Added Vents, Lost Heat?

GeekGirl913

Apologies for the length, but want to detail the series of events as much as possible in the hopes someone can help solve this puzzle. I posted a while back about our heat being noisier than a bad punk band, which you can read here.

Well, the good news is, the punk band retired. The bad news is they weren't replaced by the sweet symphony of the occasional gentle pings from quiet steam heat, either.

Had someone replace our near boiler piping, and immediately noticed a difference. Most notably, our kitchen radiators which had never gotten more than lukewarm were piping hot. HOORAY!

Unfortunately, the radiators off of our front main stayed stubbornly cold. Realizing there was no vent there, and an approximately 100 year old #1 on the longer, rear main, the guy came back and added a Gorton 2 on the long main, and a #1 on the shorter front main.

Nothing.

In fact, the kitchen radiators stopped heating altogether. Now I can't get the first floor past 65.

I have even returned to the previous state of plugged front main and a simple #1 on the rear, and still can't get them hot.

Cleaned the water in case there was a sludge problem, too. (Guy also skimmed it for the first time since it was installed.)

My goal is to troubleshoot the rear main, and then address the front. Part of that will include adding insulation, since I suspect that isn't helping. (The rear main is pretty well insulated throughout the length of it, which is why I think we were getting heat there in the first place.)

Also on the rear main is our behemoth radiator, a 20 section, three column Victorian style that won't get fully hot; however, the pitch is off, so I'll come back to that once I can adjust it.

Any suggestions or insight would be greatly appreciated, as I am now cold and stumped.

ethicalpaul

Can you feel the main with the cold radiator on it getting hot at the start of a call for heat? You should be able to start at the boiler and feel it go from warm or cool to "steam hot" where you can't hold your hand on it, then follow the steam along that pipe until the steam reaches your new main vent and the vent closes to the steam (no longer allows air or steam to exit the vent).

The heat should "travel" along the pipe at maybe a foot every few seconds or something.

Is that happening?

KC_Jones

I would not insulate until you get it working, the "feel" test for how far steam is traveling is an invaluable diagnostic tool, that and a stopwatch.

I should also add, you can't address one main then the other, it's a single system. If you get one working, then go to the other, it's very likely you will mess up the first one.

Also you mention that you can't get the first floor past 65, but what is the second floor doing? That matters, because if it's getting hot, then the steam is moving.

Have you reviewed all the radiator vents for size?

Jamie Hall

A little strange there. @ethicalpaul 's test is where to start. Where does the steam get to in the mains, and how fast does it get there? At the risk of stating the obvious, if the steam can't get to the radiator runout, or doesn't for some reason, the radiator isn't going to heat.

Check and be sure that the steam is actually getting to the main vents and closing them.

If you are feeling uncommonly brave, you can even take a vent off and see if it gets steam -- but have someone at the boiler to turn it off if and when steam does show up. You don't want a steam bath.

So -- start there. If you find a place along one of the mains where the steam slows or even stops, look for a pitch problem in that vicinity. Amazing what a puddle of condensate will do.

pedmec

Is the boiler still firing when your checking the radiators. You need to make sure the boilers are not shutting down on something like the low water cutoff, pressurtrol, etc. did your contractor skim the boiler at completion?

GeekGirl913

To address multiple comments in no particular order: yes, boiler finally got skimmed. I also used a can of Squick in the hopes that would help. (Squick did help in general; it has since been drawn off and boiler refilled. Water looks clear, and no surging, priming, or foaming.)

We tried the vent off to check for steam thing on the front main, and I heard gurgling, but no steam on that side. Just hot air puffs.

The rear main still gets hotter than the front, and I'll re-confirm we have actual steam coming out of that one.

Left the system off all weekend since we were away and was curious what would happen with the front filled with air again. Was thinking it would maybe force steam to the rear and get those kitchen ones going again. No such luck.

And boiler remains on until the cycle guard kicks in, but then immediately comes back after the two minutes or so, so it's not cutting off for true low water or pressure. Pretty sure the PSI in the boiler hasn't passed 0.5 or 1 at any point, the needle barely moves.

Oh, and the second and third floor radiators are mostly getting warm to hot. Maybe not all the way through, which would be venting or pitch, but they're definitely in better shape than what's going on on the first floor.

KC_Jones

"and I heard gurgling,"

You have a pitch or sag issue somewhere. You shouldn't hear anything except the sounds of air movement, and with an open pipe, maybe not even that. If there is enough water in the main to cause gurgling, it will effectively function like a close pipe, so no steam will flow.

