Chimney "2-3-10" Rule

The chimney 2-3-10 rule states that a chimney must extend 3 feet from where it penetrated the roof and be at least 2 feet higher than anything within a 10 foot radius. Chimneys that do not meet these minimum requirements tend to experience poor drafting which is an obvious safety issue

Water Heater Recovery Rate

Most homeowners are simply unaware how important the "recovery rate" is when selecting a water heater. Recovery rate is defined as the number of gallons heated in 1 hour by 90°. In other words, if the incoming water is 50°, the recovery rate would equal how many gallons the appliance can heat to 140° (50°+90°) in 1 hour. Recovery rate and tank capacity are often very close in value for residential units (see photo & click to enlarge).

Tank capacity is somewhat misleading. I have inspected water heaters for 12 flats that are similar in size to a 50 or 75 gallon tank but the recovery rates are 200 gallons/hour! Many home owners believe bigger is better for this appliance and that is simply not true.

Tankless water heaters are coming but thats a completely different discussion. In the mean time, think "recovery rate" and a relatively small tank capacity.

Tank capacity is 38 gallons/hour (blue oval) and the recovery rate is 39.32 gallons/hour (red oval)