Dole 1933 won't operate below 2 PSI?

jjalbert

Hello!

I have a 150,000 BTU/hr boiler in my basement and 13 rads (7 main floor, 6 second floor) that are on 2 separate loops (1 was added with an extension to the house, and has 3 rads all on the main floor). I've been troubleshooting the following issues (among others ):

-rad on the second floor, furthest from the boiler, will only heat if the boiler fires for a long time. It then hisses nonstop. The rads closest to this are also slow to heat.

-there are 4 other rads with air valves that do not close.

I checked the main valves (there are 2 on the "original" non-extension loop) and they are OK (hissed for a bit, then closed when they got hot). The extension loop does not have a valve on the main :-/

I was thinking that part of the problem is that my radiator valves aren't closing anymore, so steam was escaping from a closer rad before it could reach the one that is staying cold. They are mostly Dole 1933s. When looking for a replacement, I came across a spec that says they require in excess of 2 PSI, and that "it is imperative that this low point be reached in each firing cycle." (https://inspectapedia.com/heat/Dole-Steam-Valves-Wallin-Turnstall.pdf)

My pressuretrol is set from 1-2.5 PSI. So now I'm thinking that the problem may actually be that the valves aren't actually opening when the system starts producing steam - which might possibly explain why the further rads aren't getting hot until more pressure has built up. Aren't the valves always supposed to be open to the atmosphere when not closed due to heat? I don't understand why they have this minimum PSI setting. If this is the case, I'm thinking I should replace all the 1933s (even the ones that still close) with something else - possibly the Jacobus - Maid o Mist #41 (https://www.supplyhouse.com/Jacobus-Maid-O-Mist-41-M-41-M-1-8-Vertical-Radiator-Steam-Vent-Straight-Shank)

Any advice would be greatly appreciated!

-Joe

bburd

2 psi is the drop-away pressure. In order for the vent to *open*, the system pressure must fall *below* this level during each firing cycle.

Your system will probably work better if you reduce the pressuretrol setting to cut in at 0.5 with a differential of 1 psi. More pressure does not generally solve problems, it causes problems.

Please post some photos of the near boiler piping and your existing main vents, then we can better advise you on the other problems.

Are your steam mains insulated?

Waher

Radiators further away not getting hot is the result of insufficient air venting of the steam mains or the radiators themselves. If air is in the way, steam is blocked from getting down pipes. Increased pressure at the boiler makes this problem worse.

Your pressuretrol should not be set any higher than 2PSI cut-out (preferably 1.5PSI) with a cut-in of .05PSI.

What do you have for main air vents in your basement? Typically you want to insulate distribution pipes and replace the main air vents first to get steam as quickly as possible to the radiators and then size the vents at the radiators as necessary to balance the heating of the house. Radiators on upper floors will have larger vents due to the need to vent a larger volume of air from the vertical distribution piping connected to them off the steam mains.

Take a look at this page:
https://gorton-valves.com/products

Maid O'Mist uses the same number/letter designations. Gorton is a better quality vent.

Also see this chart:
https://www.maidmist.com/spec-sheets/cross-reference-table.pdf

Jamie Hall

Well, the documentation isn't quite as clear -- for a lay person -- as it might be.

The reference to 2 psi is in relation to the maximum pressure the vent can reopen at. If the system pressure is above that, it may -- or more likely will not -- open. If it doesn't open, then no more air can get out -- or back in.

As the literature notes, the system pressure must drop below that for the vent to reset, regardless of whether it is still seeing steam or not.

It is much more likely that you are suffering from a lack of main venting. You mention two vents on the original loop. What kind of vents are they? They might be adequate, but the odds are against it. You mention that there are no main vents on the extension loop. It needs them.

ChrisJ

bburd said:

2 psi is the drop-away pressure. In order for the vent to *open*, the system pressure must fall *below* this level during each firing cycle.

Your system will probably work better if you reduce the pressuretrol setting to cut in at 0.5 with a differential of 1 psi. More pressure does not generally solve problems, it causes problems.

Please post some photos of the near boiler piping and your existing main vents, then we can better advise you on the other problems.

