# Recirculating system with NO pump



## sparky (Jan 8, 2014)

Got a question for the higher ups,I have read on here where some of u fellers are doin circulating systems using NO PUMP,using the return line draining back to heater with slope on it.does this actually work and describe exactly how you are piping it in at the heater please.thanks guys


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## wyrickmech (Mar 16, 2013)

sparky said:


> Got a question for the higher ups,I have read on here where some of u fellers are doin circulating systems using NO PUMP,using the return line draining back to heater with slope on it.does this actually work and describe exactly how you are piping it in at the heater please.thanks guys


 yes it does work I use the system when the heater is in the basement and all connections are above. Off of the highest fixture or the farthest away you connect a return line. Back to the heater and connect it to the drain a swing check valve is required at the heater to keep it from back flowing .


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## rjbphd (Feb 5, 2010)

wyrickmech said:


> yes it does work I use the system when the heater is in the basement and all connections are above. Off of the highest fixture or the farthest away you connect a return line. Back to the heater and connect it to the drain a swing check valve is required at the heater to keep it from back flowing .


It will work without check valve! How many gravity hydronic system have check valve on return???? NONE!..


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## tim666 (Mar 11, 2014)

Without the check it can draw water from the bottom of the tank through the recirc when hot faucet is opened


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## rjbphd (Feb 5, 2010)

tim666 said:


> Without the check it can draw water from the bottom of the tank through the recirc when hot faucet is opened


Nope... high pressure goes to low pressure, always as well flow to the least reistensce(sp).


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## wyrickmech (Mar 16, 2013)

rjbphd said:


> It will work without check valve! How many gravity hydronic system have check valve on return???? NONE!..


 it will back flow which will interfere with the thermal circulation every system I have seen has a check.


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## rjbphd (Feb 5, 2010)

wyrickmech said:


> it will back flow which will interfere with the thermal circulation every system I have seen has a check.


 Every system that have a problem, removed or compromsied the check valve, problem solved.


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## wyrickmech (Mar 16, 2013)

rjbphd said:


> Every system that have a problem, removed or compromsied the check valve, problem solved.


 yes I agree that if there is a problem the check is the only component that can obstruct the flow. With that being said if a check fails in a back flow device you fix it you don't remove it. The faucet at the end of the loop will draw from the tank sense it is closer to the water heater. Most of the time there is more fittings and turns on a gravity system on the supply side than the return loop so less resistance on the return. Without the check it will draw off of the return loop. That is why the check is there.


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## PLUMBER_BILL (Oct 23, 2009)

wyrickmech said:


> yes it does work I use the system when the heater is in the basement and all connections are above. <snip>
> 
> Back in my apprentice days we also provided domestic hot water using the same principles. In a old coal fired kitchen range or a boiler there sometimes was a water-back this for lack of a better term looked like a hand in the range or boiler. This steel hand was piped to a tank above the [hand], and as hot water rises the water in the hand, piping and tank [range boiler] supplied domestic hot water. The tank was pressurized to city pressure piped into the tank with a double tapped tank union the inner tapping allowed a dip tube to allow cold water into the bottom of the tank -- hot water taken off another tapping in the tank. Some times the tanks were placed horizontal above
> ie: a boiler. Usually the only R/V was a pressure only -- if there was one


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## Redwood (Sep 8, 2008)

Sparky, What are you doing for insulation on the pipes?


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## tim666 (Mar 11, 2014)

rjbphd said:


> Nope... high pressure goes to low pressure, always as well flow to the least reistensce(sp).


Why would there be any difference in pressure without a check valve


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## rjbphd (Feb 5, 2010)

tim666 said:


> Why would there be any difference in pressure without a check valve


Even a drip from the faucet will create pressure differeanal


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## stillaround (Mar 11, 2009)

In some of the older buildings in Chicago there was a seldom seen 3/8" galv hot water return line for recirc with no pump. I favor check valves .. Something about the smaller pipe made it work.

See gravity hot water recirculation

Considerations for installing gravity hot water recirculation:

This system is only practical when the water heater is located below most of the distribution piping. Houses with rooftop units or on slab construction or will require a circulator pump.
Piping should not be insulated as the drop in temperature is what fuels the movement of water.
A check valve is required to prevent cold water from short circuiting though the return line.


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## tim666 (Mar 11, 2014)

rjbphd said:


> Even a drip from the faucet will create pressure differeanal


We might be talking about different things because I mean you will have the same pressure in the hot supply and a recirc line, an open faucet or dripping faucet can take from both lines without a check valve


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## stillaround (Mar 11, 2009)

Hot water weighs less than cold


system pressure is equalized thru the heater connection...but different temps create gravity flow evidently.


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## Redwood (Sep 8, 2008)

stillaround said:


> Considerations for installing gravity hot water recirculation:
> 
> *Piping should not be insulated as the drop in temperature is what fuels the movement of water.*


Actually you can and should insulate...
But you must leave a portion of the return uninsulated to fuel the temperature drop that keeps the convection going...


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## wyrickmech (Mar 16, 2013)

tim666 said:


> We might be talking about different things because I mean you will have the same pressure in the hot supply and a recirc line, an open faucet or dripping faucet can take from both lines without a check valve


 Tim it's more about resistance than pressure drop more fittings longer run on the hot water makes it easier for the water to flow backwards. that's why a check valve is put in the return. This type of recirculating line will work simply because heat rises and cold falls. Simple as that a slow system but works well when your heater is below.


