Old house, steam heat, new boiler - still takes 1hr15min to heat all radiators...

Glad you found the install manual. I was just reading it and yes, the pipe sizes are correct for minimum acceptable, which should allow the boiler to operate correctly.

Something just does not add up here and there must be another problem or ? The problem you identified in the first places is that the radiators are slow to heat up completely. For a boiler that is 80% oversize, this just does not add up. One would expect that the radiators would all heat quickly and completely and that the boiler would then build up pressure and begin to short cycle. But, that is not what you're seeing.

I would suggest clocking your gas meter to verify what the firing rate really is. Perhaps its starving for gas? No way to know without checking it.

Also, please give us a picture of 2 or 3 of your radiators so we can double check your EDR numbers. Include the height along with the pictures.

The issues that you mention regarding some radiator fully heating, and others not, and then very late in the steaming cycle, the pokey ones suddenly heating up.... this sure sounds like radiators venting too fast. When steam goes too quickly into a radiator, the radiator will condense the steam very quickly, so much so that it can actually pull more steam into the radiator. Over vented radiators will HOG the steam and keep it from going evenly to other radiators. I am a fan of Hoffman #40 vents. They are nice and slow and when the whole system is set up with them, they usually operate amazingly evenly. The slow radiators that may remain can then be sped up with a faster Gorton model.

At any rate, I would not think about a 2-stage gas valve at this point, slowing the boiler down will not speed up your system. Actually, 45-60 minutes to fully heat cold radiators, starting the timing when steam has started to go out into the mains, is a reasonable time. But, it should be much more even that you seeing now.

Regarding the copper riser and header. They are a big no no. Often times the sweat joints will eventually crack and leak. However, they were popular her in the Quad Cities about 30 years ago, and I have seen a few that were 20 years old that never leaked. I have seen some that did, too. Insulation would improve the system performance. I am assuming that the mains are insulated.....???? That can make a real big difference in performance. Wrapping with building insulation doesn't count, needs to be fitted pipe insulation to be effective.

Keep plugging away, you'll get this working great.

Wow! Thirty minutes is a VERY long time for steam to make it to the end of a main with an open valve. I am assuming it was a gate or ball valve and not a globe valve, which would have some restrictions in it. If it were me at this point, I would clock that gas meter first thing. Count how many cf go through the meter in 1 minute. Make sure nothing else but the boiler is running.

What you are seeing is not that unusual in the case of over venting, but it could be from starving for steam as well. In a similar example, a nearly friends house was heating very uneven. Some of the radiators would get blazing hot. Another one, in the dining room where the thermostat was located, the radiator did NOT get hot at all. I stayed stone cold, even after an hour or more. No heat, ever!! A few years earlier when a new boiler was installed, the vents on the first floor radiators were changed out to Hoffman 1A. There were carelessly set at 5 to 8 or so. The upstairs had all Hoffman 40s. I was baffled! I did a little reading and thinking. Went to the handy venting charts. Then I went back and carefully set the 1A vents (its not easy) to about the same venting rate as a Hoffman 40 would have been. The system was cold, and I started it up. First, I was amazed at how evenly all the radiator started to heat, and the dining room, even though it was the end of the line and had not been getting any steam at all, now started to get steam in balance with the rest of the house. When you remember that when steam condenses to water, it shrinks to 1/700th its volume, then realized that a radiator when vented too fast turns into a big vacuum producing device that sucks steam away from everything else.

I think this is what you need -

Bob

That indicates you are consuming about 240,000 BTU's per hour vs the 287,500 BTU's the boiler is rated for so you are about 15% underfired by my calculations. The firing rate would have to be adjusted by the actual BTU content of your gas. That is not a bad thing seeing the boiler appears much to large for your system so the problem would appear to be in the piping.

The measurement you took has nothing to do with gas pressure, it just determines your gas consumption.

Bob

Yes, it appears that way.

How long does it take just the mains in the basement to get hot? I think we need to start there for sure. For example I and some others feel like 1 minute per 10 feet of main is a good working number, so on your 40' main that should be able to heat up (header hot until end of main hot) in about 4 minutes. Some of us go even faster than that. The times you are listing are honestly completely ridiculous even if they are better. Also you don't want to "get back up to pressure" with residential steam heat like you have, pressure is evil. That's why the boiler shuts down to keep the pressure down. The higher it goes the slower the steam moves. Have you added the main venting yet?

Have you bought the venting book. It's cheap and the money goes to charity. It may help save some time. Your low-pressure gauge is also telling us two things... you ARE probably oversized to build so much pressure so quickly and/or you need MORE Main venting. I have a huge system and build 1lb on a cold day which I consider too much.

And.... I always follow with a word of warning on the Hoffman 1A vents. Some don't like them because the have a pretty loud click. And, the adjustment mechanism is touchy. You have to be very careful when adjusting. Anything that is at 3 or above is pretty fast, an probably faster than needed unless it is a Long way from the main. I find using Hoffman 40 works very well with an occasional exception for a slow one.

and.... We are not ALL fans of Gorton main vents.

I like my Hoffman 1A's. Like Dave says, you do need to pay attention when adjusting them. The easiest way is to take the cap off, position the number you want on the arrow, hold it in place with one hand and screw the cap back on. It's easy once you do one. I had one new Hoffman that clicked fairly loudly but after running for one heating season, the clicking went away completely. All my other Hoffman's were always silent. I kinda liked the one that clicked. It made it simple to know when/how often the vent opened/closed.

ChrisJ said:

How can any valve that works like a Hoffman 1A, be silent?
Seems impossible using that "oil can" system?

Either way like I said, they were a no-go for my system not counting the noise.

Trust me they are.

I've got a line on some 135 year old carbon rod vents.... I wonder how they work?

ChrisJ said:

Fred said:

ChrisJ said:

How can any valve that works like a Hoffman 1A, be silent?
Seems impossible using that "oil can" system?

Either way like I said, they were a no-go for my system not counting the noise.

Trust me they are.

I'd need to hear them in person.
I think you're loosing your hearing, too many The Who concerts back in the day.

That's always a possibility but I think they are silent.

@Fred I agree with your numbers too, with what I can see. Perhaps we should get the depth measurement too. For some reason these look deeper than standard. I am not sure what numbers the original poster was using, it appears that it is even less than a one column radiator.

mickeylewis123 said:

Based on my test, all the radiators were hot and vents shut after 1 hour an 7 minutes, and the pressure was at about 0.9#. I could adjust the Pressuretrol to shut the boiler off at 0.9#, but is that ok when the differential is 1#? It means the pressure would have to drop to nearly 0# before it came back on.

Never set a pressuretrol so that the cut in is less than 0.5. They aren't reliable below that -- and you don't need the hassle of the thing not cutting back in. Your maximum pressure is good for your system.

If they are on a dry return (before it drops down and becomes a wet return. That works too. Sometimes they were put on the dry returns because that was the most convenient point on the piping. While the returns don't need to be vented, on a one pipe system, if that's the only place they could put the vents, that's OK. I contend that, in these cases, the amount of air in the dry return has to be factored into the amount of venting you need because steam is going to take the path of least resistance and that is that big main vent. Until it closes, the steam won't go elsewhere. I think others don't feel the air in the dry return needs to be factored in ???