Hot water recirculation do they save money?

Xmytruck

Hello

I have done some research on this topic and their seems that some people agree it does save money do the fact your not wasting water, other seem to think your wasting energy because the system is keep the water a certain temp. I got one installed and did not want it installed but their was confusing of the options that were presented. I have noticed that when I shut down the recirulation pump the water temp jumps up to 140 degree and then quickly goes back down to 120. With the pump on the water instant at 99 degrees and never jumps over 120. My DHW is a navien ch240 that is set to 120 for DHW. My concern is that I spending more money just to have instant hot water. I know it's better than heating 50 gallons..

I have also heard that these systems cause Corrosion-erosion within the copper pipes has anyone experience such an issue?



Thx

Xmytruck

Alan (California Radiant) Forbes

Sure,

it wastes energy.  The electricity to power the circulator and the heat loss from the piping.  But others would call it a convenience.



Most of my customers strongly dislike waiting for hot water and will gladly pay for the convenience of instant hot water.

heatpro02920

Properly designed it can cost very little & cause no erosion issues

On the other hand not properly done it will cost a lot to run and can cause warranties to be voided and serious erosion and flood damage...



I have seen them done all sorts of ways, with your type of system I would recommend using a separate mini tank for the recirculation system. I am not a fan of running tankless water heaters for recirculation, while they work very well with recirc and it cures most all of their issues such as wait time and cold sandwich. But when done wrong they will greatly reduce the life and efficiency of the unit...



Tankless units do not like close delta t's, what his means is they want a big difference between the incoming temp and the outgoing, so with 50* ground water and 115* outgoing, the units will run great (actually anything over 50* is ideal), but when you start to close that differential like a recirculation system will do, you can run into sooting problems, low efficiency, short equipment life, ect.



So how I install them is with a timer, aquastat, circulator, electric mini tank, thermal expansion tank, a couple of check valves, and the smallest tubing I can make work for the recirc return line, that all operates after the tankless and will not run water through the fuel fired tankless for recirc at all...



Do you have a picture of the system installation, then we will have a better idea of how much energy you are "wasting"



As for saving money, I would call it a wash, if you have well water you won't run your pump as long waiting for hot water to come up, if you have city water it will lower the consumption and the sewer use, but whenever you heat something up it costs money, so heating up the loop costs money, I figure it as a wash but the comfort and time saved makes up for it in spades, IMO...

Xmytruck

Pump

Pump is on the left of the unit.

heatpro02920

Aqaustat is a plus,

that is one of the nicer navian installs I have seen...



I would have done the recirc much different, but that doesn't mean that is wrong by any means... I would like to see a thermal expansion tank on there though. {like I previously stated I would run a mini tank and not recirc through thte tankless unit at all}



How you are setup now they system is running until the aquastat is satisfied which is good, but if you add a timer it would be a little better,



I would add a timer {if the navian doesnt have one built in, I don't think they do} ... http://www.amazon.com/Grundfos-599388-Programmable-Timer-Circulator/dp/B002OJYRPE/ref=sr_1_1?ie=UTF8&qid=1368390366&sr=8-1&keywords=grundfos+timer



that can be retrofitted to a 4" box, taco makes one similar but it is 3 times the price...

wire in before the aquastat, what this is going to do it make it so you can control when the pump comes on, so you wake up at 7a and take a shower, set it to come on at 6:50 and you leave by 8a set it to shut at 8, you get home at 5 set it to go on at 5 and off when you go to bed at 11p, this will turn the pump on and off at them times, BUT only until the aquastat is satisfied... Grundfos sells a pump that does all of this and uses less electricity than that bronze taco... grundfos Up-10-16bu , I use them for the smaller recircs, they work well...



I would make sure the aquastat is set correctly, you want it short of the units setting so it shuts as soon as hot water returns, if you set it too high it will never shut the pump off and constantly run...



I have some pics of how I run recircs with tankless heaters... I will try to post one tonight...

Xmytruck

Like it

So far I like the system I normally get hot water in about 5 to 15 seconds not sure that is good or bad the temp is around 90. The only annoying is at least once day I get a cold water sandwich and it takes at least 60 seconds for the unit to kick in, i am assuming the small storage tank would solve that as you mentioned. I have also heard people state that i could set preheat but that just bugs me to have the unit running during that that time especially if no one takes a shower at that time. What temp should the aquastat be set too? How much more money am I burning with this feature?



