How Is a Water Heater Plumbed?


– How to connect a water heater?

– Coldwater connections

– Hot water connections

Are you installing a storage water heater or instantaneous water heater? In both cases, you must connect the water heater to the water supply before connecting it to the energy source:

– Electricity, using the electrical diagram for water heaters;

– gas (town gas, butane, or propane);

– solar (this is the primary circuit containing the heat-transfer fluid).

Before connecting the water heater, you will have to fix it (a tripod installation does not exclude its fixing!). In the case of a storage water heater, make sure that the mounting and support can support the weight of the water heater when loaded, and use supports suitable for heavy loads.

Caution: Before working on your water heater, take the time to read the manufacturer’s instructions carefully.

Connection steps

The installation of a water heater requires several types of plumbing connections, depending on its type and the configuration of the plumbing system:

– the connection to the cold water supply;

– the connection to the hot water outlet;

– possibly the connection to a buffer tank:

◦ installed downstream of the water heater;

◦ which complements your heating system to ensure your comfort, i.e. an additional hot water reserve.

– possibly the connection to a pressure reducer for water heaters:

◦ installed upstream of the safety group, on the main pipe, ideally just after the water meter ;

◦ if the water pressure in your pipes is too high (over 5.5 bars): this will avoid problems on your installation in general and on your water heater in particular.

Connections to cold water

Case of the storage water heater (or cumulus)

The connection of the cumulus to the cold water supply can be of two types:

– The most frequent case, with a safety group:

◦ installed just upstream of the water heater on the cold water inlet;

◦ acts as a safety valve to evacuate excess water due to expansion and serves as a shut-off valve.

– For water heaters with a capacity of fewer than 15 liters: in free flow, with a special tap that allows the direct flow of excess water, and which acts as a safety group.

Please note: before connecting the water heater, open the cold water supply, allow the appliance to fill up, and let the air out of the pipes and the water heater.

Instantaneous water heater

Connecting a tankless water heater to the cold water supply does not pose any particular problems.

Special cases of horizontal water heaters

Because of its shape, a horizontal water heater can be supplied from the side (right or left) or from below: before you buy, you must make sure that you choose the right power supply for your configuration.

Caution: for most horizontal water heater models, the mounting positions cannot be changed.

Hot water connections

The bimetallic dielectric fitting

In accordance with the NF C15-100 standard, the installation of a dielectric fitting is mandatory on the hot water outlet of the cumulus. The bimetallic dielectric fitting is an anti-corrosion system:

– installed directly at the hot water outlet;

– whose function is to reduce the corrosion of the cumulus by an electrochemical couple, i.e. the electrolysis effect which occurs between the steel of the cumulus and the copper piping);

– generally supplied with the cumulus.

For its installation, please refer to the manual of your appliance.

The temperature limiter

When connecting the water heater, if your pipes are made of synthetic material (PER, multilayer, etc.), you must install a temperature limiter at the hot water outlet of the water heater. This device guarantees a water temperature below 50°C.

Otherwise, you expose your installation to pipe bursting, as the resistance of these materials to temperature is limited, and therefore to flooding.

Hope the above helps you out! For more help, you can also get in touch with a professional plumber. And, remember to share your comments below.

How Is a Water Heater Plumbed?

One thought on “How Is a Water Heater Plumbed?

  • 04/16/2023 at 14:05

    Thanks for the reminder that it’s important to also consider the temperature regulation when getting a new water heater installed. I’d like to find a good contractor for that because I’m thinking about getting some improvements for my bathroom soon. Being able to get hot baths more easily will be great for long weekdays.


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