Replacing a Water Heater: Plans and Instructions (page 2 of 3)

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Out With The Old, In With The New

Follow our photo series for the step-by-step installation process. These tips will make your work go faster and easier:

Measure the height of your old water heater and buy a new one the same height so you don’t have to change the length of the water, gas or electrical lines.
The drain valve on old water heaters often clogs up. If the water drains slowly, be patient.

CAUTION: It’s scalding hot!
TIP: Turn your water heater off two hours in advance to allow the water to cool.
Water heaters weigh about 150 lbs. You’ll need a strong helper or a dolly when you move the old one out and wheel the new one in. Garbage services typically charge about $25 to take the old one.
Before you start, buy the tools and materials shown here at a plumbing supply or hardware store or a home center. Check the sizes of the water supply pipes (most will be 3/4 in. like the ones in our photos) and buy the right-size fittings. With everything on hand, you’ll need four to six hours to complete the job (assuming no big hitches!).
The temperature and pressure relief valve is a safety device that limits tank pressure and keeps it from exploding. A new one must be included with every installation. For the valve to work properly, the discharge pipe must be kept free of obstructions (Fig. A).
In regions with highly mineralized water, or where required by local codes, use 3/4-in. plastic-lined nipples (about $2 each; Fig. A) for joining different metals, usually copper tubing to the steel tank. This slows corrosion.
When connecting the water lines, solder the copper fittings before you screw them to the tank so you don’t heat the tank itself while soldering.
Use “slip” couplings to connect the old and new lines. Unlike regular couplings, they don’t have an internal stop. You can slide them on, align the copper tubing, then slide them back and center them over the joint.
The new inlets and outlets on the tank don’t always line up with the old supply lines. Solder in a pair of 45-degree fittings to offset each line if necessary. Also replace the old shutoff valve with a new ball valve while you’re at it.

FIG.A Water Gas Heater Details

Click image to enlarge.

Check the manufacturer’s instructions for correct vent size. Vent diameters are sized according to the heat output of the water heater. You might have to increase or decrease the vent size to ensure the best draft.

CAUTION: If you’re unsure if your chimney has a liner, ask your plumbing inspector.
Make gas connections with solid steel pipe or soft copper with flare fittings (Fig. A). Both are more reliable and less expensive than flexible stainless steel connectors, which are not always permitted. Use rigid copper rather than flexible copper water supply lines for the same reasons.
If you locate your water heater where leakage could cause damage to the floor or other parts of the house, set a pan of an approved size under it (metal for gas water heaters). The pan must have a drain tube that leads to a house drain or other approved location (outdoors where permitted). The temperature and pressure relief valve discharge tube also must lead to a drain if leakage would damage the floors. If routing is difficult, discuss options with your local plumbing inspector.
If you live in an earthquake-prone region, strap the water heater to the wall with special straps (Fig. A; $20 at plumbing stores and home centers). Your plumbing inspector will tell you if they’re required.
Set the new water temperature setting to no more than 120 degrees F to avoid scalding.