Hot water recirculating pump

[neblinc]

Anyone have one of these pumps that keeps the hot water at the tap hot?
Our bathroom is at the opposite end of the house and it takes a long time for the hot water to get there.

Does a guy have to redo the pipes to install one?

Randy

 

[jonny o]

A relative asked me to install one. I did the homework but she changed her mind. On the one I was looking at, you do not have to redo the lines, just incorporate the pump at the point of use and the cold water line is used as the "return."

She changed her mind when I told her her she would be paying to reheat the water every time it pumped through the lines and cooled down. I convinced her to let me insulate the lines as far as I could conveniently get to and think more about heating those extra gallons 24/7 when she only used that bathroom 2-3 times per week. Take note that she was not paying for water usage, and some people will recoup some cost by not letting the shower run for minutes.

There was a more costly system that installed near the water heater that you could set to circulate on a timer, but her use was very sporadic.

Hope that helps.

 

[dodgepolara500]

I have one and it works well. The one old bathroom i have without the recirc on it takes forever to get cold water. To conserve electricity, I run it off a timer so it does not recirc at night or during the middle of the day when we are not home.

 

[lawfarm]

Can someone explain the 'how it works' here? It would seem to me that if it works, you're pumping hot water back through the system through the cold water pipe servicing the faucet, no? So if you turn on the cold water side of the faucet, do you then get a pipe full of hot water?

 

[Friartuck]

The ones I've seen, you have to add a seperate line from the water heater to the fixture and include a circulator pump to create a loop where the hot water flows. At the instant hot water is turned on, its right there. And yes, putting it on a timer minimizes expenses.

 

[MrMark]

I have one, a Grundfos, with a dedicated return line. I have a timer and an aquastat too, but the system is inefficient without more . . .

This is a very complicated subject but you are essentially trading wasted electricity (to run the pump), accelerated pipe wear from scrubbing (especially at the 90's and especially if you have 1/2" line with its high velocity flow) and wasted gas to keep the water in poorly insulated pipes warm in exchange for convenience and small water savings. What I am telling you is that the system even with the timer and the aquastat OVERRUNS and causes the hot water heater to run more often than it otherwise would because now all the water in your return line and hot water line is part of your heated water reservoir.

There is only one perfect way to do this system and it is . . .

with a dedicated return line and an on demand switching system. This is what I have essentially done. This removes the issue of standby loss from the piping system. What you do is that you install switches at each point of use, or at least points of use that are important for you to have instant hot water. These switches should be on small timers that will turn the pump on for say 5 minutes and then shut off. The pump in that 5 minutes or less will take all the cold water in your hot line, push it into the bottom of the water heater tank and replace the cold water with hot water moving out the top of the tank. You are replacing all the cold water with hot from the tank and moving the cold into the bottom of the tank. No water waste, no standby heat waste, a perfect system. So before you jump in the shower you hit the switch and a couple minutes later you are good to go.

BTW, this is the ONLY system that you can do with tankless while maintaining warranty coverage. I believe that you would still need to put a small 5 gallon tank in to do this with tankless but I'm not sure as I am not a fan.

There are companies that sell this type of on demand system.

It is the only way to go if you are starting from scratch.

 

[popbigguy]

Look here:

http://www.autocirc.com/

It's what I have. I like it, I run the timer so that it doesn't run in the middle of the night when I don't need hot water right away. Bought it at a Menards (locally area store like HD and Lowes).

 

[gcan]

this is what I have

http://www.grundfos.com/web/HomeUs.nsf/Webopslag/PAVA-56TMVA

My master bath is on the opposite end of the house from the water heater so this was a easy solution. Cake to install, works great, I have it on a timer and only run it about 15 minutes at a time and have it set to go on and off 4 times a day so doesn't run all the time but hits our regular scheduled times. I did use two of the return valves so have water on tap in my daughters bath as well.
I installed this unit about 2 years ago and zero issues.... wake up get straight in the shower I highly recommend this unit!

