Anyone try?

Hilly

Anyone have an opinion on Domestic recirc lines options. I have been to put one into an old house. Money isn't as big a concern as the agony of waiting on their hot water. So I can get in out real quick if I use a Taco LinkPlus or Grundfos Comfort. Those are the type that have the mixing tee under a far away since.
Option 1: Above products - in and out little labour and extra piping
Option 2: Traditional recirc tied back into the cold water heater feed, adding pipe for return line, check valves and an expansion tank, little more labour than above.

1 seems ideal for my workload and their pocket book. But what are the downfalls? warm water back into cold line slightly. What keeps the circulator from deadheading when the mixing tee closes down on the temperature rise? Has anyone used one of this system, are there many return calls due to deadheaded or the mixing failing? Have you tried both? Is one better than the other? Am I missing anything else? My favorite part of working is... getting it right the first time and not having to return for callbacks.

JUGHNE

This has worked for me. A pump could always be added if it doesn't. Just a little slope back to the WH for the recir line.

rick in Alaska

I use the passive setup whenever I can. I set it up in my own house but could not get it to work with my smart tank. I am not sure what went wrong, and have not had time to play with it. I stuck a pump on it for now, and may get around to trying other scenarios later.
As far as the add on systems, I know of a few people who have them installed and have been told they don't like the fact when they open their cold faucet that it has warm water in it. But, it depends on the customers needs and whether they are ok with a little bit of warm water. Just something to get used to for the convenience.
I am also pretty sure the pump does not deadhead. When the re-circ pump is running, it bypasses at the furthest fixture back in to the cold water line. When the warm water gets back to the pump, a temperature sensor shuts it off. At least that is my memory of it.
Rick

Hilly

For a Passive Re-Circ line what type of check would be recommended to ensure it will open? Will the height of the passive riser be important? This current setup is a bungalow so the height would only be 8-9' maximum.

rick in Alaska

I was just on one I did the other day because she said it wasn't working. Turns out she was just having an issue with her shower valve. Anyway, it only goes up to first floor piping, so has a rise of about 6 feet in this case. Works great. I have a swing check on the return at the water heater. Spring check has too much restriction to use.
I go in to the return fitting on the water heater with a check valve, drain valve, and then a ball valve. When first starting up the system, close the ball valve and purge air out of the drain valve. Then open the ball valve back up and you should be good.
Rick

JUGHNE

For my house I cross connected the hot to the recric line under the vanity near the shower of master bath. Installed a ball valve for service.
This gave an additional 30" of height. There was about 60' of horizontal recir return. Starting at the bottom of the floor under vanity, dropping down into ductwork soffit into mech rm. The whole return has slope back as an old gravity water system.
The 6' drop down to the bottom of WH is not insulated. (cooling leg??)
There is a ball valve--swing check valve--hose bib for bleeding then ball valve into WH.
The first ball valve is partially shut to just allow the gravity to work.

This is a continuous heating loop, some may say not green, But factor in a SS or brass pump, power consumption, controls etc....I feel this is a better ROI.

The shower has hot water to it within 3 seconds.
On one job, I drilled a 1/8" hole in the lower part of the swing flap. This insures some gravity water flow thru the tank.

Mark Eatherton

According to the IECC, gravity circ returns are verbotten...


Personally, I think they work fantastic if properly set up. The return needs to be as low a pressure drop as possible, so that means 3/4" as opposed to 1/2". 1/2" would work with a forced return. When I was still actively doing this, at the inlet to the water heater, I'd install a venturi tee on the cold water inlet to the water heater. I used the conical shaped drop in venturi fitting from Nibco. Drop the venturi into the run of the tee, and bring the return into the side branch. If they (venturi) are no longer available, you could take a 3/4" fitting by 1/2" copper reducing coupling, and cut most of the 3/4" off, and then drop that into the tee for the venturi. Then, one fitting away from that, I'd take a nickel ($0.05) and drill a 1/8" hole in that, drop it inot the 3/4" fitting and hold it flat and in place with the 3/4" copper pipe. This provides a means of cooler water to circ back to the tank, and when hot water is being drawn, the venturi "enhances" circulation. It works better than a check valve, and keeps the cold water from charging backwards to the furthest point of use, causing a continuous roller coaster ride at the POU.

Personally, I am not a big fan of using the existing cold water line to return water back to the tank, because you will end up literally flushing hot water down the drain when you flush the toilet, and the chances of you getting a cool drink of water are slim to none.

Insulation of the hot and circ return line are a MUST, and at times, due to thermal migration, the cold water line is still going to get so warm that the water, energy, and the power to pump it will be wasted trying to get a drink of cold water.

If a person wanted to make this gravity system as efficient as possible, you could incorporate a zone valve (rated for potable water applications) and set a timer that would open the ZV an hour before the earliest hot water use then close it until the next high use period occurs. Don't for get to provide a solid means of purging the return line back down to the heat source/tank. If the loop is air bound, the loop won't flow.

