular. People seem to be afraid of the power requirements of electric units, although gas units need a hefty gas supply as well. Whole-house gas units typically need a 3/4" gas line or larger, may have a 200,000 BTU or larger gas burner, and special venting requirements. Whole-house electric units require a 120 amp to 160 amp circuit, but of course no venting is needed so they can be installed anywhere they'll fit (under a sink, between wall studs, in a closet).
You see, being as the water is heated on-the-fly as it flows through, a large energy input is needed. A flow of 2 gallons-per-minute or more must be *instantly* heated from input temperature (50°F to 70°F or whatever) to the target usage/output temperature (110°F, 120°F, 130°F, etc.). One BTU (British Thermal Unit) is roughly the amount of heat needed to raise the temperature of 1 pound of water by 1°F. Thus, a specific amount of energy is needed to heat a specific amount of water from a specific starting temperature to a specific target temperature. A tank unit does this slowly over a period of time with a smaller heat input, and stores the heated water in an insulated tank for later use. Tankless does it instantly with a much larger instantaneous heat input. But the end result *technically* is the same amount of energy needed in either case.
Modern tankless water heaters throttle their power usage (either gas or electric) to maintain the set temperature according to the input water temperature and the flow rate. They don't always run at full output. Even so, electric utilities typically don't like tankless because of the demand factor. If *everybody* had electric tankless, and *everybody* ran hot water at the same time, utilities couldn't supply enough instantaneous power to carry them all.
Tank capacity is limited because the cold water flowing into the tank to replace the hot water flowing out must also be heated to maintain the target tank temperature, and the energy input isn't enough to recover immediately. Run the hot water long enough, to fill a bathtub and a toploader (or two or three!) at the same time, or several successive showers, etc., and the tank will be depleated.
Tankless never runs out. Hot water is created as long as there is a water and energy flow (gas or electric).
There are many detractors to the technology, who see tankless as an attempt to fix a problem that doesn't exist. The units are more expensive than a tank water heater both for purchase and install, and have the hefty energy requirement. A common detracting point is that standby losses are actually very minimal, due to tank units nowadays being insulated very well. Electric tank water heaters are nearly 100% efficient. The heating elements are submerged IN the water tank so ALL the energy consumed goes into the water. Electric tankless is likewise efficient. Gas tank and tankless both are a little less fundamentally efficient due to some of the heat being vented. A point is often made about gas pilots light constantly using energy ... but a counterpoint is that some of the pilot energy IS going into the water.
The trick to saving energy with tankless is to use it intelligently and efficiently, and actively. By actively, I mean being conscious of hot water use. When there's a 50 gallon tank filled and waiting, one doesn't need much conscious thought in regards to hot water. Turn the tap and heated water comes out. You've *already* paid for what you've used. But on the other hand, suppose you only need 1/4 of a gallon of hot water for the task. There's a 50 gallon tank of it ALREADY HEATED. Seems a waste.
With tankless, hot water doesn't exist in advance. It's only created when a tap is turned on and the unit senses water flow. So *think* about whether you really need hot water, and how much, for the task at hand. If you only need 1/4 of a gallon, then 1/4 of a gallon is what's made (true, that doesn't include some water flow and energy use while the unit is ramping up to power, but that's still much less than 50 gallons!).
Another aspect is that since tankless creates the hot water on-the-fly, and never runs out, the water only needs to be heated to the specific temperature needed for the task, and NO HOTTER. A tank heater gets reserve capacity by heating to a higher temperature than what's actually needed. Many people may keep their water heater set at 140°F, but NOBODY could stand under a 140°F stream of water in a shower! Thus, some cold water is mixed in at the point of use, which effectively increases the tank capacity. But you're still keeping 50 gallons of water heated to 140°F 24/7. This is akin to floorboarding your car's accelerator and using the brake to maintain 30 MPH. With tankless, set the temperature to precisely what's needed, run ONLY the hot tap when showering, and you're not overheating the water needlessly. No brake needed to slow down a speeding engine. Of course, most people wouldn't bother with constantly resetting their tankless heater for various hot water tasks (showering/baths, dishes, clothes). Many tankless units, however, have remote controls for adjusting the temperature from the kitchen sink or the bathroom.
Personally, my tankless is electric. Requires a 120 amp circuit (four 7,200 watt elements). I keep it set at 102°F to 105°F for "normal" use which is my preferred showering temperature. It's installed in a broom closet in my utility room, so is EASILY accessible for raising the temperature for specific tasks. I ran my whirlpool bath a couple days ago, set it at 112°F. I checked the digital readout, and it reported running at 37% to 40% capacity (10,656 to 11,520 watts) with an input temp of 71°F and a flow rate of about 2 GPM. That sounds like a lot, but it was ONLY for the duration of filling the tub, and that was the only hot water I used for the entire day, and I rarely use the tub. 103°F at 1.2 GPM for a shower would be considerably less power needed.
As Toggles says, apologies for the logorrhea.
