OLED Thermostat & GC App Guide | Every Mode Explained

Doug Buckley ran a BISON 4000A on his boat for about six years, commuting back and forth to Gambier Island. In that time he did, in his words, "pretty much nothing" in the way of maintenance. It just kept running.

When we replaced his heater, we fitted the new OLED thermostat and walked him through the controls and the GC mobile app. This guide covers everything we showed him: every mode on the thermostat, how the timer works, what the fuel adjustment is for, and how to pair the app so you can see run time and fault codes on your phone.

First, a Six-Year Owner's Verdict

Doug bought his boat from Sherwood Marine six or seven years ago, and the heater came with it.

"It's been a pretty tremendous product… I can't say enough about the company being able to stand behind their product the way they do."

Asked whether he'd recommend it to other boat owners, he said, "Oh, 100%. My next door neighbour has one as well, same unit, and he's had the same reliable time."

One thing he did without knowing it: Doug's commute is 20 to 25 minutes each way, and he ran the heater for the whole trip, usually on high. That's close to ideal. Running a diesel heater for at least 30 minutes to an hour on a high setting gets the chamber hot enough to burn off excess fuel and clear carbon deposits. Short runs on the lowest setting are what build up carbon and eventually cause startup faults. It's the single easiest habit to get right, and it's a big part of why his heater lasted six years with no attention.

The OLED Thermostat: Every Mode Explained

The screen sleeps to save power. Press any button to wake it. From the main screen, click the knob once to open the menu, then turn the knob to move between options.

1. Variable heat mode (P1–P7)

This is the mode most people use, and it works the same way as the old analog controller's power levels. The heater ignites once and produces constant heat at the level you set, from P1 (lowest) to P7 (highest). It does not cycle off when the cabin reaches a certain temperature.

The bars on the screen show which power level you're on.

2. Thermostat mode

Set a target temperature and the heater tries to hold it, shutting down and restarting as needed.

Important caveat: without an external temperature sensor installed, the heater regulates using its air intake sensor, not the air where you're sitting. If the intake is a few degrees colder than your cabin, the heater will stop based on that reading. For most boat and van installs without an external sensor, variable heat mode gives better results.

3. Fan (ventilation) mode

Runs the blower without combustion, useful for clearing the cabin or cooling the unit down. On this screen, press and hold to turn the fan on, adjust the speed with the knob, then press and hold again to turn it off.

What the indicator light means: - Green — running - Flashing red — shutting down (the cool-down cycle is running, don't cut power) - Solid red — fully off

4. Timer: three schedules

The timer holds three separate schedules. To use one:

1. Open the timer menu and highlight a schedule. Click the name to enable it; click again to disable it.
2. Move to the arrow and click to start programming.
3. Choose the days of the week, then the start time, then how long it runs.
4. Choose the mode — variable heat, thermostat or ventilation — and confirm.
5. For variable heat, set the P level (P1–P7), confirm, then move right and hit OK to save and exit.

Use the return button to back out of any menu.

Where a timer earns its keep: Doug's marina doesn't like heaters running unattended, which rules it out at the dock. But as he pointed out, from his place on Gambier he could have the boat warm before he walks down to it. That's the use case, warming a space before you arrive.

5. Fuel adjustment (the turbo icon)

This is a newer feature. It lets you trim the fuel input up or down by a percentage from the default.

• Diesel heaters: leave it at 0%. That's correct for nearly every install.
• Gasoline models are where this matters. Pump gasoline in North America contains roughly 10–15% ethanol, which affects the fuel map. If the burn is too lean or too rich, you can adjust here.

If the exhaust sounds like it's choking or the burn doesn't seem right, this is the setting to look at. If nothing's wrong, don't touch it.

6. Settings

• Time and date — set in day / month / year, using a 24-hour clock. Worth setting properly, since the timer depends on it.
• Bluetooth — off by default. Turn it on here before pairing the app.
• Sound — the beep when you move between menu items. Turn it off if it bothers you.
• Information — firmware versions for both the heater and the thermostat panel; ambient temperature and air pressure (shown for reference only, not used to control the heater); and run time and ignition count.
• Units — switch between Celsius and Fahrenheit.
• Language.

