steam system unknown miscue

brentwantstoknow · February 2019

running a 3rd gen supply house that prides itself in wet heat, unfortunately im looked at as the go to guy on heating and do rather well on hot water systems etc and will be the first to admit im a simpleton on steam systems.. dad and grandpa "Deadmen" arent here to ask all the needs to know on steam. have a contractor that was asked to fix the steam system that someone had already replaced existing boiler and now 1/2 the house/ either side works than doesnt work etc... i had them repipe the boiler correctly with a header/equalizer/hartford etc that the original contractor totally failed on. my mystery is these piped "p-traps" on either side of mains vs water line of boiler. im thinking or guessing this was an original vapor/vacuum system and crucial to the original boilers water line as their are also no thermostatic traps anywhere. attaching a rough sketch for viewing. i dont want to throw a bunch of trial and errors at this contractor or repiping traps/vents etc. but im going to recommend installing a vaporstat with a 30-0-30 gauge and give it a try.. currently they were running it at 1/2-1# and would work a cple days until the condensate built up in either side of home and lose the heat to that area. any insight would be helpful and also grateful on this matter.

nicholas bonham-carter · February 2019

Can you identify any inlet valves/air vents/radiators as having a manufacturer’s name/model number?
What part of the piping looks original vs new? If you can find out what changed, then that may lead to correction.
I wonder if the loop seals were added, because thevents failed, and now they are interfering with the air getting out.—NBC

Jamie Hall · February 2019

Oh my. Well, for starters, can you get a picture of a couple of the radiator valves and whatever fittings are on the outlets from the radiators? That would help in figuring out what type of vapour system -- for it almost surely was that -- we are dealing with

The loops which you mention are critical to the functioning of the system -- and the pressure must be kept low enough to prevent them from being blown out. The critical dimension on them isn't from the boiler water line, but from the bottom of the loop to the dry return. Those loops serve to keep steam from reaching the dry return -- if they are blown out, you wind up with steam on both the outlet and inlet to the radiators, and it won't heat much, if at all.

The stray vent over on the right hand side isn't required, but will do no harm. On the other hand, the radiator on the farthest right does need a vent, on the drip, as -- if your drawing is correct -- it goes directly to a wet return, so the air has nowhere to go.

A vapourstat may well make all the difference here. You can figure the cutout pressure to start with fairly easily -- measure the vertical distance from the dry return down to the bottom of the two loops, and take the shorter one. Take two thirds of that, divide by 28 and multiply by 16, and take the result or 7 ounces per square inch -- whichever is less -- as the starting point for setting the cutout.

But do get us those pictures!

brentwantstoknow · February 2019

Jamie, thank you, have the contractor installing vaporstat and setting to 5 ounces based on your formula and his measurement of 27'', now do we need to manually fill these traps or let nature take its course? also have attached pics requested or for viewing what my sketch was trying to put across, the return from the added rad on porch was drawn wrong, it does tie into the dry return, copper line in question is where they have the elec. feeder tied in. my only other question i guess is the swing check valve required or is it doing more harm by having that in place? im going to guess it shouldnt be there but we are trying as im typing. thanks again and i think ill be spending some more time on heating help as there are a bunch of great reads and valuable info

Jamie Hall · February 2019

Those traps will fill in time. Wouldn't hurt to fill them, but... probably not really required (which way does the main slope? Towards them? In which case they will fill on the first run).

Looking at your sketch again, it may be that vents on the mains at their ends where they turn down wouldn't hurt. Most systems set up like that had crossover traps; yours doesn't seem to. While not required, if you find that the radiators at the ends of the mains are slow to heat, that would help.

I can't really make out the valve on the radiator (lovely radiator!) but surely a vapour system...

JohnNY · February 2019

I feel like he's got too much counterflow happening at the boiler. Those system take-offs should rise higher off the header and pitch downward to create parallel flow of steam and condensate. I think you're condensing steam prior to effective travel.

clammy · February 2019

I have seen a few of these 2 pipe system w a water seal similar to what u have the loop seals where close to 60 inches ,they dropped down and came up to a dry return which the radiators returns tied into . They had a drain valve to fill and flush them ,there was no vents on the end of the steam main the only vents where the return before dropping in a wet return . The system i remember was two mains the returns where not tied together above the water each had there own main vents . The system heat well and evenly all air in the main was vented via each raditor . The piping on most of the one I have seen was usually high up and close to the perimeter of house . Nice simple Shem most of the one I encounter where using just a pa404 pressretroll I guess a 60 inch loop seal is for dealing with that. Your mains from the pics as John had noticed looks to be back pitch which can cause a lot of issues . Like I said all of these system where Parrell flow if you have pitch counter then you better drip those mains right by the boiler . The second pic w the new loop seal should have a vent on the steam side also by the boiler those 2 dry returns should be separated and then dropped into a wet return . Peace and good luck clammy