Vaporstat Issue

Davidho

Finally got around to putting a vaporstat on. I am manually having to flip the arm to get the circuit to go open. Model L408J1009 Just been wanting to test it and can’t get it to shut off automatically . I have gone down to zero and still won’t kick off. This is very low pressure system. I have the house up to 81 degrees and my wife is not happy. I noticed the brass nipple tip that is in the center is knicked up not sure if that is the problem or if such low pressure just not enough to overcome the resistance in the microswitch itself. I just have to touch that arm with blade of screwdriver and it kicks off. Also I couldn’t imagine how hot my house would be if I ran this thing long enough to set it at the 8 and 4. I was hoping for 4 maybe 5 on the coldest of day of the year.

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ethicalpaul

you are maybe searching for a problem where one does not exist. What’s the maximum pressure you have seen?

You know pressure is not the goal, right? Comfort is

Jamie Hall

There is only one reliable way to check the operation of a vapourstat — a low pressure gauge (with a suitable range) on the same pigtail as the vapourstat.

Anything else and you are guessing.

There are a number of really good steam systems which essentially never develop much over an ounce or two of pressure.

You may have trouble getting it to cut off — but it's the thermostat which controls the temperature, not the vapourstat.

Davidho

Yea I knew that I will never ever see any type of pressure but two low pressure gauges showing around 3 ounces it should do something. This would be only triggered in an adverse condition so wanted to make sure it even works considering the cost.

KarlW

For what it's worth, I also installed a brand new L408J1009 this year. I found that the numbers next to the screw bear no relationship to my gauge. I have it set to cut-out at 4 oz, but it doesn't cut out until 8oz (which is my desired setpoint).

I expected better calibration than this.

ethicalpaul

Honeywell just doesn't seem to worry about it.

If you want to build some pressure fast for a test, just turn off a bunch of your radiators, that's what I do. The wife won't be complaining about the heat that way.

delcrossv

https://forum.heatinghelp.com/discussion/comment/1815218#Comment_1815218

Yep. The settings on the microswitch ones I think are there purely for decoration.

reggi

https://forum.heatinghelp.com/discussion/comment/1815210#Comment_1815210

Right but as long as he's showing 3+oz on his gages let's assume he reaches that much couldn't you set the differential to let's say 1oz and run the main to 16oz then under gage pressure of 3+oz turn the main down from 16oz to where it shuts off the system to get the vstat operational ability tested ? Of course the differential would have to be calculated in..

Now I still have my L408A Mercury so I'm not sure how the new electronic ones react but pressure is pressure.. and I agree about the gages..

EdTheHeaterMan

@Davidho said: "I have gone down to zero and still won’t kick off."

Am I missing something here? The pressure is lower than the cut off setting and you want the burner to go off? My understanding is that you want the burner to go off when the pressure goes higher than the cut off setting. If it is at zero PSI then it should be in the ON or CUT IN position. Right? What turns the burner off when there is low pressure is the thermostat. If you want the burner to stop when there is low pressure in the boiler just turn the thermostat down.

Jamie Hall

I quite agree that the microswitch ones are often out of calibration. Sometimes quite a bit. There are ways to calibrate them — but it's just as satisfactory to use your low pressure gauge to get it set where you want it and not worry about what the numbers say…

But. Note that I said the low pressure gauge should be on the same pigtail. Why? Because pigtails clog, and if you are using that gauge to check the vapourstat settings you really want them to be seeing the same thing.

And furthermore, if the pigtail is clogged the vapourstat may never see any pressure anyway. Make sure that it is free and open.

neilc

and other gages should be there, not on that same pigtail, or port for that matter, and I'm not meaning the 30# insurance gage either

delcrossv

https://forum.heatinghelp.com/discussion/comment/1815250#Comment_1815250

Truth be told, I'm getting less and less enamored with pigtails. Making a water trap out of brass pipe and tees is less likely to clog and much easier to service.

And they look way cooler.

Davidho

https://forum.heatinghelp.com/discussion/comment/1815271#Comment_1815271

Did my pictures not post to this post? I thought I had it set up nice.

https://forum.heatinghelp.com/discussion/comment/1815236#Comment_1815236

Maybe I am missing something. When I am at say anything over 2 ounces of pressure. My boiler has ran for at least 15 minutes on cold start up and every radiator in my home is too hot to touch your hand to for long all the way across the top. The bottom of the radiator is the same halfway across. My thermostat will be satisfied soon enough. Let the radiators radiate. Why keep pushing fuel? It will sit in a vacuum for a good 20-30 min. So yes I am assuming when my boiler reaches 2 ounces of pressure I would like the vaporstat to shut my burners off even though my thermostat still at the moment is calling for heat.

Davidho

https://forum.heatinghelp.com/discussion/comment/1815230#Comment_1815230

This was exactly what I was trying to do. Just to find off and go from there. Just clicking it on and off with my screw driver it takes around 4ounces before it clicks like it should. Anything less than that not good.

trivetman

test with the differential set higher. It looks like the differential is set to zero which tells the vstat to kick back on immediately in response to any tiny drop in pressure after it kicks off. For just testing cutout i think you would want the differential to be set a little under the pressure setting you are testing

KC_Jones

https://forum.heatinghelp.com/discussion/comment/1815313#Comment_1815313

That’s not what a vaporstat or pressurtrol is for. They are safeties to shut the boiler down before pressure gets too high. They do not interact with the thermostat and have nothing to do with comfort. Even if it did shut down on pressure, as soon as the pressure dropped, it would kick back on. The pressure, at those low levels, will drop in less than a minute, most likely less than 20 seconds.

