February 7, 2007: Heatec, Inc. has issued a revision to its Tec-Note 5-04-122, titled Setting Barksdale pressure switch used on Heatec thermal fluid heaters. The revision date is 1-31-07.
This revision to the Tec-Note fixes an error in Figure 5, which provides the procedure for determining settings for the Barksdale pressure differential switches. Unfortunately, the error results in a totally unusable setting for the low switch. The error is in line 8 of Figure 5:
ORIGINAL VERSION
8. Divide line 4 by line 2. This is the setting for Circuit No. 2, N.O. switch (low).
REVISED VERSION
8. Divide line 4 by 2. This is the setting for Circuit No. 2 switch (low).
Please notice that the revised version calls for dividing the value shown on line 4 by 2 — not by line 2 as indicated in the original version. In other words, the correct setting is half of the value shown on line 4.
This Tec-Note was originall published in May of 2004 and revised in November 2004 to fix a similar error in Figure 5.
Many of the manuals that we have furnished with HC and HCS heaters contain previous versions of the Tec-Note that contain the error. We have taken the following steps to remedy the error:
- We have corrected the manuals we have on hand as of Feb. 7, 2007 by blacking out the word line that appears before the 2.
- Future versions of the heater manual will include the revision of 1-31-07.
- We have updated the PDF and HTML versions of the Tec-Note on our website. (To download the PDF version or access the HTML version, click on the links above.)
We have been using the Barksdale switches on our construction heaters since 2003 and on our industrial heaters since 2002.
