Integrating Solar DHW with Prestige 110


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Old 01-15-10, 11:00 AM
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Integrating Solar DHW with Prestige 110

I have a Prestige 110 boiler. It has an internal tank that looks to be 5 gallons or so. I have gleaned that not all 110s have this.

I'm interested in the possibility of integrating a solar system, probably evacuated tube, with this, but I'm not clear on how that would work. Most systems seem to use an electric water heater as the secondary source.

If I were to plumb the output of the solar storage tank into the cold water inlet of the boiler, would that work? I assume that the boiler pushes out what's in the tank, and then goes into a heat-on-demand mode. Would the boiler recognize that the incoming water is already hot and not fire?

Thanks
 
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Old 01-15-10, 05:57 PM
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If it's the Prestige Excellence, that's a 14 gal mini-indirect.

To go solar, you'll need a storage tank sized to the collectors. Typically 1-1.5 gal for each square foot of collector.

Evac tubes are actually not that much better (if at all) than flat plates over the long haul in many applications. And depending on how you want to set up the system, evac tubes might not even be an option. For example, if you want to do a drainback system, there are only a couple evac tube brands that will accommodate that. Otherwise you're looking at pressurized glycol loop.

A simple system could look like mine, which consists of

80 sq ft of flat plate collectors
119 gal storage tank (an HTP SSU-119)
pressurized glycol, pump, exp tank
control (differential or dT)

Domestic cold feed goes into the solar tank. Solar tank hot out goes through an anti-scald tempering valve, then a 3-way valve that allows it to go direct to taps (April-Oct) or to cold input to boiler indirect for topping off (Nov-Mar, and prolonged cloudy stretches whenever).

There are some really good resources for solar at the Caleffi site. Particularly this one:

http://www.caleffi.us/en_US/caleffi/...onics_3_us.pdf
 
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Old 01-15-10, 06:01 PM
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Originally Posted by ereuter
If I were to plumb the output of the solar storage tank into the cold water inlet of the boiler, would that work? I assume that the boiler pushes out what's in the tank, and then goes into a heat-on-demand mode. Would the boiler recognize that the incoming water is already hot and not fire?
Yes and yes.

Minor point. The boiler doesn't push out what's in the tank, the incoming domestic cold replaces the hot lost by use at the taps via the pressure in the domestic system.
 
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Old 01-17-10, 08:48 PM
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Originally Posted by xiphias
If it's the Prestige Excellence, that's a 14 gal mini-indirect.

To go solar, you'll need a storage tank sized to the collectors. Typically 1-1.5 gal for each square foot of collector.

Evac tubes are actually not that much better (if at all) than flat plates over the long haul in many applications. And depending on how you want to set up the system, evac tubes might not even be an option. For example, if you want to do a drainback system, there are only a couple evac tube brands that will accommodate that. Otherwise you're looking at pressurized glycol loop.

A simple system could look like mine, which consists of

80 sq ft of flat plate collectors
119 gal storage tank (an HTP SSU-119)
pressurized glycol, pump, exp tank
control (differential or dT)

Domestic cold feed goes into the solar tank. Solar tank hot out goes through an anti-scald tempering valve, then a 3-way valve that allows it to go direct to taps (April-Oct) or to cold input to boiler indirect for topping off (Nov-Mar, and prolonged cloudy stretches whenever).

There are some really good resources for solar at the Caleffi site. Particularly this one:

http://www.caleffi.us/en_US/caleffi/...onics_3_us.pdf
Gonna have to disagree on the evacuated tubes comment.
I love them, I make over 120 degree water when it sunny and -4 F outside. I do understand the differences and the pros and cons. I do agree each type has it's own advantages and disadvantages
 
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Old 01-18-10, 05:39 AM
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Originally Posted by TOHeating
Gonna have to disagree on the evacuated tubes comment.
I love them, I make over 120 degree water when it sunny and -4 F outside. I do understand the differences and the pros and cons. I do agree each type has it's own advantages and disadvantages
I think we just said the same thing. It depends on the application, system design, brand, etc.
 
 

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