Why run time matters more than you'd think. That screen shows total hours and how many times the heater has ignited, and it answers two questions: how much of your 2-year / 2,000-hour warranty is left, and whether you're due for service. We recommend maintenance every 800 to 1,000 hours. See the Diesel Heater Maintenance Checklist for what that involves.

One quirk to know: you can't move into other menus while the heater is running. Turn it off for a moment to change settings.

The GC Mobile App: Setup and What It Shows You

Pairing, step by step

1. On the thermostat, go to Settings → Bluetooth and turn it on.
2. On your phone, search the app store for General Components and install the GC app.
3. Open the app and scroll down to search for new devices.
4. Tap your heater when it appears. That's it, you're connected.
5. When a phone is connected, a Bluetooth icon appears at the top left of the thermostat, so you always know if something is linked.

What you get in the app

Heater information. Serial number, total run time and ignition count, the same figures the thermostat shows.

Fault codes with fixes. Tap the vital signs icon and the app reads the heater's stored fault codes, up to six of them, the same as the old controller. Tap any fault and the app gives you recommended troubleshooting steps. Once you've dealt with them, Clear All wipes the history so you're starting fresh. For the full list of what each code means, see our Diesel Heater Error Codes guide.

Full control. Set point (thermostat mode), variable heat P1–P7, and fan mode, all mirrored between the app and the thermostat. Change it in one place and the other follows.

Live status. Tap the flame icon and the app tells you exactly what the heater is doing right now: self-check (testing the sensors), ignition (glow pin heating, fuel pump starting), then stable heat. Instead of standing there wondering whether it's lit, you can watch it work.

Rename your heater. Handy in a marina or a busy yard, where several heaters may be in Bluetooth range. Leave it alone and it keeps the default name.

Watch the Full Walkthrough

Every menu in this guide is demonstrated in the video, along with Doug's full interview and the heater replacement itself.

Watch: Boat Diesel Heater Replacement — Customer Story, Full Install & App Setup

Frequently Asked Questions

What's the difference between variable heat mode and thermostat mode?

Variable heat mode (P1–P7) produces constant heat at the level you choose and doesn't cycle off. Thermostat mode targets a temperature and stops when it's reached. Without an external temperature sensor, thermostat mode measures at the heater's air intake, not where you are, so most boat and van owners get better results from variable heat mode.

Do I need an external temperature sensor?

Only if you want thermostat mode to work accurately. It regulates by the temperature where the sensor sits, rather than at the heater's intake, which is often in a locker, under a bunk or somewhere colder than the cabin.

How do I connect my phone to my diesel heater?

Turn Bluetooth on in the thermostat's settings, install the General Components app from your phone's app store, open it and scan for devices, then tap your heater. A Bluetooth icon appears on the thermostat when a phone is connected.

Can I see error codes in the app?

Yes. The app reads the heater's stored fault codes, up to six, and gives you recommended troubleshooting steps for each one. You can clear the history once the problem is fixed.

Should I change the fuel adjustment setting?

On a diesel heater, no. Leave it at 0%. The setting exists mainly for gasoline models, where the 10–15% ethanol in pump gasoline affects the fuel map and the burn may need trimming.

How often should a diesel heater be serviced?

Every 800 to 1,000 hours of run time. The thermostat's information screen shows your total hours, so you can check where you are instead of guessing.

How long do these heaters last?

Doug's BISON 4000A ran six years on a boat with almost no maintenance. How you use it matters: running for at least 30 minutes on a high setting burns off carbon, while frequent short runs on the lowest setting build it up.

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Questions About Your Setup?

Our team in Port Coquitlam, BC can help with controls, thermostat modes and app pairing. Call 1-800-517-7740 (Mon–Fri, 9 AM–5 PM PT) or email info@generalcomponents.ca.

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