Vaporstat

crash2009

I really did not have a need for a vaporstat until now.  You all know about all my lack of pressure griping for the last 3 months.  Well now I got some, (THANKS)and feel the need to rein it in a bit.  I ordered a Honeywell L408J1009 tonight and a 0-20oz gauge.  Here is the plan, we will see how it turns out.  I am planning to keep the existing pressuretrol for a high limit device should the vaporstat ever fail.  The P-404 will reliably shut-down the gas valve at 2.55psi.  I plan to use 2 valves to isolate both the pressuretrol and vaporstat.  The 0-30psi gauge will be on top of the cross with no isolation.  I looked at a lot of your pictures and took a bit from everybody.  The only thing I don't like about this is that it looks a little top-heavy, and it may have some vibration.  There is a plug on the top of the EG-55, right beside the left boiler riser, I was thinking about using the tapping as a stabilizer somehow.  Any thoughts on stabilizing this contraption?  Or should the whole design go back to the drawing board? 

Jamie Hall

Does look a bit topheavy...

see how it works!



The only thing that bothers me about it is having a valve on the line to the pressurestat -- which you are using as a backup safety.  I am a firm believer in Murphy, and I personally don't like to see a manual valve on a safety device.  Sooner or later, someone is going to leave it closed... at the wrong time...

Charlie from wmass

Do not isolate the pressuretrol

the vaporstat sure but the pressuretrol is a safety device and should not be valved. Do you have another tapping? Then use 2 pigtails instead of the one, as pig tails are prone to clogging.

Brad White

Valves and Controls

I would advise against any isolation valves between your boiler and your operating and especially safety controls as Jamie and Charlie noted.



It is against code here in MA at least on larger boilers but I believe it also is covered under ASME. There exists the possibility that someone could inadvertently or otherwise isolate the controls and you will have a runaway boiler. If the operating control is isolated you are relying on your safety and that too can fail. Besides you would defeat the low pressure benefits.



We had a detail which indicated no isolation valve on the high limit but one on the operating control for convenience. This was wrong and we changed that.



It is permissible to isolate the pressure gauges. Our MA large boiler code stipulates that a tee and valve shall be installed below the regular gauge so that a test gauge of known accuracy can be temporarily installed to check the primary gauge. I think that this makes sense even on residential boilers.



Regardless of code, having nothing between your boiler and even operating controls let alone safety controls is a best practice. No mean to lecture, just want everyone safe.

Charlie from wmass

I do use valves for

Vaporstats but make sure the pressuretrol is not valved and is set for low pressure operation. This allows for isolation of the vaporstat during blowdowns. It would also mean two pressuretrols and a vaporstat on a larger boiler. Make sure they are all wired in series and NOT parallel.

Brad White

Good Idea Charlie

I still go by what the MA Boiler Code says (it is for commercial boilers and did not make a distinction between operating and safety controls.) I have not explored how this might affect the residential boilers though, but it is a no-cost practice to avoid valving off. Agreed, it is handy though when you need them to not have to allow a cool-down to change out a control. 

Charlie from wmass

Brad I would only valve

a vaporstat to keep it from the pressure required for a proper blow down of a boiler. The cool down would not be a factor in my valving it.

crash2009

I am hearing you guys loud and clear

  Do not valve the pressuretrol.  Valving the vaporstat is risky.  Use separate tappings if possible.  Wire the Vaporstat in series.  And of course, remember that guy named Murphy.



I am not even going to try to open the second tapping at this time of year, that will have to wait until summer.  I need to isolate the vaporstat to backflush the boiler.  I could just remove it when backflushing, but a valve would be so convienent. 



Maybe I should union the vaporstat side and install an electrical pigtail.  This would allow it to come off quick when its time for cleaning. 

crash2009

I installed the vaporstat today

 Out of the box it was set to MAIN 8 and DIFF 5.  As I understand it that should give me OFF at 8 ounces, and ON at 3 ounces.  My 0-20 ounce gauge confirms OFF at 8 ounces and ON at 3 ounces.  I had to remove the snubber from the gauge because it made the gauge too slow.  The 0-3 psi gauge confirms as well OFF at .50 psi and ON at .10 psi.  For some reason the snubber doesn't affect the speed of the psi gauge.

King valves sure make the testing easy.

crash2009

duplicate post