Are your steam mains insulated?

No,
The PDF he linked actually states to run them between 2 and 5 PSI.

Above those they have vents they claim are for systems that run low pressure but the 1933 says it's intended for higher pressure larger systems.

I have no idea why they say this, or why larger systems need 2 - 5 PSI but that's what their document says. I'm guessing it's just very restrictive.

Their Vari-Vent 1P on the other hand says it does good on systems below 1 PSI.

bburd

My mistake. I didn't look up the literature. Sounds like that system needs new vents.

Jamie Hall

Hmm... I think we need some clarification here. Is the implication that those vents won't open until the pressure reaches 2 psi? Or won't reset above 2 psi? As I say, the literature is none too clear. I have to admit that I made the assumption that the default condition of the unit -- that is cold, no pressure -- it was open. But if it requires a minimum of 2 psi to open in the first place, hmm... that surely would slow a radiator down! Got to admit I can envision a construction which would do that -- but I'm having an awful time envisioning a situation where it would be useful.

Long Beach Ed

Throw out this Chinese garbage and buy some real vents from Gorton or Hoffman.

jjalbert

@bburd and @Waher here is the near boiler piping and some shots of the main vents. In this first pic, the top 2 mains are the original loop, the one on bottom right is for the extension.


@Jamie Hall here are some shots of the 2 main vents - "Vent Rite No. 35" - which seem to be operating as they should.








Glad to know I'm not the only one perplexed by the specs on the Dole 1933. I'm going to replace these all with Gortons. There are several places in the system where parts of mains are uninsulated - and the wet returns are completely uninsulated. This is something I plan on addressing as well.

Regarding the extension loop - this was added on at some point after the original system and has 3 rads. There are no vents on the main, and the return isn't properly pitched - seems to have been installed by some knuckleheads. The first radiator has a Dole 3C attached to it, which I understand is supposed to be installed on a main



This is one of the vents that doesn't close, so it needs to be replaced. I'm thinking I should probably use a different valve - one that is intended for a radiator. The second rad on the loop has a Varivalve Quick Vent - which seems to be functioning properly. The 3rd and final radiator on the extension is a smaller convection unit in a bathroom, which has the Dole 1933 and will be replaced.

I know this line needs to be vented and the return properly pitched - this is beyond what I'm willing to attempt myself so I'll likely hire a contractor for this. My first priority is replacing the valves. Thanks to all for the quick and informative replies!

CLamb

The Dunn-Tunstall company website doesn't mention anything about a 2psi-5psi operating range for the replacements for those valves. I suggest you contact the manufacturer for clarification before deciding to trash the valves.

Waher

Your near boiler piping looks like it is probably wrong for the manufacturer's specs and I don't think your barometric damper is in the correct location either. The former is expensive to fix and can be dealt with after the low hanging fruit. The later is normally dangerous and or leads to higher fuel consumption, it hasn't killed anyone yet, so it might be working okay enough to not be dangerous.

Your main venting is undersized by a large factor, which is typically for most steam systems. Each vent should be installed vertically so that their floats work properly, being off at an angle like some of them are adversely effects their function if the system ever floods or has wet steam. Main vents shouldn't be directly installed on the tappings of the steam mains without nipples below them to provide 6-10" of elevation above the steam mains to protect them from water hammer & debris. It looks like you have 3/4" to 1" tappings which is good (capacity) for being able to add nipples/fittings to allow for the installation of multiple main vents. Search the forum for "vent antlers" to see examples of what I'm talking about.

Take a look at this chart and read though the directions on how to calculate how much venting you need and the maximum capacity of venting off of each of those tappings.
https://heatinghelp.com/assets/documents/Balancing-Steam-Systems-Using-a-Vent-Capacity-Chart-1.pdf

You can note that a single Gorton No.2 has 10x the capacity of the Vent-rite #35.

When assembling black pipe nipples and fittings, you want to wash them first with dish soap to remove any oils and loose iron flakes from the manufacturing process such that they don't get into your boiler water/vents and cause problems. As with all other pipe in the system it should always be pitched to drain.