Idea for digital vapor stat.

tim smith

Was looking around for option for vaporstat, this is good for 0-3.5 psi. Pair with a digital controller might pretty decent. Total around 250 o so. Any input? It’s rated for steam temps.

cross_skier

Quite a few of us have this --
https://forum.heatinghelp.com/discussion/156690/a-diy-vaporstat-alternative

tim smith

That’s for air pressure and dry no ombusstible gasses. Maybe there’s another option but I like the idea of figital with adjustable differential.

Chris_L

I've been using 0-5 psi transducers like these in series with the Pressuretrols on my steam boilers:
https://www.ebay.com/itm/232281554358?hash=item36150f3db6:g:MzoAAOSwB-1Y1NKh

I use them in conjunction with microcontrollers to shut off the boilers at a much lower pressure and keep them off for a much longer time than is possible with a Pressuretrol or Vaporstat.

Note that while the ad doesn't say these are specifically rated for steam, they seam to work ok. And the price is right.

I think it is best to mount them well above the water line without a pigtail to get the most accurate readings.

cross_skier

Interesting, there is more than one way to skin a cat. 

A few us have this controller to introduce a user adjustable delay with a vaporstat.  What low pressures are you trying as triggers for the delay?  Is your system's happy place less than 1" of water?

https://forum.heatinghelp.com/discussion/182874/crazy-idea-pressure-triggered-time-delay

Chris_L

@cross_skier, I did this mainly for my tenant's oversized boiler. It will run at about 3" of water before all the radiator vents are closed, at which point the pressure rises quickly. I have it programmed to shut off at 10" of water and stay off for 15 minutes. (You do get some fluctuations in this sensor output at low pressures, so I wouldn't try to control anything below 3 or 4" of water.)

I use a microcontroller because I can do a lot more with it than just controlling on pressure. I also limit the initial run (after a call for heat) on this boiler to 24 minutes and subsequent runs to 10 minutes if the pressure limit is not reached--until the thermostat is satisfied. And since this is a millivolt system, I can easily use the the microcontroller to monitor, log, and report various operating parameters.

cross_skier

The flexibility of your system is very interesting.  Thanks