Webster - Two pipe vapor with return trap: New Boiler

Pennsylvania_Steam

Hello everyone.

I’m a recent addition to the steam heat community, recently moving into a 1917 home in November of 2013.



I’m overwhelmed with all of the great information on this site – not to mention in Dan’s books!



After we moved in, I spent a lot of time learning…and reading…to the point of recognizing that the terribly uneven heat was partially due to failed thermostatic traps. So, we replaced all of them – radiators, cross-over, and end of main F&T traps. Luckily no damage to the house!



Fast forward to today; we are in the process of getting bids on replacing the current 27 year old Weil-Mclain (EGH-125) boiler, which has been leaking for some time through many rust holes in several of the sections (most above the water line).



OK, so we need a new boiler.



Four steam experts have come to look at the boiler, each of which did the EDR calculations and each of which are coming to a similar conclusion – the boiler is undersized. Turns out that the current Weil-Mclain is undersized to the tune of 18-30% smaller than required, based on the radiation requirements in the house.



So, to my questions:

1 – Following the replacement of the traps (capsules), I didn’t really notice uneven “heating” where some rooms are ice cold and others are super hot. I did notice some radiators getting extremely hot and others not so much, but the net effect was 66 degrees all throughout the house, even on the coldest days where it didn’t get above 5 degrees for 30+ hours. Will a properly sized boiler provide better (more efficient or cheaper or even) heating?

2 – one of the contractors has mentioned that it would be cheapest to keep the existing piping and replace the EGH-125 with another. Considering the answer to #1, is replacing an undersized boiler with an (nearly) identical, undersized boiler a good or bad idea?

3 - Considering the size of the current boiler (the top of the chain for that generation of Weil-Mclain) the next step larger is commercial sizing, which certainly carries more cost – both for the boiler and for the updated piping. If the EDR calculations are pointing towards a larger boiler, does anyone have ideas on how to calculate the cost / benefit for this type of decision? For example, if the new commercial boiler + piping would cost $100 (right!) more than the swap of one EGH-125 for another EGH-125, how could I calculate when I would break even on that $100?



Thanks so much for any advice offered.

Steamhead

That boiler started leaking

because it was taking in too much feed water. Some Webster systems I've seen have underground return lines. If yours does, they're probably leaking.



Where in PA are you located?

Pennsylvania_Steam

Very Interesting!

Yes, I was adding water about once a week in the coldest part of the winter. Those I called to consult indicated that it shouldn't be unexpected to have some water loss, especially if it's very cold. When I write "adding water", I mean I was refilling the entire boiler about once a week. The floor under the boiler is typically moist/damp, so I assumed the leaks in the boiler (and up the chimney) led to the water loss.



I have traced all of the return lines, but haven't noticed any other wetness...of course that doesn't mean it's not happening, just that I haven't seen it. Good news is that none of them are underground.



I'm in northeastern PA, near Scranton.

Hap_Hazzard

Undersize Boiler

If your boiler is undersize you're more likely to have uneven heating because, no matter how well the system was designed, it's tough to get the same amount of steam to every radiator in the house when there isn't enough steam to go around. When the boiler is sized correctly, each radiator gets enough steam to start radiating at its full capacity even though it may not happen at the same time, but when there's not enough steam available, the first radiators to receive steam start condensing it, making less available for the ones that are still trying to fill.

Pennsylvania_Steam

Got it!

Steamhead & Hap_Hazzard, thanks for the info.



I also found this post from a while ago, which with Hap_Hazzard's info, actually answers my question #1 (and 2).



http://www.heatinghelp.com/article/323/Boilers/281/Undersized-Steam-Boilers





Now, I'm almost convinced that I should go with the much larger boiler and that there may be a leak somewhere that I need to find, otherwise in the long run I'll end up with a hole in the new boiler too (thanks Steamhead).



Problem is that of the three vendors, two have provided quotes for exactly the same undersized boiler I have now. And both have indicated that the job would keep the existing piping (I attached some pics).



So, if the bigger boiler is the way to go, what would need to be done with the unique piping features like the boiler return trap?



Also, if there's anyone willing to trek to the northeastern PA area, please let me know offline. The Find-A-Contractor link shows there's nobody within 75 miles of me.

Steamhead

Looks like there are two headers on that boiler

the lower one is completely wrong. Can you get a picture of the upper one, to show how the steam mains tie into it? 

Pennsylvania_Steam

Of course!...my photography....

...is a little to be desired!



How's this?

Steamhead

That's what I thought

a ceiling-level header. Don't seem to see them too often, but the ones I have seen were all on Vapor systems.



These ceiling-level headers will work fine if properly piped. I've attached a couple pics of one we re-used, on a hybrid Dunham/Hoffman Vapor system. The existing header was 4-inch and the Weil-McLain 4-80 calls for a 4-inch header, so we just piped into one end, took the equalizer off the other end and plugged the remaining riser tapping that was in the middle of the header.



The 80 series boilers can be fired with either oil or gas. A 4-80 is good for 1238 square feet EDR. If you have more than that, you'd go with the 5-80 at 1608 square feet. The 5-80 can use the same single 4-inch riser to the header, so if that header is 4-inch, it can be re-used.



Leave the Return Trap piping as it is, unless the Return Trap is no longer working. Use a Vaporstat to control the boiler pressure. And I'd suggest using probe-type low-water cutoffs, as we did on this job.