Saving Water and Energy in a Brooklyn Brownstone

Modified hot water return systems in a green brownstone make a lot of sense. You want to minimize the amount of wasted water that normally goes down the drain while you are waiting for the water to heat up, thus the use of a hot water return, but you modify it from the normal hot water return system so that it also minimizes the amount of wasted energy.

Typically a hot water return system wastes lots of energy and the water savings is only secondary to its purpose. It is normally used not to save water but to provide instant hot water to the faucet – it is a typical convenience at the sake of the planet setup.

The most wasteful way, and actually pretty common way in “high end” homes is to have a return pipe situated on the hot water line near the faucet farthest from the boiler, creating one big circle to and from the boiler. Then you have a pump on that line.

The pump pumps the water in a constant circle so that the pipe is always full of hot water. The result is that you turn the tap on and immediately get hot water. For most people that is all they care about.

But the waste is astronomical by green building standards. The pump uses energy similar to a light bulb being on non stop and the pipes are constantly losing heat. Translated into money it might not be that much to the normal home owner – maybe a couple hundred dollars a year – because they are spending so much money already on home energy. What’s another drop in the ocean.

But to a green builder it is a huge waste.

In a green brownstone it is nice to have hot water to the tap quicker, but that is not the primary purpose of a recirculating pump in that house. The main purpose is that if you are on the top floor of a four story brownstone and the boiler is in the basement then you are going to wait many minutes before the shower gets hot.

And those many minutes translate into a LOT of water down the drain, which is not what green brownstones are about.

A hot water return, or recirculating pump system, eliminates that wait. But it also adds the issue of wasted energy.

That is where an energy efficient hot water return system differs. In the green recirculating system the pump only turns on the moment you want hot water. Hot water delivery is not as fast as if the pump was going the whole time because even though the pump speeds the water up you still have to wait for the cold water to clear. But remember the goal is primarily to save water and energy, not to have immediate hot water.

To further save water, you don’t turn on the tap to turn the pump on. You push a button near the sink which activates the pump. The pump turns on and pushes water through the loop, you wait a few seconds, THEN you turn the faucet or shower on. Instant hot water! At least from when you turned the faucet on :)

And not one drop of water is wasted.

Another option instead of a button is a motion sensor that turns the pump on. The logic is that you walk into the bathroom, the pump turns on and voila instant hot water when you want it. But studies have shown that 30% of the time it is a false alarm – you may just be getting tissue paper – so I don’t like a motion detector system because you are back to wasting energy.

Pushing the button is not complicated once you are used to it. One extra step.

Also, as soon as the water temperature gets lukewarm the pump is automatically turned off, thus saving electricity. This use of the pump only costs a dollar or two per year.

There are a couple pumps on the market that do this. One gimmicky one is called the Chilipepper pump. But I have heard it is crap. It sounds like a blender and has a reputation for breaking down.

Wirsbo offers the D’MAND® Hot Water Delivery System pump which is quite good.

But my favorite by far is the Metlund D’MAND pump. It is a tad more efficient than the Wisrbo and has a great reputation. It is super silent too.

That is the pump we have at the Brooklyn Green Show House. It sits in the basement near the boiler. There is a sensor at the top most bathroom that tells the pump to turn off when the temperature warms up. Each bathroom and the kitchen have a little button you push a couple seconds before you want hot water. Works like a charm.

The one issue is that we have to have the sensor on the top bathroom so that hot water is fully delivered all the way up there before the pump turns off. But this means if you push the button for the kitchen on the first floor, even though the water has arrived to where you want it in the kitchen the pump will keep running until the top floor pipe gets warm.

This is a small waste of electricity, although negligible. The main issue is that we are filling the stack to the top floor with hot water that will sit there and dissipate into the walls – wasted. Not a huge issue and definitely better than buying a pump for each floor (they run at about $350 each), but I’d like to tweak it a bit – maybe put the temp sensor in between the kitchen and the top floor.

This means you maybe get hot water a couple seconds later to the top floor but you don’t waste as much heat when calling water to the kitchen. I’m sure I could calculate it on the computer but it wold be too much effort for my attention span.

About the author: Gennaro Brooks-Church

3 comments to “Saving Water and Energy in a Brooklyn Brownstone”

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  1. Mike - February 1, 2013 at 5:32 pm

    I have to agree that the Chili Pepper is crap. My first one ran for just long enough to satisfy the warranty period and impress me enough to buy another. It’s actually a great design — the positive displacement pump serves as its own check valve, and the pump itself is made of a soft material that looks like it will last forever. The only real problem is the pump motor, which is indeed a piece of crap. The brushes grind down rapidly, and are not replaceable. It’s a shame — a few bucks more for a quality brushless motor and it’d be a fine product.

  2. Richard Nielsen Temtrol deltaT. Inc. - December 30, 2009 at 8:05 am

    I’d have to agree with Jason’s comments regarding the problems people are experiencing with the chilipepper appliance. Every year we receive multiple calls from Chilipepper owners who are tired of sending their Chilipepper appliance in for warranty repair problems only to have it break again 2 or 3 wks after putting it back in service. They call us because they want assurance that the RedyTemp will not have the same fate as the chilipepper appliance.

