Vaporstat and vent upgrades

piperx

Hello,

Long-time lurker, first-time poster. I’m a homeowner looking to fix / upgrade my one-pipe steam system.

The “fix” part is that my boiler is currently running as high as 5psi, despite the pressuretrol (PA404A) being set to cut in at 0.5 with a differential of 1.5. This is a new behavior after this year’s annual service, and I’ve read on these forums that a potential culprit is a broken pressuretrol, so this seems like a good excuse to upgrade to a vaporstat, which I’ve been wanting to do anyway. I’d also plan to replace the pressuretrol with a manual reset one wired in series with the vaporstat as an emergency failsafe.

Additionally, my main vent currently appears to have a single Maid o Mist Jacobus #1, which seems undersized based on the helpful venting capacity chart, so I am also planning to replace this with two Gorton #1s.

I’ve attached a few pictures of boiler and near-boiler piping, as well as a diagram of what I was planning to install. A few questions I was hoping to get some guidance on:
(1) Does the vaporstat / pressuretrol combo and piping (with snubber and ball valve) make sense?
(2) Does this seem like sufficient main venting?
(3) Any other suggestions while I’m at it? I will be hiring out the work to the one experienced steam technician I know of in my area but want to have a clear plan in place for him.


Thanks in advance to this incredibly helpful community – between this forum and Dan Holohan’s books, I never knew how much there was to learn about steam heat!

Waher

It's not a good idea to use street elbows with air vents because they reduce the pipe capacity slightly compared to standard nipples and elbows.

A snubber isn't typically necessary on gauges protected by a siphon loop.

How do you "know" your boiler is running at 5psi? Are you going by the 0-30psi gauge?

piperx

Hi @Waher - thanks for the tip about street elbows! I hadn't thought about that, but it makes perfect sense - I'll get rid of those.

I am relying on the 0-30psi gauge, which reads up to ~5psi during a heating cycle, so I guess another possibility could be a faulty gauge.

ethicalpaul

the street elbows have WAY more capacity than the vent, don’t sweat it.

I agree with waher though to get a low psi gauge before throwing out your ptrol 

also make sure the tech didn’t mess with its Diff wheel inside

Steamhead

How long is the steam main, and what pipe size?

clammy

Looks like your dry returns are tied together above the water line . Usually dry return are ran separately and only tied together below the water line and each dry return should have its own main vent ,some times there tough to balance due to this . With all that vertical height to bad the installer didn’t use it to his advantage and run a taller riser it’s a good habit to have . What size peerless 63 is that ? My usual riser n header for a03 to 04 is 3 inch single riser and anything larger is both risers and usually a 4 header on 05 and 06 . Also while your upgrading remove the skim tapping piping and add a nipple and 11/4 x3/4 tee add a couple of 3/4 nipple and a cross tee ,and straight pigtail and mount and raise your pressure controls and gauges up there it will stay clean and never clog .
Peace and good luck clammy

piperx

@ethicalpaul – helpful clarification about the street elbows, thank you! I confirmed that the existing pressuretrol is still set correctly, but it’s definitely possible that the 0-30psi gauge could be at fault. Honestly, this is a good “excuse” to invest in a vaporstat anyway, but it would be nice to reuse the existing ptrol as the emergency backup.

@Steamhead – the two main loops are about 50 feet long and 70 feet long, both at 1.5” o.d. pipe.

@clammy – I never noticed that about the returns, thanks for pointing that out. The boiler has a DOE rating of 98k BTU/hr. (I haven’t done a proper EDR estimate, but for reference our house has ~2k sqft of heated space.) To clarify, are you suggesting mounting the vaporstat and low pressure gauge coming off of a vertical pigtail on the pipe just above the sight glass? I found a photo of a similar arrangement and also tried to diagram what that would look like. Is the advantage of that approach the height or the larger pipe diameter?

Steamhead

piperx said:

@Steamhead – the two main loops are about 50 feet long and 70 feet long, both at 1.5” o.d. pipe.

