Why the unit is the smaller part of the bill
A tank-type heater is forgiving. Its burner is often rated around 30,000 to 50,000 BTU per hour, it vents through a simple flue, and it sits on a pan near a drain. A whole-house gas tankless unit commonly asks for 150,000 to 199,000 BTU per hour at full fire, so your house has to deliver several times more gas at once.
That gap explains why two quotes for the same model can land far apart. One contractor may have priced a new gas line and a vent run, while the other assumed the old ones would do. Ask every bidder to list what is included before you compare totals.
What affects the price of a gas tankless install
These five items account for most of the difference between a straightforward swap and a larger project.
Gas piping and meter capacity
Pipe size, the distance from the meter, and the other gas appliances sharing the line decide whether the existing pipe can feed the new burner. A plumber sizes it against the unit's input rating using the fuel gas standard (NFPA 54 is the national reference). If the line is too small, upsizing it is often the largest single add.
Venting route
Condensing units usually vent through plastic pipe out a sidewall, while non-condensing units need stainless steel vent pipe. Run length, elbow count, and whether the vent exits through a wall or the roof all change labor and material. The manufacturer's vent table sets the limit, and a run that is too long makes the unit fault.
Condensate drain and neutralizer
Condensing models produce acidic condensate that needs a path to a drain, usually through a small neutralizer cartridge. A floor drain nearby keeps this simple. A utility room with no drain may need a condensate pump.
Water-side fittings
Isolation valves with flush ports let a plumber descale the heat exchanger later. Old galvanized pipe or crowded copper at the tank location may need replacing so the new connections are accessible and sound.
Location and power
The unit needs a 120-volt outlet for its fan and controls. Moving it to an exterior wall shortens the vent but lengthens the hot and cold runs, so relocating trades one cost for another.
Permit handling, hauling away the old tank, and any utility or manufacturer rebates also change the total, and rebate programs change often, so check them directly. Want your real number? Call (215) 714-6692.
Sizing: flow rate and temperature rise
A tankless heater is rated by how many gallons per minute it can heat by a given temperature rise. Incoming water in a Pennsylvania winter is much colder than in August, so a unit that keeps up in summer can fall short in January. Sizing for winter is the safer rule.
| Fixture | Flow rate to plan for | Sizing note |
|---|---|---|
| Showerhead | Up to 2.0 gpm for WaterSense labeled heads | Older heads can run 2.5 gpm or more |
| Bathroom faucet | About 1.5 gpm for WaterSense labeled faucets | Rarely the deciding load |
| Kitchen faucet | Often 1.5 to 2.2 gpm | Matters when a dishwasher runs too |
| Washing machine | Varies by model, check the spec sheet | Hot cycle overlaps with showers |
Add the fixtures that run together at your busiest hour, then ask the installer to show the math at your winter incoming water temperature. A household that runs two showers and the dishwasher at once needs a bigger unit than one with a single morning shower.
Want the gas line checked before you buy a unit?
Call (215) 714-6692 and we will talk through your current appliances and where the water heater sits, so the price we give starts from your real setup.
Swapping in place versus relocating the heater
Replace in the same spot
- Reuses the existing gas stub and water lines when they pass inspection
- Vent may still need new pipe since tank flues differ
- Usually the lower-cost path
- Condensate drain may still be missing
Move to a new wall
- Shorter vent run to the outdoors
- Longer hot and cold runs plus a new gas branch
- Frees floor space in a basement or closet
- More wall and ceiling opening, so more finish work
What the install visit covers
- 1
Check gas supply and shutoffs
The plumber confirms pipe size, tests for leaks, and shuts off gas and water at the right points before touching the old tank.
- 2
Drain and remove the tank
The old heater is drained, disconnected, and carried out. Sediment inside the tank is a quick clue about your water.
- 3
Mount, vent, and connect
The new unit goes on the wall, the vent and condensate line are run per the manufacturer's instructions, and gas and water are connected.
