got a boiler problem.

[mopinko]

so, a bit of back story- my 10 yo boiler has been banging all winter. works fine, just noisy. i called the guys who installed it, they said it’s limed up and shd b replaced. i know it’s been 10 yrs, but they wanted twice what i paid. i figured i wd wait, at least until this tariff nonsense settles down.
but that seems a little quick to have failed. we have pretty soft water here. they said they cd do a flush, but they’d have to cut a pipe to add the chemicals, and the couldnt guarantee anything.
so i figured it couldnt hurt to just flush it myself, w just the water flow. so, i started that yesterday-
put a hose on the drain, and cut off the feed and the return, wanting to just flush the boiler itself. well, i got water for a few minutes. a bit of white stuff, but not that much. then nothing even tho the inlet valve was open. tho this worried me, i opened the other valves to let the whole system drain. got a fair amount of black sludge, but no more white stuff.

closed everything back up, but noticed no sound of water coming in. opened the bleeder on the upper most radiator, got a weak little hiss for a few seconds, then nothing. clearly, it’s not refilling. waited a while, opened the bleeder again, same. this morning it was same.

so i went and looked over everything (i dont know THAT much about boiler systems, but i’ve been living w 1 for almost 40 yrs now. this is my 3rd boiler.) i found a valve on the fresh water inlet that i didnt know the function of. so, that ja for google image search.
it’s a pressure valve, linked below. this appears to be the problem. it has a lever to fast fill. threw it, nothing.
so, reading up, and several pros say it’s not usually that the valve fails, but that there is a screen that clogs. i’m tempted to open it up, cuz i wont b getting any heat anyway. how much more broke can it get?
i have no doubt that my local excellent hardware store will have this valve. i have a contractor scheduled for tomorrow at my 2flat, and figure he can replace the valve if needed. it’s threaded, so it isnt a huge deal.
meanwhile i have a fireplace, so i wont freeze. it’s supposed to b nice most of the week.

so, before i venture out onto this limb, any advice from my betters?

https://www.plumbers-supply-co.com/2825533/product/bell-gossett-110191lf