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Old 09-06-17, 09:39 AM   #10
Geo NR Gee
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Originally Posted by Mikesolar View Post
Yes, indeed. These collectors will stagnate at 240C+ if they are sitting in the sun and doing no work. The seals won't last a long time if the system goes for weeks this way.
The units that I have are Thermomax HP200. I am not sure, but I read (here ) that they have two different options for a temperature limit.
Unique Feature –
Temperature Limitation Devices
HP200 collectors contain a unique temperature limitation device
for system protection, there are 2 types:
1. Memory spring to limit temperature to 95˚C or 203˚F
Ideal for domestic installations
2. Snap disk to limit temperature to 135˚C or 275˚F.
Ideal for commercial installations
New improved snap disk*
• Over 3.5% more efficient than before
- now up to 81% optical efficiency
• More robust
• More reliable
This collector is referred to as HP250.

HP200 collectors are available in 3 different
sizes – each one with the option of 2 different
temperature limits.
In the table below, where there are 2 figures, HP200 is the first
figure and has a limitation of 95˚C or 203˚F. HP250 is the second figure and
has a limitation of 135˚C or 275˚F. (I have the HP200 units)

Again, my plan was to dump extra heat to the ground storage for the times when we need to heat the house or a preheater for the domestic hot water. So if they are the limiting units like I read, then the only time we should have to worry about stagnation would be in a power outage.

Last edited by Geo NR Gee; 09-06-17 at 09:55 AM.. Reason: added ˚F
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