Author Topic: Maximal working temperature of a Solar hot water system?  (Read 2676 times)

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bernard

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Maximal working temperature of a Solar hot water system?
« on: June 18, 2015, 07:09:38 AM »
Hello,

I was wondering if somebody could explain to me what maximal working temperature of solar hot water system is? On a lot of place on the web, I found this value to be between 90 to 95 deg C (200 to 203 deg F)

I assume each shw system component (tank, pipes, collector, valves...) has its own maximal working temperature.
So is the maximal working temperature of the shw system, basically the lowest maximal working temperature among all shw system components?

Thank you for the reply.

Kind regards,
Bernard

DanG

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Re: Maximal working temperature of a Solar hot water system?
« Reply #1 on: June 18, 2015, 10:09:18 AM »
When solar thermal hot water heaters stagnate, temperatures can exceed 300F (149C). Having the ability to dodge/shed dangerous heat is the whole schnitzel.

http://www.chandlerdesignbuild.com/files/waterHeatersLatest.pdf <--- has some good tips and tricks.

Running 200F is borderline dangerous for small scale hobbyist heaters - hot spots flashing into steam for raw water systems is very bad with over-pressuring and corrosion plus mineral build up.

With treated water closed loops keeping boiler grade gylcols w/ their additive packages separate from potable water is another layer of complexity that becomes expensive.

An optimum temperature to attempt might be whatever it takes for effective legionnaires control if it ever can contaminate potable water...  But running just under steam producing temperatures might be foolish without a pre-engineered system...



David HK

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Re: Maximal working temperature of a Solar hot water system?
« Reply #2 on: June 19, 2015, 05:04:31 PM »
Hello,

About 10 years ago I posted on this website the building details of my solar hot water system.

Its still going and works well.

It is directly connected to the mains water supply and the usual pressure floats around 60 psi.

As this is a pressurised system the true boiling point is around 144 Celsius (292 F).

The following photographs give you an idea of its size etc.

The unit is also equipped with sensors so that I can record temperatures throughout the day directly into an Excel file.

David in HK