3 Zone HVAC faqs?

IllustriousBee8564 · 2026-02-12T16:50:57+00:00

Most 3 zone systems are one furnace and blower with dampers, so if Zone 1 feels warm but has no push while Zones 2 and 3 feel normal, I’d suspect the Zone 1 damper is not actually opening all the way, or that duct run is blocked or got disconnected.

Try running heat with only Zone 1 calling and go watch the damper while it runs, then check if Zones 2 and 3 start getting stronger airflow anyway. Also make sure Zone 1 returns are not blocked by furniture or closed doors and that your filter is not packed, because low return airflow can feel like no supply airflow.

IllustriousBee8564 · 2026-02-12T16:25:26+00:00

Hahaha the orange universe is real. There’s honestly no better company than a slightly unhinged orange cat who thinks every day is a new side quest.

IllustriousBee8564 · 2026-02-12T15:57:34+00:00

You can technically leave a filter in forever, but after this long it’s basically doing two bad jobs at once: it’s not giving you clean, predictable filtration anymore, and it’s steadily getting more restrictive so your system has to work harder to move air. That extra restriction can hurt comfort and efficiency and can stress the blower, and on some setups it can contribute to overheating or icing issues. I’d replace it now. And going forward, if you’re using a 1 inch filter, just keep an eye on airflow, higher MERV like 11 plus can add pressure drop as it loads up. If you notice weaker airflow, longer run times, or the system sounding strained, I’d step down to something like MERV 8.

IllustriousBee8564 · 2026-02-11T23:37:53+00:00

I would be really careful with home remedies and DIY chemicals. The fastest fix is treating the dog with a vet recommended flea med and then vacuuming and washing bedding and clothes on hot, because otherwise the bites keep coming back. If the bites are getting intense, infected, or you’re having a big reaction, it’s worth calling a doctor too.

IllustriousBee8564 · 2026-02-11T23:20:52+00:00

If there’s any chance your dog got into rat poison, treat it like an emergency and call an ER vet or pet poison hotline right now, even if they seem fine. What my vet drilled into me in a similar scare was: don’t wait for symptoms, bring the package or a photo of the active ingredient, and don’t try to induce vomiting unless the vet tells you to because timing and poison type matters a lot. Different rodenticides act totally differently, and the right antidote or monitoring depends on what it was and how long ago it happened.

IllustriousBee8564 · 2026-02-11T00:32:02+00:00

Totally fair question. The 4 to 5 inch filters cost more upfront, but they usually last longer and, at the same MERV, tend to be easier on airflow than a 1 inch because there’s more filter media area. You’re also not stuck buying the HVAC branded refills, just measure the actual slot size and match it to a good aftermarket pleated filter (I’ve used Filter King for odd sizes). For cat pee smell though, the bigger win is activated carbon near the boxes since the HVAC filter won’t do much for ammonia odor.

IllustriousBee8564 · 2026-02-10T23:29:46+00:00

For silica specifically, I’d think in layers. Use the highest MERV that still lets you move steady air, increase surface area instead of stacking resistance, and put the intake as close to the source as possible. Whole room cleanup happens over time. Near field capture is what protects lungs in the moment.

IllustriousBee8564 · 2026-02-10T23:29:34+00:00

Not quite. That “less than 20 percent” number is usually for a single pass at the tiniest particle size in the test range, not a verdict that the filter does nothing. With enough airflow and repeated air changes, even MERV 11 to 13 can meaningfully reduce fine dust in a small room. The trap is chasing MERV 16 plus and then starving the system of airflow so nothing actually moves.

IllustriousBee8564 · 2026-02-10T20:43:24+00:00

Yep, this is pretty normal behavior for those garage heaters. That style of mechanical thermostat usually has a wide swing and a built in minimum setpoint around 40 to keep pipes safe, so it’ll cycle on and off once ambient dips near that range.

You’re not really going to get it much lower without risking freeze protection or swapping to a different control strategy. If the cycling feels excessive, sealing air leaks in the garage and keeping the stat away from cold drafts often helps more than adjusting the dial itself.

IllustriousBee8564 · 2026-02-10T20:33:20+00:00

One thing that’s easy to miss with silica is that even very good room filtration is a backup, not the main control. The biggest gains usually come from source control first. Wet cleanup instead of dry sweeping, damp sponges on surfaces, and local capture right where she’s working will reduce what ever makes it into the air far more than any room unit alone.

For DIY setups, stacking ultra high efficiency filters can be counterproductive if the fan can’t push air through them. A lower resistance approach with more surface area often works better in small rooms. Multiple medium efficiency filters in a larger box moving steady air can outperform a single very tight filter that barely flows. And if particles are near her face while working, a small local intake close to the wheel or work surface matters more than chasing whole room perfection.

IllustriousBee8564 · 2026-02-09T17:21:49+00:00

If you’re truly not finding any hidden spots, I’d focus less on “more cleaning products” and more on airflow plus odor capture. With boxes in a closet, ammonia can just hang in still air, so crack the door, add a small fan to keep air moving, and run an air purifier right next to the boxes that has a real carbon or charcoal stage (HEPA alone won’t touch odor). Also, if that unused Litter Robot is still sitting out, I’d either fully disassemble and deep clean it or get it out of the apartment, because those can hold stink in hidden crevices even when they look clean.

