Another Vaporstat Question

Maine Vent

New system, 4 section Weil SGO, with Riello gas burner. If the boiler sits idle for a long time, like 8-12 hous no need for heat. The vaporstat seems to kick out. I have had my bioler guy on the phone the other night, we used a multi meter to diagnose the current back to the vaporstat. He suggested I take screw driver and push the flat sliver plate down and see what happens. Well the boiler sends a signal to the control and then fires the burner. What is making the vaporstat go in to a sleep mode, or loss of signal form the thermostat when heat is called for. I know there has been numerous threads about bad vaporstats, This one does not do it all the time, it just seems to lose commnunication with the control and thermostat after a long spell of calling for no heat. My main is at 8oz, diff at 4oz, System will build pressure to about 7oz and run good when it does call for heat. Any thoughts, pic in below link. Thanks for your help

Jamie Hall

Slightly wierd...

Vaporstats (and pressuretrols) don''t "sleep".  They are simple switches, activated by a pressure sensitive diaphragm (that silver thing) and they are either on or off (and oh how I long for the old mercury units, where you could see the switch operate... sigh).



They are wired in series with the other safety devices on the boiler, such as the low water cutout(s) and backup pressurestat, if any.



Generally speaking, they are not wired in series with the thermostat.  That's a separate control circuit (there are always exceptions...)



I honestly can't imagine why the vaporstat would open after sitting for a while, but cycle properly otherwise (I presume it does cycle properly on pressure on a long run?).



Do you have a low pressure gauge?  If so, what are the actual pressures at which the vaporstat opens (cutout) and recloses (cuts back in) when it is cycling on pressure?  It is remotely possible that it is out of calibration...  but if it cycles on pressure normally, that's probably not it.

Steamhead

Plugged pigtail under the Vaporstat?

I know this was recently installed, but stranger things have happened. Make sure the pigtail is clear. 

Maine Vent

Jamie Thanks

I do have a low pressure gauge. It tops out at about 6.8 oz. I have yet seen the vaporstat cut in or out on pressure. I have watched it through many heating cycles and it seems it never reaches cut in pressure. My main setting is 8oz and the diff is 4 oz what does this actually translate to? I suppose it could be out of calibration. Steamhead replied check the pigtail which I will do today after work.

I guess I'd like to know is if my pressure is only at 6.8oz should I set my main at say 7oz and my diff. at 3 or 4 oz????

My boiler pro wants to put the pressuretrol that came with the boiler on, I don't want to.



I feel this control like you stated is a off and on control, and it just needs to set up correctly.



Thanks for your advice, much appreciated.



This new system is a blessing, Give Thanks

Maine Vent

Steamhead Thanks

Going to take it off tonight after work and brush it out. we didn't skim it until a week or so later.

Maybe oil and krud got into it. Skimmed it twice since install. What is your take on the settings, as I stated in response to Jamie.



Thanks for quick response, I love the wet base system with a gas burner. Getting my insulation back on the headers and risers.



Thanks again

crash2009

?

When you say "The vaporstat seems to kick out"  Does that mean the boiler will not come back on?  How do you get the boiler to start again?  What model of vaporstat do you have?  Can we see a picture of how it is wired inside?

Jamie Hall

Testing, testing...

First thing to do is to check that pigtail, as Steamhead says.  It's rare, but they do clog.



Second thing is to double check the wiring of the vaporstat.  Some models have two sets of contacts: normally closed (open on rise) and normally open (close on rise).  If yours is this type, make sure that one of your two wires is connected to the common terminal, and the other to the normally closed terminal -- they should be identified in the unit or in the documentation.



Your pressure settings sound pretty good -- but having done the above, you will need to change them for the test.  Which goes like this.  Reset (temporarily) the cutout to 5 ounces, which is well below the pressure you have noted on the gauge, so you should be able to get there.  Crank up the thermostat to some outrageous temperature so that you are sure the thermostat keeps calling for heat.  The burner should start.  Keep an eye on the pressure gauge, and when the pressure reaches 5 ounces -- you temporary cutout -- the burner should shut off, and the pressure should start to drop -- probably rather quickly.  When the pressure drops to 1 ounce -- the temporary cutout minus the differential -- the burner should start again.  And this cycle should repeat until you get bored and reset the thermostat to where it belongs.



Now.  What happens if the above cycle doesn't happen?  First question to ask: does the pressure rise to some higher value -- be patient -- and then the burner cuts out and the cycle begins?  In this case, I would be inclined to suspect that the vaporstat may be out of calibration.  There is a calibration screw on them, but it's a bit fiddly.  If this isn't so -- the burner cuts out more or less at the vaporstat setting -- does it cut back in where it should?  Or, having cut out, does it just sit there until you manually reset it?  This could also be a calibration problem -- or it could suggest that the vaporstat isn't working properly; they are mechanical gadgets, after all.



One thing you might try -- assuming that the connections are correct! -- if it doesn't behave properly in your test, is this: if the pressure is rising above the cutout you have set, try changing (lowering) the setting on the cutout (slowly) until it does cut out -- and note what the vaporstat cutout setting is and what the pressure gauge says at the same time.  Then watch the cut in.  If the pressure drops below the cutout minus the differential, try adjusting the differential(again, slowly -- there is a lot of damping on these things) until the burner comes on again, and again note the settings on the vaporstat (and wait and see what it cuts out at!).



And then reset everything to where you had it before all this nonsense, and let us all know what you have found out!  And we can go from there.

Maine Vent

Crash ?

