dropped and oversized headers

Paul_87

I have installed many steam boilers over the past 12- 15 years. I almost always use Burnham. We use one 2" riser with a 2" header for an IN4 through IN6 and 2 2" risers with 3" or 4" header for 7-12 depending on what size the mains are. This method meets the manufacturers specifications. If it is a commercial boiler we install whatever size header and number of risers is specified in the manual. We don't install a dropped header unless we can't get the height that we need or sometimes customers ask for it. We never have problems with noise, spitting vents, etc. I notice almost all of the very knowledge steam pros that are on this site oversize the header, use two risers even when not required, and install dropped headers. I'm just wondering how much of a difference it makes. If I'm piping it according to the specs, properly venting the systems, getting dry steam, and everything is working do I really need to do it? There is a pretty big price difference between 2" CI fittings and 3", it's more labor, it's more/bigger threading equipment to set up, it takes a lot longer to thread, and we are already trying to compete with installers that have no idea how to pipe a steam boiler to begin with. We are almost always the highest bid. What will I notice different if I start doing it this way? It just seems like overkill, especially on smaller boilers. I did an IN4 with two risers and a 3" dropped header for a customer because that's what he wanted and it works great. It doesn't seem to work any better than any other system I have worked on or installed though. What am I missing?

Jamie Hall

Well, in my humble opinion you are missing something -- but it is exceedingly hard to measure. An oversized or drop header will remove more condensate droplets from the steam than will a header piped as you are doing (and thank you for doing that!). The difference will only show up as greater efficiency of heat transferred to the radiation from the boiler. That is almost impossible to measure, except under very tightly controlled -- laboratory -- conditions. How big is the difference? Couldn't tell you -- and so the next obvious question, is it worth the cost, couldn't tell you that, either.

Gsmith

Somewhere on this site is a video of a steam boiler piped with glass piping of the size and height minimum of the manufacturer, used for a trade show demonstration. Perhaps you could search for it or someone will post it. Watch it and be amazed how much water is thrown up into the header by a manufacturers min size arrangement. You will then at least have a qualitative appreciation of why to oversized and/or drop the header. As Jamie Hall said it WILL make drier steam, and that will be more efficient. Perhaps with the customer and pricing, just offer it as an option, tell them it will be in their long term fuel savings benefit, and then let them decide. Some will agree, some will not, but they get to choose, and either way your conscious is clear they get at least the minimum recommended setup. Seriously watch the video, it is amazing how much water is entrained.

Gordo

https://www.youtube.com/watch?v=ovFq-RPdK1M

Gsmith

Thanks Gordo, that's the one. Show the video to your customers, explain that it takes energy (fuel) to lift all that liquid water up 2 feet to the header to just let it fall back down as a liquid to the boiler, and that energy (fuel) will be saved if larger risers and a larger header is installed, and this savings occurs every time the boiler fires. Larger ( or two) risers and a larger header let the fuel be used to make steam down in the boiler, not to pump liquid water around in a circle. Let the boiler be a boiler and not a pump. In the long run of the boiler life they, the customers will reap the savings. Bet a lot will say yes. But not all probably. So be it , they will have had the choice.

Paul_87

I've seen the demonstration in person twice. But even watching the video I don't see any water being carried up into the system until he increases the velocity. I'm sure it is better to be oversized and drop the header but I'm still wondering how much better. 1 billion dollars is better than 900 million but if I only had 900 million would I ever notice the difference? Probably not. Maybe not the best analogy but it's the only one I can think of.

Jamie Hall

As I said before, @Paul 87, the increased efficiency in the transfer from the header to the building is real, but very difficult to measure. You won't see the water droplets in question; they are very small (thin mist might be a better way to describe it) but they are there -- and they aren't carrying any useful heat; better they should be returned to the boiler rather than wandering all over the system.

But if you need hard dollars to sell the advantages, I don't know anyone who could give them to you for a specific application.

The power generation folks figured this all out decades ago, though, which is why you see huge steam drums on power boilers -- and superheat whenever possible.

DZoro

Have your bids designed with options, show owner video of option. Let them decide which they prefer. One just never knows which way people want to go. Always nice to offer choices.
D

EBEBRATT-Ed

@Paul_87

If your in a competitive market stick to your guns it's working and meets the mfg requirements. I don't see the need to obsess over it the difference isn't something you can measure.

If you get a job where price is no object...(how often is that) go for it.

When your competing against copper tubing hacks who never put anything larger than 2" in what are you supposed to do?

Salesmanship can only overcome so much. Some people only know $$$ Value means nothing to them

Gsmith

Base bid: mdgrs min.
Better bid: 2 risers and drop header, customer can decide.