Evacuated Tube or Flat Plate ?

[warlock]

Hey Guys,

Just wanted some suggestions on wheather to get evacuated tubes or flat plate or my solar water heating needs,
I live in durban

thanks in advance

[SeanB]

Makes little difference here, it rarely hails so either will do. The advantage of tube types is you can replace failed tubes easily, while plate types are slightly more efficient area wise. Tubes have an issue with seals if not installed right, but they are easy to repair if there are leaks. There are thousands of tube types installed in low cost housing projects though. Probably will be worth going to Kwikhot and looking at what they offer, in any case if you really want to reduce power bills put a time switch on the electric backup or leave it turned off during summer.

[warlock]

Awesome shot Sean,

My local installer recommended flat plate claiming it would be the same if not better than the tubes in our area. I just wanted to make sure as there is alot of hype about tubes, in durban out day time temps are never lower than about 15deg so it would make sense.

thanks again.

[SeanB]

I stay in Durban. Biggest change will be in your habits to make efficient use of the hot water so as not to waste it.

[MJLorton]

I stay in Durban. Biggest change will be in your habits to make efficient use of the hot water so as not to waste it.

Yup...I second that.

Consider bathing / showing in the evenings and leave the heating element off in the mornings...only have it come on if the water is not at 55 degrees C by 5ish in the afternoon.

[warlock]

Well they are busy as I type installing the flat panel, 2.5m2, unfortunately they won't finish with enough time for it to completely heat me water.

We usually only show/bat in the evening, however we have a domestic that shower evening and morning, I suspect from tomorrow morning she'll have cold showers in the morning  . And for tomorrow we have rain, so I'll only really get to see the thing work Friday or this weekend.

[SeanB]

Even in overcast weather they are quite good, you get hot water in overcast and even when it is light rain. If it is so dark that you need light in the house then they are not going to work, but for overcast and partly cloudy days they do well.

[warlock]

Ok so first 2 days of sun and we find that the 12V circulation pump is not working, Fix that and the water heats very nicely, but the installers tied the solar return into the geyser delivery, so when someone takes a shower after around 3 mins, then the 12V circulation pump is pushing 18deg water into the geyser deliver and the shower water coos right down. They never installed a banjo valve, So I have one now and it will be installed Tue.

[SeanB]

Post some pictures, it will be nice to see how they are installed.

[warlock]

See attached photo

[warlock]

Preliminary results are in,

Before I installed the Solar Collector I was using between 30-35kW per day, and after the collector got installed 22-27kWh, so anything from 8-10kW per day I am saving. which over a year is about R4000 which is not bad, bay off period will be about 2 years.

[marks]

Google "Solaris hot" Bob Nape is measuring both simultaneously and logging. Flat plate is more efficient

[tillt]

Flat tubes ftw. I never use evacuated