What Electrification Changes for Each Trade

Why this matters

A conversion off gas is not one trade's job with helpers. It moves work between trades: the gas fitter's share shrinks to a removal and a test, the electrician's grows from a circuit to the whole capacity question, the HVAC tech inherits a system whose comfort depends on the house around it, and the plumber gets a water heater that needs a room, a drain and an outlet. Every one of those shifts creates a hand-off, and the failures on a conversion cluster at the hand-offs, not inside any one trade's work. This card maps what each trade now owns, what it hands to whom, and the tasks that sit between trades where nobody picks them up. The schedule that strings these together belongs to How to Coordinate the Trades on a Conversion; the order of the work belongs to The Whole-House Electrification Sequence.

The electrician: from circuits to capacity

On a gas house the electrician's part of a heating job is a disconnect and a circuit. On a conversion the electrician owns the question every other trade depends on: can this service carry the new house?

What is new. Reading a year of interval demand data, running a measured-load or standard calculation, deciding between an upgrade and load management, and configuring an energy management system so it sheds the right loads in the right order. Circuits multiply: a heat pump, an air handler with backup heat, a heat pump water heater, an induction range, a heat pump dryer, a charger, each often 240-volt and each two panel spaces. See related: Panel Space Versus Panel Capacity.

What the electrician hands off. A load letter that states the method, the result and any shed order, because the HVAC tech sizing backup heat and the plumber choosing a 120-volt or 240-volt water heater both need to know what fits. If the electrician sets a shed order of charger first, water heater second, the plumber and the customer need to know that the water heater may pause on the busiest hours.

Where it goes wrong. An electrician who sizes from nameplates the HVAC contractor has not finalized. Backup heat is the swing load: 5 kilowatts against 10 kilowatts is about 21 amps at 240 volts, which is often the whole margin. The electrician's calculation is only as good as the equipment list it was given, so the list is a dated document, not a phone call.

The gas fitter: smaller share, higher stakes

The gas fitter's work shrinks in volume and grows in consequence. Removing appliances, capping lines, and, if the last gas appliance goes, closing out service with the utility.

What is new. Testing what remains. Every removal leaves the other vented appliances on a vent that may no longer suit them, and the gas fitter (or the HVAC tech, where they hold the gas credentials) is the person in the room with the tools to find out. See related: What Removing a Gas Appliance Does to the Ones Left.

What the gas fitter hands off. A capped-line note (where each cap is, what it was tested to, and what the remaining piping still feeds), the venting check card for every remaining appliance, and a chimney note for any flue that nothing now uses. The capped-line note is read years later by someone who wants to know whether the pipe behind the range wall is live.

Where it goes wrong. A removal treated as demolition. The appliance comes out, the line is capped, and the person who would have tested the water heater on the same chimney is not on the job that day. The Gas Appliance Removal and Venting Check SOP exists because that gap is the one that produces a CO alarm.

The HVAC tech: equipment that depends on the house

What is new. A heat pump's capacity falls as the outdoor temperature falls, so equipment selection depends on the design temperature, the load of this house, and how much backup the plan can afford electrically. Ducts sized for a furnace's hot, low-volume air often move too little air for a heat pump at the same capacity. The comfort conversation, cooler supply air and long run times, now belongs to the HVAC tech as much as the commissioning does. See related: Ductwork When a Heat Pump Replaces a Furnace, and Sizing a Heat Pump for a Cold Climate.

What the HVAC tech hands off. The final equipment list, with backup heat size, to the electrician before the load letter is written; the condensate routes to the plumber where the air handler or outdoor unit drains somewhere plumbing has to carry; line set penetrations to whoever seals the envelope; and to the customer, the commissioning record and the expectation sheet.

Where it goes wrong. Sizing to the furnace it replaces. A furnace was often oversized by half or more, and a heat pump sized to match it short-cycles in mild weather and still needs its backup in the cold.

The plumber: a water heater that needs a room

What is new. A heat pump water heater pulls heat from the air around it, so it needs a volume of space or ducting, it cools the room it sits in by a few degrees, it makes condensate, and it needs a circuit: a 240-volt one for a unit with an element, or a dedicated 120-volt one for a plug-in model. Recovery is slower than gas in heat pump mode, so tank size and household use matter more. See related: Heat Pump Water Heater Reference, and Plug-In 120-Volt Heat Pump Water Heaters.

