# Rinnai Central vs Optimal°

The clearest difference is review sentiment: Optimal° at 60% against Rinnai Central's 9%. Optimal° also leads on rating (3.9 vs 1.6). Rinnai Central's advantage is update cadence (monthly vs every 5 months) and ratings volume (396 vs 9). On price, ads, in-app purchases and monetization model there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

Optimal° holds the better App Store score, 3.9 against 1.6. That said, the two scores are not equally well evidenced: Rinnai Central has 396 ratings behind it against 9, so its average is the more settled of the two. Written reviews point the same way: 9% of Rinnai Central's written reviews are positive against 60% of Optimal°'s.

Rinnai Central ships an update monthly, Optimal° every 5 months. The most recent releases landed on October 27, 2026 and October 24, 2026 respectively.

## The numbers

| Metric | Rinnai Central | Optimal° |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [1.6 (396 ratings)](https://appshunter.io/ios/app/rinnai-central/id6444321202/reviews) | **[3.9 (9 ratings)](https://appshunter.io/ios/app/optimal/id6473653236/reviews)** |
| Number of ratings | **396** | 9 |
| Positive reviews | 9.0% of reviews | **60.0% of reviews** |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | **Monthly** | Every 5 months |
| Monetization | Free | Free |
| Size | 79 MB | 19 MB |
| Requires iOS | 15.4.1 | **15.1** |
| Devices | **iPhone, iPad, iPod** | iPhone, iPod |
| Age rating | 4+ | 17+ |
| Developer | [Rinnai America Corp](https://appshunter.io/developer/1045235922) | [Its Optimal LLC](https://appshunter.io/developer/1719356914) |

## What reviewers say

### Rinnai Central

[App page](https://appshunter.io/ios/app/rinnai-central/id6444321202)

This app connects Rinnai tankless water heater owners to their devices for temperature control and scheduling. Professional installers can use it to register appliances, perform service, access documentation, and order parts.

**Highlights:** Adjust water temperature, Schedule hot water, Activate recirculation, Register appliances, Perform remote service, Access documentation, Order replacement parts

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases:** none

**What reviewers like**

- 🚀 Works great
- 🚀 Much improved
- 🚀 Fantastic
- 🚀 Working perfectly now

**What reviewers complain about**

- 🐛 Doesn't work at all
- 🐛 Bug in 4.3.0
- 🐛 Awful. Just terrible
- 🐛 Lousy App
- 🐛 Rinnai does not care

**Reported bugs**

- Control failed is still happening in latest version
- Login screen freezes
- Incompatible with older devices

**Requested features**

- Add device through Bluetooth missing
- Dark mode option
- Advanced analytics dashboard


### Optimal°

[App page](https://appshunter.io/ios/app/optimal/id6473653236)

This app provides remote control and monitoring for a specific brand of tankless water heaters. Users can adjust temperature, track performance metrics, and receive diagnostic information for efficient hot water management.

**Highlights:** Set water heater output temperature, Monitor unit activity state, Track flow rate and energy consumption, View inlet and outlet water temperatures, Access diagnostics and error codes, Enable Vacation Mode

**In-app purchases:** none


## Frequently asked questions

### Is Rinnai Central free?

Rinnai Central is free to download, with no in-app purchases.

### Is Optimal° free?

Optimal° is free to download, with no in-app purchases.

### Which has better reviews, Rinnai Central or Optimal°?

Optimal° is rated higher. Rinnai Central averages 1.6 out of 5 from 396 ratings, while Optimal° averages 3.9 from 9 ratings.

### Do Rinnai Central or Optimal° have ads?

Neither Rinnai Central nor Optimal° shows ads.

### Which is updated more often, Rinnai Central or Optimal°?

Rinnai Central ships an update monthly, and Optimal° every 5 months. Most recently, Rinnai Central was updated on October 27, 2026 and Optimal° on October 24, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*