New Heating and Hot Water
jklump
| Posted in Mechanicals on
I want to get rid of my very inefficent electric hot water and heat. Would you reccomend a propane gas furnace with indirect HW heater with a solar thermal preheat? Other ideas? House is in the cape. This woudl include runnign all new hydronic piping so I am winderign if there is better way to heat.
Thanks for any help.
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Replies
Why do you consider the electric to be inefficient?
@Julie, I generally think your idea is great. Running piping isn't all that bad, it's easier than ducts! The one thing I'm wondering about though is the fuel, because here in Vermont, heating with propane is the only thing that's more expensive than electric, though the are about the same. Look at the table at the bottom of the second page of this file, the $/MMBtu is a clear way to compare fuels that are sold in different units (ton, gallon, CCF, etc). If your prices are different, or you have access to more affordable fuels, that might be a better choice. Converting to a hydronic system so you can use solar preheating will lower you costs regardless of the fuel.
@David, probably because it's just about the most expensive way to heat, the efficiency including losses at the power plant and in transmission is about 25% compared to 80%+ in residential boilers, and because using high grade energy like electricity for low grade purposes like heat is wasteful because the primary energy that was used to make the electricity could have been used directly for heat much more efficiently.
Damon, it's different everywhere you go. Here, electric is mostly hydro and it's relatively cheap, whereas some folks out there are getting coal-fired electricity, which makes for a different equation on a couple of levels. Also, I don't understand what you mean by "high grade energy". Almost none of us are using any fuel at all without there being significant inefficiencies in production, transmission, etc., as well as externalities that are not priced into the product. In some cases I would rather use electricity than natural gas or propane (i.e. here where I live in the NW, and where I move customers from propane to electric all the time), and in other cases I would rather use NG than electric, such as where coal is dominant.
Obviously, it's a dismal and often confusing picture, with shale gas, tar sands oil, and other products being added to our already ugly mix of choices.
In any case, I wanted to hear what the OP meant by "inefficient", as I'm not sure if she meant cost or something else. More info on the system in place would be useful.
Here is an option that I am looking at. http://www.htproducts.com/versa-hydro-solar.html
This is not addressing the entire question but I think the conversation has veered anyway....The most efficient way to heat water, especially if you already have an electric tank is with a heat pump hot water system. More efficient that gas and better ROI than solar...
Richard, I agree in part. A heat pump water heater will provide low-cost water heating assuming that (a) it isn't robbing heat from the house that you already paid for, and (b) the unit lasts a very long time. In many places, water quality issues cause tanks to fail fairly quickly (hence the typical 6 year warranty on standard units), and if you paid ~$1000 for a heat pump unit vs. ~$300 for a standard unit, you will be taking a hit there. As far as ROI vs. solar, that assumes some payback period, doesn't it? What period are you assuming?
Thanks for everyone's input. Natural gas is not available and teh current equipment is ~30 years old. I am open to heating and hot water using elelctricity if it is more efficent than propane. There are some good incentives for solar thermal so I thought that woudl be a good option as a preheat for the hot water. We are considering 94 plus Buderus boiler and Buderus Indirect hot water.
Thanks again.
I'd like to piggyback a semi-related question/comment in here:
What if you install a heat pump water heater inside the conditioned space of a house that uses a very efficient heat pump for heating/cooling (ground source heat pump or air source mini-split)? During the winter it does rob heat from the house, but that heat was generated at 4:1 COP, plus free passive solar. At worst the HPWH equals the efficiency of a simple electric water heater. During the summer the unit cools the air around it, which works out well whether you run A/C or not.
And, suppose the heat pump water heater goes next to a condensing dryer. The dryer will generate heat that the water heater can use, and in turn the water heater will help supply the dryer with cooler air that it needs to keep condensing.
What I've read about HPWH models currently available is that they don't work well at all when the ambient temperature drops below the 60's. They could stay in their comfort zone if kept indoors. If kept in a closet or small room with a condensing dryer the ambient temp could be in the 80's, while the dryer operates.
This may not be an ideal solution but there aren't that many options for efficient heating without gas. Solar hot water can be quite expensive including a special tank with a heat exchanger.