Nothing beats gravity for efficiency.

ME

Zman

I installed the grundfos comfort system in my own house.
I went from having to wait for hot water to waiting for cold water. I eventually disconnected it.
The increased temp in the cold line is very noticeable.

JUGHNE

ME, I am curious as to why the IECC would not allow gravity return?.....stagnating water??

BTY, my return is about 30' of 3/8" ID, (1/2" OD) and 30' of 1/2" ID, (just wanted to use up the 3/8"). I have maybe 10' of total vertical drop of return. Did not drill the 1/8" in the check flapper. System works great by the way.

Erin Holohan Haskell

I've had Taco's Hot-LinkPlus in my home for about a year now and have been thrilled with its performance. I once had to wait three minutes for hot water and now it's there in an instant, even first thing in the morning. We've saved on our water bills as well.

Hilly

It looks like I'll avoid the retrofit version. I like the idea of the gravity but I'd be hesitant to guinea pig it on my buddy's in-laws. haha

JUGHNE

You can just add the pump later if needed.
Just no air trap humps in the plumbing for the gravity flow.

Hilly

Erin, how have you found the "warm water in cold line" to be? Do you notice it much?

Mark Eatherton

JUGHNE said:

ME, I am curious as to why the IECC would not allow gravity return?.....stagnating water??

BTY, my return is about 30' of 3/8" ID, (1/2" OD) and 30' of 1/2" ID, (just wanted to use up the 3/8"). I have maybe 10' of total vertical drop of return. Did not drill the 1/8" in the check flapper. System works great by the way.

If left uncontrolled, it creates a continuous heat loss (gain). For the same reason, they require temperature and timers on circ returns. It's all about conserving energy.

Also, pipe size is dictated by vertical rise. the more rise you have, the more cold water weight you have to overcome the check valve. I've seen swing checks calcified in the open position, causing a cross connect at the furthest POU, creating a roller coater ride of temperature.

ME

DanHolohan

Hilly, when we visit with Erin we stay on the third floor. There's a bath up there that was always a problem. No problem at all with the Taco, and I've never noticed any problems with warm water in the cold line. It pulses warm for maybe a second or two when I open the sink, but then goes cold. Very happy with it.

Erin Holohan Haskell

Hilly said:

Erin, how have you found the "warm water in cold line" to be? Do you notice it much?

@Hilly - I never really noticed the warm water in the cold line until you asked here, so I guess that goes to show you how little it bothers us!

We've got a small, brick colonial home that was built in the 1940s. Back in 2013, we installed B&G's ecocirc wireless instant hot water system. It worked at first, but then it stopped working after a few months. We replaced it with a new ecocirc and tried again with the help of some very kind reps, but it never really worked as promised, even after a hydronic retrofit. It was also very noisy. (We could hear it on the second floor.)

I was starting to think that this was just one of the quirks of the house we'd have to deal with. Then we heard about Taco's Hot-LinkPlus and installed it last December. We have had instant hot water ever since. It's fantastic.

JUGHNE

I understand the need for control of the pump, especially with a master temp valve the WH. If left running it seemed to over power the temp valve producing too high of temp.

However when plumbed as if it were gravity and then a pump added, it seems the pump should have a flow check?

Yes, if the swing check fails open at the WH then the recir line turns into another cold supply to the lav to fight with the hot.

I have a friend with 2 story house with pumped recir line. He said the system worked even when the pump was off.

As I mentioned I gained about 30" of vertical by going up under the vanity.

Gordy

My ranch had gravity recirculating from the 50's. Somewhere down the line it was disconnected. It had a 3/8" line from farthest fixture. I insulated pipes, and reconnected as gravity with no checks. Works great, and I really did not notice a huge upswing in energy usage. I like others would wait long periods for hot water at farthest fixtures. This depleats storage capacity also. So maybe it was a wash on the energy use. Just my experience.

SWEI

The HotLink is a good design -- even works in hard water country.

Scott M_2

In my moms house I used one of those tiny electric water heaters so the attached in law apartment wouldn't have to wait.Good cheap solution if you can find the space.

Aaron_in_Maine

I have the Hot link plus in my house. It uses the cold as your return it works great. Every once in a while I get lukewarm cold water to brush my teeth which is not favorable but we deal. My hot water took forever to get to the master bathroom before. 55' of 3/4 copper is a lot to purge.

MikeG

What is the main difference in the systems that use the cold supply as the return? Is it where the pump is located under the sink versus at the tank. Probably some control differences, but as Aaron stated if you turn on the cold it could be warm for a while.

SWEI

Under-sink pumps typically use the cold water supply line for recirc, but that configuration can also work with a dedicated recirc line. Look for a recirc line smaller than the supply that tees into the water heater inlet with a check valve nearby and you'll know for sure.