ERV or Central fan integrated ventilation best for hot humid climate?
I read an article by Martin Holladay who said ERV could actually make the situation worse in hot humid climate during those days when temp and humidity level are mild. That confused me. I would appreciate answers to questions about the best vent. system for a new build air tight house at approx. 2200 sq ft, in zone 3A below the red line. Heat pump HVAC system.
1. Why might an ERV make matters worse on mild days with low humidity?
2. Would a central fan integrated system be better or as good using the existing HVAC ducts to ventilate? Is that system a positive pressurized sys. with fresh air supply line cut into the HVAC ducts at the plenum next to air handler? Where is that system's exhaust line cut in?
3. Since the HVAC ducts move around 1200 cfm of air and only about 120 cfm of moving air is needed to provide good ventilation, would ventilating through the larger HVAC ductwork pose problems or energy waste because of the disparity between the ducts capacity and the actual amount of capacity needed?
4. The HVAC contractor said that running HVAC ducts can be problematic when a house has a lot of pot lights in ceiling (which our plan calls for), so, wouldn't it make it almost impossible for him to find room to run dedicated ventilation lines in addition to HVAC ducts? It seems that the only solution might be to use existing HVAC ducts to ventilate, if not the most efficient.
5. Can you use an ERV without dedicated ductwork? Having hard time picturing that system.
6. I guess either system will require a humidifier tied into the air handler with drain to outside, and a ECM with fan to run at low speed to handle moisture between the heating and cooling cycles of heat pump. Is that right?
7. I guess I also have to have a humidistat integrated with thermostat.. Does the humidistat control both the ECM fan and the humidifier?
8. Pros and cons about the two types of ventilation systems would be appreciated
9. Confused on whether ERV has any relevance regarding moisture removal in house if you also have a humidifier tied into system, and what is purpose of ECM fan running on slow speed between heat/cool cycles if you already have a dehumidifier working. I am definitely missing something. Please explain.
As you can tell, I am a lay person regarding HVAC and Ventilation, so answer accordingly. Thanks.
Posted May 23, 2014 6:42 PM ET
Edited May 23, 2014 7:08 PM ET
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