which is better for the furnace?

Ken_40

We need to return to a few fundamental issue before answering. Things like:

1) A reasonably well maintained steam furnace [sic] heating system should not need a "drink" of water during modest heating weather more than once a month. Once every two months is not uncommon.

During the coldest weather, not more than once every two weeks.

If it does need more than that, there are system leaks and they need to be repaired or the boiler will be very short-lived!

2) All "standard," commonly encountered steam boilers will run properly at a few ounces (which will not even register on typical steam pressure gages) to an absolute maximum of 2 pounds, a pound and a half is better.

All "uncommon and exotic" steam systems (typically two-pipe forms), vapor steam, vapor vacuum type systems (typically in high-end larger homes formerly coal fired and circa 1800-1935 construction) should be running in the ounce to 16 oz range, with many variables, but so low a PSI gage wouldn't even register anything.

Hope that helps. Now, let us know what's next.

Herb Lang

gas fired steam heat

In continuing below-zero weather, which is better for the furnace - and to maintain heat in the house? Maintain the normal level of water and allow the low-water shutoff to function frequently or to add an additional quantity of water? How will I know when too much pressure is being created?