The many customers and projects, the decision to install a propane tankless water heater is the smart choice.
If you are thinking about making the switch to a propane tankless water heater, there are many benefits to take into account. Moving from a traditional tank system can save you up to 50% on your energy costs and reduce greenhouse gas emissions by up to 61%.
There are some misconceptions about the venting needs of tankless water heaters that are keeping professional builders from suggesting them as an option on projects.
This article offers tips to help you find a simpler, cheaper option if these concerns are preventing you from installing them.
8 Easy Steps For Tankless Water Heater Venting Through Roof
1. Propane tankless water heaters don’t have to use indoor air for combustion.
Power-vent tankless water heaters use indoor air for combustion and simply vent the exhaust to the outside. Direct-vent units pull in air from the outside, so they have two vents for intake and exhaust.
Power-vent units require an exhaust vent and they are placed in a room with enough space to provide the unit with adequate make-up air for gas combustion. Direct vent units use outdoor air, meaning they can be placed anywhere as long as there is a hole that allows them to draw in fresh air.
2. Tankless water heaters don’t always need two ventilation pipes, even for direct-vent units.
Direct vent water heaters can use two separate pipes to bring in and exhaust gases, but some have concentric vents which combine an intake and an exhaust pipe.
One advantage of concentric vents is they only require a single opening to install, which saves time and money. Another advantage is that because warm air stays inside the pipe, it doesn’t have to be vented out as with an exhaust vent so you are less likely to bump into one while working around your house.
Both single pipes and concentric vents have their advantages. Single pipes are less expensive, costing a little more than $12 per unit on average, according to Home Advisor. Concentric vents also offer a safety benefit: A leak within the inner vent will remain contained in the intake pipe.
3. Tankless water heater venting through roof is not necessary.
Propane water heaters for storage tanks vent upward through the roof using galvanized steel B-vents. This is because they work because hot exhaust air can rise up and out of the facility without blowing back in when using natural drafts from outside air. Compared to tankless water heaters, electric tanks don’t require venting. For this reason, professionals putting in a new propane tankless water heater often put the vents on the side of the house instead of up through the roof.
Installing a water heater is more expensive and harder when the venting lines have to go through an attic space. Venting lines work much better if they can be arranged below the ceiling, taking the plumbing only slightly out of place.
4. Outdoor tankless water heaters don’t need venting.
Tankless water heaters are nearly always easier to install in warmer climates, because they don’t need a large vent for colder climates. They also self-warm, so as not to freeze and crack if the weather is below freezing outside. While tanks are more efficient to use in a cold climate, they can freeze up during periods of blackouts. Indoor installation is the better option for cold locations where electrical outages occur.
Plus, replacing a tank water heater with an outdoor unit can free up room inside your house and reduce maintenance costs because these units less frequently need repair.
5. With a condensing tankless water heater, you don’t need metal venting.
Noncondensing water heaters only transfer about 80% of the heat generated to the water. The remaining 20% creates a hot exhaust gas which requires metal venting, typically stainless steel or thick aluminum.
Condensing units are typically about 95% efficient, so the temperature of the exhaust gas is lower — around 110° to 120° F. That means they can be vented with a less expensive plastic, generally PVC or polypropylene. The cost difference in venting alone can offset the higher purchase price of a high-efficiency unit. The overall installed price is typically equal or less than that of a mid-efficiency product, making it an easy upsell at that point.
6. Placement for tankless water heaters doesn’t always have to be a box stuck to a wall.
Some companies offer recess boxes to keep the tankless water heater inside a wall for new-construction applications. The noncondensing units can fit between conventional studs; condensing units may require more creativity in framing.
7. You don’t always need separate vents for multiple water heaters.
Commercial and large residential buildings may use multiple tankless units, but they don’t necessarily require two vent penetrations per unit. For new projects where avoiding holes in the building envelope is a consideration, one manufacturer has developed a common-venting system that allows up to eight tankless units to share exhaust and intake vents.
8. Your venting system doesn’t have to be ugly.
Several manufacturers have designed aesthetically pleasing vent options. Many people really like the tankless option but they’re concerned about staining and function when their pipes are visible. Luckily there are stylish ways to cover your piping, so you can go with a tankless water heater without sacrificing functionality or style.