Replacement steam boiler: short cycling on LWCO + NBP BANGING

fdesiderio · December 2024

hi folks, happy holidays

Homeowner here, about 60mi NW of NYC in a single-pipe, 21-radiator c1840 single family two story + basement residence.

Requesting your collective wisdom please.

25yr-old Weil McLain cracked and died a few weeks ago. Old boiler and the overall single-pipe system had been running great all these years (we've been in the house 30yrs). Replaced with same make/model to try to reduce variables (Model EG-75 - https://www.weil-mclain.com/products/eg-series-6-gas-boiler) . I requestd team to replicate NBP precisely, but found some slight differences (will call them out below)

New boiler observations below. The following steps are reproduceable every time thermostat calls for heat:

Thermostat calls for heat, new boiler fires
Takes a few min to get up to temp and start producing steam
Next two steps occur at same time:
1. Two Mains (each with Gorton #1's) begin to vent
2. As they vent, gauge glass water level drops to zero/below zero (not visible)
Since water level drops completely, LWCO fires & shuts down burners
Within a few seconds, as condensate starts to form, HUGE amt of banging begins (can't exactly tell if banging location is in header and/or Hartford loop) and lasts a few seconds
Condensate returns to boiler, raising water level, so LWCO resets, boiler refires, and whole process repeats about 3-4 times

*AFTER 3-4 SHORT-CYCLES, sysetm seems to operate fine and provides heat and function as expected.

Questions:

Why the main vent—>LWCO—>resulting banging & short-cycling? e.g.
1. Insufficient in A- or B-dimensions?
2. Insufficient Hartford loop piping diameters?
3. Insufficient Hartford loop "T" location relative to mid-gauge-glass?
4. Error-prone 'horizontal' header run after risers, before step-down, piping in equalizer? (see pics)
Why does it 'correct itself' after a few cycles?
1. I notice the mains vent MOST on first cycle, then LESS each subsequent cycle. How is the venting related to 'pulling' down the water level ? I'm not familiar with that pressure relationship. Is it 'pushing' hot water into the returns during venting?

Anything I'm leaving out of the story?

happy to provide more info from homeowner perspective

Thanks in advance

Frank

Jamie Hall · December 2024

Two things come mind right away. First, did anyone thoroughly skim that new boiler, or did they just pipe it up and light it off? What you are hearing sounds as though it is surging badly, and it is very likely that a good skimming will help immensely.

Second… That header (the big horizontal pipe above the boiler). It shouldn't be copper, but even more important does it pitch strongly to the equalizer? Put a level on it and see. It's hard to tell from the pictures — and I can't see all of it — but it almost looks as though it may be pitched the wrong way. That isn't going to help any…

neilc · December 2024

a better full picture of the header,

and of the Ptrol settings,

what pressure do you get up to when the water leaves the boiler?

ethicalpaul · December 2024

Within a few seconds, as condensate starts to form, HUGE amt of banging begins

This isn't condensate starting to form. This is the boiler water being where it shouldn't be due to surging. There is probably a lot of oil in the boiler that the installer didn't skim.

Condensate returns to boiler, raising water level

This isn't the condensate returning to the boiler, this is the boiler water returning to the boiler.

Here is a video of what is happening from when I didn't know hardly anything about my boiler:

https://youtu.be/WSRvvNQ5WLc

LRCCBJ · December 2024

The EG-75 has an input of 282K BTUH. This is sufficient to heat a small apartment building (I have done it with less). It absolutely requires 3" risers and a minimum of a 4" header………………one could make a good argument for a 5" header.

You have none of that.

Instead of doing the right thing and determining exactly what size boiler you require based upon the radiation, you install a giant EG-75 with totally improper near boiler piping (in copper !!) by unqualified idiots and you expect it to actually work.

Good luck with that.

EBEBRATT-Ed · December 2024

Supposedly installed the same boiler with the same piping. Probably wrong but probably worked before.

Skim it or have it skimmed with TSP or washing soda and post more pictures of the boiler and the piping up and around it

LRCCBJ · January 1

https://forum.heatinghelp.com/discussion/comment/1831105#Comment_1831105

The operative word is "supposedly". You certainly know that this is impossible. Just look at the header.

EBEBRATT-Ed · January 1

According to the OP,

"Replaced with same make/model"

You can't see enough of the header to see what they changed if anything. The only thing I can see is a reduced equalizer.

LRCCBJ · January 1

https://forum.heatinghelp.com/discussion/comment/1831112#Comment_1831112

I see a 3" header. But, I'm partially blind…………..😉

ethicalpaul · January 1

https://forum.heatinghelp.com/discussion/comment/1831100#Comment_1831100

I and all of us are prone to frustration sometimes but I hope we can avoid blaming victims who did nothing wrong other than assume a licensed professional would be able to read a manual.

LRCCBJ · January 1

https://forum.heatinghelp.com/discussion/comment/1831118#Comment_1831118

Absolutely correct. I'm personally at wits end seeing endless installations that can be better accomplished by an 8 year old with a good reading ability.

I don't quite understand why they come here AFTER THE FACT.

ethicalpaul · January 1

https://forum.heatinghelp.com/discussion/comment/1831119#Comment_1831119

Because before the fact, they are probably under the impression that the professional they hired knows what they are doing. Then after the fact, they realize that not all of them do.

LRCCBJ · January 1

https://forum.heatinghelp.com/discussion/comment/1831121#Comment_1831121

Yes, sadly, you are correct. Barely ANY of them do.

Replacement steam boiler: short cycling on LWCO + NBP BANGING

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