Replacing a Hot Water Thermostat with Appliance Spare Parts

A man replacing a Hot Water thermostat with appliance spare parts
  • Author: Mahwish Habib
  • Posted On: October 17, 2022
  • Updated On: September 19, 2023

Hot water systems deteriorate over time, just like any other home appliance. Unfortunately, we don’t usually think to check them until it’s too late and they stop working altogether. If you’re facing a hot water system that’s no longer giving you hot water, there are two faults likely to be at blame: the thermostat, or the heating element.

DIY replacement of either is achievable with appliance spare parts. If you’re looking to save yourself money by not calling out a service technician, read on to find out how to replace these with the help of some appliance parts and our instructions for replacing your hot water thermostat at home.

Parts of a hot water system

Water heating is a significant expense for most homeowners, consuming up to 30% of household energy, and electric hot water systems are popular because they’re cheap. Also, it is easy to buy and install the thermostat. They’re made up of the following parts:

  • A storage tank to store the hot water system’s water
  • A drain valve for draining the tank if it ever needs to be moved or repaired
  • An anode rod to offset potential tank corrosion
  • Heater elements to generate heat for heating the water
  • Thermostats to control and regulate the storage tank’s water temperature
  • A temperature pressure relief valve to manage excess pressure and temperatures in the tank

Signs of a faulty thermostat

Hot water tanks have two thermostats and two heating elements in most residential systems, which take care of heating the water in the tank and maintaining the temperature.

Signs of a faulty hot water thermostat will be:

  • Inconsistent hot water
  • No hot water
  • The water taking too long to reheat

The hot water system has an upper thermostat and a lower thermostat, and identifying which one is at fault is important. A faulty upper thermostat will cause the tank to stop water heating completely, whereas a faulty lower thermostat will result in lukewarm water or water that quickly runs out.

To fix either thermostat yourself, you’ll need a few tools, including a screwdriver, an analogue or digital multimeter, and the replacement appliance spare parts for the thermostat.

Replacing a hot water system thermostat

The first thing you need to do is go to the mains power board and turn off the water heater breaker to stop power to it.

Next, clear the surrounding area of everything such as plant pots or shoes. Then, remove the exterior access covers on the hot water system, and remove the insulation to see the top thermostat and heating element under a plastic cover.

Push the built-in circuit breaker button on the thermostat to reset it; an audible snap will be heard if the unit has tripped, so if you hear this, it’s good news – turn the power back on, and the water will start heating again. If you don’t hear the snap, one of the thermostats is faulty, so you need to determine which one and replace it. To do this:

  1. Remove the plastic cover that sits over the thermostat
  2. Use the multimeter to test the top two screws for power running to the unit; you should detect no voltage. Do not continue until you are entirely sure there’s no power to the hot water system
  3. Remove the terminal screws to disconnect the wiring connections
  4. Use the black probe of your multimeter to test the left side terminal next to the thermostat’s reset button, with the multimeter set to the lowest ohms of resistance
  5. Repeat with the red probe to test the second terminal on the lefthand side; if the thermostat is not faulty, then the reading for both sides will be close to 0
  6. Repeat for the righthand side of the thermostat to determine which thermostat is faulty

Once you’ve determined which thermostat is defective, it’s time to replace your thermostat with your appliance parts:

  1. Take the faulty thermostat out by pressing out on the clips to remove it out of the bracket – use the utmost caution at this step because if you accidentally damage the bracket, it can’t be replaced, so you’ll be looking at having to replace your water hot water system in its entirety
  2. Carefully insert the new thermostat, tightly rewire it, and set the temperature to 65oC (149 oF)
  3. Put the plastic cover back over it
  4. Flip the water heater breaker back on at the mains to restore power, and you should have hot water in around an hour once the water tank heats up.

Get replacement appliance parts for hot water systems

A household without hot water is usually an unhappy one, so getting your hot water system back up and working quickly is important.

Home replacement of a thermostat is realistically doable if you’re a capable home handyman or woman with the right tools and appliance parts from a trusted wholesale spare parts stockist.

Don’t suffer through cold showers and washing the dishes by hand in cold water – the ready availability of appliance spare parts means you can get your hot water system running without fault or delay.

Avatar photo
Author: Mahwish Habib

Mahwish is known as the lifestyle editor for ConstructionHow. She works as a professional graphic designer with a focal eye toward aesthetics and overall looks for the ConstructionHow. She manages a small internal team responsible for creating unique graphics for the articles. She also provides her services as an interior decorator, enabling her to understand the language of every threshold. Embracing diverse styles, she finds the perfect opportunity to create attractive designs.