A tankless water heater heats water as it flows, so there is no tank to leak or run out. Installation, repair and annual flushing keep it working. In Londonderry, NH, we install gas and electric units, and we service most major brands.
Tankless heaters need a larger gas line or a heavy electrical circuit, correct venting and a maintenance plan. We cover all three.
Is a tankless heater right for your house?
Good fit
Smaller homes with limited floor space, households that run out of tank hot water, and builds that already have a large gas line.
Needs planning
Houses with small gas lines or limited electrical capacity. The upgrade can change the project cost.
Think twice
Homes with heavy sediment in the well water, unless a filter and flush plan are in place.
Pair with
A recirculation line if you want hot water at far fixtures without a long wait.
We walk through it with you. If a tank is the better value, we say so. See water heater installation for tank and heat pump options.
Installing a tankless unit
- Size the unitWe match flow rate to the fixtures that run together, and the winter inlet temperature in New Hampshire.
- Check gas and powerWe verify gas line size or electrical capacity, and upgrade if needed.
- Vent correctlyGas units need sealed venting that suits the model.
- Connect and commissionWe install isolation valves for flushing, set temperature and test.
Isolation valves matter. They let us flush the heat exchanger later without cutting pipe.
Tankless flush and descale
Minerals and sediment collect inside the heat exchanger, and the unit works harder as they build up. The signs are error codes, a reduced flow, temperature swings and a louder burner. A flush with a descaling solution restores performance in many cases.
Plan a flush at least yearly, and more often on well water that carries sediment. Test your tap and ask your water utility for its quality report. A visit takes roughly an hour and often prevents a repair.
Repairing tankless heaters
| Problem | Likely cause |
|---|---|
| Error code on the display | Scale, flame sensor, vent or flow problem |
| Water goes cold mid-shower | Low flow, scaled exchanger, inlet screen clogged |
| Unit leaks | Failed fitting, condensate drain or heat exchanger |
| Unit will not ignite | Gas supply, igniter or vent obstruction |
If a gas unit leaks gas or vent fumes, shut it off, leave the house and call the gas utility or 911. For a leaking tankless unit, shut the water and power and call us. If the heater is beyond repair, our replacement team can swap it.
Tankless compared with a tank
| Point | Tankless | Tank |
|---|---|---|
| Hot water supply | Continuous up to the unit flow limit | Limited by tank size, then recovery |
| Floor space | Wall mounted, small | Floor standing, larger |
| Install needs | Larger gas line or heavy electric, special vent | Standard connections |
| Maintenance | Yearly flush, sensor checks | Sediment flush, anode and valve checks |
| Standby loss | None | Some heat loss all day |
Neither is right for every house. We size the choice to your fixtures, your fuel and your well or town water.
Gas or electric tankless
Gas units deliver high flow and need a vent and a gas line sized for the burner. Electric units are simpler to vent but can need heavy circuits that older panels cannot carry. A panel upgrade can change the total project cost, so we check the panel first.
Point-of-use electric minis suit a single sink or a distant bath. They do not replace a whole-house heater.
Winter and well water in Londonderry
Cold New Hampshire inlet water lowers the flow a tankless heater can deliver. Size the unit for the winter, not the summer. Private wells can add sediment, so test the water and consider a filter.
What a tankless job costs
We quote clearly before work begins. Factors include:
- The unit size and brand.
- Gas line, electrical or venting upgrades.
- Isolation valves and a condensate drain.
- Removal of an existing tank.
- Maintenance plans and flush frequency.
Ask your utility about rebates. For your number, call (603) 815-9179.
Where we work
We serve Londonderry and nearby towns including Windham, Derry and Hudson.
Venting, gas piping and the relief valve on a tankless unit follow the manufacturer's instructions and the International Plumbing Code (IPC) where it applies.
Questions we hear in Londonderry
At least once a year, and more often if your water carries sediment or minerals.
Codes point to scale, a flame sensor, venting or flow. Check the manual, then call us if it repeats.
Sometimes. Many units need a larger gas line, so we check before quoting.
Not in the tank sense, but they have a maximum flow. Running too many fixtures at once can exceed it.
It can be, with a sediment filter and regular flushing. Test your water first.