Solar Heating Question

TheFew · 21 May 2016

Hi,

This is hopefully a simple question for someone in the know!

My house has a solar water heating system and in the loft the system has a short pipe that goes into a large blue container (see pictures). The blue container is half full with a clear liquid (presumably water?).

My questions are:

1) Is this just some overflow type arrangement?

2) Is the liquid water? And should it be emptied if half full?

Thanks

halfway · 21 May 2016

Not an expert on those, but there shouldn't be liquid (probably glycol) in there. Its presence means that your pressure relief valve has operated. With that half full, you don't have enough liquid in the system. You need to have it recharged and the cause of the problem investigated.
Might be problem with expansion vessel and/or the absence of a heat dump.

TheFew · 21 May 2016

Thanks for the info. Do the dials in the picture look to be in the normal range (if such a thing exists)?

I guess i need to try to find the installation manual and trouble shooting guide, presuming there will be one online!

halfway · 21 May 2016

The dial with the red indicator needle is showing zero pressure. It should be where the red needle is.

Finding the manual will educate you, but it wont fix it. You need a solar guy.

"You need to have it recharged and the cause of the problem investigated.
Might be problem with expansion vessel and/or the absence of a heat dump."

TheFew · 21 May 2016

Thanks I think I do need a solar guy! I would like to understand the problem a little first however, just be sure that I dont get fleeced

Next newbie question. Would the dial read zero pressure when it is not heating water? Or should it always indicate some pressure?

TheFew · 21 May 2016

Having just found a paper copy of some instructions it does indeed confirm the diagnosis that the pressure relief valve has operated and that the expansion vessel is likely to be the fault.

The odd thing is, is that the controller for the system still indicates that water is still being cycled when it is sunny.

Bosswhite · 21 May 2016

The canister is the antifreeze solution to stop the panels freezing in the winter, it may be a pick up for the antifreeze

or it could be a primitive form of a pressure relief overflow indicator,

Get the solar guy in to sort it out

TheFew · 24 May 2016

So far six companies in and around Devizes called... and all say that they no longer do Solar Thermal. Slowly getting stumped for finding an Engineer!

ServiceNumpty · 25 May 2016

With the Rhi for solar thermal being phased out, more and more installers are dropping solar thermal from their competencies. I also will not be renewing my solar thermal this year.

PullerGas · 25 May 2016

I'd get someone in pretty pronto to look at your cowboy installed system mate, with limited water in your system & a leaking PRV, your panel could flash to steam if it's sunny day!!

What a mess!! Why would anyone not terminate a blowoff correctly on a solar thermal system?? Madness!!

dcawkwell · 26 May 2016

Probably just needs the expansion vessel pumping up and some pressure adding. Sadly not worth getting anyone out as the cost savings
on solar thermal are so small not worth it. Solar thermal isn't viable in the UK.

Agile · 26 May 2016

I have to disagree!

It is just because the savings show a useful return on the capital that the Gov don't give any significant subsidy on it.

I think that the VAT on the supply and fit is still at the reduced rate of 5%. But check before committing yourself.

A system with 4 sq m of capture area can provide most of the hot water for a family of four on our sunny days and still a useful contribution even on cloudy days. That can be worth £100-£300 a year.

A good system can capture up to about 80% of the incident heat. That is nearly 1 kW per sq m of area. The PV panels only convert up to 20% and they are not viable without a subsidy.

Tony

JohnD · 26 May 2016

Agile said:
It is just because the savings show a useful return on the capital

I have to disagree!

My gas usage in summer is about 20 units a month for hw with a cylinder. Last July, including VAT, at 2.993p per kWh, that cost £7.06

Disregarding the standing charge (which will not reduce) and remembering that there are sunny days and cloudy days, how much do you think my hw gas costs could reduce? £50 a year, with luck?

If I keep my money in the bank, or invest it in gold bars or National Grid shares, which brings me an income and has no maintenance costs, the net benefit of paying for solar hw is small, nil, or negative. And after twenty years when the solar is worn out and worthless, I still have my money in the bank, or my gold bars, or my shares.

Gerrydelasel · 26 May 2016

Agile said:
That can be worth £100-£300 a year.

Doesn't that mean it will take between about 10 to 40 years just to pay off the cost of installation?

TheFew · 26 May 2016

Sounds like it may just be cheaper to burn the house down...

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Solar Heating Question

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