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Indirect DHW and solar panels
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Member Posts: 6,106
the cold water enters the first (solar) tank. It get preheated if the su is shining. If not it passes through to the boiler fired indirect.
Lets say you use a dual coil tank. One coil for the solar, the second for the boiler.
You get up in the morning and the tank is up to 140 degrees. you have little to no ability to collect any solar. Or you get up in the morning and shower or do dishes or clothes. The boiler fires to keep the "single tank" warm. Again you have a warm tank and no place to collect and store any solar energy.
this is why the dual tank offers better solar harvesting. And double the storage of course.
In my home I have a 65 gallon solar tank first online. i use a very small 32 gallon indirect connected to a Lochinvar Knight. This small tank on DHW priority (80,000 boiler)can pretty much keep up with a shower flow.
So now I have a small indirect which limits standby loss and has a very fast recovery, and the 65 gallons of solar heated water ready to go.
Since the first of the year I have taken 15 "solar only" showers in my shop. SDHW is my ONLY sourse in the shop.
hot rod
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Lets say you use a dual coil tank. One coil for the solar, the second for the boiler.
You get up in the morning and the tank is up to 140 degrees. you have little to no ability to collect any solar. Or you get up in the morning and shower or do dishes or clothes. The boiler fires to keep the "single tank" warm. Again you have a warm tank and no place to collect and store any solar energy.
this is why the dual tank offers better solar harvesting. And double the storage of course.
In my home I have a 65 gallon solar tank first online. i use a very small 32 gallon indirect connected to a Lochinvar Knight. This small tank on DHW priority (80,000 boiler)can pretty much keep up with a shower flow.
So now I have a small indirect which limits standby loss and has a very fast recovery, and the 65 gallons of solar heated water ready to go.
Since the first of the year I have taken 15 "solar only" showers in my shop. SDHW is my ONLY sourse in the shop.
hot rod
<A HREF="http://www.heatinghelp.com/getListed.cfm?id=144&Step=30">To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"</A>
0
Comments
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Indirect DHW and solar panels
I'm changing out an existing solar hot water heater with electric backup to an indirect water heater fired from the boiler. I know there are manufacturers out there that make tanks with two coils in them and am thinking of going that way.
If I wanted to use a MegaStor (or similar) but with an external heat exchanger for the closed loop solar and use the internal one for the boiler loop, can it be done?
What could use for controls and what piping considerations are there? (sketch would be really nice:-) )0 -
two tanks
would be better. One as the solar for preheat before it goes into the indirect. this way the solar has additional storage and the boiler doesn't warm the tank before the sun comes up
Vaughn makes a reasonably prices stone lined solar tank. They have a dual coil option, as well as electric element provisions.
www.vaughncorp.com
hot rod
To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"0 -
So help me understand
Water in tank A is heated by indirect boiler loop.
Water in tank B is heated by solar panels.
DHW is plumbed from A?
Normal cold water input to tank A is from solar tank B output?
If the incoming water is hot enough, no need for boiler loop to kick on. If not, boiler loop kicks on.
Advantage to this over two coils in one tank is what, just the additional storage?
Would there be any advantage to going with a larger tank with two coils?
Can my original approach even work?0 -
Solar Preheat to DHW
Hi Hot Rod,
Any Legionella issues with solar preheat to an indirect? How about a reverse indirect? We're considering options (besides a bigger boiler) to extend our reverse-indirect.
Thanks,
gf0 -
Any Legionella issues?
Hi Hot Rod,
Any Legionella issues with solar preheat to an indirect? How about a reverse indirect? We're considering options (besides a bigger boiler) to extend our reverse-indirect.
Thanks,
gf0 -
Any Legionella issues?
Hi Hot Rod,
Any Legionella issues with solar preheat to an indirect? How about a reverse indirect? We're considering alternatives to a bigger boiler to extend our reverse-indirect.
Thanks,
gf0
This discussion has been closed.
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