Tankless installation tips and tricks
Benefits and installation considerations for the technician
As an installer, technician or contractor, you will have noticed tankless water heaters have become very popular in recent years. These units, however, can only achieve the best results if they are properly sized and correctly installed. In this article, I’ll go over some of the key benefits of the units, as well as tell you exactly what to do to ensure a successful installation.
First of all, the benefits of installing a properly sized water heater are many. Topping the list is something your customer can understand right off the bat – they have up to 99% Energy Efficiency ratings. (Meaning simply that 99% of the energy that goes into them comes out the other side as hot water.) Properly sized tankless water heaters are incredibly energy efficient, primarily because they are not subject to the standby losses – heating and re-heating a tank full of water all day long whether there’s demand for it or not — associated with storage heaters. Even ENERGY STAR storage heaters typically waste roughly 33% of the energy they consume.
Tankless water heaters don’t need to keep a large reservoir of hot water. They can receive water at the supply temperature when someone turns on a faucet or starts the dishwasher and heat it instantly as it flows through the unit, ensuring hot water will be available until it’s no longer needed. Storage heaters, on the other hand, sometimes make residents and employees wait while it heats another tank full of water once the previous supply runs out.
The tanks used by storage heaters are large, which makes them impractical when space is a limitation (e.g. in apartments and smaller homes or even under as sink, such as with a point-of-use tankless water heater.) Tankless water heaters can fit in more locations thanks to their compact size.
The ability to use PVC as venting can make installations quicker and, sometimes, easier. Since tankless water heaters transfer heat more effectively, their exhaust gases are at lower temperatures than those of storage heaters. That’s why it’s possible to use affordable PVC piping instead of metallic vents on some tankless heaters.
So far everything sounds good, right? Well, all those great features are useless to the technician and the client if the thing can’t be controlled. Modern tankless heaters have more-or-less made programmable displays nearly standard equipment, allowing the tech or client to reap a wealth of information on how the unit is operating. When combined with sensors, the display simplifies troubleshooting and makes the unit easier to service. And, when you’re thinking about the Internet of Things, many tankless heaters are Wi-Fi-enabled, allowing them to communicate with you via the smart device of your choice.
Back in the day when tankless water heaters first came out there was some confusion over the term, “instant hot water.” To installers and techs that meant the heater would come on instantly and start heating water when the flow begins. The client base, however, took the phrase “instant hot water” a little more literally, mistakenly thinking in some cases the water from the hot tap should be “instantly” hot from the faucet as soon as it would be turned on.
When a homeowner wants hot water from his shower or faucet, he will usually have to wait a few seconds as hot water travels between the heater and the outlet, displacing cold water in the line. Although this can be avoided by circulating hot water constantly through the piping, this comes at an energy cost.
Many modern tankless heaters come with technology that enables a built-in circulating pump to deliver water faster without the need for a dedicated recirculation line. Circulation can even be programmed to only occur when hot water is about to be used, such as in the morning before everyone takes a shower or at around 7:45 pm when the dinner dishes are usually about ready to be washed. This eliminates the short bursts of cold water that normally occur when a heater has just been activated without the energy wastage of a dedicated recirculating line.
Even if your client has the most efficient tankless heater in the market, the best results won’t be achieved unless the installation is carried out properly. Follow these tips avoid frustration and call-backs:
- Accurate BTU Load Calculation. It’s critical you perform an accurate BTU load calculation to ensure proper operation of the added load on the gas system. The added BTU may be up to four- or five times that of the tank style water heater being removed. If your calculations reveal you’re going to have to upsize the gas line and/or the gas meter. That said, you may be able to satisfy the additional BTU load by simply relocating the water heater. For example, if climate allows, you may be able to install the unit outside near the gas meter.
- Accurate Water Flow Calculation. You must get an accurate total count of fixtures that will be serviced by the heater, and calculate the total demand in gallons per minute. This demand calculation is crucial to correctly sizing the tankless water heater.
- Water Quality Assessment. Before you proceed with a tankless heater installation, make sure you check your client’s water supply quality. If the water has excessive hardness or sediment concentration, it can reduce heater efficiency while shortening service life and drive up maintenance expenses. The client must be made aware of this prior to installation. If necessary, outline water softening and/or filtrations alternatives to your client.
- Yearly Maintenance. Even if the water supply is of high quality, you can still expect sediments and scale to build up inside the heater over time. This can compromise performance if not addressed. For this reason, a yearly maintenance plan where you flush the unit using the isolation valves is crucial. Also, make sure to remove any buildup inside the unit’s coil using manufacturer-recommended methods.