Adding a riser off skim port

steamnovice39

I recently just bought a new house that has steam heat. I bought the lost art of steam and read it multiple times. I have a one pipe system with a peerless wbv-04 boiler that is currently piped incorrectly. I want to re-pipe the riser and the header with a 3in drop header setup.
I know that 2 risers are better than one since it decrease the steam velocity coming out of the boiler to produce drier steam. However my boiler only has one riser tapping per manufacturers specifications. I want to know if I can tee off the skimming port to add a second riser even though it would be 1.25 inch instead of two. As far as I know a riser only needs to be above the water line correct? Thanks for any replies.

HVACNUT

I would say no way, no how. But I'll let the "real" steam guys give you the reasons why.

Jamie Hall

That boiler doesn't really need two risers, if the one 2 inch is piped correctly -- the velocity in the 2" is low enough to not be a concern, even if it is running at it's maximum firing rate. On top of which, there simply isn't any connection location for it. The skim port wouldn't do at all -- it's too close to the water line and would surely have a great deal of carryover, which you don't want.

Stay with the single 2", but your idea of making it into a drop header is good.

EBEBRATT-Ed

What @Jamie Hall said is correct, however if your concerned you could come out of the riser tapping on the boiler with the shortest nipple you can and install increaser coupling to make the riser 1 or two sizes larger as soon as you clear the boiler jacket.

In this case larger piping will slow the steam down.

EzzyT

You can pipe the boiler just like this one.

steamnovice39

Thanks for the advice guys. I'll stick with the single riser up to a drop header. Is there any advantage of oversizing the riser even if the tapping is only 2inch?

ChrisJ

EBEBRATT-Ed said:

What @Jamie Hall said is correct, however if your concerned you could come out of the riser tapping on the boiler with the shortest nipple you can and install increaser coupling to make the riser 1 or two sizes larger as soon as you clear the boiler jacket.

In this case larger piping will slow the steam down.

My concern, and dislike with that is it will cause water to be trapped in the riser because of the sudden velocity drop in a vertical climb. Going down a size after leaving the boiler works because the larger side exit keeps water in the boiler and the higher velocity will carry any that escapes into the header. But increasing a size after leaving just becomes an area to hold water.

I'd come straight out, go as high as you can and then go down into a drop header that is sized well. A 2.5" or 3" header should be plenty overkill with a single 2" riser.

steamnovice39

I could see how oversizing the riser could suspend water and then increase carryover to the header once saturation increased to a certain point. Thank you for clairifaction. My last question would be if it's all right to 90 the riser over and then down to the drop header since they put my boiler right under the take offs for my mains. I'm then limited how far I can move the mains over because of my equalizer. Both of my mains take off in different directions around the perimeter of the basement.

ChrisJ

steamnovice39 said:

I could see how oversizing the riser could suspend water and then increase carryover to the header once saturation increased to a certain point. Thank you for clairifaction. My last question would be if it's all right to 90 the riser over and then down to the drop header since they put my boiler right under the take offs for my mains. I'm then limited how far I can move the mains over because of my equalizer. Both of my mains take off in different directions around the perimeter of the basement.

Once the riser comes straight out of the boiler and up as high as reasonable, you can 90 over, and then 90 down into the header, no problem.

STEVEusaPA

Nice @EzzyT ! Do you have a pic of the back? I'd like to see how you tied the water pipe into the returns for flushing.

EzzyT

Thanks @STEVEusaPA. Yes I do.

EBEBRATT-Ed

Don't agree. The larger the riser the less velocity. IMHO You don't want any water to leave the boiler, you want the water to stay in the boiler. velocity pulls the water out and sends it to the header where it kills the steam and has to be separated.

So the question is this. If the given boiler has a 2" tapping is there more velocity with a 2" riser ??? or is the velocity reduced with a 2 1/2" riser connected quickly to a 2" tapping.

@Dan Holohan could give us the answer!!!

ChrisJ

EBEBRATT-Ed said:

Don't agree. The larger the riser the less velocity. IMHO You don't want any water to leave the boiler, you want the water to stay in the boiler. velocity pulls the water out and sends it to the header where it kills the steam and has to be separated.

So the question is this. If the given boiler has a 2" tapping is there more velocity with a 2" riser ??? or is the velocity reduced with a 2 1/2" riser connected quickly to a 2" tapping.

@Dan Holohan could give us the answer!!!

You still have a 2" tapping in the boiler, right where it's going to suck water out regardless of what comes immediately after it.

steamnovice39

Well it looks like I will keep the riser at 2 inch going up to a 3 inch drop header. I think that's going to give me the best results for dry steam. Thanks for all the help guys.

Noel

I just want to share a little vision here. The water in the boiler is only a "water line" in the glass when the boiler is firing, the inside of the boiler is full of foamy boiling water that is the same WEIGHT as the water in the glass, not the same HEIGHT. The height is way up in the risers, but it is lighter than non-boiling water. The glass not only shows volume, it also holds cooler water that isn't foaming. Think of the boiling water as being 24" taller than what you see in the glass, because it is lighter in weight. Here are some pictures, showing a cool boiler with a water line, as viewed through a glass tankless coil plate, and a steaming boiler.

Noel

And here is what goes on in the risers.

ChrisJ

@Noel It's been mine opinion for a while that, they did that to intentionally show what goes on with piping on a boiler. It's cool to watch, and shows how important proper piping is, but I don't believe it shows the entire story, especially under normal conditions.



These videos of commercial boilers from Spirax Sarco tell the whole story, in my opinion and more importantly under normal conditions.

Here's video 1. You'll have to go to their Youtube page to find the other ones, I believe there's 9. Some even showing water being pulled into the takeoff just as we're discussing here.

https://youtu.be/_NOftnDDOyE


Video 3 shows exactly what you were talking about with the gauge glass vs water level.

https://youtu.be/HG0M9wPDnzY



Video 6, shows the water being draw into the riser.
https://youtu.be/4yW2mKqi8Gc


Obviously these are high pressure commercial boilers, but the behavior is likely very similar even with a small low pressure steamer. As water gets drawn near the supply tapping, higher velocities will tend to draw it upward and in. The larger the tapping, the less likely it will happen.

steamnovice39

Great videos Chris thank you. What do you guys feel about running chemicals in the boiler? I've been running rectorseal surgemaster which is supposed to help prevent foaming, surging, and keep correct PH. I know other members have reported good results with using steammaster tablets.

ChrisJ

steamnovice39 said:

Great videos Chris thank you. What do you guys feel about running chemicals in the boiler? I've been running rectorseal surgemaster which is supposed to help prevent foaming, surging, and keep correct PH. I know other members have reported good results with using steammaster tablets.

I'll never run a steamer without proper treatment.
I'm using Steamaster, but I'd have no problem using Rhomar's treatment. Whichever is easiest for you to get.

I don't know anything about Surgemaster, but I'd want to be sure it protects against corrosion and has an oxygen scavenger.