three pressuretrols

eappleton

Could someone explain these three pressuretrol settings to me? We have one-pipe steam heat in a 24-unit coop building.

There are three pressuretrols with the following labels:

Open (cut in) - set at about 2 oz.
Mod (cut in) - set at just less than 2 oz. (switch to low-fire?)
HT (cut out) - set at just less than 2 oz. (Is this the same as the "heating is established" light in heat timer? Or is that based on the heat sensor? Or is this a differential with the Open pressuretrol?)

I have gotten some recommendations that I'm planning for the spring, after heating season. This includes adding vaporstats and a low pressure gauge. I'm will also be adding venting on the mains. In the meantime, I want to make sure that the boiler is running at the right pressure.

nicholas bonham-carter

These must be controlling some sort of multi-stage burner system. If the system is really going to be controlled properly, these should be vaporstats, capable of holding the pressure down in the range of a few ounces. With such low pressures, the venting must be generous.
This burner system is a wonderful thing for you to have, which many of us wish we had on our systems.--NBC

nicholas bonham-carter

Don't wait until spring to make these additions, as you can start saving the 30% on fuel, during this winter.--NBC

Fred

Those three Pressuretrols are set at just under 2 Pounds (not ounces) of pressure. One is Cut-Out. The other two are Cut-Ins. The Cut-Out must shut either the high and low stage burner off at anything over about 1.5 to 1.75 PSI.The Cut-ins seems like they should be staggered, one at maybe down around .5PSI for the high fire to kick in and something above that (maybe 1PSI to kick it to low fire) and both would allow the pressure to drop before the burner cuts back in. If the burner never shuts down on pressure, it obviously will work that way but the cut-in should be adjusted down unless, for some reason the staging doesn't work so they set both Cut-in Pressuretrols at the same setting to allow high fire to always kick in??? At least that's my guess.

eappleton

NBC,

So you would recommend adding main vents now, during the heating season? I'm feeling pretty confident about doing the work, with a friend's help, but I was a little worried about doing it during heating season in case there's a problem.

Should I also install the vaporstats this winter? If we don't have full venting yet, I don't be able to bring down the pressure to 2 oz., right?

There is a high-fire and a low-fire setting on the boiler. I'm assuming one of these pressuretrols controls the change, but I don't know which one.

Fred,

Wow! Thanks for pointing out that the pressuretrols are in PSI (of course) and not ounces. When I watch the pressure gauge during firing, it doesn't get above 2lbs. of pressure.

MarkS,

There is a sensor strapped to one of the returns. It's connected to the Heat Timer.

I don't know what MPC Platinum Control is. How would I find out if we have it?

Thanks all!

eappleton

Actually, I just remembered that the sensor was added a few years after the boiler was installed. Maybe it was installed to communicate with the Heat Timer originally, but now isn't used since there is a sensor?

eappleton

Got it. I'll check it out. Thanks for the help.

nicholas bonham-carter

New Years resolution for your group:
Get the air out quickly, with generous venting ASAP
Make the staged burner work ASAP.--NBC