Water Heaters - Recent Questions, Troubleshooting & Support

I wonder if you have this problem below caused by a drop in water pressure from someone flushing a toilet or a washing machine. I would call the company to remedy this issue.

17. What is a cold water sandwich effect? The term “cold water sandwich effect” is a term that is used to describe the introduction of cold water into the hot water supply line during frequent on/off operation of an instantaneous water heater. The cold water sandwich effect, when present, appears as a momentary drop in hot water temperature as it is discharged from a hot water supply outlet (i.e. shower, tub, or faucet). This phenomenon is present in the operation of all instantaneous, tankless style, water heaters, but is minimized with the high tech design of Rinnai water heaters.
The technology built into the Rinnai water heaters is designed to minimize the cold water sandwich effect. Rinnai water heaters are microprocessor controlled and when water flow through them ceases, they remain in a “ready to fire state” for approximately 1 minute. If water flow through a Rinnai water heater begins within the first minute following water flow stoppage, the water heater will fire back up within 1 to 2 seconds. This minimizes the cold water sandwich effect that would otherwise be experienced with a low tech tankless water heater. It should be noted that the cold water sandwich effect cannot be removed completely from tankless style water heaters. The safety standards developed to insure the safe operation of water heaters require a delay in the ignition sequence of all gas water heaters.
While the cold water sandwich effect cannot be completely eliminated from standard plumbing systems, it can be eliminated from plumbing systems that have a supply and return hot water circulating system. Rinnai has developed 2 methods to eliminate the cold water sandwich effect in residential hot water circulating systems.
The first (and preferred) method to remove the cold water sandwich from circulating systems utilizes a small electric tank water heater (powered up) that is used with a dual purpose. The small water heater acts as a mixing tank to eliminate the cold water sandwich effect from the Rinnai water heater and it uses its electric heating element to offset the heat losses from the hot water circulating system.
The second method to remove the cold water sandwich from circulating systems utilizes a small 2 to 6 gallon storage tank installed on the hot water outlet of the Rinnai water heater. This tank acts as a mixing tank to blend the cold water sandwich with hot water and eliminating its effect at fixtures.

Rinnai Water... | Answered 5 hours ago

Attempting to replace the flutter valve is ambitious and may be a ticket to a more expensive repair. First you need to locate the valve and then decide if you have the tools and skill to attempt the job. I would look at the manufacturer's website for an exploded view of the water heater and then go to your water heater and check it out. You will need to seal the threads on the line the valve is attached to, so a trip to a plumbing shop or a hardware store is also in order. By the time you pay for the sealant and your time and effort in finding the part you may be money ahead to leave this to a pro. The only web references I could find for the name and model of your water heater were in Indonesian, so good luck finding English translations of their technical materials.

Water Water... | Answered 11 hours ago

Look it up on the internet - use the model number to find a manual.

Water Water... | Answered 18 hours ago

Try mounting on rubber standoffs. The mechanical timers are noisy and when mounted on a wall that amplifies the noisy.

As a test, un bolt it from the wall and see if noise is acceptable. If so, find a cushioned mount.

Intermatic WH40... | Answered 2 days ago

make sure the water supply linee is on,and water outlet line is open.,and unit is plugged in.
If all are...u got a bad unit.

Water Water... | Answered 2 days ago

The problem might be fixed by removing the cartridge and cleaning it thourghly and resetting temp stop.Yes the cartridge could be bad but new parts are readily available. Depending on water quality conditions in you area it may be difficult to disassemble so it may be a good idea to have a plumber do it for you. Thank you.

Grohe Grohmix... | Answered 3 days ago

check the pressure control that switches the element on or off
if it is faulty then it switches on when the tap is turned on dropping the pressure but it will not recognize that the increase in pressure when the tap is turned off so it keeps heating the water.

Stiebel Eltron... | Answered on Jan 13, 2019

It does that with weak batteries - try replacing with fresh batteries.

Water Heaters | Answered on Jan 11, 2019


Water Heaters | Answered on Jan 10, 2019

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