 

[larry4406]

I had a system with a passive recirc (hot water rises, cold water falls). The hot line looped all the way back to the water heater drain valve with a check valve installed (flow towards heater). The hot line was insulated from the heater to the last tap. Each tap was a short run off the loop. After the last tap, the recirc line was left uninsulated all the way back to the heater. This set up the natural circulation loop which worked sweet. This was new install, difficult for a retrofit.

 

[jvitez]

I spec'd one when we built our house 3 years ago. Long run from the mech room to the farther faucet, plus we're on a well. I deliberately traded increased electricity use (Marathon elec water heater) for decreased water consumption. Our electricity rate is less than 7 cent CDN per KWH, so in my mind a reasonable trade off. We have uninsulated 3/4 in PEX pipes. Yup, no code demand to insulate, so plumber didn't. But in winter we need the heat anyway, so it's not wasted, just derived from another source. In summer, yes it would increase the heat load on the air conditioner, but since we have geothermal heating/cooling it's even less of an issue. And besides, comfort and convenience costs something.

Ours just runs 24/7. The plumber's motto was clearly "good enough" I wanted to install a timer, but I've decided to install an aquastat. I want to finish the garage first though. You know, getting my priorities straight

I'd never build another house without some type of recirc system. We love it.

 

[nate379]

I just throw the shower on before I get undressed and by the time I have my clothes kicked off the water is pretty much warm.

 

[redsky49]

The commercial building codes require some type of temperature maintenance if the plumbing fixture is further than 100 ft from the hot water source. There is no similar residential requirement. In practice, 50 ft. is a better cutoff distance, since that will minimize more user complaints than the allowable 100 ft. code distance.

For example, a 1.5 gpm flow (from a water saving fixture) will take about 8-1/2 seconds to travel thru a 50 ft. 1/2" copper pipe. This is about the longest that you can safely get away with.

There are three methods I have used to avoid excessive waits for how water:

1. A recirculating system. Contrary to what has been said above, the flow rates are extremely low - I will use 15-20 minutes for the water to circulate thru the loop, oftentimes longer depending on the application. You design for about a 5-10 degree maximum temperature drop in the loop. A dedicated return line is required. Piping must be insulated throughout. You cannot use the cold water supply for a return.

2. Heat traced piping. This is a good approach for residential as it can be easily regulated by a timer. As the temperature in the supply line drops below the setpoint at the furthest fixture, the heat tracing energizes, maintaining the required hot water temperature.

3. "Point of use" small water heaters. These provide a small (less than two gallon capacity) which serves well for most usage. As the small amount of stored hot water is consumed, the makeup from the hot water supply pipe is flowing into the heater and takes over for the now depleted heater. If designed correctly, the user will only notice a brief small change in the supply temp as this changeover takes place. This is a good choice for the occasionally used plumbing fixture located far from the other plumbing fixtures/water heater.

Most recirc systems are relatively expensive for residential applications, though there is no arguing the luxury of instant hot water.

As always, offered only as opinion

 

[MrMark]

my recirc system moves all the water through the system within 2-5 minutes from pump start as the aquastat turns it off within this time. The water temp in the return line just before it goes into the heater is at 120 degrees within 2 minutes as tested with a SO infared thermometer. I have 3/4 return and a loop of probably 120 feet. I have a small Grundfos pump, not the smallest, but a UP 15-18. So you are wrong about the time.

While pipe insulation may be required by code for a dedicated return line, it is essentially worthless in my testing. That is why it makes more sense to go to an on demand recirc system because then pipe insulation doesn't matter one bit.

The heat tracing is the same as the aquastat just placed where it makes more sense, ie., at the furthest fixture, rather than the water heater, where it makes the least sense. This is still an inefficient system.

I'll link an efficient system since no one has hit bingo yet.

 

[MrMark]

http://articles.webraydian.com/arti...n_System_Replace_it_with_a_Demand_System.html

Further to the time issue: the Grundfos UP pump I have moves 6 GPM. There is only about 2.5 gallons of water in 120 feet of 3/4 pipe according to sources I just looked up. You do the math on how long it is going to take that pump to move the water.


