Boiler pressure or short cycling

Howard_4

This morning was very cold in NJ. I noticed in the morning my steam boiler reached around 2 lbs of pressure and shut down for about a minute then kicked on again for another minute until tstat was satisfied. this happened 2-3 times. my tstat is set to heat up 4 degrees in the morning. it takes around 30-40 mins for the tstat to reach its temp. All my rads heat all the way across and are extemelly hot.my cutoffs are set to its lowest points.
is this normal pressure shutdown or considered short cycling.

mel rowe

Hi Howard. Since you haven't gotten any other replies yet, I'll give you a HO opinion, FWIW. What you described sounds very normal after a 4 degree setback overnight. I think what you are seeing is the rads all filling and the vents shutting off, but the stat hasn't yet seen the 4 degree increase. So the boiler keeps firing and the pressure will build until the Pressuretrol hits the cutoff and starts cycling. Obviously the latter part of this overall cycle isn't very efficient, but it takes some additional time for the system to pick up the 4 degree setback. This is why there is an ongoing debate about the benefit of the setback, but I think the conclusion has been that there is some overall gain in fuel efficiency versus just letting it run at a constant temperture.

frank_25

short cycles

If your times are correct, then you are most likely having a venting problem. Normally, after attaining 2PSI your boiler should hold that pressure for longer than one minute. Check the rad vents for slow leaks. After the rad is completely hot, and pressure is up, seek out the offending hardware and replace it. Chec the rad valves also. Sometimes a little 1/4 turn on the packing nut will do it right. BUT, don't forget the heat anticipator on an older style t'stat. If this is the first time you are having this problem, then the t'stat is probablly OK

Howard_4

Thnx for reply, sounds about right

T. McP.

Boiler Short Cycle

This is a Trianco Heat Maker, used to do domestic HW that is disconnected, its off alot as I heat with wood, when I turn it on now ,the control goes from purge to ignite to valve to flame as usual, after running for two minutes it shuts off and resarts again, it was heating up to about 125F then shut down but now it shuts down quicker. There is a boiler control and two other limit switches one on the tank for domestic I don't know where to start. I once desconnected internal pump and after rettling the coil from boiling the water something reset and it ran normal, thats not working now? Ideas please