# Heat pump ductwork assessment and modifications in Washington, DC > Upstairs too hot, downstairs too cold? We measure static pressure and room airflow in DC homes, then make the smallest duct change that fixes it. URL: https://perennialdcheatpumps.com/heat-pump-ductwork/ If your top floor never cools, a register whistles, or someone has told you the answer is a much bigger unit, the ducts are probably the problem, not the equipment. At [Perennial DC Heat Pumps](https://perennialdcheatpumps.com/) we assess and modify heat pump ductwork across Washington, DC as part of ducted installs and replacements. A heat pump moves more air at a cooler supply temperature than the furnace many ducts were built for, so we start with two measurements, static pressure and room airflow, and end with the smallest duct change that fixes what they show. ## Upstairs too hot, downstairs too cold? Uneven floors, whistling registers and a push for a bigger unit are the usual signs that ducts, not equipment, are holding the system back. A room can be short of delivered air, gain too much heat through a roof or west wall, or have no way for air to get back. Replacing ducts without a load calculation misses the second cause, and replacing equipment without checking ducts misses the first. When the problem happens tells us a lot. A bedroom that overheats only with the door shut points to a missing return. A whole top floor that struggles in both seasons in a DC rowhouse points to long supply runs from a basement unit plus roof heat. Our [sizing guide](https://perennialdcheatpumps.com/guide/heat-pump-sizing/) connects room loads to airflow, and our [rowhouse guide](https://perennialdcheatpumps.com/guide/heat-pumps-rowhouses/) covers the access limits that shape practical fixes. ## What we look at in your existing ducts We map the supply and return runs we can reach, measure their size, note crushed flex duct, loose joints and missing insulation, and record the filter type and location. Then we measure. Static pressure across the air handler or furnace shows how hard the blower works; airflow at each register shows where the air actually goes. We can only inspect what we can see. In a DC rowhouse, branches in party walls or between floors are usually hidden, so our report lists which runs we checked and which we assumed. Where access is limited, our estimate says what finding would add work. A rule of thumb is no substitute for design and measurement. ## The bedroom that’s fine until you shut the door Every cubic foot of supply air has to find its way back to the equipment. In many DC rowhouses a single central return in a hallway serves two or three floors, which works with doors open and fails with bedroom doors shut. The room pressurizes, supply air slows, and the room drifts away from the setpoint. The fixes are mechanical: a dedicated return in the room, a jumper duct to the hallway, or a transfer grille above the door. A bigger supply register adds nothing if the branch behind it stays small, and closing registers elsewhere just raises pressure for the whole system. Our [controls guide](https://perennialdcheatpumps.com/guide/heat-pump-thermostats/) helps tell a thermostat placement problem from an airflow problem. ## Leaks, kinks and static pressure Leaks lose conditioned air into basements, walls or attics; restrictions make the blower work harder to move the air it should. External static pressure is the combined resistance outside the cabinet, from the filter, coil, ducts and grilles, and every air handler’s data sheet lists the maximum it is rated against. Above that limit the blower cannot deliver rated airflow, and a variable-speed blower ramps up, gets louder and uses more power trying. Switching to a dense pleated filter in an undersized return grille is a common way to push pressure up without touching a duct. We look at return sizing first: a larger return grille and filter area lowers air speed and resistance. Our [air-handler service](https://perennialdcheatpumps.com/heat-pump-air-handler-replacement/) covers the equipment side. ## Finding a route in a narrow rowhouse A DC rowhouse is narrow, with the stair usually running along one party wall, so a new duct route competes with stairs, joists and ceiling height. Closets stacked floor to floor are often the only vertical chase. If you are renovating and the ceilings are open, that is the cheapest moment to add a return or upsize a trunk. Targeted changes include adding a return, replacing a crushed branch, sealing joints with mastic and insulating runs in unconditioned space. Broader rebuilding is for houses where the layout cannot meet the room loads. Our [renovation planning article](https://perennialdcheatpumps.com/blog/heat-pump-replacement-during-renovation/) covers sequencing; plaster, trim and flooring repairs are their own lines in your estimate. ## A few fixes, or a full rebuild? A targeted change fixes a measured problem and keeps the ducts that work. A