Honeywell Vaporstat, L408J1009...what settings?

rich pickering

the 1009 version is SPDT, 0-16 oz/sq in (0-1 psi): R-B breaks on rise (use R & B for boiler burner ctrl) and R-W makes on rise (W terminal isn't used for burner ctrl). There are 0-4 psi and SPST make-on-rise versions of the L408J series too.

Subtractive differential causes the cut-in pressure to *decrease* as you *increase* the differential, e.g. 10 oz main and 4 oz diff will cut in at 10 - 4 = 6 oz, change the diff to 8 oz and it becomes 10 - 8 = 2 oz cut in.

stevenyc_2

Honeywell Vaporstat, L408J1009...what settings?

I tried searching but didn't see anything specific about setting for the L408J1009 vaporstat. What should I set the "Main" scale to? And what should I set the "DIFF." scale to? Thanks.

Steamhead (in transit)

How low can you go?

I bet you could get away with cutting out at 8 ounces with a 4-ounce differential. Is this a Vapor or a one-pipe system?

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stevenyc_2

one-pipe steam

I thought I understood how these things worked, but either I'm mistaken or my vaporstat is not working right...

My understanding was that the "Main" is where you set the max pressure and according to The Lost Art of Steam Heating, 10 oz is a good starting point. So the boiler will steam until 10 oz and then shut off.

Now the "DIFF." is subtractive so you set that to say 6 oz and then the boiler will kick back on when the pressure drops to 4 oz.

Is my understanding completely off? What is happening is that I set the Main to 10 oz, but when I raise the Diff. up, the cut out pressure drops so it cuts out at lower than 10 oz. This continues to decrease if I increase the Diff. setting. So I kept raising the Main so the cut out would be higher but this in turn raised the cut in!!! Perhaps I'm just very confused. LOL.

I'm also noticing that the cycles are very short since now, the boiler is only building up to less that 1 psi of steam where it used to build up to 5 or more PSI with the pressuretrol. It seems to steam for about 2 minutes until pressure builds up to 10 oz and then shuts off for about 30-45 seconds and then kicks back on at around 3-4 oz.

Any help would be greatly appreciated. Thanks!

RonWHC

The \"J\" Vaporstat

is fairly new. Sounds like the 1009 may be a reverse acting control. Check w/ your Wholesaler. He may have the answer.

Steamhead (in transit)

That part # is correct

you may have gotten hold of one with a glitch.

The short-cycling might be an indication of an oversized boiler. Have you checked its rating against your radiation?

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stevenyc_2

How do I know if it is defective?

How do I know if the one I have is defective? What should the MAIN and DIFF settings be and what should be happening?

Also, what's the remedy for an over-sized boiler? I did remove two basement radiators and another smaller kitchen radiator so that probably didn't help things.

Appreciate the info.

Unknown

How did

you make out?

stevenyc_2

Update

Well, it got down to nearly ZERO last night and last time I checked it was 9 degrees! I'm still burning more oil than I would like to but at least I am running at much lower steam pressure with the vaporstat.

As far as the settings go, I think the vaporstat is now working correctly. Maybe it just needed to "break" in. Before when I changed the DIFF the main would drop and cut- out at a lower pressure. This is not happening anymore. Currently the boiler is firing up to 16 oz and then cuts out. It was cutting back in at 5 oz, but I lowered the cut-in to 2 oz so that the firing time would be longer (seemed to be short-cycling) and the main cut-out stayed at 16 oz. I know Lost Art recommened 10oz out and 4oz in but if I tried to set it to that then the firing time would be very short.

My idea is to just stay put for the winter as I don't have a service contract and things are working as is and I don't want to break anything. Come Spring or Summer, I'll look into possibly down-firing by getting a smaller nozzle. I'm pretty sure I need to do this since I had removed 3 radiators from the system.

Would appreciate any feedback as to my current vaporstat settings (is my cut-in too low or my cut-out too high???) and the idea of down-firing the boiler to reduce/prevent the short-cycling. Thanks! and stay warm...

nicholas bonham-carter

pressure

check your main vents. if you can get the air out asap, your short-cycling problems may become less pronounced. right now it seems like your boiler is pushing the air out with a bit of restriction, and this is partly responsible for the short-cycling.--nbc