Pressuretrol setting

mdmhh256

After living with my (mostly) okay steam system for 40 years I came across Dan's "Lost Art" book and realized things could be better.
I have 21200 DOE Utica boiler connected to 450 EDR worth of radiator (mostly column, a couple of tube). Boiler was installed in 1990 when the previous one rusted out. I believe the Installer swapped in an equivalent model without doing any sizing calcs. Seems oversized as there is evidence of radiators being removed over the years.
Early on I found that the boiler would chug away in the morning when it recovered from setback (about 4 degrees). I somewhat got around this by using a programmable thermostat to bring it up in 2 steps (2 degrees initially and then 2 degrees an hour or so later).
Now that I know about pressuretrols I have lowered the setting to 0.5/1.5 and I think it is better. The 0-30 PSI gauge seemed pretty useless so I swapped it out for a 0-5 PSI gauge I came across (is that bad?). Now I can see the boiler cutting out/in on pressure.
Question is..... When it cuts out it only takes a minute or so for pressure to drop to the cutin, and then just a few minutes to get back up to cut-out... Does that sound right (and how, if at all, is that related to short cycling). Thanks.....

Waher

By code you need a 0-30 PSI gauge on the boiler at all times. You should have both gauges on your boiler.

If your boiler is short cycling on pressure in a matter of minutes than something is wrong. Either your boiler is massively oversized, your air venting is massively undersized, or something is wrong with your piping to the point it is getting clogged with condensate. Can you post some photos of your boiler?

Jamie Hall

It's normal -- for an oversized boiler.

EdTheHeaterMan

what is a " 21200 DOE Utica boiler"? Is it oil or gas fired? What is the model number or a picture of the rating plate that shows the Input, DOE output and I=B=R net in both BTU and Sq Ft.

reggi

Cutting your pressuretrol back was a good start but setbacks aren't my cup of tea personally though depending on your setup a small one may work... which begs the question...Is the boiler cutting out and restarting coming out of setback(s) where it's trying to make up 2° and then another 2° instead of maintaining a set temperature ?
In other words does it usually run the same irregardless of the setbacks?

EBEBRATT-Ed

If the boiler is oversized, it will short cycle. Not a lot you can do although with a professional and combustion test equipment you may be able to down fire it slightly. Also maximize you main venting as well