Boiler will not fire when thermostat calls for heat. We multi metered the problem back to the Vaporststat. I took off the plastic cover on the L408J1009 honeywell. There is flat chrome plate, I use a screw drive and gently push the plate down. The burner fires up. I have cleaned out the pigtail, and I raised the main setting to 10oz. I was at work all day today, my wife said boiler came on fine when it called for heat. I have 4 days off starting thurs. and I will do some of what Jamie has suggested for checks. Photo might help.



Thanks for the advice, by the way very nice job with your insulation. I am interested in the covers and how they go on and stay on.



I am putting my insulation back on now, but would like a cleaner looking job than my last boiler had. Clean covers make the job.



Thanks again

Maine Vent

Jamie

Thanks for the great explanation( better than the manual) on how to trouble soot this control. I have 4 days off over the holiday and plan to test this out.



Still skimming, and insulating, and upgrading the main vent. Slowly it's coming together.



I'll keep posting on it.



Happy Thanksgiving to all

Long Beach Ed

Vaporstat

We have also had a problem with the new (microswitch) Honeywell vaporstats.  It seems that if we set them very low, they fail to operate.  On one job, we had the thing set to 6 ounces, and during our testing the boiler ran up to 15 pounds and blew the safety valve. 



We don't like these controls, and have found older mercury models for all the buildings we own.   Never had a problem with one of them.

crash2009

Wiring

Looks like you might not be getting a good connection with your wires to the microswitch.  Put on some proper wire ends and see if that helps. 

crash2009

Insulation

Here is my entire file.  The trick to the pvc covers is the stainless steel tacks.  Also it helps if you have 3 hands.  http://www.heatinghelp.com/forum-thread/137178/Insulation

Jamie Hall

Complete agreement.

And this may be the problem here...



I suspect that it is inherent in the use of the microswitch; the lovely old mercury types had almost no friction at all in the mechanism.



I think maybe I mount an armed guard on mine?

Gordo

That Last Batch of Hg Vaporstats out of Honeywell

That were dumped on the market a few years ago just before the big switchover made these newer non-Hg Vaporstats look great. Oh Boy, did they stink.  Had a few fail right out of the box, the rest so inaccurate that they wouldn't cycle below 8 oz.  The real old ones, back when they made them well, would cycle down to 2 oz.





I remember when "Honeywell" didn't mean "moneywell"

Maine Vent

Tested Control

Jamie has explained out a test for me and here are the resuys.



First, Thanksgiving Day, Boiler didn't run, I had a coal fire in my parlor coal stove for my son and his wife. Temp in downstairs room stayed above 68.



When to bed temp fell, boiler didn't start.



Pigtail cleaned out, thats fine



On to wiring check, I believe my 2 wires are connected correctly. see pics.



On to pressure check, I set the main setting at 5oz, diff at 2oz.



Boiler started by pushing down on the silver plate with a screwdriver see pic.



Pressure built up to 4.8oz boiler stopped or (cut in)



pressure lowered slowly, boiler was suppose to start at 3oz (cut out) I believe. it didn't start.



I ran the same test again cut in at 4.8 oz stopped, waited didn't start.



Calibration screw as Jamie mentioned as one possible fix is not even in the honeywell manual.

I bought this Pex Supply, not sure if they will take back.



I guess now Jamie I need some advice on this calibration screw setting and how this works.



One more request, does anyone the model number of one of these Hg vaporstats? I might get lucky here in southern Maine at one of the older supply houses.



Funny thing about this, boiler ran fine on and off for Monday, Tues, Wed, it only seems to act up when it sits idle for many hours. That's when I can't get it to fire on low temp.



Thanks again, hope I don't have to keep this coal fire going.

ttekushan_3

the first microswitch type

vaporstat I ever installed did just this.  Even when reducing the differential, it would stick "off" at lower settings.   I was irritated and it was late, so I carefully took a fine diamond file to the surfaces that rock and forth. They seemed very crudely made, as if stamped and never finished.  To complete the task I lightly lubed the parts with TriFlow which has some teflon in it.     



Well, it worked. That control works fine after 5 years and I've done the same thing to a couple others with success.  That same crude finish must be what caused problems on the last of the mercury switch versions as well.



FWIW.

Jamie Hall

Your calibraton...

seems to be close enough to not worry about -- it was cutting out about where you had it set.



Ttekushan's idea is a good one; see if you can polish or at least a little (not much!) lube on the pivots for that plate, and the all.



If not... two possibilities: the simplest (and probably cheapest overall) is to raise your cutout pressure back up to 8 ounces, or even 10 ounces (heresy!)(you don't get there often anyway...) and keep then reduce the differential (effectively raising the cut in pressure) to the point where it will reliably cut back in.



Otherwise, you could try to see if you can return that one and see if you cant get a better made one.  Or try and find one of the old mercury ones...

Maine Vent

Funny thing happened with my screwdriver

I must of turned the vaporstat main screw to 10oz the right way.



At least now the boiler is going on when it calls for heat. I have't had to press the plate down in the vaporstat.



So I guess I will just have to be patient, but I'm a little apprehensive that the control is really functioning as it should.



Thanks again

Jamie Hall

Don't you hate it when things like that happen?

Better that the gremlins improve things than otherwise, though, eh?



My bet is that you now have it set just high enough so that the cutin pressure is high enough that the pressure at the level can overcome the resistance of the mechanism -- and it will probably work fine.  In fact, as it is used, it may ger to work better and better.



But it is still annoying when all you do is turn a screw or something, and other problems just sort of disappear...