chuck172 said:
HX is an abbreviation for Heat eXchanger.
A way to heat your storage tank from hot-water solar panels.
Joe
Justification??
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HX is an abbreviation for Heat eXchanger.
A way to heat your storage tank from hot-water solar panels.
Joe
Please elaborate master! Would this be an evacuated tube? Anything else work? What is the temp boost? How many tubes are necesssary for efficient heating? Is this going to work when its 0* outside? glycol? water? Copper HX? thanks
sweetheat said:
The collector can be an evacuated tube system, a flat panel, or even the modified pool-heater-type that nofossil uses. Lots of options with solar.
The output of the collector can be anything, depending on the size of the install. A single 2-square-meter panel, or a football field.
The output of evacuated tubes is mostly relative to the solar energy level, not the outdoor temperature (the high insulating value is the benefit of evacuated tubes). There is some loss of efficiency as the temperature drops, but if the piping and manifold are insulated well, it's mostly an issue of available light.
I use Tyfocor and similar heat transfer fluids. Pricey, but the fluid content of a system (particularly evacuated tubes) is small, and it's very high quality antifreeze.
Heat exchangers are typically copper or stainless steel. Plastics are not allowed for most solar systems, since the temperature can get up to 450-degrees within the heat transfer fluid in some cases.
Joe
what's an average cost for evacuated tube vs flat panel? And average heat gain for each? 450 degrees is very hot, can all this be stored in the storage tank? At that temp you would not need the boiler. correct?
sweetheat said:
Cost and performance vary greatly depending on the specifics of the install. I don't think any professional contractor can give a price on a job, sight-unseen.
sweetheat said:
The water can be very hot, but there is limited flow from the panel, so when it dilutes in with the water in the tank, the average temperature is reasonable.
Solar cannot reasonably replace a boiler for most houses, because the time of most heat demand is when you have the least sun (middle of winter). It's possible for some very-highly-insulated houses, but the cost is high, and even then there are likely to be a few days in the dead of winter that backup heat is needed.
Joe
so what do you recommend? tube or flat panel? which gives the best performance vs cost? will solar be sufficiant in spring/summer/fall? with boiler use in winter? this is justification in itself chuck172
sweetheat said:
Flat panels are less expensive. Evacuated tubes are more expensive, but higher-performance. The best cost/benefit balance will vary depending on the particular job.
sweetheat said:
It depends upon the house. Typically, we only size solar for domestic hot water, in this area, given the cost of trying to achieve any space heating with a solar system. Sometimes we may make the collector a little on the large side, and let it provide a small amount og extra heat to the house, if the customer wants. To actually provide primary heating is prohibitively expensive on almost any real-world house.
Solar is mostly still a "I want to go solar" deal, rather than a way to save money. It can provide a return on investment, but there are a lot of other technologies that provide a more effective return.
Joe
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