[vigsom]

Introduction

This is a set of work instructions on how to replace the heating element in a home water heater (Instant or Storage), and is intended purely for those who want to trudge the DIY path. Some of what is described might also help in fault diagnosis and rectification instead of waiting for a service provider.

My experience with water heaters this far

We have been used to the good old immersion water heaters at home - very quick way of making hot water. Post that, when I moved for work and stayed at leased accommodation, the flats/ houses would sport instant water heaters which would dispense hot water albeit at a slow rate. I was always wary of such heaters and would never feel the water when the heater was powered on since I was never sure of the earthing in those houses. Although I have used several water heaters, the opportunity to open one up presented itself earlier this month, when the water heater at my place was slow in heating, which was a clear indication that the heating element had weakened. Repeated service requests with a service provider were in vain and hence I decided to do this up myself.



About the heater

This is a 3 liter AO Smith water heater meant for supplying warm water in the kitchen, but we found this installed in the bathrooms when we moved into this apartment. The limitation with this heater is that unlike the "rectangular" instant water heaters meant for bathrooms, this would run out of steam (or rather heat) if the tap were to be turned on a little more than the capacity of the heater. Although there is a water softening unit in our apartment complex, this heater has seen the heating element replaced thrice - twice under warranty and one outside warranty (that I just did).

[vigsom]

Removing the heater from position

1. Remove the heater plug from the 220V AC socket and wind the cable so that it doesn't interfere in the heater removal process
2. Close the valve feeding water to the heater
3. Open the hot water side of the mixer to drain contents in the hot water pipe
4. Using a screw spanner, remove the hose connections to the heater. Make sure to identify the inlet water and the outlet hot water hoses so that they can be connected back right after re-installing the heater
5. The heater would have 3 liters of water plus its empty weight of approx.1.5kg, which would mean a total weight of approx. 4.5kg. Lift the heater from the bottom to take it off the mounting bolts/screws on the wall
6. While lowering the heater unit, tilting it would result in some water spilling out; try removing as much water as possible

Disassembly

1. Invert the heater, open the screws holding the outer case to the heater unit
2. Take a few pics of the wiring routing and the way components have been installed so that it serves as a good aide while re-assembling

Picture taken for reference


Note a: The thermostat marked red is the trip thermostat - this is set at 75 deg.C and can be reset using the red button on the case which actuates the white trip reset button on the thermostat

Note b: The thermostat marked green is the temperature control, set at 55 deg.C. This cuts power supply off at this temperature, and resumes supply when the temperature drops back to around that value

Thermostats marked by red and green arrows



3. Remove the power supply connections to the heater unit viz. the trip thermostat and the heating element
4. Remove the thermostat assemblies from the tank cap by just pulling them up carefully
5. Open all nuts on the heater tank top plate - this plate houses the water inlet and outlet tubes, and the heating element. Note the orientation of the heating element - take a pic for reference
6. The tank top plate will come off as one unit

Top plate removed - note the scaling




7. Clean the tank internals of all the scale, inspect the heating element, and replace the element with a new one if the old one is cracked, damaged or shorted. I'd recommend a change of element even if the slightest damage is seen (in my case the element was already on its way out although I was thinking that it could be scaled up causing low heat transfer)

Heating element damaged - note the crack


Tank before cleaning


Tank after cleaning


8. Install the new heating element, taking due care to ensure that the rubber gaskets and insulating washers are properly installed and tightened

Confirmatory test

Introduce power supply to the heater for 1-2 seconds to check if the heating element gets warm - this is just to confirm that the continuity is good before re-assembly

Re-assembly

Re-assemble the unit by reversing Disassembly steps 5,4,3 and 1 in referring to the pics already taken. Care is to be taken to ensure that the earthing mark on the plate is at the longest stud (bolt) so that the unit aligns right with the mounting screws on the wall.

While tightening the tank top plate, ensure that tightening is gradual and diagonally opposite nuts are tightened, then the next two diagonally opposite nuts and so on

Unit re-assembly in progress with a new heating element


Re-installation

1. Place the heater unit back in position by putting it securely on the two bolts/screws on the wall
2. Connect the inlet and outlet hoses right
3. Open the water supply valve a bit and allow the unit tank to fill up - note for leaks if any
4. Once the tank is filled, open the mixer hot water valve a little to remove trapped air, until water issues out
5. Keep the valve opened, power the heater on and check for heater operation



Total time taken

It took me a total of 4 hours from removing the unit off the wall to disassembly to going 4km away, purchasing the right heating element, returning and re-installating the unit.

Expenses

The OE heating element was priced at INR 1200 via "Company Service", while I managed to procure a higher capacity heating element of good quality at INR 400.

Thank You for the patient read!

[Aditya]

Thread moved out from the Assembly Line. Thanks for sharing!

[Amrik Singh]

This type of Water is generally termed as Instant Water Heater in which there is very little Hot Water holding capacity but a relatively higher wattage heating element. This provides a fairly comfortable hot water albeit for a short time. The temperature of water will vary quickly.
On the other hand, Water heaters for bathrooms are generally above 15 litres capacity and one can get warm water at a nearly constant temperature during the bath.

