Oversized Boiler

homeowner_7

I converted from Oil to heat last year and the plumber installed a Williamson GSA‑250 Complete 250,000 BTU Steam Boiler. It seems like it is way oversized. My was built in the 1920's and is 2,500 square feet with poor insulation. I plan on insulating my house and am wondering if this boiler is oversized and if it is worth replacing? Also being that the boiler probably runs for less time because the home heats up quicker, would I really be saving money by replacing it?

homeowner_7

Sorry, just to clarify I converted from Oil to Gas.

kcopp

Have you or did he measure out the radiators?

homeowner_7

No, he did not.

homeowner_7

They are cast iron radiators.

New England SteamWorks

homeowner said:

No, he did not.

Oh boy. Wondering now what else wasn't done. It would be great if you could post pictures of the boiler and all it's piping, your main vents, and some of your radiators.

The radiators need to be measured to see where we are at. Measure the height of each radiator, then count how many columns or tubes deep each one is, then count how many sections long each one is. With the pics we'll help you figure it out.

JohnNY

homeowner said:

being that the boiler probably runs for less time because the home heats up quicker, would I really be saving money by replacing it?

Consider the efficiency curve of a steam boiler. It is possible to define efficiency by *the amount of fuel being burned which directly results in the temperature gain of a room*.
That being the case, steam boilers run at 0% efficiency (by that one particular definition, don't everyone get nervous) during every start up of a heating cycle. There is a point in nearly every cycle where the burner is running but steam is not yet being produced. The next part of the cycle produces steam and then pressure and steam then starts to move toward the emitters (radiators). Then we can consider efficiency.
An oversized boiler does run shorter cycles but that means it spends more time in that flat efficiency zone every hour. I know it seems counterintuitive that a longer cycle is less efficient but the farther the cycle gets away from its start-up portion, the better it is for the whole universe.
And when the boiler reaches its operating pressure and the burner shuts off, the boiler begins to cool through the chimney and jacket. That's money lost. There is no substitute for proper sizing when it comes to residential steam boilers.
Someone needs to perform an EDR survey of your system to see what size and output your boiler ought to be.

KC_Jones

To the OP if I was a betting man I'd guess you are massively oversized, but we need the EDR calcs to know for sure. It's the only way it can be sized correctly. If your contractor did not do that simple step and just sized off the existing boiler they most likely got it wrong. Pictures of the installation would be good as well too see if they did anything else wrong.

adambnyc

Same situation.I just had one of the pros on here run me a two stage gas valve which downfires my oversized boiler. If your not gonna rip and replace, I'd suggest doing that.

homeowner_7

Thanks. How much does something like that usually cost?

neilc

The EDR calc is practically free,
yet the most expensive mistake to make,
your time counting, measuring, and posting back here.

Then the pros wil ask a question or 2 more and tell you what size boiler you should be at.

Somewhere else it is written that cost will not be discussed here,
The stepped burner may or may not make sense for you,
again, you need the EDR calc.

and we're all still gonna wanna to see the boiler and the connected piping

homeowner_7

STEAM DOCTOR

1. Boiler piping leaves what to be desired.
2. Boiler was obviously not skimmed.
3. Backflo is on wrong side of feeder
Installer was obviously not a steam pro. You would be well advised to get a real steam Pro on board

neilc

ok,
piping isn't right as above,

now a pic of each radiator and its height, width, depth,
we'll count columns in the pics

adambnyc

I would need the pros to comment, but it sorta looks like you have dual stage setup already, unless I'm looking at an aquastat and a pressuretrol. Not sure why you would have an aquastat for a steam boiler without a hot water loop.

Also not sure why you would have two "pressuretrol" if you didn't have a dual stage setup. Normally in a dual stage one would be a vaporstat. I don't see that.

STEAM DOCTOR

2nd pressurtrol is a manual reset. Extra safety

ratio

Pressuretrol & manual reset limit, but no piggy tail to protect them.

Fred

Wouldn't take too much to fix the piping by dropping that tee'd main into the header and add a skim port (in the lkocation where that fiberglass insulation is showing, next to your sight glass). We do need to understand the total EDR of all the attached radiators to determine how much over-sized the boiler may be and if a two stage gas valve might help. Also, a picture of the vents on the Mains and/or the returns would help determine if main venting is adequate.

Steamhead

Look at the piping again. Can't swear to it, but it looks like 3-inch or at least 2-1/2-inch coming out of the boiler and all the way to the end of the header. And the large riser going up from the header to the reducing tee will provide enough steam for both mains.

As long as the header is 24" above the boiler's highest possible waterline, if I'm right it should work OK. I've certainly seen worse!

There should be a separate pigtail for each pressure control, so if one clogs the other control will still work.

JohnNY

That's a mess. What's with all the dust on every horizontal surface? I can just imagine what's happening inside those burner tubes. That boiler needs to be repiped to some degree, pigtails added, cleaned, and made to work safely. If it resides in an area where airborne dust is often present then consider creating a boiler room to enclose the unit and bring in clean combustion air from outside.

Dave0176

It is pretty disastrous, however as @steamhead said I think the header is 3" which is the minimum spec Weil McLain recommends, but the system risers need to be separated and both come off the header separately. Also the reeeaaal looong Hartford loop is wrong, it should be on a close nipple.