What changes when you go tankless
| Factor | Tank | Tankless |
|---|---|---|
| Hot water supply | Limited to the tank volume | Continuous while the unit keeps up |
| Space | Takes floor space | Wall mounted and compact |
| Gas line | Existing line usually fine | Often needs a larger line |
| Venting | Existing flue often reusable | Dedicated venting, often new |
| Maintenance | Occasional flush and anode check | Annual flush recommended |
| Upfront cost | Lower | Higher |
The upfront cost gap is the main hurdle. The savings come from lower standby heat loss and, in some homes, a longer service life. Whether that pays off depends on how much hot water you use and how much the conversion costs.
Cold inlet water in Minnesota
A tankless heater raises the temperature of incoming water by a set amount. In winter, groundwater is colder, so the unit has to add more heat, and the flow it can deliver at a given set point drops. A unit sized for summer can disappoint in January.
Ask the plumber to check the unit's rated flow at a winter temperature rise, not just the headline number. If you run two showers and a dishwasher at once, the capacity matters.
Not sure the gas line can handle it?
Call and describe your meter and pipe. A plumber can check what the unit needs.
A decision checklist
- Your gas line can carry the unit, or you are willing to upgrade it.
- There is a good route for the new venting.
- You use enough hot water to value an endless supply.
- You will flush the unit every year.
- The upfront cost fits your budget.
If most of those are yes, tankless is worth a serious look, and the tankless water heater page covers installation and flushing. If not, a new tank through water heater installation may be the better choice.
Sizing a tankless unit for your household
Tankless units are rated by flow in gallons per minute at a given temperature rise. List your fixtures and how many run together. A shower may use around two gallons a minute, a dishwasher a bit more, and a washing machine similar. Add the ones that run at the same time to find your peak demand.
Then check the unit's output at the temperature rise you need in winter. A higher rise lowers the flow. If your peak is close to the unit's limit, size up, because a unit running at its ceiling wears faster and gives lukewarm water.
Recirculation and wait time
A tankless heater does not remove the wait for hot water to reach a distant fixture. A recirculation loop or a small buffer tank can shorten it. Ask the plumber whether the unit supports recirculation and what it adds.
Hard water and tankless maintenance
Mineral scale builds up inside a tankless heat exchanger and cuts flow over time. Forest Lake city water is softened to an average of about 5.5 to 6.5 grains per gallon, which is moderately hard, so scale is slower than on untreated water but still real.
Most makers call for a periodic flush with vinegar or a descaling solution, and a plumber can set up service valves to make that easy. Skipping it shortens the life of the unit and is the most common reason for lukewarm output a few years in.
Gas line and vent changes
Many tankless units need a larger gas line than a tank heater, and most need a sealed vent made of a specific material. Ask the plumber whether the existing line and vent can be reused, and have the answer in the written quote.
Checking a plumber's license
According to the Minnesota Department of Labor and Industry, plumbing contractors must hold a state license, with a responsible master plumber and a surety bond. The license lookup at dli.mn.gov lets you confirm any plumber before you hire.
Forest Lake water and tankless care
The City of Forest Lake softens its water at the treatment plants to an average of 5.5 to 6.5 grains per gallon. That reduces scale on a tankless heat exchanger compared with raw hard water, but the maker's flush schedule still applies. Ask your plumber to install isolation valves so the flush is easy.
Homes on private wells, as in Columbus and Scandia, may have harder or iron-rich water that fouls a tankless unit faster. Test the water before you buy.
Questions Forest Lake Homeowners Ask
The city softens its water, which helps, but a yearly flush is still the usual maker advice. On a private well, test hardness and iron.
Often not without a change. Tankless units draw more gas, so the line size must be checked.
It depends on your hot water use, the conversion cost, and how long you stay in the home.
Many are rated for a longer life than tanks, but care matters, especially the flush.
Yes, but cold inlet water reduces flow at a set temperature. Size the unit for winter.
Most need electricity for controls and ignition, so they stop in an outage unless connected to backup power.
Sources
- City of Forest Lake Water Department page (municipal utility page)