No space for an eco drain so......

[J.P.M.]

And "on demand" recirculating systems would be analogous to remote starters to warm your car up a few minutes before you need to use it?

Probably - or at least not far off - provided the pump started only long enough prior to the beginning of water draw to ensure hot water was at the faucet when the demand began (with that time = line vol./pump flowrate), with recirc. pump shut off once water draw began.

Not my money/house/life/business, but this whole thing about residential recirc. systems seems very wasteful and a bit ostentatious to me.

I suspect if folks took a few minutes to learn how much such systems waste in terms of energy and how little water that actually save, instead of blindly and ignorantly swallowing what comes out of peddlers who sell these energy hogs, the more thoughtful users would think twice about their continued use.

[inetdog]

With attention to detail, and no gaps, 1/2 thk. insulation can cut the line thermal loss by ~ 2/3.

Roaming the halls around here @ ~ 3 A.M. today, the thought crossed my mind that a constantly recirculating hot water distribution system is somewhat analogous to, and has some of the same logic behind it as if I lived in a cold climate and kept my car running constantly with the heater running so that the vehicle interior will be warm when I get in it for a foray into the elements for a trip to the grocery store or to work.

And "on demand" recirculating systems would be analogous to remote starters to warm your car up a few minutes before you need to use it?

[J.P.M.]

Energy to run the pump is probably on the order of 1.5% of the energy for the water heating. The pump comes on with
around an 8.5 deg F differential from water heater to the end of the line. It turns off around 5.5 deg. I suppose a study
of the duty cycle could give more info on the actual heat loss. It certainly changed a lot when insulated. Bruce Roe

With attention to detail, and no gaps, 1/2 thk. insulation can cut the line thermal loss by ~ 2/3.

Roaming the halls around here @ ~ 3 A.M. today, the thought crossed my mind that a constantly recirculating hot water distribution system is somewhat analogous to, and has some of the same logic behind it as if I lived in a cold climate and kept my car running constantly with the heater running so that the vehicle interior will be warm when I get in it for a foray into the elements for a trip to the grocery store or to work.

[bcroe]

Energy to run the pump is probably on the order of 1.5% of the energy for the water heating. The pump comes on with
around an 8.5 deg F differential from water heater to the end of the line. It turns off around 5.5 deg. I suppose a study
of the duty cycle could give more info on the actual heat loss. It certainly changed a lot when insulated. Bruce Roe

[J.P.M.]

Just keep in mind that the largest factor in the energy cost is generally not running the pump but reheating the water that stands in the line from heater to point of use.

Actually, without a recirc. system, or when a recirc. system is off, the water is not being reheated. It's usually being dumped at the point of use and replaced by heated water from the heat source. But it is almost always correct to say that the relative amounts of energy used t pump water is usually very small compared to the energy required to heat water.

Assuming a non recirc. system, and assuming the water in a line loses 60 deg. F. in cooling to ambient temp, 100 ft. of 3/4" line will lose the equivalent of ~ .25 kWh (~ 868 BTU + a few BTU for the line material) of energy. With a system such as Bruce's, depending on the what the thermal hysteresis is, to a loose first approximation, the thermal losses for his recirc. system will be a bit less to a lot less than a continuously running system in something like the ratio of the of the running times of the pump for the two scenarios.

[inetdog]

I used a 12VDC pump using only about 4W, which only runs when the temp at the end of the line gets too much lower than at the heater.
The hysteresis is adjustable, and the sensed temps or differential can be selected for display.
Bruce Roe

Just keep in mind that the largest factor in the energy cost is generally not running the pump but reheating the water that stands in the line from heater to point of use.

[bcroe]

a few things I have done to save water (and some energy too) is to install "on demand" hot water re circulation system such as the Metlund or Chillipepper system. Here is a product comparison:

Only recirculates when you need hot water quickly to the sink or shower as opposed to constantly recirculating systems. I have three Metlund pumps installed and very satisfied with performance. I put them in mainly to save water since I have very shallow wells and water can be precious during the dry season here in Indiana. But I have found out they do actual save energy since less hot water is wasted by me and other family members.

I looked at systems in stores. They seemed way too expensive, and generally compromised in order to simplify
installation. Connect to the last fixture they said. That means using the cold line as the hot line return, bad idea.

