How tankless works, and its limit
When a hot tap opens, water flows through the unit, a burner or element fires, and a heat exchanger raises the water to the set temperature on its way through. There is no storage, so there is nothing to run out of. The limit is flow: a tankless unit can only add so much heat per minute. The colder the incoming water, the more heat each gallon needs, and the fewer gallons per minute it can deliver at full temperature.
That single fact explains most disappointment with tankless units. One sized on warm-weather assumptions can run two showers comfortably in September and struggle in January.
Sizing for a Connecticut January
Proper sizing starts with two questions. How many hot water outlets does the household realistically use at once on its busiest morning? And how cold is the water coming in at the coldest time of year? Water from town mains is at its coldest in late winter; water from a private well is often cold all year. The installer works from those figures, not from a brochure's best case.
In some larger homes the answer is a bigger unit, or two units working together. In others, a tank, an indirect, or a heat pump water heater simply suits the household better, and a good installer will say so. See our sizing guide.
Fuel and venting
Natural gas and propane are the usual fuels for whole-house tankless units in Connecticut. Gas-fired tankless units draw a lot of fuel when running, so the gas line to the unit may need to be larger than the one that served a tank. They also need their own venting, commonly through a side wall, and a spot on an outside wall or with a practical vent route.
Electric tankless units exist, but whole-house electric tankless can place a large demand on the electrical supply. The installer assesses whether that is realistic; any wider electrical work is separate.
Where there is no gas main, propane is the common route to tankless.
On a private well?
Tankless on well water
Two things matter. Cold well water reduces how much hot water the unit can deliver, so sizing must allow for it. And minerals scale the heat exchanger over time, so the unit will need descaling on a schedule that depends on your water. Isolation valves for flushing should be part of the installation. Tell us about the well at the start.
Sizing and descaling access planned in from day one.
What installation involves
- Removing the old tank and its flue connection where it is being replaced
- Mounting the unit on a wall with clearance for service
- Upsizing the gas line to the unit where needed
- New venting, often through a side wall, suited to that specific unit
- Condensate drainage on condensing models
- Water connections with isolation valves for future descaling
- A relief valve and, where the plumbing calls for it, an expansion tank
- Setting up and testing at several flow rates
What tankless does and does not do
It will not run out after a set number of showers. It will take a moment to deliver hot water after a tap opens, and very low flows, such as a trickle at a sink, may not trigger it. It frees up floor space. It needs periodic descaling on hard water. We do not quote efficiency or running-cost comparisons; the installer will focus on whether it suits your house.
Whole-house or point-of-use
A whole-house tankless unit replaces a tank and serves every tap in the home. A point-of-use unit is small and serves one sink or bathroom, often far from the main heater, cutting the wait for hot water there. Many Connecticut homes with a distant bathroom or an accessory apartment use a small unit for that part of the house and keep the main heater for the rest. The installer can suggest which approach fits the layout and the fuel available at each point.
Gas meters and lines in older homes
A gas-fired tankless unit draws a lot of gas while it is running, much more at that moment than a tank does. In older homes, the gas meter and piping were sized for the appliances of their day, and adding a large tankless unit can exceed what they were built to deliver alongside a boiler or range. The installer checks the line and, on natural gas, whether the meter supply is adequate. Any change at the meter is arranged with the gas utility; changes to piping inside the house are part of the installation plan.
Short draws and waiting for hot water
Tankless units need a minimum flow before they fire, and they take a few moments to deliver hot water to a distant tap. Quick hand-washing at a far sink may run cold before it warms. Some homes add a recirculation arrangement or a small buffer to smooth this out. It is worth thinking about how your household uses hot water in short bursts, not just in long showers, before choosing tankless.
What affects the cost of tankless water heater installation
- The unit's size and whether one or two are needed
- Gas line upsizing from the meter or supply
- Venting route and wall construction
- Condensate drainage
- Removing the old tank and dealing with its flue
A site visit sets the size, venting and gas line.
How long tankless water heater installation takes in Connecticut
Converting from a tank to tankless takes longer than a tank swap because of gas line and venting work. Straightforward installs are often a single long visit; more involved ones may run over two. The installer will set out the plan beforehand.
Tankless installation questions
Will a tankless heater run two showers in winter?
It can, if it is sized for the coldest inlet water your house sees. An undersized unit may manage in summer and struggle in January. That is why sizing starts with winter conditions.
Can a tankless unit use my existing gas line?
Sometimes, but tankless units often need more gas than a tank did, so the line may need upsizing. The installer checks the line and the supply.
Can a tankless heater use my chimney?
Most tankless units need venting specific to the model, typically through a side wall, rather than an existing chimney. The installer plans the vent route.
Is tankless a good idea on a well?
It can be, with sizing for cold well water and a descaling schedule suited to your water. Some households prefer the simplicity of a tank. The installer can help you weigh it.
Why does it take a moment to get hot water?
The unit has to detect flow, fire and heat the water, and hot water then travels through the pipes to the tap. It is a short delay, but it is there.
Can I install tankless in an old cellar?
Often, and the small size helps in tight spaces. The main constraints are the vent route and the gas line. The installer will look at both.
Do tankless units need maintenance?
Yes. Heat exchangers need descaling at intervals that depend on your water, and air intakes and filters need checking. Isolation valves make descaling straightforward.
Are there things tankless does not do well?
Very small flows may not trigger it, and there is a short wait for hot water. Very high simultaneous demand needs a larger unit or two units.
Can a tankless unit be installed in an unheated space?
Some models are designed for it and some are not, and water inside any unit can freeze. The installer chooses the location and model with winter in mind.
Does tankless work with a hot water recirculation loop?
Many units can work with recirculation, which reduces the wait for hot water at distant taps. The installer can explain how it would work with the unit you choose.