ᐅ Novelan Heat Pump Error 704 – Hot Gas Fault

Hello,

our heat pump just displayed an error message: high gas fault, error code 704. We have a heat pump from the brand Novelan. What should we do?
Would you call an emergency service immediately? I’m feeling a bit overwhelmed right now. It is -11°C (12°F) outside.
Thank you very much and best regards

Either a sensor error or a compressor fault. I would call the company that maintains the system and have them come to repair it. Start by checking the sensor.

It could also be that the heating circuit pump is defective or the controller (circuit board). This can cause the compressor to overheat and trigger the error.

A hot gas fault usually occurs when the compressor has to generate high temperatures, such as during hot water heating. The fault threshold is above 110°C (230°F) hot gas temperature. If you’re lucky, it’s a faulty temperature or pressure sensor, or the pump. If you’re unlucky, the compressor has a problem.

Mycraft schrieb:

Either a sensor fault or compressor damage. I would call the company that services the system and ask them to come and repair it. Probably start with the sensor.

It could also be that the heating circuit pump is faulty or the controller (circuit board), which can cause the compressor to overheat and trigger the error.

A hot gas fault typically occurs when the compressor has to generate high temperatures, such as during hot water heating. The fault threshold is above 110°C (230°F) hot gas temperature. If you’re lucky, it’s a faulty temperature/pressure sensor or the pump. If you’re unlucky, the compressor has a problem.

Hello, thanks for the quick reply. The system is 3.5 years old, it would be quite surprising if everything is already broken? Our heating technician said over the phone that he’s not available today or tomorrow. That was his answer, great, right? Now I’m stuck at home with a baby and the heating is about to fail…

I’m a bit at a loss. I tried a reset.

- Okay, new update: after the reset, it’s working again. What could it have been? The heat pump is currently running and heating.
What do you think it was, the sensor? I’ve attached current data in photos, does that help?

No one said that everything is broken. However, sensors can sometimes fail after just one month. That’s simply how it is, and a compressor can get damaged if it overheats, which can even happen right when starting up.

A pump or its controller failing after 3.5 years is also not unusual, even though ideally, you’d want it to last 20 years or more.

In your case, the system has now cooled down and you performed a reset, so now you just have to wait until the issue occurs again. If nothing happens, it might have been a one-time glitch or a sensor/measurement error. If the problem comes back soon, then it’s time to investigate the causes.

Mycraft schrieb:

Either a problem.

Okay, it’s not working... She just tried to get hot water, and the same problem with the hot gas appeared again... Nonsense! And the technician is not coming.

Well, there's no way around it—a professional will have to come.