OAS Heat Computer Online Access and Data Retrieval

For Steam Systems: In the middle of the winter, when it's cold outside, is it better to have a total runtime of 12 hours each day on high fire or to have a total runtime of 18 hours on low fire?

It depends on: 1. How "oversized" is the boiler?

2. How well insulated are the boiler and pipes?

3. What are the purge cycle losses?

Did you know? 1. Experts consider a boiler to be "properly sized" if it puts out 33.3% more Btus's per hour than the radiators are required to put out on the coldest design day. That's to allow for the pickup factor, which is an estimate of the energy flow that is needed to heat up the pipes when the system is turned on from a cold start. That's why, after the pipes are heated up, the firing rate of a modulating burner can be reduced if the boiler and pipes are well-insulated. Combining modulation control with thermostatic control can further reduce fuel consumption. 2. Whenever the burner is turned off, the hot, partially-burned gasses must be blown up the chimney and replaced with cold fresh air before it is safe to turn the burner on again. This is the purge cycle. 3 For one-pipe steam systems: Slow radiator vents are ususally recommended for systems that maintain a steady pressure. Fast radiator vents are usually recommended for systems that cycle on and off.

NOTE to Customers in NYC:
Section 501.6 of the new NYC Plumbing Code: "The temperature of water from tankless water heaters shall be a maximum of 140 deg F when intended for domestic uses."
Section 1002.2.2 of the new NYC Mechanical Code: "... a tempering valve shall be provided to temper the water supplied to the potable hot water distribution system to a temperature of 140 deg F or less."
New DEP Automatic Meter Reading (AMR) to be installed over a three year period starting in October for Brooklyn and Queens, in November for the Bronx and Manhattan and in 2009 for Staten Island. http://www.nyc.gov/html/dep/html/press_releases/08-17pr.shtml