Solar hot water

[David HK]

Solar hot water.

Today Tuesday 16th August 2011 my solar hot water reached 102.4 degrees Celsius.

Not uncommon at this time of year as it means that the sky-atmosphere is becoming less polluted. Last week I had two days when the system recorded 99.1 degrees Celsius.

My system is what the Americans seem to call a batch water heater and it is pressurised to local water supply pressure which is around 4 Bar or about 64 psi.

Interesting as an observation and may be useful information to newcomers to the forum.

David in Hong Kong

[PaulJ]

 Good stuff, I love "free" hot water.

 Do you have a PTR valve or other safety features on this system?
 Things could get interesting at these temps if you lost the supply pressure.

 My system stops heating at 65C (a valve stops flow to the panels), if that fails the PTR valve dumps water at 80C.

 Cheers,
 Paul.

[cujet]

Wow, that's incredibly hot. Can you post pics or design details on your batch heater?

[David HK]

Today - Wednesday 24th August 2011 my solar batch water heater reached 106.2 Celsius - the highest ever seem since it went into operation more than five years ago. Boiling point is around 147 Celsius.

For the information of anyone interested I have made up an Excel spread sheet that shows comparative values between water pressure and temperature. Pressure is in Bar. PSI, Kilo pascals, Metres head of water, Mercury mmHG and Celsius and Fahrenheit.

If you want a copy please PM me.

David on Hong Kong

[David HK]

Today is 12rh September 2011 and my solar hot water heater made it to 107.2 Celsius.

Its also the eve of the mid Autumn Festival in the Lunar calendar.

Much hot water about the place.

David in HK

[David HK]

Today is the 13th September 2011 and my solar hot water reached 112 degrees Celsius. Never have I seen this before in some seven years of operation.

Am getting worried! Far too hot.

Will visit local firms tomorrow for Temperature and Pressure relief valve. The existing one is only pressure and I am no longer trusting it and guess it may be "stuck".

Boom!

David in Hong Kong

[DanG]

I've got a couple of $50 salvage panels stored away (Solarhart) that can be damaged by mineral build-up from plain water flashing to steam when the systems drain-backs or system shuts off. 

Stagnation is when heat storage tank is satisfied and collector temperatures rising above 95°C and is generally to be avoided since the temps can keep climbing even to 150 - 300°C that will break down glycol fluids and damage components.

I've seen a thermostatic valve plumbed in near the panels that bypasses the normal circuit loop to allow the collector panels to dump excess heat in radiator loops of pipe using just convection flow to keep peak temperatures down and not venting water/steam/coolant or boiling dry...

Just an idea.

http://www.aee-intec.at/0uploads/dateien48.pdf
http://www.aee-intec.at/0uploads/dateien117.pdf