2 pipe steam system issues

ed wallace

I did a site visit today on a 2 pipe stem sytem that has a hoffman differential loop and f and t traps on all the convectors plus 2 f and t traps between the ends of 2 supply and return piping near where the f and t traps are located there is a 3/4 nipple tht is capped off it looks like there may have been main vents attached to the 3/4 nipples that are capped off would it help to add air vents to the convectors the boiler is an older w/m 568 boilers with a gas power burner incorrect header done in copper and the thermostat has to be turned way up to get reads hot pictures will be posted by the homeowner who lurks here and sometimes post questions

gerry gill

is this truely a hoffman system?

or did someone just add the loop? if it is a Hoffman the loop should be the high point of the return pipes and its only vent point..where is the main return vent now? it should be atop the loop or close to it.

Bonz

Hoffman Differential & Vent - Pictures

I'll leave it to Ed to assess whether the loop is at the high point of the return pipes, but the only main vent point at present is atop the loop.  Here are some pictures of the hoffman differential loop and the single vent atop it.

Bonz

Boiler Pictures

Here are some boiler pictures, which shows the (shameful copper) near boiler piping.  I tried to capture the boiler together with the Hoffman differential loop -- about the best i can do given the confined space is take these pictures and that they can be pieced together.

Bonz

Cross-Over Traps (1 of 2)

And here are the cross-over traps Ed referred to.  There are two.  Here's the one closest to the boiler.  I learned taking these pictures (on a 9 degree morning) that this return line is hot hot hot to the touch!

Bonz

Cross-Over Traps (2 of 2)

And here is the second cross-over trap.  On this one, that capped off 3/4 nipple Ed referred to is on a separate nearby return line(it's in the picture there).  This trap is on the lines a lot farther from the boiler -- and unlike the other, the return is not hot.



I just want to say that I've been reading the forum since we moved into this 1932 house this past November.  I can't tell you how blown away I have been by the knowledge on this board and in Dan's books.  It's also how I found Ed, who's been an awesome architectural historian trying to figure out our system!

ed wallace

hoffman system

yes I am sure its an original hoffman system the house was buit in the 1930s and yes the differential loop is at the highest point on the return line but is on  one of the 3 branches off the boiler

ed wallace

hoffman system

yes I am sure its an original hoffman system the house was buit in the 1930s and yes the differential loop is at the highest point on the return line but is on  one of the 3 branches off the boiler

Steamhead

The hot return line

is a clue. One or more traps is leaking steam into the return. If that is enough to close the main vent on the dry return near the Loop, the system won't heat well.



The main vent itself is so small as to be a joke on this type of system. Replace it with a Gorton #2.



That Economite burner, descended from Midco's vintage Lo-Blast units, produces a very long flame which may be impinging on the back of the chamber. It's also a non-flame-retention type, and the 68 was designed for flame-retention burners. Test it for proper combustion ASAP.



What are the lengths and diameters of the steam mains, measured from the boiler to the crossover traps?

ed wallace

2 pipe steam system issues

Hi steamhead to answer your question the pipe off the boiler is 2 in copper the steam pipes are either 2 or 2.5 pipes hard to tell they are asbestos wrapped and sealed under fibergall wrapping the crossover traps are both wihin 19 ft of the boiler most of the basement ceiling has been finished so its hard to find any other cross over traps without opening ceilings also wheres the best place to get parrafin wax need to put it on the joint on the traps hoping that will help getting them open

nicholas bonham-carter

parrafin wax

i found it in the home canning supplies section at the supermarket. you may remember being given some home-made jam or preserves with paraffin wax melted onto the top to keep out the air.--nbc

gerry gill

going back to the original post,

no don't add air vents to the down side of the returns..or the differential loop will serve no purpose..speaking of which, you have a pressuretrol on that boiler allowing operation into the pound range..after 10 ounces of pressure is achieved by the boiler, the 11 th and above ounces start to bleed pressure (steam) into the return pipe (by design), so that could also explain the heat..by the way, the differential loop has no moving parts, so until it springs a leak, its still working today.

ed wallace

2 pipe steam system issues

customer has ordered a new vaporstat and i will look for parrafin wax in supermarket in morning