Steam System - Short Cycling

Dan_29

I have the same WMc boiler (EG 55 PIDN) and Honeywell VisionPro thermostat.

My system responds well in Wakeup time boiler run with a 62-65 degree increase and upon my Return setting in the evening a 3 degree increase in temperature also. It does not respond as well with a one degree temperature drop during my up temperature cycle.(I hear the boiler running but not all radiators heat up.)

I read a reveiw of the VisionPro in e-pinions which criticised the fixed one degree diffenrential or less which makes the unit call for heat. You might check you installation manual (page 32) to make sure you set it at installer setup number 0240 setting #1 for "gas or oil steam, gas or oil gravity", as opposed to the many other settings which will cycle many more times per hour as forced hot air does.

It has not been cold out recently (in Boston) and my house is well insulated therefore, my thermostat has only called for heat every two or three hours. Your system seems to be calling for heat as often as a forced hot air furnace would. Doublecheck for correct installer setup and consider how well is your thermostat location insulated and draft proofed.

I had my system installed last May, which means no test for long cold periods, yet. I am considering installing some Gorton air eliminator vents in my long main runs (to the third floor) to reduce the effect of any potential shortcycling. Good luck!

Dan

Rich Dufort

Steam System - Short Cycling

I have a 18 month old Weil-McLain PEG-45-PIDN steam boiler. Thermostat is Honeywell VisionPro TH800. Thermostat was recently swapped under warranty but the problem was not resolved.

During the day, the thermostat is set at 65 degrees. Outside temperature is 40-50 range. System runs normally to heat the house from 55 during the morning. However, during the day the boiler will short cycle every 20-30 minutes running for about 3-4 minutes. This is enough to warm one radiator but the others stay cold most of the day. The temperature on the thermostat never drops below 65 degrees. My expectation is that the thermostat should let the house cool down a few degrees, run the boiler to warm it all up, and then shut down for a while. Am I missing something or is the thermostat functioning correctly?

Thanks for the help.

Steamhead (in transit)

Cycles per hour

Is the number of cycles per hour set properly ?

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Ken Field

What is the problem?

The whole job of the thermostat is to keep the room at the setpoint. I get complaints from people who say their thermostat lets the room drop a few degrees before it turns the system on. The new thermostat is very accurate and when it detects a degree of temp drop, I believe it will try to get the temp back up. You may have a setting in the user setup that allows a less aggressive control but I'm not positive. I think you have to decide which is more important, room temp control or run pattern. I doubt you can have both the way you want. Especially as it gets colder outside, if it ever does.

Ken

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