[Robert Gift]

If I install a 1/4 inch return flow pipe from kitchen sink faucet to the bottom of the water heater, will I have immediate warm water at the kitchen sink?
I would connect it to the water heater tank drain. Or could I connect it to the cold water supply line?

The hot water pipe out of the water heater is insulated up to the sink.

Thank you.

Robert

[ballengerb1]

This is not how you create a water recirc system. Check out this Hot Water Circulating Systems (Recirculating Pumps & Recirc Pumps)

[hkstroud]

Unless you are going to install a recirculating pump you will need a larger pipe back to the water heater.
The connections would be somewhere in the vicinity of the kitchen faucet and the cold water input line just before it enters the water heater. You must install a check valve in the cold input line to prevent hot water from going back up the cold water line. You must install a check valve in the recirculation line to prevent cold water from entering the recirculation line.

If the kitchen faucet is on a higher level (i.e an upper floor) natural, hot water rising, cold water falling will cause a circulation for a period. It will cease as water temperatures equalize. Use of hot water anywhere will cause make up water to be drawn into the water heater. As that make up water passes the connection of the recirculation line it will create a low pressure (relatively speaking) on the recirculation line and the circulation of hot water to the kitchen faucet will begin again.

[Robert Gift]

This is not how you create a water recirc system. Check out this Hot Water Circulating Systems (Recirculating Pumps & Recirc Pumps)

Thanks, gerb
The kitchen is on a separate branch line. A circulation pump, which may be worth it if it does ALL the sinks, would only do that sink.

I'd like to accomplish it passively without power, anyway.

[hkstroud]

The recirculation line will affect only the branch line it is on. Try the passive approach first, then install circulation pump if necessary.

Mine, which runs from basement to second story bath, only fails sometimes first thing in the morning when not hot water has been used for long period.

[Robert Gift]

Thanks, hk.
The water heater is in the basement and kitchen on first floor.
A tee above the hot water valve in the sink cabinet would be 5' 4 inches above the water heater tank.
Would check valves not defeat a delicate convective flow?

[ballengerb1]

There is no convection flow in plumbing pipes. You have a sealed system, no movement, when all fixtures are closed. Open a faucet and you get flow but not circulation like you may be picturing. You need a circulation pump to keep hot awter at your tap at all times. There is a system that, when you open a hot tap, it initially pushes the cool watrer that would go down the drain back down the cold water supply pipe. This saves water and does get hot water to you twice as fast but not instantly. Check out this design Hot Water Circulating Systems - Cold Water Return for Instant Hot Water

[Robert Gift]

There is no convection flow in plumbing pipes. You have a sealed system, no movement, when all fixtures are closed. ...

Would not a return pipe to the bottom of the tank allow a convective flow?
I like that return pump idea, buthat would be expen$ive and require an electrical outlet under the sink - which I could do.

[hkstroud]

Have to disagree Bob. With a return line there is a circulation flow. As stated above, I have it and it works.

Robert
You wouldn't want to try tap into the bottom of the tank. You might could do it through the drain valve but you wouldn't want to do it. Remember the hottest water is at the top of the tank and you lose the benefit of the siphoning action that occurs on the recirculation line when make up water comes into the tank.

If you put in a pump, it can be any where on the recirculation line. Most often it is located at the water heater.

[Robert Gift]

...You wouldn't want to try tap into the bottom of the tank. You might could do it through the drain valve but you wouldn't want to do it. Remember the hottest water is at the top of the tank and you lose the benefit of the siphoning action that occurs on the recirculation line when make up water comes into the tank. ...

If I do this, could I do this with the tank still full of water? I would do this when we return from a work trip so the water would be cool from the heater being off. Close the intake and outflow valves on top of the tank. Unscrew the drain hose bib and quickly screw in a capped pipe. Or would I create vacuum and implode the tank enough to damage it?
Then install a TEE to the drain hose bib for the return convective flow cool water. Then I could still drain sediment periodically.

If I bring the return convective cool water into that tank drain port, there is more differential to create convective flow.

Can't afford a pump for just the kitchen sink -unless I install another pipe to reroute the hot water to the supply line feeding the upstairs fixtures.

[hkstroud]

No, you would have to drain the tank.

There is no advantage to trying to do it that way.

The cold make up water in taken to the bottom of the tank by the dip tube. Therefore so would the recirculated hot water. What I am saying is that the taking the recirculated water to the bottom has already been done for you when you tap into the cold water line. As previously stated you would also lose the benefits of the siphoning action on the recirculation line caused by the cold make up water passing the port.

You situation differs from mine only in that I have two floors of elevation and you have only one. The system as described should work, why make it more difficult.

[Robert Gift]

... The system as described should work, why make it more difficult.

Thanks.
I'd much rather not drain the water and would prefer to tee into the cold water line.
Did not know how far down the dip tubextends.
But, the dip tube water is quickly heated.
The cool water return would remain cool until inside the tank at the bottom.
Will convective flow occur with the return Teed into the cold water line?