TWO-SPEED AC UNITS
This is the newest and best thing to hit the residential AC industry in my 45+ of being involved in it.
Because two speed systems run in low-speed 75% of the time, only costing you one half of the electric power 75% of the time. This relates to about 40% off your cooling bill. Combine that with higher efficiency furnace and the savings of another 15% in the heating mode which is normal.
This is payback for new equipment in as little as 2 to 3 years, if energy prices stay at their current rate. We both know that’s not going to happen, no energy costs are going down.
Wholesale air-conditioning equipment cost to AC dealers has increased 30 to 40% in the last three years, with government regulations to the new 13 seer minimum. Manufacturers are again, talking about price increases for 2009. High-efficiency air conditioning will never be lower to purchase than right now.
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A two speed unit can beat the North Texas cruel temperature. Let’s assume you have the average 3 ton house. Meaning that the A/C load for your house is a 3 ton load. If you were to buy a 4 ton two speed A/C unit, it will operate 75% of the time in low speed. That would be equal to about 2 ton unit, but also capable of 4 ton load in high-speed. So on the brutal 95° -105° days you would have an extra one ton of air conditioning capability.
On the low temperature days you would be operating in low speed at the 2 ton load, this will remove an excessive amount of relative humidity. Also operating at less amperage than a normal 3 ton unit. Number one saving you electric current, number two controlling the humidity in your home. 75° at 35% relative humidity feels a few degrees cooler than 75° at 70° relative humidity. This makes you feel so much more comfortable at the lower humidity setting.
If your house is properly insulated this little trick using a two speed unit gives you the capability of beating that average 20° differential that air-conditioning are designed for. The standards for air-conditioning are normally 18° to 20° on average as a differential temperature from outdoor ambient temperatures for a standard air-conditioner. If you upsizing to a 4 ton two speed you have an extra 33% above your load requirements. That extra 33% should be able to allow you to maintain a 30° differential on those brutal North Texas hot days.
The initial cost of a two speed unit is much higher than a standard unit, but gives you a considerable amount of flexibility along with energy savings 75% of the time. Being involved in air-conditioning for over 45 years I don’t know why someone didn’t come up with this sooner, including myself. This is sort of like having an air conditioner with a supercharger on it. We all owe a vote of thanks to the inventor of the two speed air-conditioning system.