{/tangent}
westyslantfront
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Hi Glenn. Thank you for the great explanation. As I had two water heaters, one for the house and one for the washers, the cost of 2 water heaters vs the cost of one tankless is not much different. I am also glad that it frees up space for more washers.
Ross
Ross
neptunebob
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Dadoes if utilities here in America don't like tankless why are they found in Europe and Japan? Don't the utility companies there have problems with too much demand too? Also if you tried to install tankless in a home would the utility tell people not to?
<blockquote>Dadoes if utilities here in America don't like tankless why are they found in Europe and Japan?</blockquote>I have no idea. I've wondered that as well! Maybe the European and Asian cultures are less gluttons for hot water than Americans? European frontloaders and dishwashers almost always have included water heating. Maybe electric service is distributed and metered differently? Not all electric utilities here do demand metering/billing on residential accounts, so it's difficult for them to "get their due" on an individual customer account for increased demand. Unlikely a utility company could forbid use of electric tankless, but retrofitting can be tricky if the household electric service can't handle the additional load. Electric is done much more easily as part of a new construction so the service drop can be sized correctly at the start.
A point that perhaps wasn't clear in my book above, is that tankless does NOT guarantee energy savings if one isn't going to adjust hot water usage habits accordingly. Energy use can be *higher* if *more* hot water is used (longer showers, for example, due to hot water supply being unlimited) and temperature settings are not controlled as I outlined above.
A point that perhaps wasn't clear in my book above, is that tankless does NOT guarantee energy savings if one isn't going to adjust hot water usage habits accordingly. Energy use can be *higher* if *more* hot water is used (longer showers, for example, due to hot water supply being unlimited) and temperature settings are not controlled as I outlined above.
andrewinorlando
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The large majority of tankless heaters in Europe are gas powered, not electric.
I've been looking at the differences between the tank and tankless gas heaters, as I've been considering one for my house. Based on comparable energy usage for each, the annual operating cost for a tankless unit came in at about $100 less than the tank unit, so there really wasn't a huge difference. I looked at the Bosch gas tankless unit ($999), compared to a 50 gallon Whirlpool gas water heater($329), and the difference in comparable operating costs over a year between the two units was little more than $100 (based on "typical" use (whatever that is). Yet it's going to cost me over $1000 more for the tankless unit between the purchase price difference, the cost to upgrade the gas service line to the tankless heater (the existing line is not big enough - need 3/4") and the cost to run a 120V electric line to the install site to power the tankless heater and its igniter. In a retrofit situation, I just don't see the benefit of going tankless given the extra cost as the cost recovery period is almost a full 10 years. I'm sure there are less expensive units out there than Bosch, and this is just an example, but the gas tank technology doesn't lag too far behind the tankless technology in terms of energy savings, though it is far from an uninterruptable supply of hot water! For a household of one person, the tank type heater seems to be the better deal, at least from a cost/payback perspective. I would imagine in a new construction scenario, the initial cost would be far lower than in a retrofit situation, and I'm sure there are less expenive tankless units out there, too.
Does anyone know what the lifespan on a good tankless water heater is supposed to be?
I've been looking at the differences between the tank and tankless gas heaters, as I've been considering one for my house. Based on comparable energy usage for each, the annual operating cost for a tankless unit came in at about $100 less than the tank unit, so there really wasn't a huge difference. I looked at the Bosch gas tankless unit ($999), compared to a 50 gallon Whirlpool gas water heater($329), and the difference in comparable operating costs over a year between the two units was little more than $100 (based on "typical" use (whatever that is). Yet it's going to cost me over $1000 more for the tankless unit between the purchase price difference, the cost to upgrade the gas service line to the tankless heater (the existing line is not big enough - need 3/4") and the cost to run a 120V electric line to the install site to power the tankless heater and its igniter. In a retrofit situation, I just don't see the benefit of going tankless given the extra cost as the cost recovery period is almost a full 10 years. I'm sure there are less expensive units out there than Bosch, and this is just an example, but the gas tank technology doesn't lag too far behind the tankless technology in terms of energy savings, though it is far from an uninterruptable supply of hot water! For a household of one person, the tank type heater seems to be the better deal, at least from a cost/payback perspective. I would imagine in a new construction scenario, the initial cost would be far lower than in a retrofit situation, and I'm sure there are less expenive tankless units out there, too.
Does anyone know what the lifespan on a good tankless water heater is supposed to be?
Actually gas or electric in Europe, that depends on the country. In Germany you see a lot electric water heaters, especially tankless ones. In the Netherlands you see more gas ones. Besides that you also see overhere many combo's, a combination of central heating boilers and tankless water heaters.
Overhere all customers all charged individually for their electricity usage.
Overhere all customers all charged individually for their electricity usage.
westyslantfront
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Hi Louis. Where I live, I am charged individually for
electric,
gas,
water which also is for sewer and rubbish removal.
Ross
electric,
gas,
water which also is for sewer and rubbish removal.
Ross
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