Outdoor Reset v Setback Thermostats

For years the Department of Energy has promoted the programmable setback thermostat as a means of saving energy.  In 2005 several field studies by the Department of Energy determined that in most cases the introduction of a programmable thermostat didn’t conserve energy and in some cases actually increased usage.  The biggest problem they found was that the thermostats either were not programmed correctly or in some cases were not programmed  at all.

Now along comes outdoor reset which adjusts the water temperature based on the outdoor temperature in an attempt to match the heat loss.  When coupled with a programmable thermostat it can be a recipe for customer discomfort.  As the water temperature is reduced the BTU’s into the space are reduced as well since the heat loss is less, the goal is to only put into the space what is leaving.  However if a setback thermostat is in play and not only are we trying to match the heat loss but raise the space temperature 10 degrees it could take a few hours.  To combat this many thermostat manufacturers have added to logic in their thermostat to learn a systems response time and come on a few hours earlier.

If a customer is setting their thermostat back at night to save energy they are better off to just set it and forget it and allow outdoor reset to manage the system.  The long run time to heat the house back up will offset any energy savings.

Or take a look at the next step in the energy saving evolution indoor feedback, with indoor feedback a system can tailor the water temperature to the actual heat loss, synchronize the zones to eliminate short cycling and ramp the water temperature up for those times when it has been setback or turned off.

Article by George Carey about Indoor feedback
Tekmar House Controls

Energy Consumption in America?

Keeping people comfortable in their homes is what the HVAC industry is all about, when energy was cheap grossly oversized boilers operating at 70% and 8 SEER air conditioning systems with Ozone depleting refrigerants where the norm.  As energy prices increased higher efficiencies and SEER ratings have begun to take over the market.  However, the United States still wastes approximately 58% of its total energy consumption, according to the US Department of Energy.  In 2012 the United States is forecast to consume 99.46 Quadrillion [i]BTU’s of energy at an estimated overall efficiency of 42%.

The answer to energy waste in the US is not that simple since people still want to be comfortable in the homes, have plentiful hot water at the disposal and drive their car to the mall.  A lot has been said about the emerging renewable energy market yet it will produce a little over 2% of all the energy consumed in 2012. 

While we have a long way to go to eliminate the energy wasted in this country there are a few changes we all can make that can have a big impact on saving energy with little or no impact on comfort. 

1. Reduce the thermostat setting on your water heater by 10° to save between 3-5%.   While there is a very slight risk of promoting legionellae bacteria when hot water tanks are maintained at 120 degrees, this level is still considered safe for the majority of the population.[ii]
2. If you have an Indirect Water Heater lower your boiler setpoint by 10° this week if you still have sufficient hot water lower it again.
3. If you have an oil furnace check your nozzle size, many of these units have adjustable firing rates.  When my wife and I lived in Maine we changed the 1.00GPH nozzle for a .65GPH nozzle, the house heated fine the unit was much quieter and we reduced our oil consumption by 20%.
4. When setting up the outdoor reset curve on a hydronic system lower the top and bottom end down 10° below where you normally do and explain the benefits to your customer.
5. If you have a boiler without a reset control that is set to 180° drop the setting to 170°
6. If you haven’t already done so take Masssave up on their offer to audit your house and give you free energy efficient light bulbs, money toward insulating and weather responsive controls.
7. And if you’re a contractor next time you offer a high efficiency heating system don’t forget to offer an Indoor feedback system, which is basically automatic outdoor reset, that Masssave will pay about ½ the cost of the control.

For 2012 lets all find a way to be part of the energy consumption solution in America.

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[i] U.S. Energy Information Administration

[ii] U.S. Department of Energy

Something for The A/C folks.

The Air-Conditioning, Heating, and Refrigeration Institute (AHRI) has recently launched a new website to provide information and hopefully reduce confusion regarding the phaseout of HCFC refrigerants, to enable decision making and to insure compliance with refrigerant laws and regulations.
The website is located at http://www.phaseoutfacts.org/