Was this a vapor system?

SethYank

I am quoting a new steam boiler for a small house in town. there are 7 radiators, approximately 187 square feet or radiation. There are no traps any where in the system. There are dry returns to the existing boiler, the dry returns meet under the only vent in the system, this line drops down and goes into the bottom of the boiler. The wet returns join up and enter the back bottom of the boiler, no hartford loop. Currently there is a leaking 250 mbh smith boiler there, with the top outlet piped directly into the steam main, no equalizer or any thing. The radiators have a top entering adjustable handle valve with a bottom exit, no trap.
I am flipping through the lost art trying to see how I should bring all these returns to the boiler, and looking at the install manual to figure out my risers and header in the space allotted. Help is appreciated.

SethYank

here are a couple of pictures

SethYank

Jamie Hall

That is indeed a vapour system. The valves are adjustable to allow just enough steam in to match the size of the radiator -- provided the pressure is kept low. Further, don't assume that the return elbow is just an elbow -- many vapour systems had one of a variety of patented designs to keep steam in the radiator, but allow water and air out. Again, however, provided the pressure is kept low.

Joining the dry returns at the boiler with a vent is correct. There should also, however, be some arrangement -- most commonly a steam trap -- at the end of each main to let air into the dry returns but keep steam out, and if the system is parallel flow (most were) there must also be a drip from both the steam main and the dry return to the wet return at that location.

The near boiler piping should be what the manual for the boiler requires, or better. Keep the single vent at the top of the dry returns before dropping. It is best, if using a drop header, for the various mains to connect with the header individually, however, rather than having a single riser and Ts at the top.

Now back to pressure. The new boiler MUST have a vapoustat with a 0 to 16 ounce range. For initial testing, try having the cutout at 8 ounces with a differential (subtractive) of 4 ounces, giving a cutin of 4 ounces. Best practice also requires a low pressure gauge in addition to the required 0 to 30 psi gauge; 0 to 3 psi is most common, but 0 to 5 is satisfactory. This is used to verify that the vapourstat settings are correct -- they have been known to be out of calibration.

Steamhead

@SethYank , that is some sort of Vapor system. Can you post a pic of the writing on the top of the valve? Also, what is at the radiator return connections? Post a pic of that too.

mattmia2

It still is a vapor system, you need to set the new boiler up as such if you want it to work right. Make sure you don't oversize the boiler, maybe even work in the pickup factor as 10% or so or calculate the piping instead of using the 30% baked in to the rating plate. Set it up with a vaportstat.

SethYank

I was using 1.5 for my pick up factor, I saw where Dan had recommended that. The risers to the second floor (4 radiators) are all un insulated.
The radiator in the kitchen is not original, I think it is bigger than original by a few sections, but it is not really working. They used a regular valve at the bottom like a one pipe system, with an air vent at the top of the same section. This radiator is at the end of the back main header. The home owner says it doesnt really heat but they dont need heat in the kitchen. There are financial difficulties and since they dont need the heat I thought I would address this later. The opposite end of the radiator is plugged at the bottom, so is the return line. Picture attached.

Steamhead

With the vent on the same section as the valve, only that section will heat.

What is on the outlet connection of the original radiators?

109A_5

Hello @SethYank,
Wow that boiler seems HUGE for that application.

Even one of these is too big.

SethYank

I did not get a picture of the top of the vent, attached is a picture of the radiator outlet.
there is no trap at the end of the mains and does not look like there ever was. The end of the mains angle down and return to the boiler below the water line. The dry returns come into a cross with the vent on top and the bottom drops straight down and into the bottom of the boiler. I am thinking the dry return should be tying into the wet return and returning to the boiler through the hartford loop, correct? I was planning on getting a vapor stat.
I am planning on using a Utica UH1604HSID, four section boiler, the iom says to use a single 2 1/2" riser, the 5 sections call for 2 risers. I was wondering if using two 2" risers into the header would work, I know I am downsizing the riser and should not but doubling the riser should slow the steam down

SethYank

SethYank

The house was built in 1927, the old rake and poker are still in the corner, so I think this was originally coal fired.

Steamhead

@SethYank that looks like a standard return elbow. Unless we're missing something, this is an Orifice Vapor system. The orifice is located in the radiator shutoff valve, and is sized to keep the radiator from filling more than 85% or so at a certain boiler pressure. In this way, steam cannot reach the dry returns.

AFAIK, MEPCO still makes orificing valves. Or, you can get orifice plates from Tunstall, drill them to the proper size and add them to standard valves.

On this system, the pressure control should be a Vaporstat that cannot be set higher than 1 PSI. The standard Pressuretrol cannot be set low enough for this system to work well.

mattmia2

the way it is now the mains vent through the radiators and through the returns. I think that works as long as the vent on the returns is big but others know better about that than i do.

the closer the boiler size is to the connected edr, the less work the vaporstat has to do. 50% pickup factor is even worse than 30%. unless there is a ton of piping it is far less than even 30%.