To be clear about the other floors. Are you saying the radiators on the second and third floor, connected to the front main are getting hot, but on the same main, first floor they are not? Just want to clarify, it's not just which floor they are on, it's also which main they are connected to.

To add to that, if they are on the same main, do the second and third floor come off the main prior to the problem radiators on the first floor?

GeekGirl913

KC_Jones said:

"and I heard gurgling,"

You have a pitch or sag issue somewhere. You shouldn't hear anything except the sounds of air movement, and with an open pipe, maybe not even that. If there is enough water in the main to cause gurgling, it will effectively function like a close pipe, so no steam will flow.

To be clear about the other floors. Are you saying the radiators on the second and third floor, connected to the front main are getting hot, but on the same main, first floor they are not? Just want to clarify, it's not just which floor they are on, it's also which main they are connected to.

To add to that, if they are on the same main, do the second and third floor come off the main prior to the problem radiators on the first floor?

There are 10 radiators that come off the front main. Four on the first floor, three each on the second and third.

Of the four on the first floor, the one closest to the beginning of the main gets hot through about 5/13 sections, even with the vent off. The middle two get mostly hot, and the one furthest away doesn't get hot at all. This is the same on all the floors. Where I heard the gurgling coincides with where there is no heat, so that seems to be consistent in terms of a pitch problem.

When my husband gets home, I'm going to very gently take a 2x4 and floor jack to see if I can raise the beginning of that front main to see if it addresses the pitch problem there. If so, I'll replicate on the rear main as well, then move to getting the vents right, and lastly insulating everything I can get my hands on.

It's just strange that the pitch on the rear became an issue when it wasn't touched.

Curious what I should use to support the mains should I be able to correct the pitch issue? My guess is that whoever finished the basement might have removed/loosened some of the supports and I'll need to replace them.

Jamie Hall

"My guess is that whoever finished the basement might have removed/loosened some of the supports and I'll need to replace them.:

Wouldn't be a bit surprised. I've had to add or tighten a lot of supports over the years...

GeekGirl913

Jamie Hall said:

"My guess is that whoever finished the basement might have removed/loosened some of the supports and I'll need to replace them.:

Wouldn't be a bit surprised. I've had to add or tighten a lot of supports over the years...

Yeah, the previous owners were big fans of bargain contractors, and DIYing things that should not have been DIYed without additional research...

Slightly propped up the front main, and immediately got steam at the other end. I think it needs to go more since it's flowing, but not as much as it should. At least it's progress forward. The rear main is going to be LOTS of fun.

mattmia2

I thought the rear main was heating? There is no reason to try to change the pitch if everything is working ok. Changing the vents may have changed things because the main that is trapping water might have had more venting(or the other vent was plugged altogether so it was only venting through the radiators in that branch) so the steam was still trying to go that way. When you fixed the vent on the main without trapped water that was the easier way for the steam to go. What generally will happen with trapped water is it will condense the steam and it won't progress past that point until the steam heats the water enough that it is steam hot so it stops condensing it.

mattmia2

Look at which way they are supposed to pitch, is there a drip or return at the end that comes back to the boiler or do they just end at a vent? That will dictate if they should pitch to the boiler or away from the boiler.

GeekGirl913

mattmia2 said:

I thought the rear main was heating? There is no reason to try to change the pitch if everything is working ok. Changing the vents may have changed things because the main that is trapping water might have had more venting(or the other vent was plugged altogether so it was only venting through the radiators in that branch) so the steam was still trying to go that way. When you fixed the vent on the main without trapped water that was the easier way for the steam to go. What generally will happen with trapped water is it will condense the steam and it won't progress past that point until the steam heats the water enough that it is steam hot so it stops condensing it.

It was, however I'm thinking that maybe when the very old and heavy king valve got removed from the front main, something might have gotten disrupted somehow?

This is the end of the rear main (the vent is hidden behind that last pipe somewhere). It looks like it drops to a partial dry return and then plummets down to a wet one since the boiler is a good distance away from here. I'm guessing that the highest point of the main should be closest to the boiler, 1" higher than the return for every 20' for proper pitch, correct? 

The radiator connected to that dry return is one of the ones that was heating but stopped. The other comes off that last supply after the vent. 

mattmia2

Does that pipe covered in disintegrating asbestos go up to another radiator somewhere or is the vent in there? If either of those sections of pipe, the main or the return that has the radiator connected are holding water that will kill the steam. As far as I can see they need to pitch in opposite directions and the fittings that are there won't allow that. The runou should come off the main or there should be a swing joint somewhere in that "u" that goes downward so that the main can pitch toward the return and the bottom pipe can also pitch toward the return.

