Help - how to fix this leaking valve?
We have hot-water based heating and when heating runs longer than 1-2 hours, one the pipe connected to boiler leaks from pressure valve. We just bought the house last month, so don't know much background. It seems that Pressure Relief Valve of the dual-unit is leaking. To my naive eyes, it looks like some large bolt at the bottom of the Pressure Relief Valve is missing. zoomed in photo here: https://imgur.com/a/zC1vjFK
Any idea how to fix this leak? Is there supposed to be a large bolt/screw on the bottom side of the Pressure Relief Valve? Or is it actually reliving pressure by leaking?