liveaboard

Those rooftop tanks are easy to install but not the best setup.
The solar collectors should feed a tank down in the house, close to users.Integrated tanks use heat from the collector when available and electric when necessary. they cost more and need space and time for installation.
"Professionals" prefer to slap a thing to your roof that looks like the business and get out with anything complicated happening.

wellinever

For me there was no choice. The house I designed and built,along with the parameters of the plot, meant that I have a bungalow with large flat roof. Due to the constraints there was just no room for a floor mounted tank.
I must admit to being surprised that despite the fact that the tank is actually directly above the kitchen sink (less than 3 mtrs) it still takes in excess of 30+ seconds to reach the tap.
But the way plumbing is installed does not mean that the pipes go directly from the tank to the tap.
Of course the panels would always need to be roof mounted, regardless of where the tank is placed and with the way it works they would always be prone to overheating the water.
when no water is being used.

I fully agree with Bill, for many, this is by no means a good solution however they are fitted, and should not be mandatory when building from new.
Yes make pre installation of pipework mandatory by all means but not to make full installation mandatory.

Score76

Canvas cover in place, short bungey cords in each corner

I'm with with live aboard, the tank should be in the house then any heat lost is lost to the house not to the sky and the pipe run to the tap is short so minimising loss each time you turn a hot tap on.

Back to the original question, we're off on holiday later today so on with the canvas cover...

fergus

Hi All. A quick note here to thank OP wellinever. So today I went to the hardware shop and got a 4mm to 3/4 straight through connector. Fitted it to my relief valve and then added a hose to the whole thing. I may have got the measurements of the connector slightly wrong, so don't take them as gospel. Hose trails down two storeys so gravity and pressure should mean if 'she blows' then very hot water will run off to where I want it to go. This was the original ask by wellinever and is still perhaps a good solution. The canvas covers shown in his pictures looks good (I have a similar cover for my boat) but the bungee cords will be destroyed by UV in the summer. Where ever you got the cover from will have good ropes. The ones fishermen use will be UV resistance and last many years. It will only cost you 10 euros for a couple of three metres. The bungees will probably hold for a while right now but they will not last many weeks once the summer sun comes. Oh and I do agree that there is a lot of water wasted by these systems every time you have a shower.

Score76

Just out of interest Fergus, where are you getting rid of the excess hot water?

When we first bought our house the excess simply emptied from the valve onto the flat terrace roof from where it sumped to one corner, through the wall and poured down onto the terrace below. Not safe at all!

My first attempt at something better was to install a pex pipe to take the dumped hot away, into a downpipe down to the terrace below, turn it through 90°, under the terrace and a lawn and into a soak away. First time the tank dumped my downpipe turned to cheese despite being very well fixed to the wall. Replaced the plastic downpipe with aluminium and that has stood the test of time ever since. It's almost steam when it dumps.

fergus

Sorry for delay in reply. You have a good point about heat and steam. It is bloody hot when it blows. However, we only need to have prevention measures when we are not here and I also cover one panel now at those times, in the summer. It was going straight onto patio and then down gutters and washing feet of dinners on the pavement below. We were not popular when it happen! So, after prompt from OP I now have a hose pipe that goes to a different patio run off, which then goes to sewer drain. As said before, is only for when we are not here. I also see that Aldi have a 1m x2m artifical turf looking carpet that is solar resistant on sale from Sunday. It might be perfect for covering one panel. I do have similar size very thick cardboard with a plastic table cloth wrapped around it that has stood the test of time, but will not last many more summers. Covering one panel seems to be enough to prevent it overheating. Unfortunately, when it did blow whilst we were not here (before we covered it), the cafe owners below, improvised their own solution, which was to turn off our water at the mains. I think this lead to the water that was left in the tank super heating and it blew a welded joint on the system. €1,200 for a complete replacement system. So had to make a heath robinson fix, which a year later is doing just fine. Cost €8 and I enjoyed the challenge. I do hope that I haven't felt smug too soon. This summer will be the test.

wellinever

hi
As you can see from my image, I bought 4 x 2m x 0.60 m blue insulation boards from maxmat, really cheap. Yes I needed to cut some but easy. These I stuck down with jaffer tape.
and then some chord just in case. Been up a week so far and almost immediately water was cold. Store underneath unit when I get back or replace for next time.

wellinever

as follow up......i decided not to return to UK last week, having already covered both panels with insulatoin board which reduced the water temp to normal cold water.
But as I will now go next week, I decided to uncover one panel this afternoon, about 2pm. Took temp of hot water before and it was at 16deg. (no same as cold water), after 2 hours I ran hot water until it got as hot as it would go withing that short time, and surprised it was at 30deg.
It will be interseting to see what it does after a full day sun, hopefully tomorrow will do that.