which way should main steam pipe from boiler pitch?

http://www.weil-mclain.com/sites/default/files/field-file/boiler-replacement-guide.pdf
Go to page 9 of this document. Post back if you have a rad not on the chart and someone could help.

If the boiler is sized correctly awesome! IF it is not, even though they won't do anything, you at least know how to move forward with getting things corrected.

Also don't forget about that water usage issue. 11 gallons in that short a period is way over the top, don't want to kill the new boiler prematurely like the last one.

The reused an old safety and didn't reinstall the vaporstat? The boiler comes with a new pressuretrol so I would think they would have installed it.

Vaporstat is a separate purchase item that they would have had to add.

Did you by any chance keep that mercury Vapourstat? If not, the company that put in the new boiler effectively stole it. Those things are good forever, and are quite expensive. They should either return it in the same condition, or should replace it with a new, calibrated one plus a low pressure gauge on their dime.

Before I would go thru the grief cutting open walls and replacing the return....which BTY will not guarantee fixing the problem, I would flush from the boiler end.
If it does not work then nothing lost.

The old piping ends in a tee with I assume has the water fill line in the top branch. The new copper connects there and it would be easy to disconnect that new male adaptor and connect a temporary drain hose fitting with a valve. Then use the manual water fill to back flow into the return. Again back and forth with water and wash sludge out. Replacing the return would require cutting the copper out anyway.

In either case whoever does this will wish there was a low drain port/hose (as there should have been) to drain out the wet return....not just the boiler.

The first filling of the boiler would have washed water back into the return and might possibly caused the blockage, if there is one.

As far as water usage/loss, is this hidden return pipe such that a leak would show itself on the floor?

Does your sight glass show too high after the boiler has been off for several hours.....possible slow condensate return.

That extra water could be trapped in your piping with each cycle and not return at all.

Is the darkroom rad heating or could it be full of water?
Is the return for that connected to the suspicious pipe?

You can do the feel the pipe temp test from the vertical drop to the boiler. Any cold pipe in between each end may be the blockage.

I have been called lazy for looking for an easy way out, trying to avoid repair work like this and attempting to just fix something.

Occasionally though, someone will insinuate that I work smarter not harder.

A few thoughts. First, check the leveling of the vapourstat. They are very sensitive to being off level, and it is quite possible that it is. There are two ways to do this: in the case, on the back, there is a plumb bob. That is a good way. A double check is to put a short level -- say a 6 inch -- on the top of the case. It should show level. Double check by reversing the level, as always.

That, however, is not likely to be the problem, as you say the problem continued when you bypassed the vapourstat. So... what you need to do is to find out exactly which control it is that is stopping the firing. Not difficult, really, for someone who has some idea as to how to use a multimeter...

Plugged return

Agree with @Charlie from wmass on the underground return. Not worth the effort.

On the cycling. The pressures you have set seem quite reasonable, so I will ask: how long after the boiler fires up does it go until it starts to cycle? What are the cycle timings? I still don't see what the system EDR is, nor what the boiler's EDR is, so I can't comment on how oversize, if any, it is... and without that, it's kind of hard to decide whether the cycling is inadequate venting or just simply an oversize boiler.

Does it start cycling like that right away when it starts, or does it wait a while -- say 15 to 20 minutes -- after it starts and gets warm? Makes a big difference in the diagnosis.

It would be useful to know which of several safeties is shutting off the boiler...

EDR is "equivalent direct radiation" and is a measure of how big the radiators are. It's also found on the boiler rating plate, and is a statement of how much radiation the boiler matches.

The fact that the new boiler is the same as the old boiler is not necessarily good -- the old one may have been oversize. They often are.

borowiec said:

When the boiler first comes on in the early morning we are too far away to hear it, so I don't know if it cycles right away. I know that when I come downstairs it's cycling and it takes several hours before it reaches the set temperature. Also, if I turn up the thermostat to make it come on, it cycles right away.

Is this the boiler rating plate?

@borowiec That is a BIG boiler 770 sq ft of steam output (EDR). You really need to measure the radiators to come up an EDR. Here is a chart I use which has most of the basic radiators listed.

The fact that it starts cycling right away when you turn the thermostat up, and that it didn't do that with the old one, makes me just a wee bit suspicious of some other safety than pressure making it cycle (although @Charlie from wmass has a very good point about leaks). Such as, for instance, a misbehaving or poorly placed low water cutoff?

@borowiec is there a way to get one us pros to your house to get a good assumption of what’s going on. Biggest question, were are you located.

has main venting been discussed here yet ?

I thought @gerry gill went to Akron? Maybe he just had enough work in Cleveland?

Steam Main Venting,
I think I see a riser on the return that's over the boiler,
and I think that is possibly a main vent on top there,
or it's a dry return.
But in all your pictures I don't think I see any steam main vents.
What do you have for steam main vents?
cause that will be affecting your pressure cycling.

Argh. That is probably what passes for a main vent. It's way too small -- for a system with a boiler that size, regardless of mains, you need at least two Gorton #2s.

Now as to location. If, and only if, the mains have crossover traps at the ends which go into the dry returns, you can -- and should -- get away with having those main vents more or less where that one is. However, if you don't have crossover traps -- never did, or someone took them out -- you must have main vents at the ends of each of the steam mains.

The difference in the cycle timing is another clue to inadequate main venting. What is happening is that with the inadequate vents the pressure rises to push the air out. The vapourstat senses that -- that's what it's supposed to do -- and shut things off until the vents can catch up. The pressurestat operates more on the bigger hammer principle, and just fires longer to build more pressure to force the air out. The extra firing doesn't help with the heating, so I fuel you don't need to burn. If you had adequate main venting.

On who is responsible for what -- the boiler and the rest of the system should be regarded as all parts of one big system. However, if the job contracted for was to replace the boiler, and that's what your man did, then I can see his point that the venting problems aren't part of the boiler installation. Sorry about that.

And the boiler is about 25% oversize for the rest of the system. No help for that, and not unusual...

borowiec said:

Dave0176, I don't think there is much I can do about the boiler being too big. The plumber claims that he sized it correctly fifteen years ago when he installed the earlier boiler. Even if I get him to agree that the one he just put in is too big, he's not going to replace it!
He has already offered to put in a Hoffman vent in a tee next to the existing vent but I doubt I can get him to put in a gas valve, as I suspect he will discount any suggestions I pass on that I found on the internet. So it would be better to have two Hoffman 76 valves side by side, rather than just one plus the existing valve?
I confess that at this point I don't have much confidence in the plumber, but I can't find any recommendations for another option in my area.

Not saying replace the boiler, it’s brand new, however if you still have cycling issues, remember that the gas valve is still an option. And no I wouldn’t put much confidence in that plumber, he really hasn’t a clue about steam systems.