CV and VAV in hospital 1

[seanhkim]

I looked up CV and VAV choice in hospitals from va HVAC design guide as atlas06 suggested in eariler threads.

And I found that corridors, patient rooms, kitchen/dining room and treatment rooms are recommended to use VAV. But others are recommneded to use CV. The reason I assume is that others are highly functional rooms so that there may be a likelihood of leaking out of pollutants? What if VAV has a predictive capability and resume the pressure relationship before the room is in use, wouldn't it still have some risk? For example, before operating room is in use, VAV gives out more air and restore a positive pressure.

Is it common to turn on all the ventilator for 24hr, even if the room is not in use? Even CV is used in a functional room, can it be either turned off or reduced during unoccupancy unless that room is to be used for 24hrs?

 

[cme]

vav can be used in administration and kitchen

patient rooms are typically fan coil units with a dedicated makeup air unit for osa ventilation

treatment is cv reheat

pressure differential is established via the difference between supply and return/exhaust ...... 75 cfm in most cases

 

[atlas06]

cme,
I am sorry that you and I keep finding diagreements, but fan coil units are not allowed in most patient rooms with critical care, especially ICU's. If you look at the column talking about recirculation allowed/disallowed, you will notice that most patient rooms do not allow recirulation. The reference to recirculation is for Fan coil units and fin-tube radiation, convectors, and the likes. Anything that can build dust.

Pressure differntial is established using pressure differential monitoring stations.

You do not need a dedicated make-up air unit for OSA ventilation, at least not by AIA or IMC that I know of.

Some special spaces such "special procedure rooms/Angiography rooms" are provided with manual override switches to switch the VAV to max position (at 15 ACH) when in use, and resume normal operation when un-occupied.

 

[lilliput1]

A lot of old hospitals have fan coils in the patient room.
This was allowed provided a central AHU system with minimum 90% efficient filter provide the ventilation air / toilet exhaust makeup to each patient rooms. It would be very difficult to remove the fan coils and use all central air because additional mechanical rooms would be required to house new airhandling units. What is also interesting is when I did an energy simulation comparing fan coils with central system , it turned out that the fan coils used less energy. The central system uses a lot of reheat to maintain the minimum 6 total ACPH for patient rooms. Also less fan energy is required.

 

[atlas06]

Liliput
I don't know what allows recirc in those rooms but a FCU filter will not filter much. All you are filtering are 90% is 2 ACH, the remaining 10 ACH are usining swiss cheese filtration.
Won't fly around a frim with a serious healthcare practice.
You cannot renovate a space today using yesterday's technology, you need to tell your client that yes, he needs new mechnaical room, additional space and all. I don't see how several FCU's (each sized at 125% of BHP) can use less energy that a central fan when comparing apples to apples.

 

[lilliput1]

You can't close existing hospitals down to make the ideal renovation. So Code Officials have been practical and allowed use of fan coil provided the central ventilation air is filtered 90% efficient.

Fan coil use less fan energy because they only need about 1.2"wg wheras central systems need 6"wg.

 

[lilliput1]

The 2006 AIA Guidelines for Health Care Facility, General Hospitals page 118 Appendix A10.2.1.2(2)(2)(c) says noncentral air-handling systems (i.e., individual room units used for heating and cooling purposes such as fan-coil units, heat pump units, etc,). These units may be used as recirculating units only. All outdoor air requirements shall be met by a separate central air-handling system with proper filtration as noted in Table 2.1-3.

Table 2.1-3 requires 90% efficient (MERV-14) final filters for all areas for inpatient care.

Protective environment rooms however require HEPA final filters & no recirculation.

 

[atlas06]

I see that you've been doing some reading. Good to see someone who cares about what he does.
Suggest that you look into Dynamic air filters when using FCU's in hospitals, they can give you 85% filtration with 2" filters (long lasting and low pressure drop too - 1.5 years to change filters according to MFTR).