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## tim666 (Mar 11, 2014)

I was just saying that you do need a check valve


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## sparky (Jan 8, 2014)

Redwood said:


> Sparky, What are you doing for insulation on the pipes?


Nothing I'm not installing this right now but in my own house I have a bath that takes forever to get hot water to and I remembered reading on here about some plumbers that swore by this layout and in my house this type system will work I.e. Heater in basement and I was thinking bout using this as a cheaper circulating system as I have never heard of this till reading it on here and I can see how it works. Thanks for all the input but I have one question,can I tie the return line into the cold water feed at the heater??wouldnt that be the same thing as into the bottom??


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## sparky (Jan 8, 2014)

Redwood said:


> Actually you can and should insulate...
> But you must leave a portion of the return uninsulated to fuel the temperature drop that keeps the convection going...



How much slope should you put on the return line??1/8"-1/4" or as much as possible??


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## sparky (Jan 8, 2014)

Redwood said:


> Actually you can and should insulate...
> But you must leave a portion of the return uninsulated to fuel the temperature drop that keeps the convection going...


So as the hot water cools off then that is what allows the flow to take place, is this what I'm reading here???excuse my ignorance on this but this is a first for me and I don't care to tell you I'm lost on this and never heard or seen it before.


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## Tommy plumber (Feb 19, 2010)

sparky said:


> Got a question for the higher ups,I have read on here where some of u fellers are doin circulating systems using NO PUMP,using the return line draining back to heater with slope on it.does this actually work and describe exactly how you are piping it in at the heater please.thanks guys












Solar systems can be piped either with or without a re-circ pump. With a pump is called an 'active' system. Without a pump is called 'passive'.


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## rjbphd (Feb 5, 2010)

tim666 said:


> I was just saying that you do need a check valve


Not a hydronic heating guy..


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## rjbphd (Feb 5, 2010)

sparky said:


> Nothing I'm not installing this right now but in my own house I have a bath that takes forever to get hot water to and I remembered reading on here about some plumbers that swore by this layout and in my house this type system will work I.e. Heater in basement and I was thinking bout using this as a cheaper circulating system as I have never heard of this till reading it on here and I can see how it works. Thanks for all the input but I have one question,can I tie the return line into the cold water feed at the heater??wouldnt that be the same thing as into the bottom??


Want to do it right??? Tie the 1/2" return to the drain connection without checkvalve and no stinking pump!


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## sparky (Jan 8, 2014)

rjbphd said:


> Want to do it right??? Tie the 1/2" return to the drain connection without checkvalve and no stinking pump!


I will do it as you advise,thank you all for the vast knowledge as it has helped me a lot and I have been told numerous times that I am beyond help!!!lolol


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## tim666 (Mar 11, 2014)

rjbphd said:


> Not a hydronic heating guy..


Sure I am, this is not a closed hydronic system. When you open the faucet it will draw from both.


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## Archie (Mar 5, 2014)

rjbphd said:


> Not a hydronic heating guy..


Haha Now that's funny:laughing:


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## Redwood (Sep 8, 2008)

sparky said:


> How much slope should you put on the return line??1/8"-1/4" or as much as possible??





sparky said:


> So as the hot water cools off then that is what allows the flow to take place, is this what I'm reading here???excuse my ignorance on this but this is a first for me and I don't care to tell you I'm lost on this and never heard or seen it before.


More pitch is better but it must all be pitched, any backpitch or, places where the pipe goes up will create a heat trap and stop the flow. Then you'll need a pump.

con·vec·tion noun \kən-ˈvek-shən\ : *movement in a gas or liquid in which the warmer parts move up and the colder parts move down;* 
also : the transfer of heat by this movement

1: the action or process of conveying
2a : the circulatory motion that occurs in a fluid at a nonuniform temperature owing to the variation of its density and the action of gravity
b : the transfer of heat by convection — compare conduction, radiation
— con·vec·tion·al adjective


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## rjbphd (Feb 5, 2010)

Redwood said:


> More pitch is better but it must all be pitched, any backpitch or, places where the pipe goes up will create a heat trap and stop the flow. Then you'll need a pump.
> 
> con·vec·tion noun \kən-ˈvek-shən\ : movement in a gas or liquid in which the warmer parts move up and the colder parts move down;
> also : the transfer of heat by this movement
> ...


Pitch like waste pipe..


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## Titletownplumbr (Feb 16, 2011)

rjbphd said:


> Want to do it right??? Tie the 1/2" return to the drain connection without checkvalve and no stinking pump!


Yep, that's how I do mine. My own house has been like this for 11 years and it works like a charm.


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## sparky (Jan 8, 2014)

Redwood said:


> More pitch is better but it must all be pitched, any backpitch or, places where the pipe goes up will create a heat trap and stop the flow. Then you'll need a pump.
> 
> con·vec·tion noun \kən-ˈvek-shən\ : *movement in a gas or liquid in which the warmer parts move up and the colder parts move down;*
> also : the transfer of heat by this movement
> ...


Ok but what about the existing hot water line??it is not pitched at all,just nailed to bottom of joists so will this make a difference??or can I just put pitch on the return line where it goes back to the heater??


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## rjbphd (Feb 5, 2010)

sparky said:


> Ok but what about the existing hot water line??it is not pitched at all,just nailed to bottom of joists so will this make a difference??or can I just put pitch on the return line where it goes back to the heater??


 That part u can't do much about.. but getting the pipe from the hot side of shower and pitch the return down to heater..


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