Equipment Heat Gains / Diversity During Winter

[MMAnd]

Hi, I was wondering how you manage the following general situation:

Say you have an electrical equipment room, which when the equipment is running, the sensible heat gains are X. I want to heat / cool the room via VRF systems.

The equipment rooms need to be maintained at a temperature range.

Generally, I would expect this equipment to run all the time. My question is, would you typically simulate (i.e. thermal modelling) the room for the winter condition, with the equipment off. This will show much greater heat loss than will normally occur. What is accepted practice in this regard?

My feeling is that for conditions where electrical rooms' equipment is off during the winter months, the room temperature could be managed by the user switching on some plug-in electric heaters, for example.

Thanks

 

[LittleInch]

Why not make your system double acting as a chiller and heater?

Just set min temp to say 16C and max to say 24C and let the system work out whether to heat or cool?

Normally you look at both extremes, so max cooling when internal heat and ambient temp high and max heat when ambient temp low.

It's called design.

 

[HVAC-Novice]

Talk to the owner about what their expectation is and what they think when the equipment runs. if there is water, you need to provide heating for at least freeze protection.
What about if the equipment is down for repair?

Do NOT rely on space heaters they need to plug in. Those are a fire hazard and should not operate unattended. I doubt the client was hiring a mechanical designer so they have to drag space heaters around....

 

[3DDave]

As a pedantic observation, when the electrical equipment is off there is less heat loss. The temperature tends to equalize and heat flow falls.

Does it get cold if it is cold outside? Certainly. But the first step is a correct mental model of the thermal situation.

I would examine the insulation part of the installation as a way to prevent heat from the rest of the building escaping through the electrical equipment room.

Also seconded on portable heaters. There are properly installed and safe heaters available.

 

[Antifed]

I'd been taught to account for the extremes (i.e., assume the equipment load is not there to help you with heating). In reality, you heating mode may never turn on, but it is there if you need it.

 

[Snickster]

Here is a performance specification I wrote for an electrical room for an HVAC design subcontractor to design. We used a high diversity factor (indicated in spec) and specified heat pump system.

 

[Snickster]

Here is general specification for ductless heat pump unit specified in the same specification.