GeekGirl913

mattmia2 said:

Does that pipe covered in disintegrating asbestos go up to another radiator somewhere or is the vent in there? If either of those sections of pipe, the main or the return that has the radiator connected are holding water that will kill the steam. As far as I can see they need to pitch in opposite directions and the fittings that are there won't allow that. The runou should come off the main or there should be a swing joint somewhere in that "u" that goes downward so that the main can pitch toward the return and the bottom pipe can also pitch toward the return.

Clarified the picture a little. The vent has a separate pigtail that goes up behind that pipe.

The return drops there and goes to run behind the walls back to the boiler.

mattmia2

Radiator connection (1) is what doesn't heat, right?

EBEBRATT-Ed

B4 you use the 2x 4 start at the boiler end and figure out which way the pipes need to pitch and use a level.

Your technician who installed the vents and the new near boiler piping should have gone through the system and figured this all out

GeekGirl913

Actually, I stand corrected, the vent comes out of the top of radiator connection 2, and neither of them heats now. I'm going to try capping it off and see if that magically does something. 

And while the guy who did the new NBP understood the concept of dry steam, I had to drag him back to put the vents on in the first place. When we continued to not get heat, he told me that he didn't know what it could be since the pitch "looked good" and he didn't want to waste time on it... He eyeballed the pitch, didn't check it with a level. I checked it with a level in the middle-ish area and it's flat. Also noticed a spot where it looks to possibly be sagging. 

I'm going to check additional spots with the level, but I need to cut away more ceiling. 

mattmia2

EBEBRATT-Ed said:

B4 you use the 2x 4 start at the boiler end and figure out which way the pipes need to pitch and use a level.

Your technician who installed the vents and the new near boiler piping should have gone through the system and figured this all out

but that return at the end of the main can't pitch right because of the way it is piped

mattmia2

See this part should pitch this way:


And this part should pitch this way:


but because these are both 90's it can't do both:



one of those 90's should be 2 90's connected at the side so it can swivel to more than 90

connecting the lower runout up here somewhere would also more or less fix it:

GeekGirl913

That's helpful, thank you.

I measured the length of the two mains best I could using a laser measure. The front main is about 22 feet long, and the rear is about 38 feet.

Going off the theory that one pipe steam should pitch 1" for every 20', that means the beginning of the front main should be about 1" higher than where the return is, and the rear should be 2" higher at the beginning, 1" higher somewhere in the middle. All consistently sloping down towards the ends.

Next, I'm going to measure the distance off the floor joists they're attached to and see if that theory holds and do more checking with the level.

Given the age of the house (108), the fact that there was a fire in the basement at some point, whoever did the finishing was from the local clown college, etc., I'm expecting to find some sags/deviations from this.

Assuming I do, what's the best way to adjust the supports that are there? Adding new ones seems fairly straightforward with some strapping, but the existing supports are chain link and don't look like they can be adjusted (unless they've loosened from the joist).

mattmia2

I like the type of hangers that use threaded rod but it isn't my area of expertise. Make sure the joists are level if you're measuring off of them, i'm sure they won't be. a string or water level could help measure the pitch

GeekGirl913

Still getting nowhere, but something dawned on me, and wondering if this could be why I suddenly lost heat in the kitchen.

Thinking back, I realized that I hadn't drained the system from last year (when it was still essentially a hot water boiler) when it first started up. That's why a few days after the piping was redone, I drained it, filled it fresh, it got skimmed, etc. Pretty sure that's really when the heat in the kitchen stopped.

Is it possible that because the return is now empty and there's a fresh vent there, there's no longer the force of the higher water that was essentially pushing steam to those radiators? Like a reverse vacuum? I have a strong suspicion there's a leak somewhere in that return that might have been temporarily plugged with sludge. 

I know this sounds like insanity, if it even makes sense, but if a leaking return can somehow cause heat loss to radiators, then I know where to look next. 

KC_Jones

Slopes, sags, water traps, and venting. Steam pipes should be empty with a vent at the end, if that criteria is met the steam will flow.

So make sure all pipes are sloped in the correct direction, make sure they are also straight with no sags and make sure no one did something weird with the piping creating a water trap. After that ensure you have adequate and balanced venting.

One of those criteria are currently not met in some way and it’s preventing the steam from flowing.