rebuild replaces more of the network because the layout or capacity cannot support the project. We follow the measurements, not the number of feet of duct replaced. Adding one return often lowers static pressure more than enlarging several supplies would. A house with an added third floor may need its own trunk or a second zone. When we quote a [replacement](https://perennialdcheatpumps.com/heat-pump-replacement/), we state which duct limits remain after the work rather than promising even temperatures we can’t back up. ## How we price duct work We price duct work from the site visit and put it in your written estimate. Access, route length, material, insulation, testing and finish repair move it. A run exposed in an unfinished basement is a different job from one inside a plaster wall, and opening and restoring that plaster can cost more than the duct, which is why we don’t price by the room or the foot. Our typical range for a whole-home ducted heat pump is $8,000 to $18,000 before rebates, and it leaves out major duct reconstruction; our [cost guide](https://perennialdcheatpumps.com/heat-pump-cost/) explains what else sits outside it. In our [cost estimator](https://perennialdcheatpumps.com/tools/heat-pump-cost-estimator/), flag duct work as its own line and fill in the amount once you have our written estimate. Duct work tied to a heat pump install falls under the project’s DOB mechanical permit, which we file before work starts. ## Proving the fix worked After the work we measure static pressure again under the same conditions as before, compare it with the air handler’s rated limit, and recheck airflow at the changed registers. Our records note any runs still out of reach. A quieter register is a good sign, but not proof every room gets its design airflow. Our [quote checklist](https://perennialdcheatpumps.com/guide/heat-pump-quote-checklist/) has space for the before and after readings. Keep the layout notes and photos, especially where a remodel will cover access points. To [request a ductwork assessment](https://perennialdcheatpumps.com/contact/), tell us which rooms are affected, whether shutting doors changes the problem, and the install or replacement you are planning. Please don’t remove duct panels or reach near a running blower to investigate. ## What this work looks like ## Questions before you decide ### Does installing a heat pump automatically require new ducts? No. If measured static pressure is within the new air handler's rated limit and your rooms get their design airflow, we keep the ducts. Age alone does not decide it. ### What can make one room uncomfortable despite operating equipment? Too little supply air, no return path, a high heat load from a roof or large windows, or a thermostat in the wrong room. When the problem happens points us to which one. ### How should external static pressure be interpreted? It is the resistance the blower sees from the filter, coil, ducts and grilles. We compare the reading with the maximum on the air handler's data sheet; above it, rated airflow is not reached. ### Can closing a bedroom door affect its return airflow? Yes. With one central return, a shut door traps supply air in the room. A dedicated return, jumper duct or transfer grille gives that air a way back. ### Do duct sealing and duct insulation address the same issue? No. Sealing stops conditioned air leaking out of joints; insulation slows heat moving through the duct wall. Runs in an unconditioned attic or crawlspace usually need both. ### Can a stronger blower replace the need to correct a restriction? Not well. Pushing harder against a restriction raises noise and power use and can exceed the blower's rating. We fix the restriction instead, which is often an undersized return. ### Who should restore surfaces opened for duct alterations? Our written estimate lists every opening and says who patches and paints. In plaster-walled DC houses, restoring the wall can cost more than the duct itself. ### Can a filter choice change the distribution assessment? Yes. A dense filter in an undersized return grille raises static pressure sharply. A larger return and filter area lets a better filter work without starving the blower. ### Is major duct reconstruction included in the base equipment band? No. Our typical range of $8,000 to $18,000 for a whole-home ducted system leaves out major duct reconstruction, which we price from the site visit as its own line. ### What checks should follow an agreed duct modification? We measure static pressure again under the same conditions as before, check airflow at the changed registers, and note any runs still out of reach. We agree those readings with you before work starts. ## Continue planning Perennial DC Heat Pumps DC rowhouses Heat pump sizing Humidity control Quote checklist DC heat pump buying guide Heat pump replacement Air-handler replacement Furnace conversion Get an estimate Heat pump cost estimator Heat pump services Heat pump costs