What the plumber hands off. The circuit request to the electrician, with the unit's nameplate, before the load letter; the condensate route or pump and who powers it; and the setting choices (heat pump only, hybrid, or electric) to the customer and to whoever configures any time-of-use schedule.

Where it goes wrong. A tank that fits the closet the gas heater was in but has no air to work with, or a condensate line run to a spot that freezes. Either one shows up as a call about lukewarm water in February.

The envelope trades: the work nobody quoted

Insulation and air-sealing contractors, roofers and chimney sweeps, and carpenters each have a slice that is easy to leave off.

• Insulation and air sealing shrink the heating load, which shrinks the backup heat, which is often what decides whether the service needs an upgrade. Their hand-off is a before-and-after blower door number or a scope of work the HVAC tech can use in the load calculation.
• Roofers and chimney sweeps own the chimney once nothing uses it, or once a single appliance is left in it with a liner. A capped, abandoned chimney still sheds water and still needs its crown and flashing; a lined one needs its liner inspected. See related: How to Handle the Chimney a Furnace Left Behind.
• Carpenters build the louvered door, the duct chase or the platform the heat pump water heater needs, and patch the walls the line sets and circuits went through.

The gray zone: tasks between trades

These are the tasks where the failures concentrate, because each trade reasonably assumes another has them.

Who may do which electrical task is a state licensing question. Some states let an HVAC contractor wire from the disconnect to the equipment under its own license; others require a licensed electrician for anything at line voltage. Check your own licensing board before you split a scope that way.

Worked example: one conversion, divided by trade

A 1,600 square foot house with a 150-amp service converts its furnace, water heater and range in one project. The coordinator broke it into trade scopes, with labor estimates in hours as planned:

• Electrician: 16 hours. Load calculation from interval data, three new 240-volt circuits (heat pump, air handler with 5 kilowatts of backup, induction range), one dedicated 120-volt circuit for a plug-in heat pump water heater, outdoor disconnect, condensate pump receptacle.
• Gas fitter: 4 hours. Remove furnace, water heater and range, cap three lines, close out with the utility because nothing gas remains.
• HVAC: 24 hours. Heat pump and air handler, return duct enlargement, line set, commissioning and the customer walkthrough.
• Plumber: 6 hours. Water heater set, condensate route to the floor drain, expansion tank.
• Envelope: 10 hours. Attic air sealing before the HVAC sizing was final.
• Carpenter and chimney: 5 hours. Louvered door on the water heater closet, chimney capped and flashing checked.

Total: 16 plus 4 plus 24 plus 6 plus 10 plus 5 is 65 hours. The HVAC scope is the largest at 24 of 65, a little over a third. Electrical and gas together are 20 of 65, under a third, and on a gas-to-gas replacement they would have been a fraction of that.

Two things changed the plan in the field. The attic air sealing let the HVAC tech drop the backup heat from 7.5 kilowatts to 5, which took about 10 amps off the electrician's calculation and kept the service at 150 amps. And because the last gas appliance left, the venting check applied to nothing; the gas fitter recorded that on the card rather than skipping it, so the file shows the question was asked.

What would change the division. Keeping a gas dryer moves the utility close-out off the job and puts a venting check on the remaining appliance's card, though a dryer vented to its own wall termination has no shared chimney to check. A 240-volt water heater instead of the plug-in adds about 19 amps to the electrician's calculation and two panel spaces. A house with a heat pump already for cooling may need almost no HVAC scope beyond controls and backup heat.

How to verify the division held

• Every trade's scope lists what it receives and from whom, and every hand-off document (equipment list, load letter, capped-line note, venting card, chimney note, commissioning record) is in the file with a date.
• Every row of the gray-zone table is assigned to a named trade on this job, even if the answer is "not applicable."
• The customer can name who to call for each system.

References

• Your state's contractor and electrical licensing board rules on line-voltage work by HVAC contractors
• NFPA 70, National Electrical Code, 440.14 (disconnecting means in sight of the equipment), as adopted by your jurisdiction
• See related: How to Coordinate the Trades on a Conversion
• See related: The Whole-House Electrification Sequence
• See related: What Removing a Gas Appliance Does to the Ones Left