Opinions on using double syphons

JUGHNE

I have a vaporstat and 0-32 oz gauge on a new brass 1/4" syphon tube. When the pressure approaches the 6 oz cut out both the vaporstat and gauge start to jiggle/chatter and the mercury tube will be shut down from vibration. There has been suggestions of using two syphon tubes or snubbers. I think the snubbers would be an added maintainece issue.

Any opinions? I would like to build the first syphon with pipe fittings for stability; this would incorporate tee and cross fittings for easy cleaning; then install the brass syphon on the first syphon.

Another problem is when shutdown occurs the vacumn creates quite a twist on the low pressure gauge and does it do anything to the vaporstat? There is a vacumn breaker installed just under the syphon for these items. But it does not help. Manually opening the vac breaker or opening the PRV does not release the gauge once the vacumn is created on the upper side of the syphon.
(Where is spell checker when need???)

Thanks to everyone.

Jamie Hall

For what it's worth, I've had a snubber on my vapourstat for four years now. Never touched it. However, there are two quirks in my setup. First, the snubber is at the vapourstat, beyond the pigtail, so it should never see even steam, never mind crud. Second, the vapourstat is on the header, not on the boiler (the two pressuretrols are on the boiler), so that it is seeing the real system pressure.

JUGHNE

Thanks Jamie; This header is almost 10' above the floor so not a practical place to install controls. I think the snubber or double syphon would work. But there is still the question of the vacumn effect on wrecking the gauge or vaporstat.
Thanks again.

vaporvac

Hi Jugne, My control header is probably 8', but 10 might be pushing it. I have a vaporvacuum system and the vacuum has never affected the vstat or the gauge, both of which I reused when I put in my new boilers. Most gauges seem to be rated for vacuum. I recall your vacuum system, but don't remember a vacuum breaker. Is this original to your system? If not, why don't you keep it that way?

JUGHNE

Vaporvac, thanks for responding. Maybe I worry too much about this vacumn issue. This is a 100+ year old 1 pipe system that was of course coal fired. 15 connected rads totaling 1218 EDR. There were at least 3 Hoffman 2A vac rad vents left in use when I started on this project. (Plus a wide variety of others installed over the years including 1 HW hot water air vent!). All have been replaced with # 40 or 1A's.
The vacumn hissing was very noticeable at rad valves; just today I finished with main venting project. A total of 8 Gorton # 2 and 2 Hoffman #75's. I will listen for the rad hissing on the next heating day. I did add the vac bkr before finishing main venting and that may have been a premature idea.
Jugne

vaporvac

The guy who finally got my burners up and running (a steam expert), said he converts all his two-pipe jobs to natural vacuum so it's clear vacuum isn't bad for the instruments. However, I'm not so familiar with one-pipe. Maybe one of the pros can advise on that vac breaker. I personally, can't believe it's necessary if it wasn't there in the first place. Similar to those who put in feed pumps instead of a simple reservoir tank.

SWEI

vaporvac said:

The guy who finally got my burners up and running (a steam expert), said he converts all his two-pipe jobs to natural vacuum

I've been hinting about this for awhile here. Is there any reason this shouldn't be a "standard upgrade" for two pipe systems?

What (if any) device or mechanism does he use to establish or keep the vacuum in these conversions?

vaporvac

It's buried somewhere in my "Trane Odyssey". I'll have to review.:)

Jamie Hall

On a purely theoretical basis, I agree here. Certainly there will be an efficiency increase if the system is allowed to go into a vacuum.

From a practical standpoint... the biggest problem is getting hold of big enough main vents which seal against a vacuum; our lovely favourite Gorton's don'! Back in the bad old days it wasn't a problem; there was no way you could build steam quickly with a coal fire, and so even relatively small main vents like the old Hoffman ones were quite adequate. And, by the same token, being able to keep heat going at a lower temperature (under vacuum) was a more substantial benefit, too, as again there is no way to get a coal fire to cool off that fast.

But there's no good reason not to do it, provided your piping is set up properly (or can be modified to be) and you have no leaks to compromise the vacuum. And you don't mind a whole candelabra of vacuum vents!

PMJ

Years ago I ended up with a 3/4" solenoid valve on the dry return as the only vent in my 2 pipe vapor/vacuum system as the solution to the venting/vacuum sealing problem. So when I am venting I have a wide open pipe and when closed no leaking. It closes immediately when the burner turns off and opens via a pressure switch set to about 1/10 of an ounce at the same location. Complete vacuum control.

vaporvac

That's fascinating, PMJ .Any chance we might see some pics?

PMJ

Sure. Also search my previous posts as I have commented about this setup several times.

nicholas bonham-carter

Go with two pigtails, joined at the top and bottom. On my Peerless 211A, the siphon is a horizontal pipe anyway. I extended it, and built a sort of manifold joined at the top as well as both to the original peerless syphon. This gives me a long enough length for the 0-15 ounce gauge, safety pressuretrol, and vaporstat. The verticals are high enough to put them all above the top of the boiler, so as to avoid skimming problems, from the elevated waterline.
On my main venting antlers, I put check valves isolated with a ball valve, for vacuum relief, but haven't had to open them as I have plenty of Gorton 2's.
Vacuum can make the rad vents squeal louder than the reaction to the arrival of Joni Ernst in Washington.--NBC

JUGHNE

Thanks for responses. As far as syphon goes I'm going to try the first trap-type built of 1/2" black pipe with the traditional brass pigtail as the second cushion. Tee-plug clean-outs as needed. I still haven't been back to the job for the vacumn hissing noise test. I have not noticed the main Gorton #2's very quick to open.

As far as retaining originality in steam installation, the speed of gas fire over coal has is now an obvious situation to be coped with by all. This Church had no main vents at all until now. Returns were replaced 35 years ago and there might have been one main vent like a Hoffman # 5 or such on each of the two returns.

I'm off to the next steam adventure where I can pose as a "professional" because it is a 150 mile trip to the south and I have a clipboard to carry.
Thanks!