Clement Boston Heat Pumps runs every install in the same order, because each step of the heat pump installation process depends on the one before it. Skip one and the problem shows up months later as a noisy blower, a cold bedroom or backup heat running in March. Here’s the sequence, and what to look for at each step.
The sequence at a glance
A ducted install moves from measurement to equipment, then through the house from outside in, and ends with proof that it works.
| Step | Depends on | Sets up |
|---|---|---|
| Load calculation | The house as it is | Equipment size |
| Duct evaluation | Equipment airflow needs | Duct changes |
| Outdoor placement | Snow, noise, rules | Mount and line set route |
| Permits and approvals | The written scope | The start date |
| Removal and mounting | Permits in hand | Room for new equipment |
| Air handler, ducts, line set | Placement and duct plan | The refrigerant circuit |
| Electrical | Equipment ratings | Controls |
| Pressure test, vacuum, charge | A sealed circuit | Safe startup |
| Airflow and controls | A running system | Commissioning |
| Inspection and handoff | Commissioning | Rebate paperwork |
Before the work: measure, then choose
The first visit decides everything after it: a room-by-room load calculation, a duct check, a panel check and an outdoor spot.
Load calculation to equipment
We calculate the heating and cooling load room by room with the ACCA Manual J method at your town’s design temperature: 7°F at Logan, colder inland. That number picks the equipment and its capacity at 5°F, not the old furnace’s label. The sizing guide explains the method.
Equipment to ducts
A heat pump moves more air than a furnace at a lower temperature. We measure static pressure, return size and leakage, then list any duct changes on the estimate. Ductwork covers what those changes involve.
Placement to mounting
The outdoor spot comes before the mount: a stand, bracket or roof frame each suit a different site. See snow stands and placement.
Permits and approvals
Once you sign the written estimate, permits are pulled for the trades involved. In Boston that usually means electrical and sheet metal permits, plus others as the job needs.
| Permit (City of Boston) | When it applies | Fee |
|---|---|---|
| Electrical | Every install; a service upgrade too | Service upgrade $20 plus $0.25 per amp |
| Sheet metal | Ducts added or changed | $20 plus $25 per 200 linear feet |
| Short-form building | Walls or ceilings opened | $20 plus $10 per $1,000 of work |
| Gas | Capping a gas line | Set by the City’s gas fee schedule |
| Oil tank removal | Boston Fire Department | $110 |
Historic district reviews and condo board approval come first where they apply. Other towns set their own fees; Cambridge charges triple for work started before a permit is issued.
On site: outside in
Most ducted installs take two to five working days on site. The order keeps the house heated as long as possible.
- Removal and mounting. The outdoor stand or frame goes in, and old equipment comes out when the switchover day arrives.
- Air handler and ducts. The air handler or coil goes in, with return and supply changes.
- Line set. Copper refrigerant lines run between the units, brazed or flared to the manufacturer’s instructions.
- Electrical. New circuits from the panel, a disconnect at the outdoor unit and control wiring between the units and the thermostat.
Electrical to controls
The control wiring depends on the equipment. A variable-speed system with a communicating control needs the right cable and settings, or it falls back to fixed stages. The thermostat guide covers the choices.
Extra steps when the job is a conversion
Switching fuels adds work around the core install, and each piece has its own timing.
- Oil: the burner comes out, the fuel line is capped, and the tank is pumped and removed under a Fire Department permit; see oil tank removal.
- Gas: a licensed gas fitter caps the line once the furnace or boiler is out; see furnace to heat pump conversion.
- Service upgrade: a new panel or meter socket needs an inspection and a utility visit before the heat pump can start; see electrical upgrades.
The refrigerant circuit: test, evacuate, charge
The sealed circuit is proven before refrigerant moves through it. Three steps, in order.
Nitrogen pressure test
The line set and coil are pressurized with dry nitrogen and held, so any leak shows on the gauge before refrigerant is at stake.
Vacuum below 500 microns
A vacuum pump pulls moisture and air out of the circuit until it holds below 500 microns. Moisture left behind forms acids that shorten a compressor’s life; see heat pump lifespan.
Charge by weight
The refrigerant charge is weighed in for the actual line length, following the manufacturer’s tables, rather than guessed by feel. Too much or too little cuts capacity and efficiency.
Airflow setup and commissioning
With the system running, airflow is set to what the equipment needs, then commissioning checks the whole system against the design.
- Airflow measured at the air handler, against what the equipment needs per ton
- Static pressure measured across the duct system, with blower settings adjusted to match
- Controls set, with staging and any dual fuel switchover programmed
- The backup heat lockout temperature set and recorded
Commissioning to verification
The readings go on a commissioning record you keep. They’re the baseline any later service visit compares against, and they’re how you know the system matches its design, not just that it turns on.
After the install
Inspectors sign off the permits, and the rebate paperwork goes in. Mass Save needs equipment serial numbers and your signature on its forms.
We keep the paperwork straight and walk you through the settings. On a whole-home heat pump job, the old system must be removed or disconnected for the rebate. Before you sign anything, our quote checklist lists what to look for in the scope. To start with a first visit, call us or send the form.