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What actually fits an older house?
Tick what your building genuinely has. Six approaches then sort themselves into the ones worth looking at and the ones that will fight you. No price, no email field, no recommendation dressed up as a result.
Nothing is sent anywhere and nothing is stored. There is no email field on this page.
Nothing ticked yet. Every approach below is written out in full; ticking the constraints your building has simply marks up which ones fit it.
This is the big one, and it is the reason ductless exists. Retrofitting a full duct system into a house that has never had one is possible, but it is building work rather than heating work, and the cost is mostly carpentry.
Usually a system that was put in for the original footprint and never extended. Often the cheapest good outcome is to keep and fix what exists and treat the unserved rooms separately, rather than replacing everything.
Rules out anything that assumes you can open a wall cheaply. It pushes you towards approaches that need only a small penetration, and away from conventional ducting.
The attic is where most retrofit ductwork goes. Without it, any conventional ducted answer needs a route through the living space, and that route is the real cost.
Workable, and very common here. Crawlspace ducts need particular attention to sealing and insulation, because the space they sit in is humid for most of the year.
Changes what the load calculation produces, which changes the size of everything downstream. Money spent on the envelope reduces the size and cost of the system it feeds, which is why it belongs in the conversation first.
The most common cause of one room that never keeps up. An extension teed off the nearest trunk without rebalancing takes air away from wherever it came from, so you often have two unhappy rooms instead of one.
Where a property is in a locally designated district, exterior alterations may need review before work starts — and outdoor units, line set covers, grilles and vents on a visible elevation can all count. Find out what applies to your address before you commit to anything, not afterwards. Your local review board or planning office is the authority on it, not us.
Replace the ducted system like for like
The default answer, and the right one where a serviceable duct system already reaches everywhere it needs to. New equipment sized from a load calculation, connected to ducts that have been measured rather than assumed.
- Cheapest per unit of capacity when the ducts are already there
- One system, one thermostat, familiar to everybody
- Falls apart if the ducts cannot carry the new airflow, which is why we measure first
Keep the equipment, fix the ducts
Frequently the best value in an older house and almost never the thing that gets quoted. Sealing, resizing a return, correcting a crushed branch and rebalancing can fix a complaint that looks like it needs new equipment.
- A fraction of the cost of replacement
- Makes any future replacement smaller and cheaper
- Needs measurement to justify, which is the point
Ductless throughout
Wall or ceiling units in each area, fed by small refrigerant lines rather than ducts. In a house with nowhere to run a duct this is usually the honest answer rather than the upsell.
- Needs only a small penetration per indoor unit
- Room-by-room control, and no duct losses at all
- Indoor units are visible, and some people mind that a great deal
- Outdoor units and line set covers on a visible elevation can matter in a historic district
Ductless for the problem rooms only
Keep the existing system for what it serves properly and add a unit for the sun room, the converted garage or the upstairs bedroom that has never worked. A hybrid, and the most underused answer there is.
- Much cheaper than replacing a system that mostly works
- Stops an extension stealing air from the rest of the house
- Two systems to maintain rather than one
Small-duct high-velocity
Flexible tubing of around two inches routed through joist bays and closets, with small round outlets instead of grilles. Designed for exactly this problem: a building where conventional ducts will not fit and visible indoor units are unwelcome.
- Far less invasive than conventional ducting
- Outlets are small and discreet
- Still needs a route and a place for the air handler
- Fewer contractors work with it, so get more than one opinion
Do the envelope first
Air sealing, crawlspace and attic insulation, and dealing with the worst of the glazing. Not our trade for the most part, and it is still the first thing we will raise, because it changes the size of everything that comes after it.
- A smaller load means smaller, cheaper equipment
- Fixes comfort problems that no amount of capacity will
- Window changes on a visible elevation can need review in a historic district
- We will tell you when this is the better place for your money, and it costs us the bigger job
What this does not do
It does not know your building. It cannot see whether there is a route, what the joists run like, what the load actually is or what your budget can carry, and it deliberately produces no price. What it does is stop the conversation starting at “which brand”, which is the wrong end of the question in a house like this.
The historic-district point is the one to take seriously on your own: what needs review, and for which elevations, is decided by your local board or planning office, and it is worth a phone call before you commit to anything visible from the street.