Replacement steam gas boiler reducing the steam riser pipes? Will this cause a problem?

bob eck

Contractor told me he is replacing a gas steam boiler. The old steam boiler is in 20 plus years. The old steam boiler riser fittings are reduced to 11/4” and piped 11/4” back up to the larger steam piping.
He wants to install a new steam boiler with 2 1/2” tappings and bush them down to 1 1/4” and run that piping up to the larger pipe above the boiler. He said the old boiler worked this way why would the new boiler not work if piped the same way.
I do not know a lot about steam boilers but if the steam boiler manufacture has 2 1/2” tappings coming off the boiler I take it the riser piping should be 2 1/2” piping as shown in the manufacture installation guide.
What will bushing the 2 1/2” tapping down to 1 1/4” and piping the steam boiler with 1 1/4” pipe back up to the larger piping?

Danny Scully

Step 1, do not let this contractor install your boiler. As you’ve already suggested, riser tappings should never be bushed (in my opinion) but even more so they can never be 1-1/4”. Step 2, tell us more about the situation you find yourself in.

Jamie Hall

You'll be sorry... it may have worked, after a fashion (steam is remarkably forgiving, sometimes), set up that old way, but neither as well or as efficiently or quietly as it should have.

As @Danny Scully said, don't let this contractor near your boiler.

mikeg2015

It depends on the size of the boiler. The manual shows size of tapping and how many and the size of the header.

First, I’d use 2 tappings regardless. Then use a drop header. Then connect to the equalizer and main. 1-1/4” is pretty small. Based on area, it has about 1/4 the capacity of 2-1/2 at the same velocity. You might manage with a really small boiler.

Can you take pictures.

New England SteamWorks

Consider yourself lucky. Most of the time folks would go ahead and have the boiler piped wrong, experience problems, and then find this site. You found us first.

So don't be that guy. Back up and reevaluate.

BobC

Installing a new steam boiler is an expensive preposition and labor is the most expensive part. If it's not done right you get to pay the labor part of the bill TWICE because the person who did it wrong is often unwilling or just incapable to do it the right way.

Do yourself a big favor and select the installer with care, ask for references (and then call them) and ask for pictures. Make sure any contract you sign includes the phrase "installed to manufacturers specifications". It might cost a bit extra but tell them you want a drop header and if both boiler risers are used you want the boiler header to be larger than the boiler risers.

Bob

JohnNY

Wow, what a terrible idea. Please find another installer.

j a_2

With all the work around these days I just can’t imagine someone coming in and low balling a job....But then again there seems to be a lot of articles about the shortage of available licensed qualified plumbers these days...Maybe there are a bunch of misfits out there pretending to be plumbers..1 1/4 risers ya got to be s###ing me...

Fred

@bob eck, don't do it. Just walk away from that installer!

EBEBRATT-Ed

I don't believe it's a boiler on his property. he works for a supply house.

Doesn't change the message. Don't do it. Just follow the manufacturers instructions in the installation manual

bob eck

I do work for a wholesaler told customer to pipe it in according to manufacture instructions but he said old steam boiler worked that way for 20 plus years why won’t this one. I as a wholesaler can only suggest ways to pipe the steam boiler. Contractor can take my advice or read instructions or do both or they can do what they want to do. If this boiler bangs and makes noise I am sure the home owner will complain and the contractor will be repiping this job the correct way to correct the banging noise.

By reducing the pipe to 1 1/4” does this effect the efficiency of the gas steam boiler. Will it use more gas to produce the correct amount of steam?

Danny Scully

It will make the boiler produce wet steam. The velocity of the steam will be such that water will leave the boiler and enter the header. In addition to the noise, the heat transfer will not be adequate. Tell your customer if he’s interested in a warranty of any kind, he should follow manufacturerers specifications.

Jamie Hall

I think you may be stuck, @Bob Eck. Not a good situation to be in.

It would be difficult to answer your question on efficiency with any exactness -- but in a general sort of way, the answer would be that yes it will use more gas per BTU actually delivered to the system. The high velocity in the risers will carry significantly more water up into the risers and the system, and that reduces the overall ability of the system to carry heat -- even if it doesn't bang. It may also result in occasional low water problems, but maybe not -- that depends a good deal on the exact piping of the header (if any) and the equaiizer.

The joker in the deck, though, is that that loss of efficiency won't show up in any combustion measurements. The boiler will still spec. out just fine (assuming they don't mess up the adjustments too badly) -- so you won't have anything to point to.

Overall system efficiency -- as opposed to boiler combustion efficiency -- is something folks don't pay enough attention to. In my humble (? yeah, right) opinion.

EBEBRATT-Ed

Using supply risers or a header that are too small will increase the velocity of the steam leaving the boiler (miles/hour if you will). The increased speed of the steam will pull water out of the boiler and carry the water into the header and maybe the steam mains.

Lots of water hammer, wet steam, lack of heat, unstable water line eteetcetcetc All kinds of issues that guys like me get called in to fix.

Unfortunate for the homeowner though.

I would impress on the contractor the need to follow the mfg instructions.

After that he's on his own

Fred

I don't know how much less efficient it might make the boiler but it will increase the steam velocity out of the boiler and that will carry a lot of water with it, making for very wet steam.
When the Contractor says it worked for 20 years that way, how does he know? Is it his house? What does he consider "working"? Is that something the Homeowner told him and does the Homeowner have some other point of reference for a properly functioning steam system?

Steamhead

Was this an older Pensotti steamer? I've heard of these using very small pipes, but they must have had good internal steam separation for it to work.

bob eck

I think he said it was an old Sears Nat gas steam boiler. Not sure who was making their boiler 20 - 25 years ago.
On average a Nat gas steam boiler if sized right, piped in right, does not require a lot of new fresh water added to the system and if given proper maintenance how many years does a steam boiler last.

Steamhead

I think Dunkirk made those. But, at least from what I've seen, the Sears install crews didn't bother to read the manual when they installed boilers.

mikeg2015

bob eck said:

I think he said it was an old Sears Nat gas steam boiler. Not sure who was making their boiler 20 - 25 years ago.

On average a Nat gas steam boiler if sized right, piped in right, does not require a lot of new fresh water added to the system and if given proper maintenance how many years does a steam boiler last.

It depends. Water quality is I think the big wild card. Some areas have really poor water with lower PH, higher minerals, high chlorides. After that short cycling can be hard because it encourages condensation. Also frequent large temp swings.

All that being said, the typical number is 30, but 40+ is not uncommon. I'm going on 33 years on my boiler. I'm hoping for 5-7 more years not that I've invested in some corrections and updates. But it had minimal maintenance for most of it's life from what I can tell. I suspect I have once section starting to leak a bit when cold or higher pressures (which is not never sees), so it it spring a major leak I won't be shocked. I'm losing about 1/2" every 10-15 hours of boiler run time now.

BobC

If the leak is in something that connects to the boiler it can probably be fixed. If you do have a hole in a section I would plan on replacing that boiler in the not to distant future, boilers tend to fail at the worst possible time.

Bob