[dhanushs]

Originally Posted by Amrik Singh

... one can get warm water at a nearly constant temperature during the bath.

If you are living in a not so cold place, this would be the ideal option as it heats up the water quickly, and you dont need to wait unlike the bigger ones.

However, in extremely cold places, this wont work if you want a steaming hot bath.

[Amrik Singh]

Originally Posted by dhanushs

If you are living in a not so cold place, this would be the ideal option as it heats up the water quickly, and you dont need to wait unlike the bigger ones.

However, in extremely cold places, this wont work if you want a steaming hot bath.

My point was a supply of water at fairly constant temperature during bath.

[Benoit]

Interesting thread. I have always wanted to do some DIY with household appliances. But I have always restrained myself as I didn't want to risk playing with electric power. The result could be fatal if proper care is not taken.

Please share the results. How much has the heating improved?

[Miyata]

Vigsom - What do you use for the inner tank cleaning? I have replaced the heating elements of the geysers our home, but only largely done a superficial cleaning of the inner tank.

Also, when buying the heating element, I've felt it might be good to take along the older heating element part to the store for good matching with the new / replacement part. Mismatches can lead to leaks.

[GTO]

Perfect timing for this thread, thanks Vigsom!

Guys, what are the best & fast water heaters? I like my showers long (15 minutes, sometimes 20) & piping hot. Current geyser was bought decades back and takes 15 - 20 minutes to really boil things up.

[ravib]

Originally Posted by GTO

Perfect timing for this thread, thanks Vigsom!

Guys, what are the best & fast water heaters? I like my showers long (15 minutes, sometimes 20) & piping hot. Current geyser was bought decades back and takes 15 - 20 minutes to really boil things up.

Hello GTO, i suggest you to go with AO Smith and found it to be very reliable, best and fast over years. Prior to that was using Venus which was great, but was more power consuming. With 5 star rated A0 Smith water heaters, it is super quick.

And like you, i do enjoy longer showers in hot water in Bangalore cold weather, so it works out well

-Ravi

[amit_purohit20]

An instant water heater with no storage capacity (normally less than or equal to 3 litres) is good to save electricity when family members take bath at different times of the day. It's good for small families. It cannot provide hot water with sufficient amount of water flow through shower. Either you have to compromise with water flow rate or the temperature of water. I prefer instant water heaters because I am ok with the bare minimal flow through shower and get the temperature right by initially heating the water without letting the water flow out of the geyser. Plus I stay in Pune where ambient temperatures are not very cold like Delhi.

Storage type of water heaters are good when you need a good flow of water plus it should be piping hot. They save energy only when family members take bath one after another ie. no reheating of stored water again and again is required. Storage types save energy when you prefer long baths as the wattage of the heating coil is less.

Instant water heaters are easy to maintain and especially when you can yourself replace the coil. The coils don't last more than 1.5 to 2 years when in contact with hard water. Good brands are Bajaj, Racold. Personally I prefer Bajaj as spare parts are easily available and found no difference in longevity of parts when compared to foreign brands. I hope this helps

[Amrik Singh]

Installing Solar Water Heaters as pre Heaters to supply Water to Water Heaters is an energy saving technique. However, it may not be feasible on existing bathrooms as piping may have to be done accordingly.

[PreludeSH]

Originally Posted by Amrik Singh

Installing Solar Water Heaters as pre Heaters to supply Water to Water Heaters is an energy saving technique. However, it may not be feasible on existing bathrooms as piping may have to be done accordingly.

True. In Bengaluru, with rain and clouds almost 9 months the solar heater can just provide luke warm water most of the time ! Only for 3 months we can use pure solar heated water. Its still better than nothing

[saket77]

Got the same done to my Racold water geyser (storage type) a few days back. Replaced the heating element from normal type to instant geyser type. The difference between the two, physically, is that the normal storage type heater elements have long coils while the instant geyser coil is more like that of immersion rod to look at. Technically, storage geyser heater elements are rated at 2000W whereas instant geyser coils are of 3000W. This helps in quicker heating of water as I have noticed. This modification required change of thermostat too as the storage geyser type thermostat is longer.

Heating elements at our place are sold at higher prices than what I anticipated- Rs. 1300-1400. Cost of thermostat was another Rs. 300/-. This is the second time I have changed the heater element of my storage geyser. Next time it fails, I would change the entire set or go with company service as the original heater elements have a much longer life as compared to ones sold in open market- my observation.

Regarding the best heaters in market, I would say Racold, AO Smith and Crompton are among the best.

[sagarpadaki]

Originally Posted by GTO

Guys, what are the best & fast water heaters? I like my showers long (15 minutes, sometimes 20) & piping hot. Current geyser was bought decades back and takes 15 - 20 minutes to really boil things up.

Get a 25L capacity cylindrical geyser from any reputed brand and it should meet your long and hot shower requirements.