Diagnosing if pressurestat needs replacement

agurkas

I got the 3PSI gauge couple days ago and have been following it. I have noticed that cut in and cut out has been insonsistent. Sometimes it does 0.7PSI with 1.7PSI cut out. But sometimes cut in and cut out creep up by 0.5PSI.
Pressurestat is dialed down to 0.5PSI (basically as low as it will go)

Faulty pressurestat?

Don_197

that's about as accurate as a pressuretrol will work on a low pressure or vapor system.......it is probably functioning normally. If you do replace it.....I suggest a vaporstat.

agurkas

Vaporstat is definitely what I have in mind. Question is what is the ROI on spending $180 on it be able to operate at lower pressures.

Don_197

Your mileage may vary.....................being able to actually see what is going on in your system? "Priceless"

KC_Jones

Just a homeowner here, but this is my take on it. The pressuretrol or vaporstat simply keeps the burner from running above a certain pressure. This is for some efficiency of the system as well as a safety feature. If you are trying to keep the pressure low that in reality is a venting issue. If you get the system tuned in really nicely you might never hit the cutout of that pressurtrol or the vaporstat. I put vaporstats on my new boiler, but I was replacing everything anyway and I needed control for my lo/hi fire setup. Instead of worrying about the cut out of the pressuretrol I would spend the money on other improvements to the system that will get you more bang for the buck venting, piping whatever else you can. The gauge is your friend use that as a tuning tool not the pressuretrol. Or you just save the 180 for future boiler replacement repiping whatever else. If you are trying to keep pressure low with the vaporstat all you will do is make the burner cycle on and off more often which isn't really as efficient and could possibly have zero ROI. Again just the opinion of another homeowner.

agurkas

At this point I actually think I may be overventing the dang thing :-(

KC_Jones

Just a guess based on my limited experience with my own system, but if you are building that kind of pressure i doubt it. I can't get mine to even hit 1psi at this point. I watched it for about an hour of continuous run time the other day (set the stat to 75 on purpose) and I never hit 4 oz and I still think my mains are under vented due to speed. I know all systems are different and I am not an expert just know what I have read and seen.

SWEI

@MarkS‌ was using a Dwyer 1823-20 as an operating control for awhile. No marked scale like a Vaporstat, but you really can't argue with the price.

KC_Jones

SWEI said:

@MarkS‌ was using a Dwyer 1823-20 as an operating control for awhile. No marked scale like a Vaporstat, but you really can't argue with the price.

I found out about that after I spent money on the vaporstat. If the vaporstat ever dies I will buy the Dwyer. After getting the vaporstat I wish I hadn't. It was wildly inaccurate. I had to tune it in and it is now close, but still not dead on by my gauge.

Mark N

Why not wait until after the boiler is converted to gas. Hopefully you won't be as much oversized. See how it runs after that. A pressuretrol or a Vaporstat is only a high pressure limit control. It doesn't determine what pressure your boiler runs at. It only controls at what pressure it turns off and on at. The size of the boiler, the size of the pipes and the load determine what the operating pressure will be. An oversized boiler will always run the pressure high because there is not enough radiators to condense the steam so pressure builds.

agurkas

So the Dwyer unit you just basically tune by watching the gauge?

KC_Jones

You will have to read up on them @ChrisJ has one on his boiler as well, but I don't think they use it for limit control and not sure if they should be or not. I would use my for fire control, but not sure about limit. I THINK it has a very narrow band of adjustment, but someone that has used one would know better.

vaporvac

MarkS also has a modulating burner and his pressures never even built high enough to trip his Vstat when he originally had it. I bought his when he moved to the Dwyer and he kindly calibrated it for me. I needed two. (If anyone can get the old ones, I think they're meant to be better. I noticed on a recent install posted here that they had replaced the original one which was still working.)

gerry gill

KC_Jones said:

Just a homeowner here, but this is my take on it. The pressuretrol or vaporstat simply keeps the burner from running above a certain pressure. This is for some efficiency of the system as well as a safety feature. If you are trying to keep the pressure low that in reality is a venting issue. If you get the system tuned in really nicely you might never hit the cutout of that pressurtrol or the vaporstat. I put vaporstats on my new boiler, but I was replacing everything anyway and I needed control for my lo/hi fire setup. Instead of worrying about the cut out of the pressuretrol I would spend the money on other improvements to the system that will get you more bang for the buck venting, piping whatever else you can. The gauge is your friend use that as a tuning tool not the pressuretrol. Or you just save the 180 for future boiler replacement repiping whatever else. If you are trying to keep pressure low with the vaporstat all you will do is make the burner cycle on and off more often which isn't really as efficient and could possibly have zero ROI. Again just the opinion of another homeowner.

KC- you don't give yourself enough credit 'just a homeowner''--you know more about steam than you realize.

agurkas

Actually I spent the money couple weeks ago (I rarely treat myself to gadget anymore) on a IR camera attachment for my phone. Will do separate thread on some pictures I took. But you want to bet I am trashing 1/2" crap and redoing all the mains with 1 1/2" stuff.

KC_Jones

Thank you for the compliment! I will always consider myself a student you guys are the true experts.