Thx

heatpro02920

Tough call on how much extra fuel it uses

check the meter, run it for a day with no recirc, then run it for a day with recirc, may give you an idea...

You will greatly reduce the amount of energy with the timer though, that is a fact...



As far as temp setting, that depends on you, on tankless units I set the temp at the temperature the customer takes a shower at, I tell them to take there thermometer in the shower with them and rite down the temp, most people are around 108 so you set the unit between 110-115. I set my unit to 120 in the winter and 115 in the summer... the lower the better... you want it so when you take a shower you use full hot no cold....



I would think hard about the timer if you are worried about the energy use...

Gordy

Another resource to consider saving

Is water, and how long people let the shower or sink faucet run before hot water is present.

TonyS

Easy to calculate

the energy your consuming with a circulator.

Turn on your water heater until it goes off and dont use any hot water at this point.

Place a temperature probe against the side of the tank(inside of the insulation) and read temperature. Turn on your circulator and time out for 1 hour and record your temperature drop. Take your size of your tank in gallons x 8.3 will give you pounds of water x temp drop will give you BTUs lost per hour.

Now do it without the circulator to get a base mark to compare.

Once you have this info it is easy to compare it to the fuel your using.

Dont forget to also add the wattage of the pump to the cost.

heatpro02920

That doesn't sound so easy Tony

LOL ez for you maybe, I was lost at measure the temp of the tank on the tankless unit...



I am also curious how much "extra" energy your recirc is using... I think I got the system at my house nailed down...

The Bosch mini tank uses are $5.50 a month and the circ uses about .38 cents.... But I just got the killawatt meter, I need to run it for a solid month and then I will know better..

TonyS

I missed that part

about being tankless LOL

Gordy

Kill o watt

If your usage is pretty much the same daily you can calculate it out heatpro, a week would be a good average.

heatpro02920

Gordy that is how I came up with

the $5.50 and .38 for the pump, I bought 2 killowatts so I can get the power usage of both the pump and the electric mini tank separately.



Here's why I want a month, this week we have had people home most of the days so they may use the hot water during the day causing the tank not to run because the Rinnai unit has just filled it with 120* water...



For the sake of the test I also, turned the pump on to run a little more frequent with the time... I normally set it for the morning and then after 4 when people are here, and the thing hardly runs at all...

I really want a good number to advertise to my customers, I hate saying "you should use X amount" and its nothing more than my best guess... My house has a climate contolled basement so it is tough, but I have a customer that I am going to ask if I can install the kill owatts on his system since it is more like the worse conditions one of these will see, unit is installed in the garage, plumbing goes through a crawl space over a slab, and they have there timer run all day 7a-11p so its literally only off for 8 hours a day {although the aquastat shuts it down of course}....



I figured my usage around $7 a month and it turns out I am very close to that. That is $84 a year for hot water to be rite at my faucets, I think its worth it but others may not... Now I am not figuring in the time my well pump doesn't run pumpping water down the drain waiting for how water, although my well pump system is pretty efficient its a grundfos sqe with cu301 control, I'm sure I save a little running the water less, since it takes a full 5 minutes to get hot water in the master bath on a cold morning {very far from heater}... also the wear and tear on the well and septic system...



If I figure I run the shower an extra 5 minutes for each shower we take in the house, thats 6 showers a day at 5 minutes of waste with our 1.5gpm heads {high sierra, they work great}.

That's me and my wife twice a day and the kids once a day {its tough to get them to do that, ahhh boys}



Thats 1.5gpm for 5 minutes each shower = 7.5gal x 6 showers = 45gallons a day thats is 16425 gallons per year.... Now I'm not counting that amount of time when washing dishes and clothes {my wife will run the faucet in the kitchen and in the laundry room to make sure the hot is there to clean the dishes or clothes {when recirc is off}, plus washing hands, ect.... But even if it is taking 10K gallons out of my septic that my pump doesn't have to push up my 500ft well, I think that alone is worth $84 a year.... as far as the comfort and time savings, that is probably worth about $600 per year, because I would pay $50 a month to be able to just jump in the shower and turn on the water, not have to reach in, turn the water on, wait for a few minutes testing it every minute or so and then jump in... Having 1 inch pex water mains and low flow shower heads really makes the wait long, then add onto that my master bed is on the top level with 12 foot ceilings on the opposite side of our house....

heatpro02920

I do the same thing

read a question on here fast, then already hav ethe answer half way through {or so I thought} and start posting with out finishing the post.... lol...

