Posted by Harold Kestenholz - Hydronic Network on September 28, 2001 at 21:14:30:
In Reply to: Re: Temperature limit control posted by Jason Peterson on September 28, 2001 at 14:02:47:
At a temperature drop of 20F, the flow rate is 1 gallon per minute per 10,000 btuh of boiler output. The methods used to derive this information and how to size the circulator are in the lessons at http://www.hydronic.net
Unless there has been a serious leak over time, a boiler does not take on fresh water as it does not 'use it up', so there is little likelihood of accumulated scale otherwise and scale removal is not necessary, in fact it may be harmful. If there is a drop of 20F or less, there is sufficient flow.