How to Buy a Tankless Gas Water Heater
Estimate your average hot water consumption., Decide between a centralized or point-of-use installation., Plan for the ventilation of the exhaust gas.
Step-by-Step Guide
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Step 1: Estimate your average hot water consumption.
Sizing and positioning your tankless water heater begins with knowing how much hot water you will need.
Water consumption can be measured in gallons per minute (gpm) or liters per minute (l/m).
Begin by estimating the water usage of each fixture in your home.
Reasonable guidelines for water consumption are:
2.5 gpm (9.5 l/m) for a shower,
2.5 gpm (9.5 l/m) for a washing machine, and
1.0 gpm (3.8 l/m) for a sink.
Next, determine how likely you are to use these fixtures at the same time.
For example, if your maximum water consumption at any given time means running 1 shower and 1 sink, then your total hot water need is (2.5 gpm +
1.0 gpm) or
3.5 gpm (13.3 l/m). -
Step 2: Decide between a centralized or point-of-use installation.
Because tankless water heaters can only handle a limited flow, it may be necessary to use more than one.
Centralized installation works well for small apartments and condos, while a multiple-unit setup may be better suited to a large home.
Centralized installation is usually the simplest and least expensive.
In this setup, a single water heater is installed that services the whole home.
Because tankless heaters can rarely handle more than 5 gpm (19 l/m) of hot water, this type of installation won't be able to meet large water needs.
Point-of-use heaters are installed in close proximity to a hot water source.
For example, you might install a separate water heater in each bathroom of your home.
This setup is more labor-intensive and expensive, but it ensures that each tap will receive adequate heating and eliminates long pipe runs that cause a significant delay when waiting for hot water to flow.
Your current utility setup will influence which type of installation is easiest.
Installing new gas lines to service multiple point-of-use heaters will significantly increase the amount of work and money needed.
In this situation, you could consider installing a large, centralized gas heater and supplementing it with several electric point-of-use heaters. , Gas water heaters, unlike their electric counterparts, produce exhaust gas that must be vented to the outdoors.
This is accomplished using stainless steel venting lines and running them through a wall or through the roof.
If you are replacing an existing gas water heater (tankless or not) with a new one, you will likely be able to use your existing exhaust setup.
Consult the installation guide included with your new heater to ensure that your current exhaust lines are adequate.
If you are installing a new gas water heater, you can usually purchase a venting kit from the same manufacturer.
This will ensure compatibility with your heater, but you should consult with a contractor to ensure that the kit works with your installation location. -
Step 3: Plan for the ventilation of the exhaust gas.
Detailed Guide
Sizing and positioning your tankless water heater begins with knowing how much hot water you will need.
Water consumption can be measured in gallons per minute (gpm) or liters per minute (l/m).
Begin by estimating the water usage of each fixture in your home.
Reasonable guidelines for water consumption are:
2.5 gpm (9.5 l/m) for a shower,
2.5 gpm (9.5 l/m) for a washing machine, and
1.0 gpm (3.8 l/m) for a sink.
Next, determine how likely you are to use these fixtures at the same time.
For example, if your maximum water consumption at any given time means running 1 shower and 1 sink, then your total hot water need is (2.5 gpm +
1.0 gpm) or
3.5 gpm (13.3 l/m).
Because tankless water heaters can only handle a limited flow, it may be necessary to use more than one.
Centralized installation works well for small apartments and condos, while a multiple-unit setup may be better suited to a large home.
Centralized installation is usually the simplest and least expensive.
In this setup, a single water heater is installed that services the whole home.
Because tankless heaters can rarely handle more than 5 gpm (19 l/m) of hot water, this type of installation won't be able to meet large water needs.
Point-of-use heaters are installed in close proximity to a hot water source.
For example, you might install a separate water heater in each bathroom of your home.
This setup is more labor-intensive and expensive, but it ensures that each tap will receive adequate heating and eliminates long pipe runs that cause a significant delay when waiting for hot water to flow.
Your current utility setup will influence which type of installation is easiest.
Installing new gas lines to service multiple point-of-use heaters will significantly increase the amount of work and money needed.
In this situation, you could consider installing a large, centralized gas heater and supplementing it with several electric point-of-use heaters. , Gas water heaters, unlike their electric counterparts, produce exhaust gas that must be vented to the outdoors.
This is accomplished using stainless steel venting lines and running them through a wall or through the roof.
If you are replacing an existing gas water heater (tankless or not) with a new one, you will likely be able to use your existing exhaust setup.
Consult the installation guide included with your new heater to ensure that your current exhaust lines are adequate.
If you are installing a new gas water heater, you can usually purchase a venting kit from the same manufacturer.
This will ensure compatibility with your heater, but you should consult with a contractor to ensure that the kit works with your installation location.
About the Author
Thomas Ramirez
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