Is the main hot where the underperforming radiator is connected?

Have you timed how long each of the mains takes to heat? Shouldn’t take more than about 5 minutes.

GeekGirl913

KC_Jones said:

Have you timed how long each of the mains takes to heat? Shouldn’t take more than about 5 minutes.

Just timed the front main, without the one end supported, and it took 16 minutes to get my first paltry steam puff. Granted, the system was on the cold side, but still, that's quite a while especially since the cycle guard cuts the burners off after 20 minutes to do its thing. 

Going to let it cool down, then try it again with the front main propped up a bit to see how long it takes then. 

The rear main was/does get hot, but even when I have gotten steam out of it, it's not flowing to those last two radiators out of nowhere. 

ethicalpaul

Don't let it cool down. You want to time the filling of the main with steam when it is pretty warm to hot because you don't want to time how long it takes to heat up the cold main--you want to time how long it takes for the air to be pushed out.

mattmia2

Note that the main you showed the end of has a return at the end so that main should slope toward the return. Also not my notes above showing that the way it is piped you can't get that radiator branched essentially off the return to heat well.

CKNJ

Throwing my 2 cents in based on experience. Qualifying this by saying if your main vents are correct and the piping is pitched correctly read on. Have a 120 year old foursquare, 2 floors with 11 radiators. 2 mains just like you are describing, a long and a short one. Decided a couple of years ago to balance the system and properly sized the main vents.

I used to subscribe to the faster is better school on radiator vents (read on before commenting). Living room has 2 38" tall, 3 column, 12 and 10 section radiators (single connection across the bottom) along with 4 upstairs radiators feeding off the long main. Short main has 1 upstairs and 3 downstairs radiators.
So, i had Gorton 5 valves on most radiators (it worked okay) and decided to push the envelope and put Gorton 6s on the 2 big living room units to get it heated faster. When i did this, the long main stopped heating but the short one continued to heat normally. I mean nothing on the long main. When i downsized the radiator vent to a 5, it heated again. Yes, over-venting is a real thing.

Decided to go back to the drawing board and put Ventrite #11's on all the radiators in the house thinking i can adjust from there. Almost every radiator heated up evenly, just had to downsize the small bathroom radiators to Hoffman 40. On a 30 degree day, only about 1/3 of each radiator gets hot and keeps the house at 68/69 degrees evenly on both floors. Takes about 20 minutes of boiler run time to do this.

Sorry for the long post, but my point is that your main vents might be correct, but the radiator vents might be too large.

GeekGirl913

GeekGirl913 said:

KC_Jones said:

Have you timed how long each of the mains takes to heat? Shouldn’t take more than about 5 minutes.

Just timed the front main, without the one end supported, and it took 16 minutes to get my first paltry steam puff. Granted, the system was on the cold side, but still, that's quite a while especially since the cycle guard cuts the burners off after 20 minutes to do its thing. 

Going to let it cool down, then try it again with the front main propped up a bit to see how long it takes then. 

The rear main was/does get hot, but even when I have gotten steam out of it, it's not flowing to those last two radiators out of nowhere. 

Only for this instance because the 16 minutes at the end was on a relatively cold system. It's moot anyway, because I propped it back up, and lifted a couple of radiators and they're now getting hot for the first time ever, woo hoo!

mattmia2 said:

Note that the main you showed the end of has a return at the end so that main should slope toward the return. Also not my notes above showing that the way it is piped you can't get that radiator branched essentially off the return to heat well.

Oddly, when the guy first redid the near boiler piping, it heated quite nicely, I was shocked. Our kitchen is a converted mud room and is all windows, so it's quite cold in there. 
 

GeekGirl913

CKNJ said:

Throwing my 2 cents in based on experience. Qualifying this by saying if your main vents are correct and the piping is pitched correctly read on. Have a 120 year old foursquare, 2 floors with 11 radiators. 2 mains just like you are describing, a long and a short one. Decided a couple of years ago to balance the system and properly sized the main vents. I used to subscribe to the faster is better school on radiator vents (read on before commenting). Living room has 2 38" tall, 3 column, 12 and 10 section radiators (single connection across the bottom) along with 4 upstairs radiators feeding off the long main. Short main has 1 upstairs and 3 downstairs radiators. So, i had Gorton 5 valves on most radiators (it worked okay) and decided to push the envelope and put Gorton 6s on the 2 big living room units to get it heated faster. When i did this, the long main stopped heating but the short one continued to heat normally. I mean nothing on the long main. When i downsized the radiator vent to a 5, it heated again. Yes, over-venting is a real thing. Decided to go back to the drawing board and put Ventrite #11's on all the radiators in the house thinking i can adjust from there. Almost every radiator heated up evenly, just had to downsize the small bathroom radiators to Hoffman 40. On a 30 degree day, only about 1/3 of each radiator gets hot and keeps the house at 68/69 degrees evenly on both floors. Takes about 20 minutes of boiler run time to do this. Sorry for the long post, but my point is that your main vents might be correct, but the radiator vents might be too large.

