In this video, This Old House plumbing and heating expert Richard Trethewey installs a reserve tank so a homeowner can finally fill their tub with hot water for a relaxing bath.

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Plumbing and heating expert Richard Trethewey helps a homeowner solve a hot water shortage problem. Thinking that they had an on-demand water heater, the homeowner couldn't understand why the water from the tub spout would cool before the tub would fill. Richard discovers it's a combi unit with a water tank and helps the homeowner solve the problem by installing a reserve tank.

Difficulty: ⅖
Time: One day
Cost: Around $2,000 including the tank

Where to find it?
Richard Trethewey helps a homeowner understand how different flow rates in water fixtures could be the culprit behind a bathtub that turns cold after only being halfway filled.

Richard discovers the tankless water heater [https://www.thisoldhouse.com/plumbing...] can’t keep up with the tub spout’s flow rate. He suggests installing a separate 80-gallon reserve tank [https://homedepot.sjv.io/6ekgLK] that can easily handle the 60-gallon soaker tub. With the assistance of a plumbing specialist, an ideal location for the new unit is identified. Richard suggests an area near the existing tank that isn’t prone to freezing.

After disconnecting the electrical supply, connect the tankless inlet to a bronze or stainless-steel
circulator. On the tank, tankless outlet, use both thread tape [https://homedepot.sjv.io/m542qe] and pipe dope [https://homedepot.sjv.io/daK9DM] and connect a 3/4 inch tube adapter [https://homedepot.sjv.io/75XJ6A] and connect this to the hot tankless coil outlet on the boiler. Use both thread tape and pipe dope to connect a 3/4 inch NPT brass tee [https://homedepot.sjv.io/eKnAWr]. In the run of the brass tee, install a 3/4 inch NPT brass Ts [https://homedepot.sjv.io/AWgEN1] long element for hot water heaters, as required by local codes. In the bottom of the tee vertically down, install a 3/4 inch NPT x 3/4 inch tube adapter. Then install two 3/4 inch sweat street 90-degree elbows [https://homedepot.sjv.io/3ekdNB]. Fill the storage tank by opening the cold water shut-off valve. Make certain any drain valves are completely closed. Purge air from the system by opening a hot water outlet at a fixture in a kitchen or bathroom.

When water flows freely from the outlet, the system is purged. Set the storage tank to the desired
temperature. Boiler high limit should be set at least 20 degrees F higher than the storage tank temperature setting.

Water heater products were manufactured by Heat Transfer Products (HTP) [https://htproducts.com/] and Jomar Distributors [https://www.jomardist.com/].

Expert assistance provided by Papalia Home Services [https://papaliaplumbing.com/].

Looking for more step by step guidance on how to complete projects around the house? Join This Old House Insider to stream over 1,000 episodes commercial-free: https://bit.ly/2GPiYbH

Materials:
Reserve tank [https://homedepot.sjv.io/6ekgLK]
Expansion tank [https://homedepot.sjv.io/6ekgLK]
Thread tape [https://homedepot.sjv.io/m542qe]
Pipe dope [https://homedepot.sjv.io/daK9DM]
Bronze pump [https://homedepot.sjv.io/ZQVyGq]
Copper piping and fittings [https://homedepot.sjv.io/WqOGkM] (press or push to connect)

Tools:
Wrenches [https://amzn.to/3nSEoL1]
Pliers [https://amzn.to/3VVe53y]
Hose [https://amzn.to/3LNzeYC]
Bucket [https://amzn.to/3I0oxAL]
Tubing cutter [https://homedepot.sjv.io/9gLXyQ]

A Pro Press [https://homedepot.sjv.io/DKWqxq] is optional if you plan to do this job more than once or twice a year.

Plus, download our FREE app for full-episode streaming to your connected TV, phone or tablet: https://www.thisoldhouse.com/pages/st...

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From the makers of This Old House, America’s first and most trusted home improvement show, Ask This Old House answers the steady stream of home improvement questions asked by viewers across the United States. Covering topics from landscaping to electrical to HVAC and plumbing to painting and more. Ask This Old House features the experts from This Old House, including general contractor Tom Silva, plumbing and heating expert Richard Trethewey, landscape contractor Jenn Nawada, master carpenter Norm Abram, and host Kevin O’Connor. ASK This Old House helps you protect and preserve your greatest investment—your home.

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How to Install a Reserve Tank | Ask This Old House
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