solar hot water problems....

[Ian Geary]

Evening all

a couple of years ago we got some solar panels to generate hot water, with a dual coil hot water tank.

there were a few problems: the chaps had to come back to remove a blocked flow meter, fit a new controller, and last year refill and re-pressurise the system after it lost it's fluid.

Now, exactly a year later, the system appears to be again empty of this fluid - solar transfer fluid, which I believe is basically ethylene glycol (antifreeze).

Last year it took a bit of arguing as to why this should be done for free, and not cost us £155 the company tried to charge.

But now the company have gone bust! So we don't even have anyone to service the damn things


So does anyone have any pointers or advice how to re-pressurise such a system?

From watching the chap last year it seems quite straight forward - basically connecting a pump to the filling port on the system, and pump in fluid until I reach the right pressure (1.5 bar)

Otherwise, it's try and find a plumber who specialises in solar systems, and pay through the nose.

Given how poor savings the system gives, it would be more cost effective to just turn the thing off than fork out on getting someone to fix it.

cheers

Ian

[DavidY]

Ian

I think you need to find out why it's loosing the fluid, rather than just fill it up again. I would suggest that you get a specialist in, yes it may cost you money, but it should work afterwards and it does save money and add to the value of the house.

I would suggest you give this guy a call, he fitted our system and to date we've had no issues:-

Justin from JW Solar Solutions http://www.jwsolarsolutions.co.uk/Contact-Us.php

davidy

[Ian Geary]

Hi David

thanks for your reply.

It's strange, the system has been working well recently ( 2 days ago), so I assume it had fluid in. Unless it's venting out of the valve on the collector, there's no visible leak I can see in the plumbing, and only really went mad yesterday ( collectors shooting up to 130 degrees, with no heat getting to the tank). It almost seemed like a blockage, but the pump was going full tilt. It's a shame there's no way to install a site glass or fluid level gauge on the system.


As for pressure, the installers never quite explained if the pressure gauge should read 1.5 bar all the time, or just when the system is working. It sits at zero most of the time.

I thought it was like a car's radiator - it's only pressurised when the coolant is hot, and the system pumping.

But then I read that expansion vessels have a diaphram inside which is pre-set to a certain pressure (e.g. 1.5 bar) which makes me think the system should remain pressurised.

very strange.

I'll see what the wife says about getting someone in, but the whole solar thing has been a complete white elephant as far as we're concerned, and further repairs seem a case of good money after bad.

but I'll get some quotes, starting with the guy you recommended.


Ian

[mas99]

If you're happy to do some investigation yourself, the navitron forums are very helpful.
http://www.navitron.org.uk/forum/

Navitron sell evac tube panels, but the users/installers that use the forums are helpful on any system - and good on the principles and fault finding.

[Ferg]

I'd suspect the air vent, or possibly the vessel has either lost charge or ruptured it's diaphragm and it's pushing out a safety valve when hot. I repressurise Solar systems with a modified Hozelok garden sprayer pump.

[jaybkay]

The pressurised system should retain its pressure - otherwise the pump won't circulate correctly. Hopefully you have a valve on the pressure vessel - check it as the pressure should be about 1.5 bar, it can be pumped up with a bicycle pump.
It's quite likely the system will only need a small amount of water - personally I would top it up from the mains - any dilution of the antifreeze will be minimal.

[Ian Geary]

well, I've been reading up on the navitron site - which is pretty useful.

It turns out my garden sprayer which is rated at 3 bar is ideal for pressuring these systems.

All I needed to do was solder a 8mm - 15mm coupler to a spare sprayer tube, and then with a compression join on the end it was an easy fit into the filling port of the solar heating system (which uses 15mm copper)

I topped it up about half a litre with de-ionised water by just pumping up the sprayer, and pressing the trigger.

the system picked up immediately - and started shifting heat from the collector to the tank much better.

there was a bit of air and bubbles to vent off, but I'll check up on the pressure over the next few days to see if the system is water tight. If its not, then I'll have to seek pro help.


Ian