Working on a steamer

Harvey Ramer

and they aren't necessarily my thing, but anyway. The system has the supplies piped into the top of the rads. A much smaller condensate return comes out of the opposite bottom of the rad. The returns all run back to the boiler where their is one vent for the whole system. The mains have condensate lines piped off the bottom immediately after turning horizontal. The boiler does have a Hartford loop piped in.
I went over the system and fixed a few leaks hear and there. I replaced the LWC (float type) and pigtail, which are piped right off the sight glass assembly. I also have to replace the pressuretrol. I have a vaporstat 0-4 psi ordered. When I have the system in operation and all the rad valves open, every rad gets hot and the boiler never builds enough pressure to move the 0-30 psi pressure gauge.
My question is, what type of system is this and what should be the operating pressure?

Jamie Hall

Any traps on this thing? Crossover traps between the ends of the mains and the dry returns? Sounds like one of the many flavours of vapour steam. And if so, the maximum operating pressure should be on the order of 12 ounces, maybe even less...

Harvey Ramer

I looked and I didn't see any traps anywhere.

Danny Scully

It’s likely an orifice system then. Also, @Harvey Ramer, the vaporstat you got has a really low range. Next time, choose the vaporstat that is 0-16oz. Take a few more pictures maybe we could get a better idea. You can always just do the math as well if there is noting indetifying about the system.

delta T

definitely sounds like orifices. If you feel inclined, pull apart one of the supply valves and look inside the union spuds for an orifice plate. The idea is that the steam entering the rad through the orifice plate is never enough to fully meet the radiator's ability to condense it, thus the rad can never pressurize, and you don't need a trap to keep steam out of the returns. This system can likely run at incredibly low pressures. After all the only thing you need to overcome is the pressure drop in the supply piping. You may not even see a 0-3 psi gauge move....

How much of the system looks original? as always, pics please!

The new LAOSH edition has a ton of info on different types of vapor systems.

Harvey Ramer

I'll take a few more pics next time I'm out. I'll also order a 0-16oz vaporstat to take along out.
If it is an orifice system, where might I find the orifices? One of the things that puzzled me is I really couldn't see anything to keep the steam out of the returns. Yet when I had the rads piping hot and put my hand on the condensate return at the bottom of the rad, it was only slightly warm to the touch.

Jamie Hall

That's the beauty of these things, @Harvey Ramer -- only enough steam is allowed into the radiator to be condensed fully by the radiator. There are three possibilities for orifice control: one, as @delta T noted, is in the union assembly between the valve and the radiator. Another is at the outlet to the radiator. But not uncommonly, there isn't a separate orifice at all -- instead, the valve itself is set so that even when it is wide open, only enough steam can get through (Hoffman and Dunham both worked that way). Take a picture of a radiator valve!

unclejohn

I like this place, the education never ends. Like a wimen there always something new or old we need too know.

EBEBRATT-Ed

The lowest pressure that will heat the building is all you need. If it heats without building pressure that is exactly what you want

Harvey Ramer

Here are some photos of the rad valves and the boiler piping.
I installed the new vaporstat today, added a riser to bring it above the water line in the boiler. I played with a few different settings and ended up leaving it set at 14 oz with a 12 oz differential. Once the whole system was up to temp, this gave me a 3min on time and 1.3min off time.
I also found more leaks which I repaired. The system must have been using crazy amounts of water prior.

EBEBRATT-Ed

Near boiler piping is wrong...no header. But, some of the older model boilers that had larger water content seem to work ok when piped that way even if it is wrong. If there are no issues, leave it until the boiler is replaced

ScottSecor

I certainly have not seen them all, but those radiator valves look like run of the mill to me. I would guess around 1950's or thereabouts. I do not see anything that appears to be an orifice to me. Only way to tell for sure is to open on up I guess.

I agree with less than ideal boiler piping, always amazes me when they are piped improperly and they last forty years? Imagine the comfort and fuel savings if they actually read the installation manual...

gerry gill

Probably just an orificed inlet system. Vapor steam

Danny Scully

Few things i noticed from the near boiler piping @Harvey Ramer:

1) generally piped incorrectly without header/equalizer
2) main drips are connected above the waterline
3) returns are connected above the waterline

Neild5

Also the Hartford loop is too long, it is supposed to be a close nipple to avoid hammer.

lchmb

and this would be the one you touch and all hell breaks lose... no hammer no complaints... fix the leaks and see you next year..

Dave0176

Really weird way to build an equalizer or more like riser drips??

mikeg2015

EBEBRATT-Ed said:

Near boiler piping is wrong...no header. But, some of the older model boilers that had larger water content seem to work ok when piped that way even if it is wrong. If there are no issues, leave it until the boiler is replaced

I represent that remark. If you only build 1-2oz of pressure, equalizing just isn't a huge deal. Wet steam can be, but so long as there's plenty of vertical, I think it's manageable.

As the others have said, you don't need traps if all the steam condenses before reaching the end of the radiator.

JUGHNE

There is such a system as a 2-pipe with counterflow steam main.
I have never seen it in a book but actually did a study of one 2 blocks from my home.

Are your steam risers/mains above the boiler the high point or the low point of the steam main piping?

The "equalizer" drips may be actually the main counter flow drips to the system.

The advantage of the 2-pipe counter flow is obvious when you see one. Headroom is gained because the low point of both mains and dry returns is at the boiler. As you get to the ends of the system the pipes are both just about at the bottom of the joists. No low end of main draining into a return line that gets eventually lower yet on its way back to the boiler. You do not need the typical overpitched main because only the condensate of the main is counter flowing back to the boiler (via the main drip which in your case doubles as an equalizer.). The rad condensate is all in the dry return.

Also, there should be no steam in the dry returns because it goes no further than the end of rads with orifice in valve, (for your case) or traps on rads (my case).
Dry returns would only see air to main vent or condensate water from controlled rads. Stream dies in the rad in either case.
So dry returns are only a drain pipe and could be teed above water line as there is (should be) no steam/pressure to jump across the tee to the other return.

This seems to be a better method than the standard parallel flow we are accustomed to seeing......can someone tell me the drawbacks of this??

Harvey Ramer

I'll go along with the orficed inlets. When i put my ear up to the rad inlet, I can hear the steam hissing through.

The system works and there is no hammer. It is actually quiet silent.

The top of the risers at the boiler is the low point of the mains. The condensate drips/equalizer is piped right off the bottom of the mains at that point.

I got to thinking about the pressure. The limiting factor on the pressure is the water column in the return up to the vent.

The only real issue i see, now that repairs have been made, is boiler cycling. The system is installed in a duplex townhome. I believe the system may have, at one point, served the entire house. As it sits currently, it only does the one side. There are only 4 rads connected to the system.

So the boiler will cycle. Not much I can do about that.

EBEBRATT-Ed

@jughne, good eye.

This is yet another example of piping that many will say is wrong (and it is, the supplies should be headerd at least), not textbook but it works fine as is

gerry gill

2 pipe counterflow mains were popular back in the day. Its really nothing more than a glorified runout. They were usually short and the pipe had to be sized properly.