I have a gas hot water boiler with 6 zones for heating a 2.5 story building, plus a 7th one for hot water with a coil inside the boiler. It has individual flow check valves on the supply side and individual circulators on the return. One of the zones has constant heat even when the thermostat is off and not calling for heat. The pipe on the return size for that zone is hot. I already replaced the flo control valve for that zone and the output of the flo control valve is not hot. Any ideas?? It was fine previously. It’s zone 5 (top floor), the one with the green Taco 007, and the shutoff valve partially closed now to control the heat till I figure it out. [img]https://cimg3.ibsrv.net/gimg/www.doityourselft.com-vbulletin/2000x1504/img_20230103_064334675_1__eff1b6a869c5c0b19a1b4aca4fa3622561d51054.jpg[/img][img]https://cimg4.ibsrv.net/gimg/www.doityourselft.com-vbulletin/2000x1504/img_20230103_064325798_1__d45ccb86c77e64ed181cb1725a6cde810bd0b866.jpg[/img] [img]https://cimg5.ibsrv.net/gimg/www.doityourselft.com-vbulletin/2000x1504/img_20230103_064309950_1__a2447ac47888c9bb3798189b9702aa21c31a0dd4.jpg[/img] [img]https://cimg6.ibsrv.net/gimg/www.doityourselft.com-vbulletin/2000x1504/img_20230103_064253271_1__6a329dfb8bd374008be6e6d87b2da223ce83a234.jpg[/img]

My (7 year old) Navern Combi boiler stopped working with an error message indicating to check the air vents. It did this a few years ago and the problem then was a tree had overgrown and was blocking the air input pipe. Now that not the issue, so I cleaned the air filter (it was quite dirty but not not excessively). After doing that the error message changed to a different one, now it's saying there is a problem with the air pressure. The manual says to try turning the boiler on/off when this happens but that didn't fix it. While cleaning the air input filter, I thought I might as well clean the water strainer filter. It itself wasn't dirty, however the water that come out when I pulled the filter out was fifty - a yard red/brown color, like brackish water. That couldn't be due to rust I'm presuming as the boiler and house are only several years old, or could it? If not, could the water coming into the boiler be dirty due to a broken pipe or something? However if that were the case I'd expect the filter to be clogged up and filthy too, which is wasn't. What might causes for the water being a fifty red/brown color be? And could that somehow lead to the error message about the air pressure?