1. [Home](/) 2. [Guides](/guides/) 3. [Water heaters in Dayton area homes](/guides/water-heater-guide/) 4. Tank vs. tankless water heaters: how to decide # Tank vs. tankless water heaters: how to decide Tank and tankless water heaters both work well when they fit the house. The right choice depends on how you use hot water and what your home can support. ## Key takeaways - Tanks are limited by stored volume, and tankless units are limited by how much water they can heat at once. - Cold winter water lowers tankless output, so size for winter. - Switching to tankless often means new venting and a larger gas line or electrical service. - Both types need regular maintenance in hard water areas. ## Household demand A tank heater gives you its stored volume plus what it can reheat. It handles several fixtures at once until it runs low, then needs time to recover. Back-to-back showers and filling a big tub are where tanks fall short. A tankless heater does not run out, but it can only heat so many gallons per minute. If two showers, a dishwasher, and a washing machine all run at once, the unit may not keep up and the water cools off. That limit shrinks in winter, when incoming water in the Dayton area is at its coldest and the heater has to raise the temperature further. Tankless units also have quirks. A very low flow, such as a trickle at the sink, may not turn the burner on. A brief burst of cooler water can come through between uses. Neither is a defect, but it helps to know about them before you choose. ## Gas or electric Many Dayton area homes already have natural gas at the water heater, which makes a gas tank or gas tankless unit the natural fit. - **Gas tankless** heaters use a much larger burner than a tank. The existing gas line, and sometimes the meter, may not supply enough gas. Upsizing the line is common. See gas lines. - **Electric tankless** heaters for a whole house draw a large amount of current. Many older homes do not have enough electrical service, and an upgrade may be needed. Electric tankless units also lose the most output when winter water is cold. - **Electric tanks** are simple to install but recover more slowly than gas tanks. Most tankless units, and power-vented tanks, need electricity to run. A standard gas tank with a chimney vent can often still make hot water during a power outage. ## Venting and gas supply A conventional gas tank usually vents into a chimney by natural draft. In older homes, that chimney may have been shared with a furnace that has since been replaced, and it may no longer draft properly for the water heater alone. Tankless gas units vent differently. Condensing models typically use plastic vent pipe run through a wall. Non-condensing models need special stainless vent pipe. Either way, the termination has to meet clearance rules for windows, doors, and grade, and it should sit high enough to stay clear of drifting snow. Venting and gas sizing are jobs for a licensed plumber, and a permit is often required. ## Space and installation location A tank takes up floor space and needs room around it for service, plus overhead room to pull the anode rod. In a basement that may not matter. In a closet or a finished space, it can. Tankless units mount on a wall and free up floor space. They still need access for service, clearance for venting, and a spot that will not freeze. In this climate, they are generally installed indoors. Installing one where the old tank stood is common, but the vent, gas, and water lines usually have to be reworked. ## Maintenance differences Both types need attention in hard water. - **Tanks:** flush sediment regularly and check the anode rod every few years. - **Tankless:** descale the heat exchanger and clean the inlet filter screen. Hard water can mean doing this more often than the manual's minimum. Skipping maintenance on a tankless unit tends to show up as reduced flow, temperature swings, or error codes. Skipping it on a tank shows up as noise and a shorter life. See [why and how often to flush a water heater](/guides/water-heater-guide/flushing-a-water-heater/). A plumber who handles [water heaters](/services/water-heaters/) can look at your house and walk through both options. ## Frequently asked questions Will a tankless water heater give me endless hot water? It will not run out the way a tank does, but it can only heat a certain number of gallons per minute. Run too many fixtures at once, especially in winter, and the water cools. Sizing it for your busiest use and your coldest incoming water matters. Can I switch from a tank to tankless in an older house? Usually yes, but it often means a larger gas line or electrical upgrade, new venting, and some changes to the water piping. A plumber can check your gas supply, electrical service, and vent options before you decide. 3 min read. ### Want us to handle it? Mammoth Plumbing works in Dayton, Oakwood, Kettering, Beavercreek, Fairborn, Centerville, Washington Township, Springboro. [Get a quote](/contact/)[Call 937-815-2006](tel:+19378152006) ### More in this guide - [Water heaters in Dayton area homes](/guides/water-heater-guide/) - [Signs your water heater is wearing out](/guides/water-heater-guide/signs-water-heater-failing/) - [Why and how often to flush a water heater](/guides/water-heater-guide/flushing-a-water-heater/) ### Related services - [Water Heater Installation](/services/water-heaters/) ### Service areas - [Dayton](/areas/dayton/) - [Oakwood](/areas/oakwood/) - [Kettering](/areas/kettering/) - [Beavercreek](/areas/beavercreek/) - [Fairborn](/areas/fairborn/) - [Centerville](/areas/centerville/) - [Washington Township](/areas/washington-township/) - [Springboro](/areas/springboro/) ### Other guides - [Drains, sewer lines and basement backups](/guides/drains-and-sewer-guide/) - [Leaks, frozen pipes and water pressure in Dayton-area homes](/guides/leaks-and-pipes-guide/) ## Call or text 937-815-2006, or send a quote request and we'll set up a free estimate. [Get a quote](/contact/) [Call 937-815-2006](tel:+19378152006) --- **Mammoth Plumbing** · Dayton, OH 45402 · 937-815-2006 · matt@mammothplumber.com [Get a quote](/contact/) · [Services](/services/) · [Guides](/guides/) · [FAQ](/faq/)