Book a visit
Call(762) 293-9650 OrBook a visit
  1. Home
  2. Humidity
One number

What does your humidity reading mean?

Put in what your hygrometer says indoors and which season it is. This tells you whether the number is fine, whether it is telling you something about the system, and what to do about it. No price, no email field.

(762) 293-9650

What that number is telling you

Check the reading That does not look like an indoor reading

Enter a figure between about ten and ninety-nine. If your meter genuinely says something outside that range indoors, the meter is the first thing to doubt — cheap hygrometers drift, and one that has been in a window or above a radiator will not be reading the room.

  • Put it in a room you use, at about chest height, away from windows, vents, bathrooms and kitchens.
  • Give it half an hour to settle before reading it.
  • Read it over several days. One reading during a thunderstorm tells you about the thunderstorm.
Unusually low Drier than a Macon summer usually manages

That is a comfortable number, and in this climate in the cooling season it is low enough to be worth a second look — either the meter is reading badly, or something is drying the air harder than a normal system would.

  • Check the meter first, in a normally used room, over a few days.
  • A very oversized system will not produce this; if anything it produces the opposite.
  • Dedicated dehumidification set aggressively can, and so can a system running far more than the building needs.
  • If the house genuinely feels fine, nothing here needs doing. Comfort is the point, not the number.
In range This is where you want to be in summer

Broadly the range most people find comfortable in the cooling season, and the range at which a system is doing its job. Nothing here needs fixing.

  • If the house still feels clammy at this reading, check where the meter is — one room can sit well above the rest.
  • Keep an eye on it through the worst fortnight of the summer rather than in June.
  • Ordinary maintenance is what keeps it here: a clean coil, a clear drain and correct airflow.
Higher than ideal The system is not running long enough

Cooling removes moisture only while it runs. At this reading the usual explanation is that the system satisfies the thermostat before it has run long enough to dry the air — which is what an oversized system does, every cycle, all summer.

  • Turning the thermostat down makes it worse, not better: colder and still damp, and more expensive.
  • Check blower speed. It is frequently left at whatever the equipment shipped with rather than set for this house, and it costs nothing to correct.
  • Check the return sizing and duct leakage. A return pulling humid crawlspace or attic air is bringing the problem in on purpose.
  • A load calculation settles whether the equipment is genuinely oversized, which decides what to do at replacement.
Too high High enough to cause damage, not just discomfort

Sustained readings at this level put condensation on cold surfaces — supply grilles, ductwork in unconditioned space, the inside of closets on exterior walls — and keep materials damp for long periods. That is a fabric problem as well as a comfort one.

  • Look for the obvious first: a condensate drain that is not keeping up, a coil that is filthy, or a system that is barely running because something has failed.
  • Duct leakage in a hot attic or a vented crawlspace can bring in more moisture than the system can remove.
  • Where the building genuinely needs it, dedicated dehumidification is a real answer — but only after sizing, airflow and drainage have been checked, because it is the expensive one.
  • We will not tell you what this does to anybody’s health. We will find the water and stop it; the rest is a question for people qualified to answer it.
Dry Normal for the heating season

Indoor air gets drier when it is heated, and a reading in this range during the heating season is ordinary rather than a fault. Whether it bothers you is the only real question, and in a climate with winters as mild as this one it usually does not for long.

  • Static shocks and dry skin are the usual complaints, and they are comfort matters.
  • A humidifier will raise the number. It will not fix a draughty house, and pushed too far it puts water on windows and inside walls.
  • Before adding equipment, it is worth checking whether the house is simply losing a lot of air, because that is what makes it dry.
In range Comfortable for winter

A sensible heating-season number for this climate. Nothing here needs doing.

  • If you are seeing condensation on windows at this reading, the windows are cold rather than the air being wet.
  • Worth reading again during a genuinely cold snap, which is when the number moves.
Too high for winter This will show up on your windows first

Warm moist indoor air meeting cold surfaces condenses. In the heating season a reading this high puts water on window glass and frames, and — less visibly and more seriously — inside wall assemblies where it cannot dry.

  • If a humidifier is fitted, turn it down. This is the commonest cause by a distance.
  • Check bathroom and kitchen extract actually works and actually goes outside.
  • A crawlspace or basement that is wet will supply moisture to the whole house all winter.
  • Condensation on the inside of windows is a useful early warning and costs nothing to look for.

This is a guide to what a reading generally means, not a survey. It knows nothing about your building, your equipment or where the meter is sitting, and it produces no price. It also makes no health claims of any kind.

Have somebody measure it properly
The method

How to get a reading worth acting on

  • Buy an inexpensive hygrometerDo this first

    Any of them will show you a trend, which is what matters. Absolute accuracy is a laboratory question and you are not doing laboratory work.

  • Put it in a room you actually useChest height

    Away from windows, supply vents, bathrooms and kitchens. A meter in a bathroom is measuring the shower.

  • Read it over several daysNot once

    Weather moves the number. A single reading during a storm tells you about the storm rather than about the house.

  • Read it in more than one roomIf you can

    A house that is fine in the living room and damp in a back bedroom has an airflow problem, and the two readings together prove it.

  • Write the numbers downSend them to us

    A week of readings from two rooms tells us more before we arrive than an hour of looking would.

What we will not sell you off the back of this page

Equipment, before the free things have been checked. Blower speed, coil condition, drain condition, return sizing and duct leakage are all capable of moving that number, and all of them are cheaper than a dehumidifier.

And not a health claim. Damp is a building problem and we treat it as one: find the water, stop the water, keep the air moving. What it might be growing and what that means for anyone is not a heating contractor’s call to make, and any company that tells you otherwise on a website is selling on fear.

Book a visit