There are several ways of overriding calculated Pipe and Duct diameters, some of which are explained below.
Scenario 1.
You have selected Copper pipe internally, but this is fed by an external MDPE communicating pipe. In the original “Pipe Selection Rules”, choose a suitable copper pipe as the default as this is the prevalent material used inside. Then, simply “Double Click” on the external copper pipe, which will present the “Override Calculation Defaults” options, click on the “Pipe Type” as shown below:
Then select the database entry required from the dropdown list (Blue MDPE).
Once recalculated, the system will behave exactly as intended using mixed pipe materials.
Scenario 2.
You are happy to use Ø10 Polybutelene (PB) pipe on a heating system with appropriate water treatment, but want to restrict the minimum pipe diameter to Ø15 on the HW Services in case of any scale build up and to ease pipe flushing. How is this best done?
Go directly to the Pipe database program and use the Edit Pipe Option. If you are editing sections of any database make sure that you have a copy of the one you intend to edit, and if necessary, name the original range as to its purpose e.g. “PB Heating” and name the Copy of the range to “PB HWS” or similar. Detail who and what has been done in the DBP Notes File for Quality Assurance purposes and save with a unique name, preferably using a project or Company based format.
Then in the “PB HWS” file, highlight the Ø10 row and use the delete key to remove. Therefore, regardless of how low the flow rate is calculated, a pipe smaller than Ø15 will never be selected if using this rule. Note also that you will not be able to override to “Ø10” as was done in scenario 1 above.
Scenario 3.
For gas, using copper pipe below Ø50 and steel pipe above can easily be automated to use different pipes according to a chosen range of parameters. Hopefully, once in the Pipe database program all will become evident. All you need to do is use an appropriate name and detail the various design choices, similar to those shown below. Oh, and don’t forget to save the database, and not just the Rule, with a unique name😉.
I hope you found this helpful and look forward to hearing from you.