Riser smaller than header

radcon

I can't find answers anywhere so I'll ask here. We own a 1928 bungalow 2 bedrooms 1500 sq. ft.. As far as I can tell the entire 2 pipe steam system is original except for the boiler. The existing boiler was installed prior to 2000 and was a used boiler when installed so probably was not sizes for the original EDR of 317. The boiler needs replacing and I've chosen a Peerless 63-03. The existing boiler has a 3" riser which was joined to the original 2-1/2" header by welding, and the system (mostly) functioned OK. So my FIRST question is the Peerless 63-03 has a 2" riser from a 3 x 2 bushing which will be joined to a 2-1/2" header and will that work? Or should I get a 3 x 2-1/2 bushing as used in the Peerless 63-04 and run a 2-1/2" riser to join the 2-1/2" header? I'm assuming the riser to header will have to be welded. My SECOND question is that, other than Hoffman #8 thermostatic vents on each radiator, there were no vents of any kind that I can find in the entire system. (I did have a vent installed at the end of the dry return at the point where it drops down to join the wet return but it probably should be removed). I've looked and read and searched but cannot find any system that looks like mine. There are what appear to be check valves, one in the dry return and one in the wet return just before they join the equalizer piping. The dry returns start at the last radiator on each branch and slope back to the boiler picking up air and condensate from each radiator and then tie into the wet return near the boiler. The supply piping continues beyond the last radiator served on each branch then drops down to floor level, get joined together and become the wet return and travel back to the boiler.
My question is how does this system work without vents?
Pipe sizes are as follows. Header is 2-1/2" , each branch is 2", after the last radiator each branch reduces to 1", the wet return is 1", the dry returns are 1" for each branch then becomes 1-1/4" when they join to run back to the boiler.
I've attached some photos, hope they show what I'm talking about, and thanks for any ideas or answers you might have!

Danny Scully

Where are you located @radcon? I see a few locations vents belong but are currently capped.

gerry gill

dont base anything off of what you have - which is horrible..follow what the manufacture says as what they say is the MINIMUM standard. So if they say 3 you don't bush to 2-1/2.

radcon

First, I'll respond to Danny - Thanks for your response. I'm in upstate NY, and the contractor search doesn't list one within a 100 mile radius. Yes, there is a plug in the tee at the end of each supply branch which would accept a vent, but when we bought the house there weren't any vents at those locations. The only vent we have is the one I requested to be installed at the drip end of the dry return, once again the tee had a plug when we moved in. Once the Hoffman #8 traps were rebuilt any knocking we had was almost totally eliminated. My question is, is there a 2 pipe system without vents?

Second, I'll respond to Gerry - Thanks for the information. My existing header is 2-1/2" and feeds 2 - 2" supply branches. My question is will a 2" riser off a Peerless 63-03 boiler work ok or should I increase the riser size to 2-1/2" to match the existing header?

Jamie Hall

First off -- no, you have to have a vent or vents somewhere in your two pipe system. However... there are several different ways to do the job, and before we got thundering off into the shrubbery, a question: at the ends of the steam mains. Are there dry returns right near the ends of the steam mains? And if there are, is there any sign -- plugged tees anything -- that there might have been a connection at that point? If so, that connection may have had crossover traps, and you could reinstall those rather than main vents at the ends of the mains.

The vent on the dry return which got removed needs to come back. Depending on the overall size of the system, at least one and more likely two Gorton #2s. They are better in that location than a Big Mouth, as they will block water should your pressure get too high and a Big Mouth won't...

On the boiler riser. If that Peerless has a 2 1/2 inch tapping for the riser, use that. If larger, go larger. If it's a 2... well... hmm... you'll have to make do with a smaller riser. I'll have to think a bit about whether you should go larger right away, or at the header, but my first reaction is to stay with the 2 up to the header. In any event, go bigger if you can.

gerry gill

I looked it up. The manufacturer says 2'' will work for that size boiler. Table 4.1 in their install manual.

Jamie Hall

gerry gill said:

I looked it up. The manufacturer says 2'' will work for that size boiler. Table 4.1 in their install manual.

Thanks, @gerry gill -- then I'd go up with 2" and transition to the larger header at the top.

radcon

Thanks again Jamie & Gerry -

I'm attaching a schematic of my system. How does it work?

As far as the riser goes I'm going to install a 2-1/2". The piping listed in Table 4.1 is the minimum size required per section 4.C.2 (pg. 15) of the installation manual. I'll install piping for models 63-04 & 04L per the chart in section 4.F. figure 4.6 (pg.17). The steam is going into a 2-1/2" header so might as well use a 2-1/2" riser to get it there.

I'm still at a loss as to how this system has operated for 90 years without vents or traps in the supply & return piping. There are fittings with plugs at the end of the 1" dry return branches and the 2" supply branches where they reduce from a 2" supply to a 3/4" (run out?). Those fittings are close enough so an F & T trap could be installed between the supply and and return. However, there is no sign that the plugs have been disturbed or had a wrench on them since they where installed. The finish and patina match the fittings. Also, one of the 1 x 3/4 ells on the dry return would have to be tightened another 20 deg. to be vertical and useable.

Instead of using a connecting trap between the supplies and returns the installers ran 59' of 3/4" insulated pipe and 47' of 1" pipe, plus fittings and hangers. Thats a lot of material and labor and for what? The attached schematic shows the layout and sizes and height above floor so the slope of the pipes can be checked. The dry returns slope toward the boiler, the supply piping slopes away from the boiler, and the wet return on the floor is level.

As far as I can tell the 3/4" pipe would relieve the air and excess steam/condensate from the end of the 2" supply lines and empty it into the 1" wet return to the boiler. I can understand the condensate going through the wet return but where does the air go? Does it get pushed through the return and up the riser and back into the supply piping?

I've been doing a lot of research and haven't found a 2 pipe system like this one. Any Thoughts?

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