109A_5

Hello @SethYank,
I think the Boiler Sq. Ft. needs to match the EDR.

SethYank

So I should step back to the 1603, I just get worried because years ago I undersized a boiler and it created all kinds of problems.

SethYank

I presumed the air is venting through the radiator back to the central vent at the radiator, I am not sure if there are orifice plates somewhere around the radiator.

SethYank

Should the dry return drop be coming in before the hartford loop.

Steamhead

SethYank said:

Should the dry return drop be coming in before the hartford loop.

Yes.

SethYank said:

I presumed the air is venting through the radiator back to the central vent at the radiator, I am not sure if there are orifice plates somewhere around the radiator.

The orifice is likely built into the valve. It might be some sort of adjustable shutter or similar device, but in general is not a separate piece. It would help if we could see what's on top of that valve.

Jamie Hall

Well... try it without adding main vents. However, if the pressure behaviour of the boiler says you need them, which it may, the system will work better (faster) if you can figure out how to add them. Some old systems didn't have either main vents or crossover traps, as a coal fire doesn't heat fast enough to really make that much difference.

There is, from your description, nothing much wrong with the dry return except, as you note, it probably should hook into the wet return before the Hartford Loop.

109A_5

Hello @SethYank,

SethYank said:

So I should step back to the 1603, I just get worried because years ago I undersized a boiler and it created all kinds of problems.

Basically, yes. However I would double check the EDR calculations (any hidden radiators). My 9 radiators are 347 EDR and even if I remove the two biggest ones from the calculations I have more EDR than 187, and my radiators are not that big. My boiler is the rare undersized one at 300 Sq. Ft. and even at 0 degrees Fahrenheit outside it only runs at about 60% duty cycle. My system never goes above 1.25 WC or 0.722 Ounces of pressure.

With your case the other thing is the existing boiler is so big, does the system have other issues that it does not heat the building correctly ? Was it down fired ? The old boiler must have been short cycling on pressure miserably or the structure's heat loss may be incredible.

SethYank

The supply piping to the first floor radiators is very short and insulated in the basement, 3 radiators.
The supply piping to the 2nd floor ( 4 radiators) is about 8 feet tall each and uninsulated.
Most of the radators are thin tube, 5 tube. The bathroom is a column type and so is the kitchen.
LR 5 tube 13 section 8 1/2" x 25" 3 1/2 edr each 45.5 total
DR 5 tube 7 section 8 1/2" x 25" 3 1/2 edr each 24.5 total
kit 3 tube 14 section 9" x 25" 3 3/4 edr each 52.5 total I undersized this one
bath 3 tube 4 section 5" x 35" 2 edr each 8 total I over sized this one
back br 5 tube 6 section 8 1/2" x 36" 5 edr each 30 total
mid br 5 tube 4 section 8 1/2" x 36" 5 edr each 20 total
frt br 5 tube 12 section 8 1/2" x 22" 3 edr each 36 total
216 1/2 edr total
The kitchen radiator is a replacement wider than the original, I can see the original riser hole.
They also brought the steam in the bottom right side like a one pipe system, and put the air vent at the top of the same section as the inlet, so it has never heated well ( the owner has lived there 20 years) but he has no complaints of the kitchen being cold. I plan to address this with him later. But how much edr do I want to assign to this radiator. The 216 1/2 is more than the 195 edr for the 1603 But do I need more?
I will go back to look at the vent top, I expect it is the original from the coal fired boiler, which means it should lock shut to hold a vacuum, so I should probably replace it.
I appreciate every ones help, I am trying to fix this system since the last install was an abortion.

reggi

Yes, that one pipe wouldn't of worked nicely with the vacuum system at all... That would of upset the entire system??? Single Vent/Vacuum trap and the one pipe radiator?? Right ?

109A_5

Hello @SethYank,
I would use the actual EDR of the actual radiators, since that is what is there and defective venting or piping could be repaired with the new boiler install or after. As far as the kitchen radiator, if someone increased the size of that radiator at some point there was an issue, whether they fixed the issue or not maybe forever unknown.

I don't know if there is a rule of thumb to go to the next size up or down when the EDR fall between available boiler choices, and if a "Vapor" system actually makes a difference. Maybe a slight bias in size if in North Carolina versus Northern Minnesota, since the design day temperature may be different.

Steamhead

@SethYank , use the 1604.

mattmia2

the kitchen radiator was probably replaced to get more space.

reggi

Steamhead said:

@SethYank , that is some sort of Vapor system. Can you post a pic of the writing on the top of the valve? Also, what is at the radiator return connections? Post a pic of that too.

That's beefier than the Kriebel but that return outlet probably has a surprise inside .

SethYank

The writing on top of the vent is "Jas P Marsh chicago, thermodisk #5"