That is incredibly helpful, thank you! Perhaps my gorton 2 on the long main is too much? Figured at nearly 40 feet, it made the most sense, but perhaps not. I'll try tinkering. 

KC_Jones

With a boiler replacement the system could have dried out and with open pipes it will work great....for a while.

mattmia2

over venting of the mains isn't really possible. Venting a radiator close to the thermostat such that it heats and satisfies the thermostat before much of other radiators heat is certainly possible, especially if the radiators near the thermostat are close to the boiler.

BobC

Your not going to over vent a main however maims venting goes have to be balanced so steam reaches the end of each main at about the same time.

Steam takes the path with less resistance. A Gorton #2 vents about 3x as fast as a Gorton #1 , sometimes 2ea #1's are a metter match than a single #2

Bob

GeekGirl913

Still not enough heat on the first floor, and the noisy punk band is back for a reunion tour... 

I took an inventory of the vents on each radiator, and those were done correctly as far as conventional wisdom goes. But, seeing as I can roast the Christmas ham in my home office on the third floor, I've started playing vent musical chairs. 
Some C and D vents from the 2nd and 3rd floors were swapped with 6s from the 1st.

However, when I took some of those vents off, they were filled with water. Not a bit of condensate, but fully blocked by water that had to be shaken out. 

I know water + steam = banging. The banging I'm getting is at particular individual radiators, so I'm guessing the build up of condensate is catching up. For the radiator I've nicknamed the drum machine, it has a new valve and proper pitch so my only conclusion is that because the heat is on so regularly that there's still water pooling up somehow. That vent wasn't one of the flooded ones either, just adding to the mystery.

Is there perhaps a vacuum situation that I'm missing or something like that? All I want for Christmas is a house that heats evenly. And quietly. 

KC_Jones

Let’s be clear about banging. Banging is steam, picking up water, and “banging” the water into the next thing it encounters, which is usually a fitting. So if you hear banging at a radiator inlet valve, the problem could be 1’ or 20’ away. You can only “sort of” use the sound as a diagnostic, in that the problem is in that pipe, but most likely not where you hear the sound.

So again, every pipe in the house needs to be checked for proper slope and sagging, all of them, no exceptions. Replacing a valve does zero, pitching a radiator will only eliminate that as a possible cause, after that move on.

If the house has settled (very likely) then the pipe running to a particular radiator may be sloped wrong or sagging, and you may need to lift the entire radiator and after the whole thing is higher, add extra shims so its sloped towards the valve.

With proper slope and no sagging, there is no water build up, it all freely drains back to the boiler. Also keep in mind under normal operation we are talking about trickles of water coming back from the entire system, it’s a surprisingly small amount.

@ethicalpaul has posted videos showing this, I don’t have links, but maybe he can post them again to give you a visual. 

GeekGirl913

KC_Jones said:

Let’s be clear about banging. Banging is steam, picking up water, and “banging” the water into the next thing it encounters, which is usually a fitting. So if you hear banging at a radiator inlet valve, the problem could be 1’ or 20’ away. You can only “sort of” use the sound as a diagnostic, in that the problem is in that pipe, but most likely not where you hear the sound.

So again, every pipe in the house needs to be checked for proper slope and sagging, all of them, no exceptions. Replacing a valve does zero, pitching a radiator will only eliminate that as a possible cause, after that move on.

If the house has settled (very likely) then the pipe running to a particular radiator may be sloped wrong or sagging, and you may need to lift the entire radiator and after the whole thing is higher, add extra shims so its sloped towards the valve.

With proper slope and no sagging, there is no water build up, it all freely drains back to the boiler. Also keep in mind under normal operation we are talking about trickles of water coming back from the entire system, it’s a surprisingly small amount.

@ethicalpaul has posted videos showing this, I don’t have links, but maybe he can post them again to give you a visual. 

