DIY Series 33: Water Heater No Hot Water? How to fix it?

Instant Water Heater: Magnet & Reed Switch

How Does a Reed Switch Work?

[Source]: https://lastminuteengineers.com/reed-switch-arduino-tutorial/

The two contacts of a reed switch become opposite magnetic poles, which is why they attract and snap together. It doesn’t matter which end of the magnet you bring closer: the contacts still polarize in opposite ways and attract each other.

When you take the magnet away, the contacts separate and return back to their original position.

How to fix your Water Heater?

If your home water heater is not supplying hot water, it might be caused by one of the followings:

1. Faulty Magnet or/and Reed Switch
2. Faulty Heating Element
3. Faulty Thermostat
4. Blown Fuse

I would like to share specifically on Item (1), where the magnet is broken/malfunction, however the Reed Switch is still working fine.

Video:

• 1st part of the video shows the magnet is away from the Reed Switch or broken, "Heater" LED is OFF, thus the water heater is NOT working. 
• 2nd part of the video shows the magnet (good condition) is purposely pushed to be near to Reed Switch, "Heater" LED is ON, thus the water heater is working.

Photos:

• 1st Photo: You can refer to [Before] & [After] fixing with the new flow sensor magnet.
• 2nd Photo: Refer to this photo for procedures to remove the broken magnet.
• 3rd Photo: Refer to this photo for procedures to insert a new magnet.
• 4th Photo: Refer to this photo if you need to change a new Reed Switch.

Tools required:

• Screwdriver, plyer, screw (to remove the stopper in order to take out the magnet)

Costs involved: 

• Magnet = US$2.20 (roughly) 
• Reed Switch = US$1.10 (roughly)

[ Pensonic PWH-800E ]

Same flow sensor (magnet) is used by Pensonic PWH-800E. Thus, you can follow the same DIY steps to do the fixing.

Photos:

1. Pensonic PWH-800E
2. Use a screw and plier to remove the stopper
3. Replace the broke flow sensor (magnet) with a new one
4. New flow sensor (magnet)