Solar hot water controller

Br716 · Oct 5, 2017

Hi all

I have a viridian solar clearline v200 controller which has failed. The warranty on the unit is 2 years and it's 2.5 years old. Having spoken to them they aren't willing to help me at all and no longer stock the controller so I can't replace it. Honestly Viridian Solar are just useless. The PV inverter they installed failed too but luckily that was in warranty.

Anyway the solar thermal controler clicks on at the right time, but once it is on it doesn't trip off and will run all night.

I need some help finding a new controller for my system. It is a drainback system and I'm happy to replace the current 3 sensors.

Ideally I'm looking to spend less than £150. Does anyone have recomendations?

Thanks in advance

Worcester · Oct 9, 2017

There are loads of good quality solar thermal controllers out there. and one can almost certainly be configured to your setup.

Give SeconSolar or Navitron a call. We use RESOL controllers for lots of functions other than solar - after all they only differential temperature controllers.

Controllers - https://www.seconsolar.com/controllers-433-c.asp

if it's old, its probably a non-PWM controller if new then it is a PWM controller.

The Solar King · Oct 9, 2017

Be careful in relation to the age of your system. Older Viridian panels and controllers use PT100 temperature sensors. The later ones use PT1000. The latter are compatible with most Resol controllers. Also PM me, I might have a controller, but not sure if it is PT 100 or PT 1000.

Br716 · Oct 9, 2017

The system is only 2.5 years old (clearline v200).

The odd thing is that the controller does seem to work. It will kick on at the right temperature but won't stop unless I hold the tank bottom sensor in my hand for about 30 seconds.

Today the tank temp was around 55 deg at the top. By the time I had pulled the bottom sensor to put it in my hand, the circulating cold solar feed had reduced the temp to 45deg at the top.

The the sensors on my system are USB for bottom sensor and Ethernet for collector sensor, so as far as I'm aware not an easy swap.

Br716 · Oct 10, 2017

The above temp drop was with no water usage btw. It has run itself right down to 35deg before from 50-60deg, but that's when I turned the system off at about 1am as it was still going flat out.

Viridian said it's likely the controller unit but if you have any other ideas please let me know.

The Solar King · Oct 11, 2017

They are both ehternet (network type cable) connectors. If you look carefully you will see that only two of the wires are used. It is very unusual for the sensors themselves to fail.

You could go back to Viridian with the serial number of your controller. They should be able to confirm whether it is one that uses PT100 or PT1000 sensors. This will then help with effecting a solution. There is also a sticker on the inside of the controller/pump station which has some manufacturing and test dates. This could also be useful in identifying this information.

johntheo · Nov 6, 2021

Is the system pressure 1.5 to 2.5bar??, is there a flow gauge to show circulation with solar circ pump on, possibly air in system although one would expect collector temp to be sky high.
Its easy to test the PT1000/PT100 probe, check the resistance as per table (if PT100, divide by 10), remove sensor wires at nearest JB and test with a M.meter and compare with display temperature, remove from pocket and see does resistance compare with equivalent ambient temp. Of if no M.meter does the displayed temperature fall with sensor removal. Also check differential on/off settings in controller.

Solar hot water controller

Br716

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Worcester

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The Solar King

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Br716

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Br716

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The Solar King

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johntheo

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