Run Time Steam

M Ransley

First, many thanks to to this group of Pros, youve been alot of help. Ive been to alt.hvac and its alot different . It is like going into the wrong bar trying to be carefull to say "the right thing" getting laughed at, beat up and thrown out the door by the drunks in the back.
Well another question, My old Kewanee is probably oversized, and now runs 8 min cycles apx twice an hr at 20 outside. Maintaing a 2 degree spread at bldg ends, and 1/4 degree in controll apt. Am i correct that this is to short a cycle and is inneficient. What % efficency could or would I gain if any, at a 3 or 4 degree spread . Thanks again. Any Chgo pros out there.

Fred Harwood

Cycles

I assume you mean 8 minutes on, and 20 off, twice an hour. Depending upon your system, that could be too long a cycle. For example, a modern boiler and oil burner with chamber refractory can efficiently ru, say, 5 minutes on and 15 off 3 times an hour. The more frequent on times reduces mains reheating times and temperature differentials in the house. In this example, which you might be able to achieve, your run time per hour would be 15 minutes vs. 16, and more evenly heat the house.
Describe the size and design of your system (even post digital pictures), and The Wallies can help you fine-tune your system.

M Ransley

Thanks Fred Its an old kewanee. Bldg is apx 60 yrs, its a 14 unit 1 bedrooms reg size. I beleive the burner is a Smith 251000 btu [ a friend just read what he could on the label ] There are turbulators . Would an auto damper help ? I will have someone test the burner, stack temp etc soon . Any ideas to get optimal performance would be apreciated. Thanks group.

Fred Harwood

Run time

And what thermostat do you use, and where is it?

M Ransley

I had a honywell cronotherm that just broke, so now the round Honywell. It is on the first of 2 floors in the bldg middle

Drod

Interesting comment-got me thinking...

It sure would be nice if my boiler (single pipe steam) cycled more frequently and thus kept the house more evenly heated. Does that approach increase fuel (natural gas) consumption/costs? Do you think it's significant?