Phil_8

Circluate only when needed

What about the pumps that are located at an appliance (sink or shower) and pump the water from the domestic hot water line into the cold water line (thus no loss of water) and shuts off when the hot water reaches a preselected temperature.  A push button is installed at the sink or shower to start the pump. They also come with a remote control so that the pump can be activated from an adjacent bath or nearby sink.  Has anyone used these and know of the manufacturer.

SWEI

D'Mand

is probably the best known.  Taco licensed it IIRC.



You can roll your own without too much trouble.  Pushbutton or occupancy sensor plus a Taco 563-2 will work.

Phil_8

Thanks

I assume that the Taco 563-2 is lead free and thus acceptable for potable water.

SWEI

563-2

is a snap-on aquastat.  Should not have any contact with water unless something goes quite wrong.



I like the B&G/Laing Autocirc e-series pumps -- dead quiet and ultra low power.



In order to use a momentary contact, you'll also need a double pole relay wired for latch-on:  Wire one set of NO contacts in series with the coil, then wire a NO pushbutton in parallel with those.  Put the aquastat in the same series string.  Control the pump using the other set of relay contacts.  Pushing the button energizes the relay, which holds itself in via the first set of relay contacts until the aquastat breaks the circuit and resets it.



My favorite method is to install a current switch on the AC wire feeding the overhead light  Replace the wall switch with an occupancy sensor and the whole shebang gets automated without even needing a relay.

heatpro02920

I looked into this type

you get warm cold water, taco uses 006 008 and I believe their commercial unit was 0011... I wasn't crazy about the system, if you can run a third pipe I would, if the retro is impossible then its better than no recirc I suppose, but I would want to buttons vs the motions, because you walk up to a sink for cold water and can only get warm, kind of sucks...



As far as pumps, the bronze tacos are of the past, the Laings are nice, the grundfos up-10 is nice to, you can get the model that has the union mount, check valve, thermostat {adjustable, I think the laings are fixed}, and the timer for around the same price as an e1... For the larger systems I use a ss 15-55 alpha with a grundfos timer, a jonhson a419 digital aqaustat, with the grundfos dielectric ss isolation flanges costs a little more than going with the all in one unit but unlimited-ish abilities and when one component goes you just change that single device, with the all in ones, you are buying a new $300+ circ...

Vette333

Hot Water Recirculation

Hello Xmytruck,  as you probably know, domestic hot water recirculation systems  are designed to provide instant hot water comfort and convenience, and save thousands of gallons of water per year.  A Department of Energy study determined that the average family of four can waste up to 12,000 gallons of water per year waiting for hot water to arrive at the faucet. There are many types of DHWR systems available with a variety of methods used to control the circulator pump and provide instant hot water.  The more advanced systems control the circulator by limiting the run time through the use of aquastats and/or timers or starting mechanisms.  And DHWR systems like Taco's new "SmartPlus", actually learn the home's household hot water usage patterns, and cycle the pump only when needed to provide instant hot water.  Typically, the more efficient the DHWR system, the less taxing it is to the hot water source.  As far as cost - if you pay for municipal/city water to reach your home, and pay a sewage tax for waste water going down the drain as you wait for hot water, it's costing you money.  Typically more money than the slight increase in electrical consumption that an efficient DHWR systems requires. A properly sized, efficient DHWR system in the right application, will not create errosion/corrosion issues, and should provide years of instant hot water comfort and convenience.

I hope this information is helpful.  Please feel free to contact me with any questions.



Best Regards,

Carl Perrone

Product Manager - Water Circulation

Taco, Incorporated

Kevin Koenig_4

EcoCirc Wireless

Here is a cool DHW recirc pump new from B&G.       http://unitedstates.xylemappliedwater.com/brands/bell-gossett/pumps-circulators/small-circulation-pumps-boosters/ecocirc-wireless-instant-hot-water-system/

cliffs

Hot Water Recirc Pumps

They are great and should be in every home especially in drought areas (I'm in southern California). I have to say that I am biased as I am a distributor, but I am only a distributor because I really think this product is one of the best I've seen (I am a CPA by trade). My pump only costs about $1 per year to run because it isn't on a timer, but rather on-demand. You only activate the pump when you want hot water. Those on timers start out great, but people soon realize that they don't have a regular schedule for hot water need so they end up putting the timer on for most of the day. It is easy to install (one caveat is that you need an outlet under the sink so that adds to the cost). No corrosion of pipes. See my pumps at www.needhotwater.com.

