Offset Those Oil-Fired Water Heaters with SOLAR
Why oil-fired water heaters? In many parts of the country there are no local gas lines for residential distribution. In the Chesapeake Bay region where we operate, this issue is very common in the many river communities that are close to our world famous estuary. The reason for this is primarily because there are so many peninsulas that don’t offer the high density to justify pipeline expenses. In these areas, customers are forced to use other fuels like electricity, propane, and oil to heat their homes and domestic hot water. This article will focus on the oil-fired boilers that are common in this region as well as in the Northeast US.
Cost of Gas Alternatives: Many homes have heating boilers that run on fuel oil. These boilers have tremendous heating power and can recover loads quickly. They also tend to be relatively inefficient, dirty, and expensive to run. Many of these boilers also have an on-demand water heating feature that adequately satisfies the household’s water heating load without the need for a standby tank. This all sounds great except the price of home heating oil continues to climb with recent prices around $4/gallon on in our area. To put that in perspective, the equivalent price for natural gas on an energy density basis would be about $1.00/gallon. When oil users are paying 4 times the rate of those who have access to natural gas, they can hardly afford to be wasteful in how they operate their boilers.
Summertime Blues: Here’s the dirty little secret about that on-demand oil-fired water heater on your boiler. It is typically programmed to keep that big hunk of metal hot, all summer, waiting for you to call for hot water. So a premium for your oil (compared to gas) is not the only thing you are paying for. During summertime your air conditioner is competing with your heat-radiating oil-fired water heater. So, here’s the way I – a not-so-proud owner of an oil heater – circumnavigated this issue:
My Solution: I have solar photovoltaic (PV) on my home, but when I got into the solar business in 2008 the first thing I did was deploy solar water heating in my family’s home which allowed me to shut down our boiler for about half the year. We also did some other control modifications for efficiency. The first simple control is used to automatically reduce the boiler target temperature as the outside air temperature increases – for example, you don’t need 180 degree water to heat the house when its only 50 degrees outside. Secondly, we converted the boiler to “cold start”, so it no longer wastefully heats on standby when we have a big tank of solar-heated water waiting to be used. My family’s solar thermal system is slightly oversized (there are 3 forty square foot panels instead of 2) so that it could be integrated with our hydronic space heating system to give us a little space heating help from the sun. [See our recent blog on combi-systems (hyperlink)].
So that’s the good news. The GREAT news is that there has been absolutely no convenience impact on how we use hot water or space heating. The system has saved us about $800/year in oil expenses, the majority from offsetting our inefficient water heating, and the remainder from space heating.
Furthermore, the solar heating system is optimized in the summertime, all-but-negating the use of the oil-fired water heater. The air conditioner has to work far less without having that heat-radiating boiler inside the home – like most are.
People are learning that different homes and circumstances often can benefit substantially more than others when you consider various renewable or energy efficiency technologies. Oil fired water heaters are some of the sweetest low hanging fruit in solar. In fact, I joke with my residential oil supplier that we should team up so he can get out in front of this trend that is eating into his oil sales. He said, “no thanks – I’ll ride this as long as I can”.
If you forgot to make a new year’s resolution this year and you heat your home and your water with oil, then plant your flag! If you’ve got some solar exposure, you must commit to get a free solar thermal assessment in 2014 and stop pouring money and finite resources down the drain.