Fan speed

Perfect quality mushrooms

To grow perfect quality mushrooms, creating a stable climate is essential. A stable climate is determined by the fresh air inlet, the cooling and the heating. The faster these respond, the faster the growing room climate will change. On the one hand, we want a fast enough response to any changes in the indoor or outdoor climate, but an over-fast response can be too much. This means you have to take counter measures to compensate immediately. This situation should be avoided at all times. You can adapt the response speed of inlets and valves yourself, but even I always ask the installer to make these adjustments. A mistake is easily made, and results in incorrect settings. An installer, presuming they are a good one, knows what they’re doing. As a grower, you should work along with the installer to check if the response is adequate in your situation.  One important aspect is often overlooked: the fan speed. Does a change in the cooling valve position, for example, have more influence at a high or low speed?

Fan and temperature

If the fan speed is low, so only a few cubic metres of air are flowing through the climate installation, a slight change in the valve position has a big influence on the temperature of the air discharged by the cooling coil (cooling temperature). Why? The air flows through the cooling coil slower, so it has more time to adopt the temperature of the cooling coil. A little more cooling then has a greater effect. If the fan speed is high, more cubic metres of air will pass the cooling coil. In this case, the air has less time to cool to the temperature of the cooling coil, so the effect is reduced. The cooling temperature therefore remains higher. If you look at your cooling and inlet temperatures, you’ll notice they are more stable at high fan speeds than at low fan speeds.

Variable fan speed

In a climate control computer, the fan speed can be set to depend on the compost temperature or the position of the fresh air inlet. Ask yourself what happens when the fan speed keeps changing:

• A higher fan speed with the same fresh air inlet position automatically results in more outdoor air.
• A higher fan speed with the same cooling valve position results in less cooling.
• A higher fan speed with the same heating valve position results in less heating.

In other words, if the fan speed is changed, all the other controls will respond as well – which is naturally a good thing. However, when the fan speed fluctuates, all the other valves and inlets automatically fluctuate accordingly. This creates an instable growing room climate that involves high energy costs and mushroom quality will suffer.

What should you do?

Check the conditions in the growing rooms in the morning and evening. If you see that the fresh air inlet, for example, is above 80%, increase the minimum fan speed by 5% so the fan automatically runs at a higher speed. You often see these conditions during the first flush.

Mark den Ouden | Mushroom Blog