Flow meters opening halfway in other zones when one zone comes on

mgrt67

I had a radiant floor heating system installed in new construction a couple of years ago. I seem to be using way more propane to heat my home than I was told I would use when I had this system installed. I noticed my garage was virtually the same temp as the house and after looking at the system closely, I noticed the garage zone (which the thermostat is set at 50 degrees) manifold flow meters are opening halfway when other zones come on and hot water is flowing through them even though the circulator for that zone isn't on. I've tried adjusting the manifold flow meters to be closed in the garage when other zones come on, but then when heat is called for in the garage zone, the manifold valves don't open at all. This happens vise versa with all zones. One zone calls for heat and comes on, the other flow meters open halfway and let water into those zones too. I'm not sure this system was installed correctly or adjusted to work properly. Anything I can do to fix this problem or should I call a service tech to come out? Here are pics of the system and the issue.

pecmsg

Where are the Check Valves?

hot_rod

Looks like a Navian combi boiler?

A close up of the piping below the boiler could help.

It should be piped as a primary secondary. There is a pump inside the boiler that may be pushing flow through all the zones to some extent. Even when the zone pump is not running.

If you turn off the red handle valve off, the flowmeters should drop to zero.

A garage can suck a lot of heat $$.

The manual shows various proper piping options.

mgrt67

I don't think there are check valves, I only see shutoff valves, should they have installed check valves? I added a closeup of the piping below the Navian, hopefully that helps.

hot_rod

I don't think it is piped correctly under the boiler. The very left copper, red handled valve, where does that connect into the system? It should have the boiler connected into the horizontal tube like this. Two closely spaced tees. I think the installation manual shows that?

Usually the pumps push into the red, supply manifold. Are yours pumping into or out of the blue return manifold? I can't quite see where the red manifold piping connects into the piping?