Yes, should have added I've been going around with a pair of 2x4s to use as leverage to lift and check every radiator and see if it lifts at the valve side; some have, some haven't, and it's helped. Some I was able to get a full piece of furring strip under because they had dropped so much. Have a couple left to do, but it's absolutely already on the troubleshoot list. 

For the big behemoth in the living room, that radiator has a dedicated pipe running to it. Oddly, didn't sag, but the radiator itself definitely settled. We addressed the pitch a couple days ago, and today I finally got around to changing the valve on it since it just felt like it wasn't working right. (And I was correct, it doesn't open fully.) While it was open, I stuck my hand in the radiator and there was a considerable amount of water in there, definitely beyond a trickle. I was able to take several paper towels and wick the water out to the point they were soggy. Oh and this radiator doesn't bang, just doesn't heat all the way through, though the water collection explains why. 

Since my Christmas wish is proper heat, my gift to myself will be lifting the last couple of radiators, properly fastening the drooping main to the joist, and hoping for a miracle. 

GeekGirl913

Inhales deeply... Well, mystery solved, and yet another new problem. 

It wasn't the vents. Wasn't really the drooping main.

The culprit was the dingus who came and put in the vents turned the gas regulator down because "it's better for the boiler." It was at less than 0.5" w.c. and is supposed to be at 3.5". This was thankfully fixed by someone competent. 

Now that the boiler is boiling instead of simmering, the latest problem is excessive makeup water. I don't have the counter to tell exactly how many gallons, but I hear it turn on several times a day. 

Seems like it could be either a leak in one of the returns or we're losing it up the chimney.

On the front main, I can see the whole return path and no leak. On the rear main, I cannot see the whole return path which follows the wall, including the asymetric curve along the wall. I'm not seeing any obvious signs of leaking, but the basement is fully finished so it could be running down behind the walls and not into the main area.

Is there any way to determine if there's a leak, and if so, where it might be without going on a fishing expedition?

Waher

If it is going up the chimney from a leak you'll have a large white plume of exhaust.

KC_Jones

Turn the boiler off, let it cool for a bit, say an hour. Open up the manual fill and fill it until the water is up to the outlet pipes. Let it sit for a few minutes and look for water on the floor. If there is water on the floor, the boiler has a hole and will need replaced. If that is the problem I would honestly just limp it through the rest of the winter and get the planning in place for a warm weather replacement.

If it is not the above, then it is most likely a return line that is behind finished walls. And while you could experiment with creative ways to determine this, in the end the walls will need to be opened up for a replacement, so for me, the easy thing is going to be opening the wall and finding the entire return line.

If the returns are the problem, I would probably look and see if it's possible to route them a different way so that they can remain exposed. They do not have to be below the water line if they currently are, they also don't have to stay above the water line if they currently are. Return piping just needs to be well above or well below the water line, with any transitions happening in the vertical.

Jamie Hall

If you are adding water even once a day, you have a significant leak -- or leaks. They can be remarkably hard to find, and even an apparently trivial leak can add up (one drip every ten seconds is a gallon a day).

Boiler -- as noted, look outside on a cool but decent day when the boiler is running. If you see a plume of white "smoke", it's steam -- and there is a leak in the boiler above the water line. This can be confirmed when the boiler is off (spring is coming!) by raising the water level in the boiler up to the header, and then looking both inside and outside for signs of water. Shouldn't be any.

There may also be leaking below the water line -- or often, right at it. This can be found, again in the spring, by lowering the water level to the bottom of the Hartford Loop and seeing if it stays put. If it doesn't...

Then the next thing is wet returns. Having found out that the boiler itself is holding water, fill the boiler to the top of the gauge glass and see if it stays put. If it drops even slowly to the Hartford Loop there is either a leak very near the water line but above the Hartford Loop -- or, more likely, in a wet return somewhere.

Now. Back to winter. The most likely leaks on most systems are at the valves on the radiators. Most valves have packing to prevent leaks around the stem, and most of that packing gets tired. These are hard to find, as steam leaking into the air evaporates very quickly. If it's a significant leak, there may be signs of moisture on the valve stem or the body. You can also wrap a tissue around the stem when the boiler is running; it shouldn't get damp. Valve packing is easy to fix. Another place is at the union joining the valve to the radiator -- same thoughts as for valve packing.

Rarely there will be a leak at a pipe joint somewhere out in the system. You will see rust or staining at the joint, but you may well not see any actual water. Be suspicious...

GeekGirl913

Pretty chilly night with a nice moon to give me some light, but I took a peek outside after the boiler clicked on, and sure enough it's coming out the chimney...

That means the block is busted from the top?