A gas water heater is set for one gas at the unit, and the sources do not treat a change to the other gas as something every unit allows. The U.S. Department of Energy’s archived Energy Saver page (captured January 1, 2026) names natural gas and propane as fuels for gas-fired water heaters; it is cited here for guidance on what to ask, not for what is offered at any address today. A State Water Heaters manual adds the detail that matters most in practice: its unit is set for natural gas at the factory, and propane requires the included conversion kit installed by a qualified installer. This page sets out what the sources say changes, and what they do not say.
Venting And Carbon Monoxide
Venting and carbon monoxide are questions for any gas-fired unit, and the sources we read do not compare the two gases on either. A gas storage or tankless unit still needs combustion air and a vent to the outdoors, and a State Water Heaters manual says improper venting can result in excessive levels of carbon monoxide. Our venting types guide and carbon monoxide guide apply either way, and our types overview shows where gas units sit among the options.
What Changes
The fuel supply, the unit’s gas setting and the gas piping and pressure are the items the sources tell you to confirm. The DOE says fuel type and its availability in your area may narrow your water heater choices, and that if you convert from one fuel type to another there are other cost considerations, such as adding a breaker or running a gas line to the water heater and venting it outside. Whether a property has natural gas service is a question for the utility, and the DOE advises contacting your utility for current fuel costs or rates. These DOE statements come from an archived capture of its Energy Saver page and are used as general guidance only.
The State Water Heaters manual for its gas tankless units says gas piping must be installed according to local and state codes or, in their absence, the current edition of the National Fuel Gas Code, and that any gas regulators used must be operating properly and providing gas pressures within the specified range. Excess gas inlet pressure, it says, may cause serious accidents. Those are that manual’s statements for those models; other units publish their own ranges.
Not sure which gas your current heater uses? Call (717) 500-8528 with the model number from the rating plate.
Conversion Between The Two Gases
Treat a conversion as possible only where the documents for the exact make and model provide for it, name the approved kit and procedure, and call for a qualified installer or service agency. The State Water Heaters manual for its THR-series gas tankless units says its unit is set only for natural gas at the factory, and that a propane conversion must use the included kit and instructions, installed by a qualified service agency. It tells the installer to verify the type of gas that will fuel the unit before installing the conversion components, and the data plate states the gas the unit is set for. Those are that manual’s statements for those models. They do not make any other unit convertible, and a unit whose documents provide no conversion should not be assumed to allow one. This page does not describe any procedure.
Why The Wrong Gas Matters
The manual warns against connecting a unit to the other gas. It says not to connect a natural gas water heater to an L.P. gas supply and not to connect an L.P. gas water heater to a natural gas supply, and that failure to follow its instructions can result in serious injury or death from explosion, fire or carbon monoxide poisoning. It also tells the reader to read the data plate to determine the type of gas required. The same manual says the gas supplier adds an odorant, that it may fade, and that it should not be relied on as an indication of leaking gas; our shut-off guide covers what to do about a gas smell.
What To Ask Before You Decide
- Which gas does the data plate say the unit is set for, and is the supply the same gas?
- Do the exact model’s documents provide a conversion kit and procedure, and who is the qualified installer or service agency that will fit it?
- What would a fuel change add to the quote: gas line, regulator, venting, breaker, permit? See how to compare installation quotes.
- What does your utility or supplier say about current rates, as federal guidance advises, rather than a figure from this page?
For installation and service, see gas water heater installation in Lancaster, PA and gas water heater repair.
What This Page Will Not Say
It will not say which fuel is cheaper to run, which is more efficient, or which is more common in Lancaster County. The DOE tells you to compare current rates with your utility and gives no figure we can cite for a Lancaster property, and two prices do not become a running-cost comparison without your usage and the unit’s efficiency. We also state no cost for a conversion kit or a gas line, and no claim about rural or urban properties, because no source we read supports one.
Sources Used
U.S. Department of Energy, Selecting a New Water Heater (archived January 1, 2026); State Water Heaters, residential gas tankless manual (THR-160, THR-180, THR-199). The DOE page is an archived capture and is not used here for current incentives, regulations or availability. Details are in our claims registry.
Switching Fuel Or Replacing A Gas Unit?
Service requests and emergency service are available 24/7 across Lancaster City and Lancaster County.
Call For Emergency ServicePropane And Natural Gas FAQ
Can a natural gas water heater be converted to propane?
Only where the documents for that exact model provide for it. A State Water Heaters manual says its unit is set only for natural gas at the factory, and that a propane conversion requires the included kit installed by a qualified installer or service agency. That is one manual’s statement for its THR-series gas tankless units; it does not make every unit convertible. Check the exact model’s documents, kit and installer.
What happens if a water heater is connected to the wrong gas?
The manual says it can result in serious injury or death. State Water Heaters says not to connect a natural gas water heater to an L.P. gas supply or an L.P. gas water heater to a natural gas supply, and warns of explosion, fire or carbon monoxide poisoning if its instructions are not followed.
Is propane or natural gas cheaper for a water heater?
We do not compare them. The U.S. Department of Energy says to contact your utility for current fuel costs or rates, and a fair comparison also needs the unit’s efficiency and your own usage. We have no authoritative figure for a Lancaster property.
What else changes if I switch from electric to gas, or back?
The DOE says there are other cost considerations, such as adding a breaker or running a gas line to the water heater and venting it outside. Those items belong in every quote; see our quote comparison guide.
Does the fuel change the carbon monoxide risk?
The sources we read do not compare the carbon monoxide risk of the two gases. A State Water Heaters manual says improper venting can result in excessive levels of carbon monoxide and recommends a fuel gas and carbon monoxide detector. See our carbon monoxide guide.
Who can advise on a gas water heater near me in Lancaster County?
Lancaster Water Heater Pros services water heaters across Lancaster City and Lancaster County. Call (717) 500-8528 with the rating plate details. Service requests are accepted 24/7.