Almost nothing people repeat about heat and energy recovery was invented as a lie. Most of it described real houses accurately, and then the houses changed. So instead of marking each claim true or false, this page gives it an expiry: what made it true, what event ended it, and what is left. Then it points you at the one week of evidence that settles your own address.
Furnace Direct installs and replaces balanced recovery ventilators in Bayport, along the river flats, and up on the bluff fringe. We sell no equipment, which is why nothing on this list is bent toward a product.
Expired the moment the house was air-sealed, re-glazed, or had its rim joists foamed.
This was a reasonable description of an old river-town house with a working chimney, loose sash, and no insulation at the rim. Air changed constantly, at enormous heating cost, and nobody needed a plan for it. Every tightening project since has removed a little more of that accidental ventilation without appointing anything to replace it. The sentence does not become false gradually — it becomes false on the day the last significant leak is closed, which is usually a day nobody marks on a calendar.
Narrowed from a rule to a condition once households started getting smaller inside tighter shells.
It is still perfectly true of a crowded house that is already producing more vapor than its windows can tolerate. It stopped being a general rule when a large share of houses became tight enough, and lightly enough occupied, that keeping some of the outgoing moisture is the entire point. The honest version today is conditional: in a vapor-surplus house, keeping moisture is a defect; in a vapor-deficit house, it is the feature you are paying for.
This one had no valid era. It recovers nothing, by design.
A bare duct from outside teed into the return, with or without a motorised damper, imports cold outdoor air and dumps it at the furnace. There is no core, so nothing is recovered in either direction, and the house pays in both comfort and fuel. We find these regularly, usually in homes whose owners believed for years that they had ventilation. Discovering it changes a quote from a replacement into a first install, and it often explains the arid winter the household has been fighting with humidifiers.
Expired with the idea that ventilation is an event rather than a rate.
Cracking a window produces a short, violent, unrecovered air change driven by whatever the wind is doing, concentrated in one room, at exactly the moments nobody is there to manage it. Balanced recovery is a low, continuous, measured rate through a core that gives most of the heat back. The two are not small and large versions of each other; they are different categories. The window habit survives because it is free and it feels responsible.
Mostly expired, but it survives wherever installation shortcuts survive.
Noise complaints are now far more often an installation story than an appliance story: a cabinet hung rigidly against a finished wall, undersized duct forcing high velocity, a sharp transition right at the plenum, or a unit commissioned at its top speed because nobody balanced it. The appliance class got quieter. A badly routed install in a small river-flat basement will still be audible in the room above it, which is why hanging and duct sizing are not places to economise.
Expired the first winter after your install, every time.
Filters protect the core; the core is not a filter. A packed core moves very little air while continuing to look and sound exactly as it did when it worked, which is why it counterfeits every symptom that would otherwise point at the wrong technology. A large share of the "my ERV does not work" calls we take are resolved with a wash, an airflow reading, and nothing else. Any page that sells you an appliance without telling you this is not being straight with you.
True about the outdoors in several seasons; never true about the indoors in January.
Standing on the flats in August, the claim is self-evidently correct. In deep winter, outdoor air near the river holds very little absolute moisture regardless of what the relative number says, and heating it indoors drops its relative humidity through the floor. A tight house ventilating continuously with that air gets drier, not wetter. The river changes fog, frost on terminations, and late-summer load. It does not rescue a January humidity complaint.
Expired as soon as houses got tight enough for over-ventilation to be possible.
In a leaky house, extra capacity disappeared into the noise. In a tight one, running more air than the household needs means heating and re-heating air you did not need, drying the building out in winter, and spending more on a cabinet that will spend its life throttled. Airflow gets sized to the house and the household, and then it gets verified with an instrument. The right unit is the one that hits the number quietly, not the largest one the wall will hold.
Every claim on this page has the same life cycle. Someone describes a building honestly. The description gets repeated at job sites and across fences until it detaches from the building it described. Meanwhile the housing stock quietly changes underneath it — windows, attic, rim joists, sealed-combustion appliances, an unused chimney — and one day the sentence is being applied to a house that is physically incapable of behaving the way the sentence assumes. Nobody lies at any point in that chain. The sentence simply outlives its subject, and the only defence is to ask what has been done to this specific building since.
Nothing about a packed core has ever stopped being true, and nothing about it will. It is the only maintenance fact in ventilation that reliably decides whether the appliance you paid for is doing anything at all. Everything else here has a date attached.
The outdoor-air tee. Homeowners live with it for a decade, buy humidifiers to fight the dryness it creates, and only discover it when somebody finally looks at the return. It is the single most expensive misunderstanding in this category.
The winter-ERV objection. It is wrong as a rule and right as a condition, and telling those apart is most of the value a survey adds.
Housing near an old industrial river town tends to come in two populations: buildings that have been worked on continuously for a century, and buildings that have barely been touched since they were put up for mill workers. Both populations exist on the same street, often next door to each other, which means two neighbours can both speak accurately about their own houses and completely contradict each other. That is the real reason the first claim refuses to die here. It is still true of one of those houses. It expired years ago in the other, and the only way to know which is which is to look at the rim joist, the glass, and the chimney rather than at the street.
Pick the sentence your decision is still resting on and we will test it against your house.
Have a claim checkedBuy the cheapest hygrometer you can find. Put it on an interior wall of the room that bothers you, away from registers and sunlight. At dawn, note the reading, the outdoor temperature, and whether the nearest north or east window is clear, filmed, beaded, or frosted. Do that for seven days during a genuinely cold stretch. Clear glass with low readings means the arid claims apply to you and an energy-recovery core protects what little moisture the house makes. Filmed or beaded glass with higher readings means the surplus claims apply and a heat-recovery core carries the vapor out. Wild day-to-day swings usually mean something is wrong with airflow, and that is worth finding before any appliance is chosen.
Because most of them were accurate descriptions of houses once, and calling them myths is both rude and inaccurate. The useful question is not whether a sentence is true in the abstract but whether it is still true of a building that has been tightened since the sentence was coined. Expiry framing tells you what event made it stale, which is exactly what you need to check at your own address.
They were applying a rule that fits a crowded house to a house we have not measured yet. If yours is full, busy, and sweating its windows in January, they are right. If yours is tight and lightly occupied with floor seams opening every winter, the same rule produces exactly the wrong appliance. We would rather settle that with a week of dawn readings than with a rule.
The first one applies hardest, and the direction depends entirely on how much tightening has already happened. Untouched stock of that generation ventilates by leaking and does not usually have a humidity complaint. The complaints arrive after the windows, attic, and rim work — which is also when the first claim finally expires for that building.
Park a hygrometer on the coldest interior wall of the room that bothers you, read it at dawn for seven days, and photograph the nearest window each time. That single week settles more of this list than any amount of argument, because it tells you which direction your house actually runs rather than which direction houses in general run.
Possibly not, and that is a fine outcome. The point is to make sure the decision rests on what your house does rather than on a sentence that stopped being true before your envelope work. If you can point at the observation behind your choice, this page has already done its job.
Mostly in exposure and staging. Bluff-fringe properties get more wind at the terminations, so hood selection and flashing detail get more attention, and winter access can be the hardest part of the day. The claims expire on the same schedule; it is the install that changes.
Name the sentence your decision rests on and what your house actually does. You get a straight answer and a licensed flat install price.
Sibling pages never put a claim on trial. They reach the same call with forced matchups, scope sheets, and a walk around the lot.