Relays turning on at shutdown and boot

[ulfh2018]

I have a project where I want to control some valves using relays controlled by switches and GPIO on Rasberry Pi. I have installed Domoticz on Stretch light, and alo install rpi.gpio. On the end of domotzc.sh I have added lines like this:
gpio export 17 out
....
sudo sh -c "echo 1" >> /sys/class/gpio17/active_low"

I use 433 Mhz sensors, dummy devices and SetPoint Thermostat to get the information, and dzVents to check for changes. This works fine as long as the system is runnig, but I observe that when the system boots or is shut down, all the relays will turn on for some seconds. It's not a serious problem, since the valves I want to control is just delivering hot water for the floor heating at the house of my twin brother, but it would be nice to know if there is a way to avoid this. My relay board can be swithced between high and low triggering.

Best regards

Ulf