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Solar Water Heating Problem


UlsterRugby1999
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Good morning kind people. Long time no post. I trust you are all well.

I have just finished installing my own solar water heating system. I have a 300lt tank, 36 Evac tubes, controller, pump, expansion tank etc. There are 3 probes - top tank, bottom tank and collector. The controller is set to factory settings (10C degree diff between for switch on and 5C degree diff for switch off). The flow from the collector is connected into the correct end of the manifold and that is the end where the collector probe is connected also.

The problem is that over the last few days since installing the system, the flow pipe, from the collector, isnt really hot at all as it enters the tank. Our water isnt being heated anywhere near the 60C degree mark and we are having to force heat with the electrical element. As I write this the pipe is very cool and its full glorious sunshine outside. The tops of the tubes which enter the manifold are hot enough that they would burn you if you tried to hold onto them.

Any ideas anyone? Please. Cheers. Paul.

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Merci

Théière - as far as I know we purged the system of air after we filled it with

the water/anti-freeze mix. We followed the instructions. I have just had my son

climb up there and put a digital thermometer on the flow pipe as it leaves the

collector and it showed 38°C. The T1 (bottom tank reading) reading on the

controller shows 32°C. We have virtually clear skies and temps of approx. 16°C.

Surely it should be hotter than that exiting the manifold.

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Hi

BIG MAC, there is one isolator valve, after the pump, which is open. The pump

is circulating and I increased it from its No1 speed to No2 speed and the temp

actually dropped a couple of degrees. By vented do you mean bled. I have bled

the pipework system containing the HTF but not the pump. We've actually

unseated all 36 tubes and re-seated them and this actually produced a few

degrees more (but would this have occurred anyway as we did this earlier in the

morning). Given the lovely afternoon we had today I'd have thought that the

manifold would have been way hotter than it was.

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Agreed Théière – but I don’t know what else to do. Its up to

37°C

just now but I’d still have thought with the clear blue skies today it would

have been much higher.

Is there a possibility that the manifold has a problem, or

could I be seating the tubes incorrectly? I’m more inclined to look at me before

looking at the actual parts first.

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Mmmmmm - strange things here - T1 - bottom of tank shows 36C --- T2 - Collector shows 37C --- T3 - Top of tank shows 38C. Surely if the bottom of the tank is 36C and the collector shows 38C then the pump should switch off as the differnetial is less than 10C. Or have I completely misunderstood this whole thing. :-(
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Mmmmmm

– not sure I fully understand Théière. Do you mean the return point at the

collector?

Update

– we spent an age yesterday removing and shaking the tubes and inner elements,

lots of other wee things to try and find the problem. THEN, I discovered that

our spark friend had actually connected the differential pump directly to its

own feed and not via the controller. I connected the pump to the controller.

Obviously the pump had been running 24/7 and also during the night so that must

have been having a totally negative effect. So, today, with brilliant clear

blue skies and lovely temps the T1 – lower tank temp peaked at 45°C, T2 –

collector at 54°C and T3 – top tank at 49°C. That’s a vast improvement from

previous days. Given the temperature (21°C) and clear skies today did I do okay

or should I have expected more. I have no previous experience of this but in my

wee head I had imagined it would have been somewhat more.

Thanks

to all for all your input, as always. 100% appreciated. Paul

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