This is promoted by SoCal Gas:

http://www.socalgas.com/construction/builders/Builders Resource Guide/Hot Water On.htm

I like this; I think it is state of the art based on my research and personal experience with recirculation sytems

http://www.gothotwater.com/D'MAND/how.asp

 

[JamieK]

On This Old House, they installed one, where the pump was operated by a motion detector. The pump started running when someone walked into the bathroom, and theoretically, there would be hot water at the faucet by the time they used it.

Also, saw this, but know nothing about it. Looks liKe a good idea, though...

http://www.hotwaterlobster.com/

 

[BillGalbraith]

I'm halfway through this project myself. My pipes are buried in the slab. I think tapping into the cold water line is retarded, because that would give you hot water on the hot side, but also hot water on the cold side.

I ran another flex hose from the bathroom back to the water heater. The hose is 1/2" flexible pipe from HD, about $25 for 100 feet. Slip-on insulation is about $1 for 6 foot sections, and I used 16 of them. I ran the flexible pipe through the attic, so not a big problem. You have to use special fittings to connect this to CPVC, PVC, or copper pipes, but they aren't too expensive. Total cost for all of that was less than $100.

I tapped in at the bathtub because it was accessable, but a pain in the **** to plumb a TEE in there, since there wasn't enough flex in the line. I ended up having to put a series of elbows that allowed me to put my TEE in there. I also installed a shutoff valve, just in case.

On the water heater end, I unscrewed the drain valve and installed an extension with a TEE in it as well. I have a one-way check valve in there, and a hose bib so that I can bleed the air out. I left the last 6 feet uninsulated, hoping that the convextion of hot and cool water would circulate the water, but it isn't circulating, so I'll have to put in a small pump. Prices run about $140 for that. I just haven't done it yet. I'll insulate the last 6 feet when I put in the pump.

In the meantime, I just send the wife into the bathroom a couple minutes before I go in there. The water at the faucet is always hot when I get there. ;-}

 

[mikeyr]

Interesting concepts here, I was thinking of going with a recirc pump when my water heaters go but I was concerned about costs of electricity. For some reason I never considered a timer, thanks guys.

My "primary" water heater is giving up, I don't know how old it is but it no longer heats like it used to, it does not take long to run out of hot water in the shower. The house has 2 30gal heaters because my Father-in-law did not like waiting for hot water so one heater is outside between the 2 bathrooms and the other is at the other end of the house near the kitchen laundry room. Having 2 heaters just does not seem very efficient to me, I guess I need to look into replacing both heaters it might be more efficient then doing a recirc. system but I can't see how it would be. Either way I have plumbing work ahead of me since it really is 2 separate hot water systems, the hot water lines are not shared from one side of the house to the other.

 

[neblinc]

Wow! Lot's of info here!
We are on a well system, so I thought I should try and conserve water.
Looks like the consensus is saving water may lead to higher electric usage for the pump and hot water heater.
All my pipes are in a nasty crawl space so running a return line would be challenging.
What to do, what to do.

Randy

 

[Nostraquedeo]

Here's what I done. The kitchen is upstairs and water heater down stairs. I made a loop to the kitchen sink and tied the return loop into the drain valve at the bottom of the water heater. I installed a valve in front of where it ties in to the drain. That way I can shut it off if I need to drain the tank. I insulated the pipes. It is about 60-70 feet away. Generally when I turn the water on, it takes about 5 seconds to get warm water.

 

[TheShrine]

We've got one. Save a nickle on water...then we spend it on electricity!

Bottom line, I've got hot water in 3 seconds anywhere in the house! That's what is important to....her.

 

[VHF]

Take a look at the Chilli Pepper pump and the D'Mand system.

When you push a button, it pumps the cold water in the hot water line back into the cold water line. As soon as it detects hot water, it stops. Typically installed under the sink farthest from the water heater. You can hook up multiple buttons in another bathroom, kitechen, etc. It will bring the hot water faster than just letting the sink or shower run, no wasted water, and no wasted energy when not in use.

The D'Mand is twice the price of the Chilli Pepper, but it is a higher quality unit and the pump is quieter, although the Chilli Pepper looks slightly easier to install.