As we are under another heat advisory, François at #46 shares his experience on how he has been able to balance his AC across three floors and create a very comfortable home. Hope this can help those with heat issues on your top floors.
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By François Gagnon #46
By design our Units tend to exhibit excessive temperature differentials across our Units, vertically and level wise depending on the sun exposure. I would like to share my experience in balancing the AC for my Unit at 46 KL which may provide ideas to do your own balancing for your own Unit design particularities and latent/sensible heat loads around the day.
Here are my latest summer configuration (ONLY):
1) All basement and first floor air outlets valves closed and plugged with blue mechanic’s «Scott Towels» formed into a ball shape in the air duct just upstream of the outlet (watch for PK screws to avoid hand scratches !),
2) Basement door kept closed to turn the system into a three story rather than a four story building ventilation wise (helps reduce the vertical temperature gradient),
3) Thermostat (located on the second floor) set at 23 C,
4) All blinds kept shut during periods of direct sun exposure (to reduce radiation cooling load - sensible heat),
5) On the last floor (third floor), I have changed the air outlets from the valve style outlet to an air return style outlet (no valve and canted grill providing the lowest head loss); This substantially minimizes the head loss thus greatly improving the airflow of cold air to the last floor rooms, much needed as they are at the end of the line of a marginally designed system and where the cooling loads are the highest. This tends to maintain the West exposure bedroom temperatures to 25 C (26 C for a few hours at sunset). Here are pictures of the previous and later outlets:
The later outlet style can be procured at «Boone Plumbing & Heating Supply Inc.» at 1282 Algoma Rd (near Star Top Rd)
Further the last West bedroom has a ceiling fan which help cold air mixing and further improves comfort at night.
6) I adjust the valves of the second floor outlets adjacent to the windows/exterior walls such and only as to maintain comfort on that floor; The outlets away from the windows/exterior walls are all kept shut.
Results may vary from Units to Units and systems but at least this provides ideas to avoid going to expensive additional air condition capacity on the last floor using better balancing of the existing AC system.
7) As an option that I have not applied yet, there is still a possibility to slightly increase the furnace blower say by 10% to improve the flow of cold air to the last floor; Of course this setting could be maintained year round as it will not adversily affect in the heating mode.
8) Note that my AC Condensing and Evaporator Units are the original R22 system (over 16 years old) that has never been serviced and still exhibits plenty of capacity. So beware of AC salesman who only want to sell you a new system for alleged reduced capacity.
My 2 cents and hope this may give you ideas to balance your system to economically get more summer comfort.
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