Gordy

On demand?

So I walk into the bathroom, push a button, and turn the hot water on .



I use a recirc with a thermostat so the pump only runs by temperature not a timer. All I have to do is turn the faucet on no buttons to push, and the recirc pump is 1/2 the price of the on demand.

cliffs

Runs only by temperature?

I'm glad your pump works for you. What kind is it? For the on-demand pump, pushing a button hasn't been a problem so far.



Just curious, how is it that the pump only runs on temperature? So when the water in the pipes cools below a set temperature, the water is recirculated? If so, seems like your pump could be running more often than needed.

Gordy

Laing 303

Is the name of the pump. It has a built in thermostat adjustable 68-158 egrees with a 10 degree differential. Runs very little and it's 40 watts.

cliffs

thanks gordy!

I guess each pump has its own benefits, but the on-demand is the most energy efficient. The pump only turns on when you push a button. Third party tests have shown that on average it costs $1 per year to run. I think the Laing is running more often than needed. It would run as long as the water temp triggers the thermostat. I wonder what the pump life is when it has to click on and off constantly, for example, in colder regions.

In any case, I'm glad your pump is working out well. I think all homes should have these products to save wasted water.

Bob Gagnon plumbing and heating

Brush Your Teeth

I use the hot water to brush my teeth when I'm waiting for the water to get hot, so there is no wasted water. I think recirc lines are an incredible waste of energy and expensive to install. I recently did a Radiant Job at a house where they had a 120 gallon SuperStor, and about 40' of uninsulated copper recirc line. I shut the boiler off over night and forgot to turn off the recirc line, and it drained the 120 gallons of heat overnight, without the occupants using the shower, I talk my customers out of recirc lines.



Thanks, Bob Gagnon

cliffs

Recirc Lines vs. Recirc Pumps

If I understand your comment correctly, I agree, recirc lines can be expensive to install; not sure how they are a waste of energy since only the cold water goes back to the water heater through those dedicated return lines. However, recirc pumps are different. Pumps use your existing plumbing so there is no need to install a dedicated line.

Some wait 5-6 minutes for their hot water to come so brushing their teeth while they wait in those cases is still wasting a lot of water down the drain.

Bob Gagnon plumbing and heating

I Have Never Seen

A house so big that it takes 5 or 6 minutes to get hot water, it's usually a minute of two. Recirc lines waste energy by losing heat from the recirc line into the basement, I stated in the thread above that an uninsulated recirc line sapped all the heat out of a 120 SuperStor overnight, that's a huge amount of energy, the customer shut off the recirc line when he saw that. And it's been off ever since.



Thanks, Bob Gagnon

cliffs

I can see how that can happen.

Like I said, pumps are different from recirc lines.

The house with a 5-6 minute wait time is about 3000 sqft that had an additional master bath added. It was the furthest from the water heater. I don't think the plumbing was done in the most efficient way, but they now have a pump there and are amazed at the results. I've been seeing on average 2 - 3 minute wait times for those seeking a solution.

Paul48

Gordy

Forty Watts? Seems high....746 watts/1 hp.....Taco 007=1/25 hp= about 30 watts

Jean-David Beyer

Taco 007=1/25 hp= about 30 watts

Not exactly. The motor puts out 1/25 horsepower, but it is not very efficient. It draws 0.71 amps, so at 120 volts,that is 85.2 watts.

Paul48

Yes

I stand corrected.

Gordy

Gravity

Honestly I don't even need the pump I could just do it gravity. I threw the circulator in because I had it and it controls the gravity circulation.

Gordy

Bob

I don't deny your statement, but it does save water, and get ya in the shower a bit sooner. That basement must have been unconditioned . My water heater never kicks in unless there is actual usage. My lines are also insulated, and basement a conditioned space.

Kevin Koenig_4

a Better way

This is a convenient method od getting the job done.  Very low power.

http://bellgossett.com/pumps-circulators/small-circulation-pumps-boosters/ecocirc-wireless-instant-hot-water-system/

cliffs

just spoke with b&g rep

They said their pump lists for $555 and the optional button, which would make it an efficient pump, lists for $200. He did say that there will be warm water in the cold water pipes.



Can you confirm any of what he said (price and warm water)?