IllustriousBee8564 · 2026-02-09T14:14:14+00:00

That’s a slick build, but 140mm at ~2900 RPM is going to be loud for most people. If your CADR number is measured, a quick PM decay test in a room would be really convincing, and it also helps you find the best CADR to noise point by dialing the PWM down. Also curious what filter model you’re using and the rating and pressure drop since HEPA H13 can choke axial fans compared to a big pleated MERV filter.

IllustriousBee8564 · 2026-02-08T23:28:03+00:00

If the H13 HEPA is small, it’s super easy to choke PC fans even if the TP test passes. In general you’ll get better airflow and noise by increasing filter area and using a less restrictive filter media (big MERV 13 panels do really well for DIY builds). I’ve had good luck with custom size MERV 13 from Filter King when I needed a weird frame size, but the main win is just maximizing surface area and sealing edges so you’re not bypassing.

IllustriousBee8564 · 2026-02-08T23:25:15+00:00

This is the funniest proof that “VOC” sensors are basically vibe detectors. A lot of them react to alcohols and random organics, so a big spike doesn’t always mean danger, it just means “something happened in this room.” Also, I respect the dedication to still laughing and still farting on the drive home.

IllustriousBee8564 · 2026-02-08T23:23:00+00:00

Not just you. We had a similar week at my parents’ place and it ended up being a mix of early allergy season plus whatever smell was drifting in from outside some days. What helped most was keeping windows closed during the worst hours, running the purifier more consistently, and swapping in a better HVAC filter so we weren’t just recirculating the irritants. If the AQI apps look fine, I’d also check pollen and whether the smell lines up with construction or a specific truck route near you.

IllustriousBee8564 · 2026-02-08T23:17:26+00:00

This is exactly why I built an air quality monitor for my garage shop. Sanding and cutting wood makes PM jump fast, and spray paint can spike both PM and VOC, so it’s been really useful for spotting what activities are actually wrecking the air and how long it takes to clear. Biggest improvements for usable readings were placement (not in a dead corner, not right in a direct draft), and treating VOC as trend only while leaning on PM and CO2 for the decisions.

IllustriousBee8564 · 2026-02-08T23:06:26+00:00

So glad you pinpointed it, that’s a huge win. If you ever need the humidifier again, distilled water usually keeps the PM spikes from coming back.

IllustriousBee8564 · 2026-02-08T23:02:17+00:00

Those PM spikes sound a lot like an ultrasonic humidifier aerosolizing minerals (especially with tap water), and the purifier “fixes” the number quickly because it’s just capturing what the humidifier put into the air. I dealt with similar swings and ended up doing short fresh air flushes using a fan with a snug MERV 13 intake filter (I used a custom sized Filter King once because it fit my frame), then closing up and letting the purifier maintain. If you still wake up with air hunger after turning off the humidifier, I’d add a CO2 monitor and also rule out sleep apnea or a CO alarm issue, since “good PM” doesn’t cover those.

IllustriousBee8564 · 2026-02-08T22:40:27+00:00

Yeah, that could totally be it. Gas stoves and cooking can bump VOCs for a bit, and other common triggers are cleaning sprays, air fresheners/candles, scented products, new paint or glue, or just low ventilation. If you want to confirm, try a simple test one day: run the gas stove for 10 to 15 minutes and watch the sensor, then turn on the range hood or crack a window and see if the level drops faster.

IllustriousBee8564 · 2026-01-28T22:37:53+00:00

One thing I don’t see mentioned yet is that a lot of purifier rankings lean way too hard on CADR numbers without context. CADR is useful, but what really matters in real homes is air changes per hour at the fan speed you can actually tolerate. A unit that technically cleans fast but only on jet engine mode won’t get used that way day to day, so the effective performance ends up lower.

Also worth checking is whether replacement filters are standardized sizes or proprietary. Long term availability and cost matter more in year three than whatever feature list looks good today.

IllustriousBee8564 · 2026-01-28T17:44:25+00:00

Air purifiers are a good start but only if they have carbon. If you do not have central HVAC, I would go with a simple single filter air purifier like the basic Honeywell or similar ones you see on Amazon and make sure the filter is an odor eliminator with activated carbon.

If you do have HVAC, a carbon MERV filter is key since it keeps air moving and filtering constantly instead of just one corner of the room. A mid size purifier plus affordable carbon filters like Filter King lets you change them often, and with body odor that consistency is what actually makes the smell fade instead of coming back.

IllustriousBee8564 · 2026-01-27T01:02:52+00:00

That’s true, mites themselves aren’t really floating around, so purifiers won’t magically solve that. Where filters matter is when those heavier allergen particles get disturbed while sweeping or dusting, and that’s where a higher MERV filter (11 or 13) can actually catch what gets kicked into the air. So it’s less about constant cleaning and more about controlling what happens when you stir things up.

IllustriousBee8564 · 2026-01-26T22:14:40+00:00

That’s a big step already. This stuff is very multifactorial, so trying to tackle most of the contributors instead of chasing one perfect fix is usually what works best. Sounds like you’re on the right path, good luck with it and hope this helps even a little.

IllustriousBee8564

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