Vaporstat on One Pipe Steam System

MAPSteamhead

Hi,

I recently moved into a 1922 colonial house with a one pipe steam system. I've upgraded all the Gorton vents to balance the system and I added 3 Gorton #1s to the end of our very long main return. This evening I swapped out an old Honeywell pressuretroll for a new Honeywell vaporstat (L408J1009). I set it at Main 10 and Diff 6. It does cut out at 10oz but will not reset and come back on (i.e re-fire the boiler when the thermostat is still calling for heat). I've tested the vaporstat and it does cut out and in per the described ohm loads. I have two wires, one on the top screw and one on the bottom. Does anyone know why the system will not kick back on? (see attached pic) PS. I'm adding a low pressure gauge next to the vaporstat but its still in the mail. Any help / advice is greatly appreciated!

Steamhead

Some Vaporstats have been problematic. First try turning the Differential down as far as it will go. If that doesn't cure it, contact the seller and get it replaced.

Gordo

I am sorry to say that all too often, vaporstats are hit or miss as to their precision and accuracy. For such a relatively expensive control, it sure is maddening, isn't it?

For now, you may try to increase the main setting to a slightly higher oz/in2. Sometimes, the differential setting seems to have absolutely no effect on when (or if !) the control resets.
https://www.youtube.com/watch?v=3dBTUp7SAMo

MAPSteamhead

Hi Steamhead, Thanks for responding so quickly! Just to make sure I'm understanding your comment correctly.. I should set the Main to 10 and the Diff to 1? Thanks!

MAPSteamhead

Cool, Thanks for posting the video Gordo! I did hook my multi-meter up and manually screwed the diff all the way up and down. It did move the ohm meter to infinity but only when I got the diff all the way to zero...

BobC

The old mercury bulb vstats seemed a lot better.

Bob

Jamie Hall

One thing which is sometimes overlooked -- vapourstats, by their nature, are working with very small forces in the mechanism. It sometimes gets a bit gummy. A quick shot of WD-40 into the moving parts -- all the pivots etc. -- can help.

Sometimes...

MAPSteamhead

Hi Everyone, One thing I noticed when testing the new vaporstat further this morning is that the old pressuretroll would stop the thermostat but nothing would display on the screen (It would just refire the boiler a few min later). When the new vaporstat stops the boiler / thermostat it displays a "Power Out" message.

Does a vaporstat require a different wiring configuration than the old pressuretroll? (Currently I have the same two wires that were hooked up to the pressuretroll hooked up to the vaporstat)

Thanks!

Jamie Hall

Something is messed up with the wiring. The thermostat should be sending a signal to the burner control. In most cases, the vapourstat (and pressuretrol(s)) and low water cutout(s) should remove power from the whole thing -- except, if you have a thermostat which takes a common power, the 24 volt transformer for that.

MAPSteamhead

Hi Jamie Hall, Thanks for messaging back! I agree it could be something with the wiring, however I haven't changed anything. I literally just took off the old pressuretroll and moved the wires to the same positions on the new vaporstat.

I put the pressuretroll back on before I left for work this morning and verified it is turning off and turning on the boiler without issue. (I'll try the new vaporstat again this evening.) Do the vaporstats need to be wired differently than the pressuretroll's?

Jamie Hall

Shouldn't be any different. Just make sure that you're using the normally closed contacts -- open on pressure rise. It should be in series with any other pressure controllers and with all the low water cutouts...

Fred

@MAPSteamhead , Is that a new Vaporstat? It looks like it may be a use one. Cover Screw head looks like it has been turned many times. Also, the upper conduit knock-out missing. Did you also clean out the Pigtail when you took the Pressuretrol off and mounted the Vaporstat? Many times that pigtail will get clogged enough that it still lets pressure through to hit cut-out (albeit the pressure may well be over what the Vaporstat is actually set at) but will hold enough pressure between the vaporstat and the clog that the Vaporstat can't drop low enough to reach Cut-in pressure to allow the Vaporstat to make again.

MAPSteamhead

Hi Fred, thanks for responding! I did take the assembly apart including the pigtail. I flushed all of it out with water and even blew my compressor through the pipe sections. I hope the vaporstat is new. It was advertised as such. I received the low pressure gauge in the mail today. Will hook it up tonight and see what the system is reading. If I still can get the vaporstat to cut the burner back on at a low psi I'll return it. I did try to reverse the wires on the unit in case the org hvac installer miss colored them but it sees to be correctly wired. If you can think of anything else let me know! Thanks again!

Fred

I'm sure you checked your connections in that bundle under the unit to make sure a wire didn't come loose in those wire nuts?

MAPSteamhead

Hi Fred, yes, the bundle is zip tied so the connections don't come loose. I did not wire the connections. (to messy for my taste) but I did check the connections and everything checks out. The old pressuretroll was working correctly with the existing wiring. Not sure what else it could be.

Fred

@MAPSteamhead , the last possibility, that you can check is the linkage on the Diff. If you take a flash light and look inside the front of the Vaporstat, you will see a large red spring that is attached for the "Main" (Cut-out) pressure. That obviously is attached as you indicate the boiler shut off when it got to set point. If you look , at an angle, from the right, you will see a smaller red spring right behind the "Diff" scale. That spring is attached to a lever that is attached to the small screw on the top of the unit that adjusts the tension for the differential. See if that spring is attached. It is possible that someone turned the Diff adjustment screw down to a point where either the screw was turned off of the top lever or the spring came off at either the top or the bottom. If that spring is attached, that Vaporstat is just bad.

MAPSteamhead

Thanks everyone for the assistance and feedback. I reattached the old pressuretroll and am returning the vaporstat to the seller. It was obviously defective. Gonna spend the money on two more Gordon #2s instead. My mains are 60+ft long so those may help more than the vaporstat anyways! Thanks again, happy holidays!

gerry gill

Honeywell has no competition on vaporstats. So they have no incentive to make one that works. If i were a controls guy, i would smell opportunity all over that.

BobC

One Barnes and Jones Bigmouth vent is equivalent to two Gorton #2's at the same cost as one gorton.

Bob