Looking At A Heating System As A Whole Not Just Pieces

I recently was out on a troubleshooting call to look at a heating system in one of the housing authorities in the Metro Boston Area.  The trouble they were having was excessive cycling of boilers, under heating of some apartments and daily boiler lockouts.  The housing authorities’ efforts to date had been focused solely on the boiler, which seems logical. If you don’t have enough heat it must be the boilers right?

The system’s main components where supplied by seven different manufacturers boilers, pumps, controls, VFD’s etc… add in the different Manufacturers Representatives and Wholesalers and the housing authority was stuck trying to piece together the solution.  As the head of facilities and I began to look at the system as a whole we found the following problems. 

1. The primary or building side of the system was operating at a 50° Delta T, since the heat emitters were all baseboard the units at the end weren’t getting hot enough water.
2. The secondary or boiler side was operating on a 10° Delta T and we were returning hotter water to the boilers than was coming back from the building.
3. In order to compensate for the lack of heat someone had set the BMS control to target 190° in the building loop.
4. The internal safeties kept the boilers from going above 185°, so they were limiting the boilers but the BMS control was sending a 10 VDC signal to the boilers, trying to drive them to 100% modulation.
5. Looking at the boiler cycling the units were banging on and off trying to obtain a target that was out of reach.  As they would be driven to an internal limit shut off, cool down and start again.

The solution we placed the VFD controls in hand and sped up the primary or building side pumps to create a 20° Delta T, this in turn created a 20° Delta T on the secondary or boiler side as our system was now balanced.  The BMS control was set back into a normal outdoor reset mode and began targeting a lower building water temperature.  Since the boilers could reach the target and we were actually taking the heat off the boilers the BMS began ramping down and turning off boilers.  By the time we left the building was being maintained by 1 of the 6 modules.

When I followed up the following week the report was no boiler lockouts and they actually had gotten some complaints about overheating for the first time so they were working with the balancer to find the happy medium in the system.  This case is a good example of what happens to us so many times when we get focused on what seems the logical source of our trouble only to find it somewhere unexpected.

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

Net Zero Homes more than just reducing utility bills.

A Net Zero Home is defined as a house that produces as much energy from renewable sources as it consumes.  This doesn’t mean a Net Zero Home won’t have an electric bill, they may purchase energy from the grid in the winter and sell it back in the summer but the end tally must be zero.  In 2006 the HERS Index or Home Energy Rating was created with 100 being the standard building and a Net Zero building receiving a rating of 0. A Net Zero home will have higher upfront costs, but lower monthly expenses, since the energy improvements are paid for in the initial building. 

In 2005 the average New England household spent $200.00 per month on utilities; at current interest rates on a 30 year mortgage a person spending $40,000 extra in upfront energy efficiency costs would spend an additional $190.00 per month on their mortgage payments.  So the net might be the same but the real savings is the 129 million BTU’s of energy the average New England home consumes annually, and no that wasn’t a typo.  And this is the real goal of Net Zero building not eliminate energy bills but eliminating off site energy consumption. 

The other part of the equation is making the upgrades not only efficient but economical. New Town Builders, In Colorado has built a model Net Zero home that costs just $26,900 more than their standard home offering.  However,  taking these costs into consideration in the mortgage process has been a challenge since there currently is no mechanism for evaluating the reduced utility bills into a borrower’s ability to afford the loan.  Soon there may be the Sensible Accounting to Value Energy Act would direct federal mortgage agencies to consider the reduction in energy costs in the loan qualification process. 

The SAVE Act is not just for Net Zero Homes,  if passed any energy efficiency improvements will be taken into consideration as long as they reduce the consumer’s utility bills.  The SAVE Act is expected to create 83,000 new jobs by 2020 and save over 1 billion dollars in energy use annually.  Consider a boiler replacement that reduces a home’s energy bill by 30%, in New England that could equate to a $500 per year savings.  And a person looking at a home with a high efficient boiler could qualify for mortgage that is $9,000.00 higher than a home without one. 

BYE BYE Incandescent Light Bulbs

The Lighting Energy Efficiency portion of the Energy Independence and Security Act began phasing in January 1, 2012 this effectively bans the manufacturing and importing of 100 watt incandescent light bulbs.  In 2013 the ban will eliminate the 75 watt with the 60 and 40 watt being eliminated in 2014.  What does this mean to the typical consumer?  They have 4 options; stockpile all the incandescent bulbs you will need, switch to Halogen bulbs, CFL (compact fluorescent light) or LED.  Will this affect your wallet?

Based on the life expectancy, purchase and annual operating cost the 4 options match up like this:

Bulb Type	Unit Cost	Total Cost to own & operate
Incandescent	$0.62	$12.50
Halogen	$1.75	$10.58
CFL	$1.66	$2.95
LED	$19.78	$2.50

Interesting how the LED bulb that cost almost as much as 32 incandescent bulbs will actual cost less to purchase and operate over the course of a year and with a $10.00 a year savings the payback is 2 years. And in terms of payback the CFL is indeed the winner with a 1.25 month payback.

 

How can this help the HVAC industry?  As the consumer becomes more aware of looking in terms of higher upfront costs being offset by energy savings, it should hopefully make the conversation easier when discussing High Efficiency Heating and Cooling equipment.