The 7H controller fault

Posted on December 2, 2022

In todays video Jamie show us why this fault may be showing up and how to fix the problem.

The dreaded 7H fault. You will come across this fault when you’re commissioning, and it’s usually down to error in the system. So 80 percent of the time it’s going to be down to an error issue in the system itself. It can reset itself sometimes. And if you go to reset, if you press the button on the left-hand side and press reset, it sometimes takes a little while to reset itself.

So don’t worry if you keep pressing reset and it doesn’t go away. It will go away eventually and sort itself out. When the 7H fault shows up, And we’ve spoke about it generally being air. The first thing to check is to make sure that all your automatic air vents are open at your highest points. There are air vents inside if you’ve got buffer vessels or, uh, low loss headers.

There’s always an air vent on the top. And inside the outdoor unit there’s also air vents, so check everything. If you’ve got a hydro box or an integrated unit, there’s also air vents inside the top of those as well. Another thing to check, if you get the 7H fault, is that your bypass valve is set up correctly.

And we set these up one or two litres per minute above the minimum flow rate of the unit you’ve got. If you’ve got one of the hydro boxes, a thing that is easily missed, and lots of installers have done it, is there are two plugs on your pipework which goes in and out of the hydro box itself. Make sure you’ve removed them on installation.

That can cause a 7H error. Thanks for watching today’s video on the 7H fault for the Dakin air source heat pump units. In our next video, we’re going to be looking at how to set the air purge mode to get rid of the air in the system. If you’re interested in more information about air source heat pumps, please like and subscribe to our channel for more information.