Vitherma

Independent home product guides and reviews

A home that actually feels good — in any season.

Honest guides on everyday home products, researched from official sources, with a Tested badge on the ones Jenny has tried herself. No press-release copy.

Affiliate disclosure: Vitherma may earn a commission on links to products we recommend. It never changes what we recommend or what you pay.

Warm, cozy living room with a portable heater and armchair by the window in winter light

Researched first, tested when marked

Every guide starts with official sources and manufacturer specs. When Jenny has tested a product herself, the review carries a Tested badge.

No hype, no scare copy

If a heater is loud, we say it. If a portable AC only works with a vent hose, we say that too. Cozy is honest.

Written to save you a return trip

The right heater for a 120 sq ft bedroom is not the right one for a 400 sq ft open living room. We keep saying that until it sticks.

The library

Every guide, in the order that helps most

Start with the pillar guide if you're new. The rest go deep on one decision each.

Portable ceramic space heater running next to a reading chair in a warm room
Pillar guide · Start here

The Complete Guide to Home Comfort: Portable Heaters & Coolers That Actually Work

The framework Jenny uses to pick heaters and coolers by room size, insulation, budget and noise — plus a comparison chart of the categories that matter (ceramic, oil-filled, infrared, evaporative, portable AC).

Read the guide
Space heater safely placed on a hard floor away from curtains and furniture
Safety

Are Space Heaters Safe to Leave On Overnight?

The honest answer, the four features that decide it, and the 7 placement rules the fire department actually cares about.

Read the answer
Portable evaporative air cooler next to a window in a bright summer room
Cooling

Portable Air Cooler vs Portable AC: Which One Actually Works?

They look similar, but one needs a window hose and one doesn't. The rule for humid climates vs dry climates that changes everything.

Compare them
Heatoor portable heater running in a living room
Review · Tested

Heatoor Portable Heater: Jenny's Full Test Notes

What it can heat, what the bundles really cost, and the honest math on that "75% off" bundle claim.

Read the review
Minimal home office desk where a compact CosyJet heater would sit
Review

CosyJet Compact Heater: 500W of Desk Warmth, Honestly Reviewed

Real size, the 500W vs "600W" contradiction on the producer's own page, running cost per hour, and why the 70% off badge is really about 15%.

Read the review
Derila Ergo contoured memory foam pillow under a sleeper in bed
Review · Tested

Derila Ergo Memory Foam Pillow: Honest Test for Side Sleepers

The shoulder gap, the cooling cover, the downsides the producer lists itself, and the guarantee detail that does not add up. In 7 languages.

Read the review
A hand adjusting a radiator thermostat dial to control home heating cost
Cost

How Much Electricity Does a Space Heater Really Use?

Real cost per hour by wattage, the four settings that actually cut it, and why plug-in "power saver" gadgets don't.

See the real numbers
Sleeper's head and neck supported by a contoured pillow
Sleep

Best Pillow for Side Sleepers: The Four Things That Actually Decide It

Loft, the shoulder gap, contour shapes and foam heat — plus the pillow mistakes that keep waking you at 3 a.m.

Read the guide
Warm slippers and a cup of tea on a bed in a small, heated bedroom
Efficiency

Best Energy-Efficient Heaters for Small Rooms (Under 200 sq ft)

Bedrooms, home offices, walk-in closets — the wattage for each, and the picks that don't trip a 15-amp circuit.

Size it to your room
A fireplace glowing in a living room, the kind of radiant heat you feel on your skin from across the room
Types

Ceramic vs Infrared Heaters: What's the Real Difference?

How each one moves heat, when infrared is worth the premium, and when a basic ceramic wins outright.

Compare the two
A desk fan running beside a sunlit window in a wood-paneled room on a warm summer afternoon
Cooling

Evaporative Cooler vs Fan: When Does the Extra Cost Actually Pay Off?

A simple humidity rule to know if a swamp cooler will help in your home, and what it costs to run next to a plain fan.

Compare the two
A living room with a leather recliner, a coffee table and a rug arranged around a stone fireplace
Safety

Space Heater Placement: 7 Rules That Prevent Fires

The 3-foot rule, the outlet rule and the cord rule, room by room, with the CPSC and NFPA guidance behind each one.

See the 7 rules
Coming soon · Cooling

Do "Ventless" Portable Air Conditioners Really Work?

Why most of them are evaporative coolers with a fancy name — and the two situations where they still make sense.

Coming soon · Noise

Best Quiet Heaters for the Bedroom (Under 45 dB)

The decibel figures makers publish, what they mean at 3 a.m., and which bedroom heaters really stay quiet.

Coming soon · Seasonal

Winter-Ready Home: Heating Setup Checklist, Room by Room

Bedroom, bathroom, home office, kids' room, garage workshop — one right-sized answer for each.

Jenny Johnson, home comfort researcher and writer at Vitherma

The writer

Jenny Johnson

Jenny writes about the everyday products that make a home comfortable, and reads the manuals, the safety agencies and the fine print so you don't have to. When she tests a product herself, the review says so with a Tested badge. She's not an engineer or a certified inspector; she's the person in the family who reads every review before buying.

Vitherma is where those notes live now, so the next person doesn't have to buy the wrong one first.

More about Jenny & how this site works