Sure about that? 1-1/2" O.D. would be 1-1/4" I.D., that's way too small for a long main that feeds groups pf radiators in the house.

109A_5

Hello @piperx,
I think @clammy may have meant to build out a good Skim port and add your Vaporstat / Pressuretrol / gauge to it. Also possibly just make the pigtail out of 3/4" pipe cross fittings, plugs and nipples, so easier to clean out and will take a lot longer to plug up, if ever.

Kind of like this.

clammy

Here s how I do it on a recent peerless I did . I don’t really post my own work seems to lead to a lot of tire kickers and those looking for a bargain lol ain’t happening . I ve been piping my trolls and gauges this way for maybe 10 or more years never had an issue . Peace and good luck clammy

Jamie Hall

A bit of clarification. If you have a two pipe system with traps and true dry returns, the dry returns can be -- and in some systems must be -- connected above the water line at the boiler, and must have a generous main vent or vents on them at that location. If you have a one pipe system, the "dry returns" are actually steam main extensions, and must NOT be connected together above the water line at the boiler, as @clammy siad.

piperx

@Steamhead – whoops! You are right. It looks there are actually two different diameters - the first ~half of each loop is 2.5” o.d. and the second ~half is closer to 1.75” o.d. I’ve attached a photo here.

@109A_5, @clammy – thanks very much for the clarification and additional photos. I’ll look to have the gauges and controls put on some 3/4“ piping attached to a skim port, something like the updated diagram attached.

@Jamie Hall – if I’m understanding correctly, I have one pipe steam with returns connected above the water line, so fall into the “must not” category. Yikes! Would you mind sharing the reasons behind the “must not” and the consequences?

Steamhead

piperx said:

@Steamhead – whoops! You are right. It looks there are actually two different diameters - the first ~half of each loop is 2.5” o.d. and the second ~half is closer to 1.75” o.d. I’ve attached a photo here.

For now, you might be able to get away with replacing the existing vent with a Gorton #2. This is a relatively simple job that should go pretty quickly. If the system vents quickly and evenly, you might not have to split the returns. But if it were mine, I'd split them.

Jamie Hall

The reason for not connecting "dry returns" (this is an ongoing battle in nomenclature, by the way) in one pipe systems is that... they aren't returns. They are actually steam mains, and an attempt to put a main vent on them -- or main vents -- is doomed, as the steam will approach the vent location from one side faster than the other -- and that side will get there first and close the vent, and any further venting has to occur from the hapless radiators connected in between that now closed main vent and the other side of the loop -- and they will heat poorly.

This problem is eliminated by dropping the ends of these pipes below the water line at the boiler and putting a main vent on each one. Then they can fill with steam independently, and the radiators will be much happier.

Steamhead

In this case, with no radiators connected to the 1-1/2" portions of these pipes, it doesn't matter if one side doesn't quite vent out completely- as long as the 2" sections where radiators are connected fill completely with steam. Yes, I know it's not textbook, but sometimes it works.

If that were my project, not only would I split the returns, but also move the main vents to near the point at which the pipes get smaller. This way, no steam would fill those smaller pipes, and they would really be "returns".

However, I would prefer to do this during milder weather, since the job would take a while. Hence my vent upgrade suggestion, which can be done relatively easily and quickly, so the house will not be without heat for long.

109A_5

Hello @piperx,
Personally I like a blend of @clammy and @EzzyT method. @clammy gets the sensitive stuff further away form the boiler that can contaminate things. @EzzyT gets rid of the very small area at the bottom of the classic pigtail that can plug up easily, and replaces it with a significantly larger area by using 3/4" brass pipe, basically unfolding the pigtail. Both have ample clean-outs so no or minimal disassembly and no electrical disassembly to inspect or service the pipes. Both are vast improvements as compared to typical installs.



Pipe Pitch ?


Two mains with main extensions connected above the water line may not vent the air out correctly since the steam may get to the main vent faster (and close the vent) though one path leaving air remaining in the other path. I suppose if the air is trapped in the main extension, past the last radiator run-out it may not matter much.