# Sightglass: Superheat PT Chart — HVAC charging & subcooling

> HVAC charging & subcooling (iPhone/iPad app by Serdar Oztetik.)

- Source: https://appshunter.io/ios/app/sightglass-superheat-pt-chart/id6830173381 (this page in markdown: same URL + `.md`)
- Developer: [Serdar Oztetik](https://appshunter.io/developer/1758747041)
- Category: Utilities, Reference
- Price: Free with in-app purchases
- Age rating: 4+
- Requires: iOS 17.0 · 1 MB
- Languages: American English
- Released: 2026-11-06
- Data updated: 2026-11-06

## What is Sightglass?

Sightglass tells you whether a system needs refrigerant, needs some taken out, or is right where it should be. Type the gauge readings and line temperatures and it gives you the number, the target and a plain call: add, recover or leave it.

Everything runs on the phone. It works in a basement, a crawlspace or on a roof with no signal, and there is no account and no login.

SUPERHEAT (FIXED ORIFICE / PISTON)
Suction pressure and suction-line temperature give the superheat. The target comes from indoor wet-bulb and outdoor dry-bulb on the standard fixed-orifice charging chart, or type a target yourself. Where the chart says to weigh in the charge, Sightglass says so instead of guessing.

SUBCOOLING (TXV / EEV)
Liquid pressure and liquid-line temperature against the bubble point, with the target from the unit's rating plate.

AIRFLOW
Temperature split across the indoor coil, against the target split for the return air. Enter wet-bulb or relative humidity, either works.

PT CHART
29 refrigerants, including R-410A, R-454B, R-32, R-22, R-134a, R-404A, R-407C, R-448A, R-449A, R-513A, R-1234yf, R-290 (propane), R-600a and R-744 (CO2). Blends with glide get separate liquid (bubble) and vapor (dew) columns. Type a pressure to get the saturation temperature, or a temperature to get the pressure. Vacuum shows in inches of mercury.

WET-BULB
From dry-bulb and relative humidity.

UNITS AND ELEVATION
°F or °C; psig, kPa or bar. Set your elevation once and every saturation temperature is corrected for the thinner air.

WHERE THE NUMBERS COME FROM
Saturation tables are computed with CoolProp, the open-source thermophysical property library, and checked against published manufacturer PT charts. Airflow targets follow the Proctor Engineering temperature-split table.

Sightglass is a calculator for trained HVAC/R technicians. Follow the equipment manufacturer's charging instructions where they differ, and handle refrigerants as your certification requires.

SUBSCRIPTION
Sightglass requires a subscription. Weekly: $4.99 per week, and eligible new subscribers get the first 3 days free before the first $4.99 charge. Yearly: $24.99 per year. Payment is charged to your Apple Account when you confirm the purchase, or when the free period ends. The subscription renews automatically unless you cancel it at least 24 hours before the end of the current period. Manage or cancel it in Settings > Apple Account > Subscriptions, or from Settings inside Sightglass. Prices are in US dollars and vary by country.

Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/
Privacy Policy: https://callmemcp.com/sightglass/privacy/

## Pricing and in-app purchases

Base price: Free.

**Subscriptions**

| Subscription | Price | Period |
| --- | --- | --- |
| Sightglass Yearly | $24.99 | per year |
| Sightglass Weekly | $4.99 | per 7 days |


## Is Sightglass safe?

Not enough ratings yet to assess Sightglass.

## Is Sightglass legit?

Sightglass: Superheat PT Chart appears legitimate, with a few gaps. The AppsHunter Legitimacy Score for Sightglass is 65 out of 100 points across 7 verification signals from App Store and developer data.


## Version history (last 1 release)

### 1.0 — 2026-11-06

No release notes.

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All apps by Serdar Oztetik: https://appshunter.io/developer/1758747041

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-11-06.*