The West End
the office · 240V · decided
Update — the FS09 is gone. Stock-checked July 18: the matched FS09 system is genuinely unbuyable (the indoor head is discontinued everywhere; the lone $925 condenser at HVACDirect is an orphan), and the Senville 9k outdoor unit is out of stock too. The pivot was verified properly, including the question that matters — both options below credibly keep the CN105 connector for the ESPHome local-control mod (~$30 board, fully local climate entity, no Kumo cloud).
| Tier | System | The trade | Price |
|---|---|---|---|
| Best | Mitsubishi MSZ-FX09NL / MUZ-FX09NLHZ | The FS's true successor — H2i hyper-heat to −22°F (better than the FS), current R454B platform, in stock and shipping (also at HVACDirect, "5 left," $2,812). CN105 per vendor compatibility lists; for zero residual doubt, one question in the CN105 project's GitHub before ordering closes it. | $2,652 |
| Value | Mitsubishi MSZ-GS09NA / MUZ-GS09NA | Same family, CN105 teardown-proven (a published GS09NA + ESPHome build) — but heating floor is only −4°F. Since cooling is the mission and the furnace still exists, that's a defensible $700 savings; hyper-heat is winter insurance, not a requirement. | $1,923 |
- Why 9k, and why 240V: the office is 169 sqft with spillover duty to the mudroom and a hot landing next door — 6k leaves no margin, 12k short-cycles. Voltage doesn't set efficiency (SEER2 does); 240V is simply where hyper-heat and the proven local-control catalog live, and the panel makes the circuit trivial. Post-insulation the load only drops — a modulating 9k covers both eras.
- Self-install notes: dedicated 2-pole 240V circuit sized to the nameplate (this class typically wants a 15A breaker — read the plate, not the internet), outdoor disconnect + weatherproof whip at the condenser, and the head on the office's west wall throwing across the long dimension. A door fan handles the mudroom; its awkward supply/return pair stops mattering.
The ecobee
already owned · install, then pair twice
- Run both integrations at once — they coexist: HomeKit Controller for local, cloud-free control plus the SmartSensor's per-room temperature and occupancy (pairing code from the ecobee app, not the sticker), and the stock cloud integration (no developer key needed since HA 2026.3 — just the account login) for the extras HomeKit omits.
- The nursery SmartSensor feeds Noctling through the local path — Walter's room temperature on the dashboard without ecobee's cloud in the loop.
- Quirk to remember: the thermostat's "current temperature" over HomeKit is ecobee's blended average, not the wall unit's own reading. Individual sensors come through clean.
- Zoning with the mini-split: no native coordination exists across brands — Home Assistant plays conductor, two climate entities sharing home/away triggers.
The Attic
contract the misery · own the middle · let the rebate blow it back in
1. Contract the removal (~$1.25–2.25/sqft in KC, haul-away included — the old batts-plus-settled-fill mix is confirmed junk and confirmed vermiculite-free). 2. Own the open attic — no schedule but yours: electrical cleanup, new circuits, Cat6, air-sealing, baffles. 3. Blow-only contractor puts back R-49 (~$1–2/sqft) — and contractor installation is what makes the Spire $750 rebate plausible; one call confirms it (833-841-4639). The federal 25C credit is gone as of 2026 — utility money is the only money.
The middle window, itemized
- Electrical: every splice into a covered, accessible box (NEC 314.29), each one staked taller than the final insulation depth and photographed. Non-IC can lights get clearance dams.
- Air-seal: foam-gun the top plates and every penetration, seal bath-fan collars, weatherstrip + foam-board the hatch. The highest-ROI hours of the whole project.
- Baffles — rigid only: thin foam crushes flat under R-49. ADO ProVent (~$5/bay, Home Depot) or an Owens Corning Raft-R-Mate 70-pack (~$130). Roughly 63–70 eave bays here → $130–350. Staple to the deck at every eave bay, after sealing, before the blow.
- The homelab clause: Cat6 to the ceiling-AP spot and toward kara, a smurf-tube stub for the future, neutrals fished down to the exterior-light switch boxes (Rooms), an attic temp/humidity sensor, and a hard look at the hot landing's ceiling.
All-in: removal ~$1.7–3.8k contracted, the middle ~$700–900 DIY (seal + baffles + boxes), the blow ~$1.9–2.4k contracted less the rebate — or DIY the blow free-with-bags if Spire says no.
The Windows
original aluminum single-pane · verdict: guilty · deep dive published
The worst window assembly ever mass-installed, feelable from feet away — replacement justified on merit. The short version: order block-frame (flangeless) replacements for the brick-inset openings (a factory option — no fin-snapping), fiberglass or Fibrex over vinyl in a masonry pocket, double low-E + argon as the house glass standard, sash-replace the bay if its box is sound, and order the picture trio factory-mulled with the tempered-glass check done up front.
The Window Job → — ordering, the 10-step brick-inset install sequence (with the jamb-section sketch), brand tiers with buy links, glass strategy, the bay and picture-trio decision rules, and the budget math awaiting the count + dimensions.
The Whole-House Fan
a keeper — with three upgrades from the attic project
- The lid: the ceiling shutter is the biggest hole in the new air-seal plane (~R-1, leaky louvers). A DIY gasketed 2" foil-faced polyiso box over it in the attic — ~$35, R-10+, lifts off for fan season — beats every commercial cover on R-value.
- The math check: old belt-drives this size move 3,400–5,100 CFM and want ~1 sqft of net-free exhaust area per 750 CFM (5–7 sqft). Read the fan's plate, sum the stamped NFA on the freshly baffled vents before running it hard.
- The control: a $12 Zigbee relay (Sonoff ZBMINI-R2) switches the coil of a $22 motor-rated contactor — the ⅓–½HP inductive load never touches smart-home silicon. Two-speed stays on its existing HI/LO switch; the relay gates the master.
- The interlock is the house rule, hard-coded: windows first, fan second — already policy, learned the loud way. A $15 window contact sensor gates the relay in HA, so a closed house physically can't start the fan, whoever flips the switch. (With sealed-combustion appliances throughout, this is about airflow, wall-cavity dust, and not fighting the radon system — not CO.) The evening automation runs off the Tempest: cooler out than in, dew point tolerable, window open → flush the house.
- Keep vs replace: a modern quiet unit costs $1.8–4.2k and buys silence plus a motorized damper. The old fan plus ~$70 of parts does the same job louder. Keep it.