Water Conservation, Low Flow Fixtures, and Tankless Water Heaters
Low Flow Fixtures
Now days all faucet fixtures for residential plumbing are low flow devices.
While they do aid in water conservation efforts, they can be a bit inconvenient. They don’t save you water if you are filling a pot, getting a glass of water or where a measured volume of water is to be had. They can be a nuisance when you have to wait and wait for the sink to fill with water, or if you are trying to get hot water to the faucet.
Low flow fixtures cause the hot water to flow through the pipes more slowly, and so it takes longer to get your hot water. This can be especially trying when you have long pipe runs, or when your pipe is under a concrete slab and not insulated.
Slow hot water can lead to water wastage. It can take so long to get hot water at a fixture that many hot water users let the hot water run while they do something else before returning to see if it is hot yet. By the time they come back and check they are running hot water down the drain.
At this point energy is being wasted as well as water and the energy to heat the water being run down the drain is substantial… much more expensive than the water being heated.
Tankless Water Heaters
Tankless water heaters are not water conservation friendly to begin with. It takes a tankless unit longer to deliver hot water than a storage water heater since it has to heat the water first which can take 10 to 20 seconds longer than a storage water heater would deliver it.
To obtain the hot water temperature you desire you typically mix hot and cold water to get the desired temperature. This works fine with a storage water heater but can be a problem with tankless units when lower flows are used.
To turn on the tankless heater you must draw ½ to ¾ gallons per minute, depending on the water heater model you have. The outlet temperature with a tankless unit does not change as long as you don’t exceed the maximum flow, so the minimum flow of say ½ gallon per minute is at the full outlet temperature.
If you need to mix half cold and half hot to get the desired temperature you are then forced to use 1 gallon per minute which can often be a much larger flow than you need or want. This of course results in wasted water being run down the drain.
Hot Water Demand Systems
Hot water demand systems can overcome the inconvenience of slow hot water caused by low flow fixtures. Hot water demand systems pump the water to your fixture fast without running water down the drain. Your hot water is faster and you save time water and money.
A hot water demand system typically locates a small pump under the sink furthest from the water heater. When hot water is desired the user pushes the start button which activates the pump and speeds hot water to the fixture. The cooled off hot water from the last hot water use is returned to the water heater through the cold water piping so no dedicated return line is needed.
Demand systems are especially nice when used with tankless water heaters since you save both energy, with the tankless heater and water, with the demand system while having the convenience of fast hot water.
Solar with Tankless - Water Heater Guide - Water Conservation
Now days all faucet fixtures for residential plumbing are low flow devices.
While they do aid in water conservation efforts, they can be a bit inconvenient. They don’t save you water if you are filling a pot, getting a glass of water or where a measured volume of water is to be had. They can be a nuisance when you have to wait and wait for the sink to fill with water, or if you are trying to get hot water to the faucet.
Low flow fixtures cause the hot water to flow through the pipes more slowly, and so it takes longer to get your hot water. This can be especially trying when you have long pipe runs, or when your pipe is under a concrete slab and not insulated.
Slow hot water can lead to water wastage. It can take so long to get hot water at a fixture that many hot water users let the hot water run while they do something else before returning to see if it is hot yet. By the time they come back and check they are running hot water down the drain.
At this point energy is being wasted as well as water and the energy to heat the water being run down the drain is substantial… much more expensive than the water being heated.
Tankless Water Heaters
Tankless water heaters are not water conservation friendly to begin with. It takes a tankless unit longer to deliver hot water than a storage water heater since it has to heat the water first which can take 10 to 20 seconds longer than a storage water heater would deliver it.
To obtain the hot water temperature you desire you typically mix hot and cold water to get the desired temperature. This works fine with a storage water heater but can be a problem with tankless units when lower flows are used.
To turn on the tankless heater you must draw ½ to ¾ gallons per minute, depending on the water heater model you have. The outlet temperature with a tankless unit does not change as long as you don’t exceed the maximum flow, so the minimum flow of say ½ gallon per minute is at the full outlet temperature.
If you need to mix half cold and half hot to get the desired temperature you are then forced to use 1 gallon per minute which can often be a much larger flow than you need or want. This of course results in wasted water being run down the drain.
Hot Water Demand Systems
Hot water demand systems can overcome the inconvenience of slow hot water caused by low flow fixtures. Hot water demand systems pump the water to your fixture fast without running water down the drain. Your hot water is faster and you save time water and money.
A hot water demand system typically locates a small pump under the sink furthest from the water heater. When hot water is desired the user pushes the start button which activates the pump and speeds hot water to the fixture. The cooled off hot water from the last hot water use is returned to the water heater through the cold water piping so no dedicated return line is needed.
Demand systems are especially nice when used with tankless water heaters since you save both energy, with the tankless heater and water, with the demand system while having the convenience of fast hot water.
Solar with Tankless - Water Heater Guide - Water Conservation
Labels: Hot Water Heaters, save water, slow hot water
posted by Hot Water Guy at
5:50 PM
1 Comments:
You have a very informative blogspot. Thanks. I would love some advice you might give about what to choose in our situation:
We just replaced an old, leaking gas tank water heater in our garage (ground floor). We live on the third floor, so with this standard set up, we "waste" alot of water to get the hot water flowing. Really, we catch it and attempt to use it in other ways like toilet flushing, etc. Surely, a pain in the neck...
This replacement preceded our kitchen/laundry room remodel which is now starting, and we are faced with the decision about putting a hot water system into our design.
Another thing to note is that we also just installed solar panels. So far, they have not produce an excess of electricity for us, but that isn't too surprising given the season. In an ideal world, I would use no gas, but since it isn't, I would like to decrease using it if possible.
In a very small kitchen (less than 200 sq. ft). and home (1 bath, family of 3), I am faced with the decision of switching from the standard system and would like to know what you think about the options.
Obviously water conservation and eco-friendly energy are a concern, but if price is not within reason, I, the average consumer, probably cannot afford it.
Electric, gas, tank, tankless, hot water recirculator, insta-hot, a combo, etc.??
It all seems so overwhelming especially when my kitchen is currently torn up!
Please advise! Thanks, Carol
email: gardenboyd@yahoo.com
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