My plumbing did get modified, and a much smaller dia return line was added with a pump. I used a 12VDC pump
using only about 4W, which only runs when the temp at the end of the line gets too much lower than at the heater.
The hysteresis is adjustable, and the sensed temps or differential can be selected for display. The pump is an
Ivan Labs El Sid SID3.5PV DC Circulating Pump
Bruce Roe

[cebury]

I don't think the intended purpose of bidets is for making penetration.

Depends on gender.. well not so much. Anyhoo.

[J.P.M.]

For the first time, couple months back i saw a bidet for sale on display in Costco... not sure if that means they are making penetration at all, but something was convincing enough for them to take a risk on it.

I don't think the intended purpose of bidets is for making penetration.

[cebury]

In Japan.....the land of cleanliness.......those types of toilet sinks are ubiquitous.

A short plumbing lesson has convinced my family that the water is coming from the pipes before entering the toilet fixture, just like the regular sink. The amount of water saving is great and no hot water down the drain.

For the first time, couple months back i saw a bidet for sale on display in Costco... not sure if that means they are making penetration at all, but something was convincing enough for them to take a risk on it.

[DanS26]

That toilet seems like a great idea so I excitedly click ked the link. (After seeing the pic): I don't think I could convince family and guests they aren't using toilet water to wash their hands... even though it's technically true.
I let my lawn basically die last summer by reducing its water. I verified that it was 60% of my water consumption during 6 months of the year. But I have 6000sqft. total of lawn.

In Japan.....the land of cleanliness.......those types of toilet sinks are ubiquitous.

A short plumbing lesson has convinced my family that the water is coming from the pipes before entering the toilet fixture, just like the regular sink. The amount of water saving is great and no hot water down the drain.

[Mike90250]

I let my lawn basically die last summer by reducing its water. I verified that it was 60% of my water consumption during 6 months of the year. But I have 6000sqft. total of lawn.

Next year, you will be asked to conserve 20% from your lowest year

[cebury]

Maybe a little off topic....but a few things I have done to save water (and some energy too) is to install "on demand" hot water re circulation system such as the Metlund or Chillipepper system. Here is a product comparison:

http://www.chilipepperapp.com/Artcls27-Metlund-Chlppr.htm

Only recirculates when you need hot water quickly to the sink or shower as opposed to constantly recirculating systems. I have three Metlund pumps installed and very satisfied with performance. I put them in mainly to save water since I have very shallow wells and water can be precious during the dry season here in Indiana. But I have found out they do actual save energy since less hot water is wasted by me and other family members.

Besides low flow shower heads and <1 gal flush toilets, I have installed toilets that have a mini sink built into the top of the holding tank. Thus you wash your hands in the cold water that is used to fill the toilet tank. Not only saves water but no hot water is used. Double savings here again. This unit is available in the USA:

http://www.caromausa.com/products/index/cu_products/39.php

That toilet seems like a great idea so I excitedly click ked the link. (After seeing the pic): I don't think I could convince family and guests they aren't using toilet water to wash their hands... even though it's technically true.
I let my lawn basically die last summer by reducing its water. I verified that it was 60% of my water consumption during 6 months of the year. But I have 6000sqft. total of lawn.

[jflorey2]

Maybe a little off topic....but a few things I have done to save water (and some energy too) is to install "on demand" hot water re circulation system such as the Metlund or Chillipepper system.

I have something similar. It's a standard always-on hot water recirculator pump with a thermostat so it only runs when the hot water line is cold. It's plugged into a remote controlled switch that turns on for ten minutes whenever you push the button on the remote. You press the button, it runs for three minutes and then the thermostat turns it off - then the power to the pump is turned off ten minutes later. It takes about 30 watts while running.

[DanS26]

Maybe a little off topic....but a few things I have done to save water (and some energy too) is to install "on demand" hot water re circulation system such as the Metlund or Chillipepper system. Here is a product comparison:

http://www.chilipepperapp.com/Artcls27-Metlund-Chlppr.htm

Only recirculates when you need hot water quickly to the sink or shower as opposed to constantly recirculating systems. I have three Metlund pumps installed and very satisfied with performance. I put them in mainly to save water since I have very shallow wells and water can be precious during the dry season here in Indiana. But I have found out they do actual save energy since less hot water is wasted by me and other family members.

Besides low flow shower heads and <1 gal flush toilets, I have installed toilets that have a mini sink built into the top of the holding tank. Thus you wash your hands in the cold water that is used to fill the toilet tank. Not only saves water but no hot water is used. Double savings here again. This unit is available in the USA:

http://www.caromausa.com/products/index/cu_products/39.php