snubbed by the snubber ...

jpf321

On 2 different boilers where I have a snubber & vaporstat installed, I am suddenly having problems whereby the vaporstat is not "resetting" after pressure drop ... in actuality, the pressure is not dropping through the cut-in but being held slightly above it .. and thusly leading to a no-heat condition.



Is any other snubber-lubber seeing this problem? I removed the snubber in one of the units and things seem to work much better now.



<strong>On a slightly different yet very similiar point, i</strong>s there any way to allow complete/automatic vaccuum release in the vaporstat tree above the pigtail? I was thinking about a Taco 417 hydro air vent (coin valve) or something. Perhaps a small vaccuum breaker, which I can't seem to really source from anyone...

ChrisJ

Ah

This sounds like the same problem I'm having with my 3 psi gauge.  It *always* ends up reading in the negative even though the boiler doesn't have a vacuum in it.



I'd also love to know a way to release the vacuum automatically.

Jean-David Beyer

Do you mean one of these?

http://www.watts.com/pages/_products_details.asp?pid=917



I suppose one could work, but watch the maximum temperature rating. Also, these should not run under pressure all the time. Oops! i do not think these work for steam.



I am not a pro, but could your snubber be defective?

jpf321

exactly...

i just realized that insulating the pipes around the gauge area would help since the severe vacuum is caused by the cooling off as well. But i'd love to hash out an automatic way to break that vacuum as well.

jpf321

looked at

a 288a todaY. I sucked and blew and couldn't figure out how it worked.



i don't believe snubber defective. i think more likely, vaporstats are the culprit and perhaps they wear out or drift  out of calibration enough to cause a problem at the very low pressures.

Jean-David Beyer

How they work.

Inside that unit is a little disk that used to be metal, but they are now made of plastic. It will float on water. The disk has a washer around the side. Water enters the valve from the bottom and goes out the side, normally.The reason the water does not go out the top is that if water comes in it pushed the disk to the top, blocking the escape port. If the pressure of the incoming water is too low, it falls back down to the supply port, which uncovers the escape port, allowing air to enter. It also covers the supply port, tending to reduce back flow. The link I gave on page 1 of the specification sheet shows the insides of the valve.



When I made my post, I forgot that this was for a steam system, and these valves sork on water only. Now if you put one after the pigtail, and had enough water in the thing it might work. But bear in mind the valve should not get above 180F and must not be subject to pressure all the time.

jpf321

thanks ..

I get it now ... thanks for the description ..



I still think that a little Taco 417 valve might do the trick .. but again it may not since there is never really supposed to be water up that high .. or maybe there is at a few oz of pressure .. i've never been inside a pigtail. http://www.taco-hvac.com/uploads/FileLibrary/100-7.1.pdf



I'll get one tomorrow and test it out .. will report back



jpf

Long Beach Ed

Vacuum??

What you are contemplating will void the boiler's warranty and violate many codes.



By tampering with a safety devise such as a pressuretrol, or its installation, you're defeating its protection.   A safety device must be installed as specified by the manufacturer.  There's no room or accommodation in them for a vacuum breaker.



Your problem has nothing to do with vacuum.  It has everything to do with a defective control. 



Replace the vaporstat.  Try to find one that uses a mercury bulb, they are MUCH more reliable.   The new ones with snap switches are extremely unreliable, especially when set to low settings. 

jpf321

2 different issues ...

the vacuum "problem" is not related to the inability for the vaporstat to reset the cut-out. i submit that the snubber may be the culprit here,and I was looking for anyone else with a snubber to chime in.



the vacuum "problem" has been discussed here on the wall several times .. it is due to the contraction of the cooled air between the pigtail and the gauge (presuming the gauge is on the same pigtail). where, as the singular place in the vented system, vacuum is never broken, i was simply looking for a way to break that vacuum.



i have an independent 0-30 manual reset p-trol which is a safety control and NOT an operating control such as the vaporstat.  they are out of different taps on the boiler and are on their own pigtails.