To get what you describe will require additional digital controls and programming that basically doesn’t exist, so you’d be on your own to develop it, well somewhat on your own.

ethicalpaul

Why keep pushing fuel? It will sit in a vacuum for a good 20-30 min.

I agree with your thinking here, but the vaporstat doesn’t: as soon as your pressure drops from the steam condensing after boiler shutdown, the boiler will start up again

I did what @KC_Jones described above. I have a Dwyer pressure switch tied to a timer relay module that shuts off my boiler for 10 minutes when pressure hits about 5 oz

This lets the full radiators radiate for awhile

Davidho

@ethicalpaul I have a Dwyer pressure switch tied to a timer relay module that shuts off my boiler for 10 minutes when pressure hits about 5 oz.

This was my exact plan. I was just looking to see if the issue was with this thing not turning off was a defect or that it just cant calibrate below 4 ounces. I will look into that Dwyer switch.

Mad Dog_2

Make sure the cut in & cut out aren't too close together. Mad Dog

KarlW

I thought about installing a timer relay, but if the heat is forced off for the duration of the timer setting, don't you risk not having enough heat on the coldest days? It seems like you are at level of a PLC if you need to do that.

neilc

https://forum.heatinghelp.com/discussion/comment/1815313#Comment_1815313

I am suggesting that with all 3 gages, after the same pigtail, they will all read over, or under, if the pigtail clogs and blinds your Vstat,

your gage tree and pigtail are set up nicely for servicing, and you seem engaged enough to be on top of things there,

another gage, somewhere else, may, or may not, reveal issues, and that said, who says which gage fails first , , ,

it's endless

Jamie Hall

The fundamental principle with any gauge or safety — and it doesn't matter whether it's a pressure gauge, vapourstat, low water cut off, air speed indicator, whatever — is that to be of any value at all they must be independent. If you want that level of redundancy, don't set it up for a single point of failure.

ethicalpaul

https://forum.heatinghelp.com/discussion/comment/1815344#Comment_1815344

no, because once the radiators are full of steam, that is about the maximum heat they can radiate anyway. After 10 minutes they are still hot and radiating. The difference is I’m not burning fuel that whole time.

Additionally almost every system is oversized both in radiation and in boiler size (often dramatically), so there’s no risk of it not keeping up.

This really only comes into play during setback recovery

Long Beach Ed

If you are a guy who wants accuracy with this thing, get an old mercury one and you can calibrate it precisely to the ounce. You can try calibrating this Mexican snap switch one, but you'll find it incredibly sloppy. It will do the job of shutting the boiler when the system fills with steam, but it's no precision instrument.

In a properly sized system, the vaporstat or pressurtrol should seldom shut down the system. Considering the high cost of these, most homes derive little benefit from them.

Davidho

@Long Beach Ed Figuring out they don’t make em like they used too.

EdTheHeaterMan

Analyzing this statement by @Davidho:

Maybe I am missing something. When I am at say anything over 2 ounces of pressure. My boiler has ran for at least 15 minutes on cold start up and every radiator in my home is too hot to touch your hand to for long all the way across the top. The bottom of the radiator is the same halfway across. My thermostat will be satisfied soon enough. Let the radiators radiate. Why keep pushing fuel? It will sit in a vacuum for a good 20-30 min. So yes I am assuming when my boiler reaches 2 ounces of pressure I would like the vaporstat to shut my burners off even though my thermostat still at the moment is calling for heat.

Maybe I am missing something. When I am at say anything over 2 ounces of pressure. My boiler has ran for at least 15 minutes on cold start up and every radiator in my home is too hot to touch (Steam @ 1psi is about 214°F, so don't put your hand on the radiator when it has steam in it) your hand to for long all the way across the top. The bottom of the radiator is the same halfway across. (That is because there is some air left in the radiator. Air is heavier than steam so it will go to the bottom of the radiator. Steam at the top is hot, air at the bottom is not as hot) My thermostat will be satisfied soon enough. (That is because the radiators are hot) Let the radiators radiate. (Try and stop them) Why keep pushing fuel? (Because you have the thermostat set that high. If you want the burner to stop earlier, then lower the thermostat) It will sit in a vacuum for a good 20-30 min. (again… Try and stop it) So yes I am assuming when my boiler reaches 2 ounces of pressure I would like the vaporstat to shut my burners off (when the burner stops and you see it go into vacuum, that is no longer 2 ounces of pressure. Vacuum is the opposite of pressure. Your vapor stat can't see that vacuum as anything other than a pressure lower than the cut in pressure) even though my thermostat still at the moment is calling for heat. (Yea, that darn thermostat again. If it only had a brain and not just a set of contacts that operate at a given temperature. It's just like that darn brainless pressure switch that only has contacts that make and break on pressure.)

Maybe I am missing something.

Hope this helps you find what you are missing.