    The noise from the chilipepper appliance is only mentioned on their website as “you’ll know when the hot water has arrived because you’ll hear it stop”, or words to that affect. They continue to fail to mention just how loud it is, but the link below pretty much sums it up. I’ve also heard it described as “so loud the neighbors could hear it” and “so loud it scared the hair off our cat”. http://supersoundproofing.com/forum/index.php?PHPSESSID=31dg6e6cij1ekd0aef8&topic=1332.0

    Interesting fact, the Chilipepper appliance and the ACT Metlund d’mand system were both invented by the same two people, Dennis Metzger and William Lund. As, Mr. Lund wrote in his chilipepper article;

    “Our company was a tiny little two man operation. Needless to say marketing a new product with no money is difficult. We ended up licensing it to ACT, assigning the patents to ACT, and giving them the name Metlund. The product is now known as ACT Metlund D’MAND system. Dennis and I are no longer affiliated with the company. It was one of those cases where the two naïve inventors meet the new company’s lawyers and the next thing we know we are out on our behinds with nothing to show for it.but that’s another story.”

    The full story is on chilipeppers website http://www.chilipepperapp.com/Artcls31-D-mand.htm

    While both ACT Metlund D’mand system and RedyTemp Hot Water Optimizer use TACO pumps there are some distinct differences between the two systems. The Metlund system has only one mode of operation and requires activation by push-button or sensor. The RedyTemp has 4 user selectable modes, Single-cycle on demand, timer/scheduled, combination of timer w/on-demand overide or always on (cycling on-off based on temperature).

    The Metlund system stops pumping when it senses a 3F to 5F degree rise in temperature (ambient temperature) typically a 30 second wait after activation and then a bit more after running some amount of water down the drain waiting on above ambient temperatured hot water to arrive. The RedyTemp stops pumping when the water temperature at the sink / sensor is at “your” chosen / dialed-in temperature. RedyTemp owners who desire cooler cold water simply turn the temperature dial down just a hair (adustable to 0.5F interval). The Metlund systems require installing “T” fittings just before shutoff valves (requires draining line) while RedyTemp utilizes existing hoses from faucet to RedyTemp.

    RedyTemps RJ11 jack makes multiple push-button installations easier using affordable phone cords (.99 cent store 100′) wires and phoneline expansion adapters. RedyTemp TL-series systems work with tankless and tank water heaters and have relocatable “water contacting” temperature probes. This allows for the system to be installed most anywhere on a closed loop system (with dedicated hot water loop) and by locating the temperature probe near the last hot water load on the loop significant energy savings can be realized by not needlessly heating the pipes between the last load on the loop and the hot water source. Thus, extending the life of both the water heater and the pump.

    The biggest difference between the RedyTemp and other systems on the market is RedyTemp’s dual directional flow control by utilizing a built-in checkvalve and a “normally closed” solenoid valve that opens only during an active pumping cycle. Todays, typical systems use a single check valve which prevents cold water to hot waterline crossover. But, often does little to prevent water from the hot water line from entering the cold water line during cold water usage events. When cold water is used in / out of the home the water pressure in the cold water line drops leaving the hot water line water pressure higher.

    This higher pressure in the hot water line can easily overpower spring based checkvalves and “normally open” thermostatic / comfort valves, making it difficult for users to obtain water exclusively from their cold water line, let alone cold water. The biggest mistake people make when choosing a hot water circulator is making their choice based on ease of installation and / or cheapest price. Only after they’ve installed the system do they realize that the choice they made will now affect the efficiency of their lifestyle everyday.

    Do hot water circulators waste energy, yes they can…a lot. Can even the most efficient, optimized, timer-based hot water circulation system save energy? I believe it is possible but, not through push-button on-demand because asking people to push a button and then still wait for 30 seconds is asking a lot of most people. Most families live a lifestyle that is routine, Monday through Friday, everyone wakes up, gets ready for school or work, everyone comes home, dinner, getting ready for bed, etc.

    Accurate circulation scheduling together with back-to-back shower schedules can minimize system operations. A lot of bathrooms have multiple lights / vanity. Entering the bathroom, pushing a button, waiting 30 seconds multiple times a day vs. entering a bathroom, turning on hot water that’s instant (scheduled), depending on the watts of the lighting and number of bulbs. I think it is possible to save energy, but only if the hot water circulator has the right technology, control capabilities and a family that is willing to live a greener lifestyle.

  3. anna - December 27, 2009 at 11:13 am

    hot water….way over engineered, way
    the life of those pumps flashing on and off everytime any hot tap is turned …..short life, repair bills.

    also, maybe you can justify the energy waste since you’re (still) on mains, but the pump is a vampire in an exclusively solar home. one is conscious in turning it on and off, balancing this against the water waste.
    i feel that by 2010 all building should be done for easy translation to solar and wind.

    only the Amsih will still have main electricity in 20 years (hahahaha…i think that’s funny)

    a bucket in the shower, a basin in all the sinks…..flush the piss down, water something, ….
    this too is ‘just another step’, but one the re-inforces one’s connection to one’s use of resources.

    the important words here are :conscious and connection.

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