Water hammer - novice question

use a level and extend your normal water line around the boiler to the hartford loop, then post that new pipe picture again, loop connection should be 2 inches below normal water line,

then in the manual, note the loop connection should be as short as possible, a close nipple, not the foot that you have there,

has it been skimmed since the work? a few times? the oils from the fresh work make the boil more violent, water in the glass bouncing? how much does it drop from burner off to end of burner run?

look again, the vapor stat is in ounces, it's good the way it is,

the hartford is the higher horizontal, post that same picture from a further distance to show the whole side

If the hammer sounds like it is coming from this horizontal pipe it should be a lot shorter, like #19 in the factory example shown below.

The water hammer may have been a contributing factor to the premature dilapidation of the pipes that needed replacing. Basically you should be able to run the boiler at any level in the sight glass water hammer free. That being said I would run it at the recommended level or a bit higher.

Don't know why when the water level finally settles after shutting down it is higher than when you started.

It seems to me it is taking a long time for the water to come back to the boiler. If it was me I would ditch the check valve in the return line and depending on what you see in the return line flush or replace the returns and fix the Hartford loop nipple.

that type of lwco doesn't need a weekly blowdown, you are just adding oxygen and minerals to the boiler by doing that. testing it once or twice a year isn't a bad idea.

skimming is the first thing to try although if there wasn't work on the system before this started then it is probably something else.

since it is a vapor system there are a number of things that could have gone wrong from pipes sagging to crossover traps that have failed if it has them to metering valves somehow being opened too far or being replaced with incorrect valves.

8 oz/in^2 looks just right for a vapor system. make sure the pigtail is clear. does it cycle on pressure? did it in the past?

if the water level is too low it could uncover water seals and let steam get places it shouldn't so bringing it up to the marked level is another thing to try.

near boiler piping is very wrong, both outlets should collect in to a single header then that header should connect to the steam mains individually, then the header should connect to the equalizer. you have that happening on half then another main connected randomly to the other tapping.

the check valve should work with a boiler return trap to equalize pressure in the returns to allow the water to return to the boiler. There probably is some level of water that has to stack up in the returns to open that check valve to allow water to return to the boiler.

we need to know if the boiler return trap is still in place to know if the check valve is doing anything or not.

the hammering appears to be happening when a differential develops between the mains and the return and the equalizer has to equalize them, allowing steam to push down through the equalizer and giving it access to the pool of water in that way too long nipple in the hartford loop. If the water level is higher the differential probably can't push through the water. if the water level is below that nipple then there isn't a pool of water for the steam to hit.

the stuff moving in the sight glass is probably little drops of dirty oil being moved around by the water. the oil in black iron pipe and fittings is usually very thick and dark and dirty, almost like axle grease.

setting up a phone camera on a tripod or other stand can capture the cycle without you having to sit there the whole time.

Did the water hammer start before or after you had your Hartford loop redone?

should be disassembled and cleaned once a year or so

First off, what is that vapourstat set at? I can't quite read it, but I have a sense that it may be higher than it needs to be for the system to run well.

Second, checking a trap isn't all that hard. With the system running long enough so that all the radiators are nice an full, check the temperature of the outlet of the trap (an IR thermometer is really handy). If it is even as little as even 5 or 6 degrees cooler on the outlet pipe than on the inlet, the trap is working. However, if there is little or no temperature difference, the trap is stuck open — and, of course, if it is stuck closed the radiator itself will be only partly warm, if at all.

You can make a real fast first pass in the basement. The dry returns should be warm, perhaps, but never even close to steam hot. If you find one that is really hot, start looking for bad traps on the connected radiators.

The near boiler piping is miserable. What you are labelling as a header is… sort of, though much too low. Worse, the other outlet isn't hooked into it at all. In a sense the short horizontal pipe up high, which both risers hook into, might be called a header — but it has no good way for carryover to get back to the boiler. One has to wonder why it was piped that way… it would have been so easy to do it right.

On the water hammer which stops when you drain a little water. Wander away from the boiler room, and see if there are any horizontal or near horizontal pipes which are at or very near the present waterline of the boiler. This is not uncommon — the new boiler may well have been installed without regard to the old water line elevation, but just plopped on the floor — but will give you water hammer problems (it may also give a number of other problems as well).

Looks like the short horizontal pipe (up high) was the former boiler's header. The new risers were just connected to the old risers. The lower header was just added to accommodate the equalzer pipe. They had an opportunity to make it a lot better, they did not take it.

Remove the large gauge (probably the easiest) and blow into the pipe to verify the pigtail is not plugged. next time the pigtail is cleaned out put a union on both sides of it for easier future service.

i didn't pay a lot of attention to what was going on at the ceiling until now. that is some very…unique…piping. they halfa$$ reused some previous header which was also wrong.

my guess is that the hammer caused by the wrong piping is making the water in the equalizer bounce and letting steam get down in the equalizer where it finds the surface of the water in the hartford loop and causes more hammer. hot water from the boiler should be in the equalizer and return but steam generally shouldn't be unless the differential pressure between the supply and return pushes it there. that shouldn't happen if the vaporstat is keeping the pressure very low. that is why i was asking if the pigtail was clear.

any carryover or condensate in that "header" has to flow back to the boiler which is likely to collapse at least some of the steam coming out of the boiler.