Appendix A: Frequently Asked Questions
Q: Why are some actions on the Monodraught HTM® navigator greyed out?
A: If the action is greyed out but also has a small padlock icon shown on its checkbox ( ), this indicates that you do not have a suitable view license to carry out that action. See Requirements for using HTM in the Virtual Environment for more details on the licenses required to use the HTM integration within the VE.
If the padlock is not displayed but the action remains greyed out, this means the action requires you to tick one or more previous actions (therefore acknowledging that you have performed them) before you can carry out the action.
Q: I have a number of rooms contained in one HTM unit group. I want one of these rooms to use slightly different HTM properties (e.g. operation profile) to the others – how can I do this?
A: All rooms assigned to an HTM unit group will share the same HTM properties. If you want one or more of the rooms to use tweaked values, you must create a duplicate of the unit group, tweak the relevant values in that duplicate group, then re-assign the appropriate rooms to that duplicate group instead. See Duplicating Unit Groups for guidance on how to achieve this.
Q: Can I have different HTM units within the one room (e.g. an HTM FS unit and an HTM F unit)?
A: This is not currently possible – for modelling within the VE, a room can only be assigned to a single HTM unit group (and therefore a single unit type). It is advisable that is only done for rooms which can be separated into two independent rooms with a folding partition or such like. In this instance, it is recommended that the rooms are modelled as two separate rooms.
Q: Do I need to use the Monodraught HTM® navigator workflow to apply HTM to my model, or can I do it myself?
A: The navigator acts as a guide to best-practice and offers the most straightforward workflow for applying HTM to your model. However, you can import HTM components from the source library, assign rooms to the unit groups, set which openings are used by the HTM units and so on without using the navigator. The only step that specifically requires the use of the navigator is the Apply HTM ® assignments to ApacheHVAC system files action, used to add the HTM assignments to an HVAC network file prior to simulation. It is recommended that you follow the navigator for convenience and practicality, unless you have a specific situation where you need to do otherwise.
Q: I have an external louvre that is a different size to those specified for the HTM system. Can I still use this or does this need to be changed?
A: The Monodraught HTM has the flexibility of working with slightly different sized louvres. We recommend that the louvre for the HTM F has a minimum area of 0.45m² and the HTM FS has a minimum area of 0.27m². In reality, a transition/spigot would be manufactured to match the louvre size and provide the connection to the HTM system. However, it is recommended that the louvre proportions are designed to match the HTM as closely as possible.
Q: How do I utilize a cross ventilation strategy within a room assigned with HTM systems?
A: Assign any additional external opening windows and/or louvres, as detailed within the earlier sections of this guide, either on the same elevation that the HTM units will be located, or to the opposite elevation of the room. For exhaust path that will be into another room, a door with a suitable air transfer profile will need to be created and assigned
Q: I would like to locate the HTM system on an internal wall to draw air in from a central atrium, but the Navigator only allows the system to be assigned to an external façade.
A: The HTM system is designed to operate utilizing external air and should only be located on an external façade of a room. The design and comprehensive control strategy of the systems has been developed to allow wintertime air mixing/tempering to minimize any cold drafts and maintain a suitable minimum temperature of the supply air.
Q: Does the simulation of HTM units take account of the optional heating coil for real-world HTM units?
A: Although the prototype HVAC networks used in the VE to simulate HTM include a heater coil component, it is switched off by default – this is because Monodraught have indicated that it is not an option that is generally specified. Although not currently exposed through the VE user interface for HTM, you can modify an ASP in which you have applied HTM pre-simulation to account for the heating coil in the following manner:
- Follow the navigator in the normal manner through to the Apply HTM® assignments to ApacheHVAC system files action, applying to either an existing or new .ASP file.
- Switch to the ApacheHVAC module and open the .asp file
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Open ApPro using the button on the toolbar.
- Select Weekly Profiles from the Pattern drop-down, then select the HTM In-Use Hours profile.
- Click the Copy button, then click Save before exiting ApPro.
- In the HVAC Components browser, navigate to HVAC Network->Airside->Controllers->Independent controllers with sensors and double-click on HTM Heater Battery Control - <9DegC. This controller is located immediately above the Heating Coil within an HTM F/FS prototype network:
- Change the Time Switch Profile for the controller to the HTM In-Use Hours profile copied above (in place of Off Continuously).
- Repeat for any other HTM F/FS prototype networks in the .asp.
- Save the .ASP file
- Return to ModelIT and continue with the navigator steps to simulate (ensuring that the .ASP you’ve been editing is selected for use when simulating).
These steps must be repeated if the Apply HTM® assignments to ApacheHVAC system files action is subsequently reapplied on a .ASP file you had previously modified.
