Removal of plastic heat trap from new Rheem water heater for recirculating gravity loop

[Quicksilver340]

I just replaced an old traditional GE water heater with a new Rheem water heater (also traditional). I have two gravity recirculating loops that worked great with old water heater. They don't work with new heater. After some research, I think it's because the new heater has heat trap inserts in both the hot and cold nipples (made of plastic / rubber flaps). These inserts are doing their job and preventing "leakage" which in my case would be intentional with the hot water rising and cold returning in a gravity loop.

Any thoughts on the above? How easy is it to remove these heat traps? The hot side trap is at the top of the nipple, but the cold side trap is deeper in the nipple due to a leak detection/auto shut off valve mechanism.

 

[Reach4]

Not going to tee into the drain valve hole for the cold?

 

[Sponsor]

 

[Quicksilver340]

I actually have two separate gravity loops (setup existed when I purchased the house). One return is going into the drain valve and the other merging into the cold inlet.

 

[Mliu]

Not going to tee into the drain valve hole for the cold?

I honestly see no advantage in plumbing a recirc line into the tank's drain valve. What would be the reasons for doing so?

 

[Reach4]

I honestly see no advantage in plumbing a recirc line into the tank's drain valve. What would be the reasons for doing so?

Gravity. More drop on the way to the cold water entrance.

 

[Mliu]

Gravity. More drop on the way to the cold water entrance.

I did think about this for a gravity-recirculation system (it would have no bearing on a pump recirc system). But for a gravity system, would 2.5 to 4.5 feet of dip tube length really make a significant difference in overall performance? I suppose if it's in a single-story house (with the heater in the basement), it might. For a two-story house, probably not so much.

 

[Reach4]

I did think about this for a gravity-recirculation system (it would have no bearing on a pump recirc system). But for a gravity system, would 2.5 to 4.5 feet of dip tube length really make a significant difference in overall performance? I suppose if it's in a single-story house (with the heater in the basement), it might. For a two-story house, probably not so much.

It has to matter. There is a siphon effect to help drive the hot up as the cold comes down, but I think the bottom of the pipe carrying the cooled water will have to be lower than the bottom of the pipe carrying the hot. The way I see it, no altitude difference, no gravity-driven flow.

But wait! How is it Quicksilver340 had a loop that connected at the top, and that loop still worked? I think that would have fed the cold into the dip tube, and its output was lower. The flow would have been slowed by the heating in the dip tube fighting the water falling in the dip tube. However the new dip tube will have a small hole at the top of the dip tube to try to prevent siphoning and a resulting vacuum. This hole may be small enough to be overcome, but the loops will work better if the cold comes in low.

 

[Quicksilver340]

Well both loops worked with old heater and now they don't with the same setup, except for the plastic heat traps in the nipples. Anyone have experience removing those?

 

[Lladnar]

New energy saver water heaters (WH) now come with vertical (top-mounted) heat trap nipples to reduce heat loss by up to 60% from convection.

On vertical models, the cold water inlet (blue cap) features a dip tube containing a thermoplastic or Teflon ball which is lighter than water and floats to its seat when the incoming downward water flow stops. This prevents the hot water from rising into the cold water supply line. The hot water outlet (red cap) contains a polypropylene ball that is heavier than water and sinks to seat when the outgoing upward water flow stops.

In order for a thermo-cycle system to function properly, the vertical heat trap for the hot water must be replaced with a regular nipple to allow the free flow of hot water. The heat trap for the cold can remain installed.

Without a check valve on the return line, when the hot water is turned on water from both directions, the hot line and the return line, will rush towards the faucet.

A check valve is required to prevent the colder water at the bottom of the WH from being sucked out and back up through the return line when the hot is turned on resulting in cooler water arriving at the fixture, especially if the return line is a smaller diameter allowing the cooler water to arrive sooner and continuously mix with the water from the hot line resulting in luke warm water. As the hot water is replaced with cold supply piped to the bottom of the WH the return line becomes even colder.

There are several types of check valves: spring, swing, and ball. For thermo-cycling, the spring is too powerful. The swing must be mounted horizontally and maybe even a little tilted and maybe with a hole.

I am considering installing a ball-type check valve for cold water (ball floats) in the vertical input line to the bottom of the water heater to prevent pulling the colder water into the hot water return line and back to the last fixture in the loop. The vertical cold water ball valve will float at the top preventing any water from traveling up the return line from the bottom of the tank. And the floating ball should not interfere with the cooler water 'falling' down into the bottom of the WH.

I think a picture would help. Does this sound correct? If so, I can draw up a sketch to visualize the thermo-cycle system.