- 4
Fire it and test it
The plumber checks combustion operation, flow at a few fixtures, the temperature setting, and any error codes before explaining how to flush the unit yearly.
Running costs after the install
Many manufacturers recommend flushing a tankless unit about once a year, especially where water carries scale. Skipping that flush can shorten the life of the heat exchanger. Ask if your install includes isolation valves so the flush is a short job rather than a plumbing project.
Our tankless water heater service page covers installs and maintenance, and the water heater installation page explains the tank-type options if tankless does not fit your gas supply. We also work in Hatboro and Warminster, where the same gas line question comes up whenever a tank-type burner is replaced with a larger tankless one.
Questions to ask before you accept any quote
- Is the gas line size checked against the unit's BTU rating, and who pays if it is too small?
- Is the vent type condensing plastic or stainless steel, and how long is the run?
- Where does the condensate drain, and is a neutralizer included?
- Are isolation valves with flush ports included?
- Who pulls the permit if one is required, and who schedules the inspection?
Tankless heaters, Horsham hardness and the fuel in your house
Horsham Water & Sewer Authority publishes its source water hardness as ranging from about 200 to 350 mg/l as calcium carbonate, and suggests roughly 275 mg/l (16 grains per gallon) when a softener asks for incoming hardness. That is hard water. For a tankless buyer it means scale will coat the heat exchanger, so insist on isolation valves with flush ports and plan a yearly flush instead of waiting for error codes.
Gas is the largest heating fuel in the township, but not the only one. Census survey data counts 4,011 of 9,857 occupied homes on utility gas, 3,696 on electricity and 1,704 on fuel oil. If your house heats with oil or electric, do not assume a gas stub sits near the water heater. Confirm the gas line before you price anything, since a missing line changes the whole project.
The township's permit page lists plumbing fixtures including water heaters, and heating and AC replacement, as permit work. Code Enforcement at 1025 Horsham Road, (215) 643-3131, is open Monday to Friday, 8:30 to 4:30, and wants 24 to 48 hours notice for an inspection. Call before the install date so the inspection fits the schedule.
Questions and answers
The total depends on gas line size, vent length, condensate drainage, and the unit's size, so we do not quote a flat number online. We give a clear price before work starts once we have seen the existing setup. Call (215) 714-6692 to describe your system.
Often it does not without changes, because a whole-house tankless burner can draw several times the gas of a tank burner. A plumber sizes the pipe against the unit's rating and your other gas appliances. If it is undersized, expect an upsized branch in the quote, and if no gas line reaches the heater at all, that is a separate utility and piping question.
Yes, mainly through hardness. The authority publishes its source water at about 200 to 350 mg/l as calcium carbonate, with 275 mg/l (16 gpg) as a working figure. At that level scale builds on the heat exchanger, so plan a yearly flush and ask for isolation valves.
It depends on household size, gas pricing, and how much the install costs. Tankless gives continuous hot water and frees floor space, while a tank-type replacement usually costs less up front. We can compare both on your actual house.
Expect to. The township's permit page lists plumbing fixtures including water heaters as permit work, and fines apply to work done before a permit. Code Enforcement at (215) 643-3131 can confirm the details for a gas tankless swap, and inspections need 24 to 48 hours notice.
A same-location swap is commonly a single visit, while relocating the unit or running new gas pipe can take longer. The plumber will tell you after seeing the vent route and gas line. Same-day appointments are available when the schedule allows.
Sources we checked
Local facts on this page come from these public pages. Plumbing work in Pennsylvania falls under the Uniform Construction Code, which adopts the International Plumbing Code (IPC) provisions, so ask Horsham Code Enforcement which edition applies before a permit is pulled. Rules and phone numbers change, so confirm with the office before you act.
- horshamwater-sewer.com/hardness Authority page
- censusreporter.org/profiles/06000US4209135808-horsham-township-... Census
- horsham.org/10737/Permits Township page
- horshamwater-sewer.com/history Authority page