Solar panel/shower pump

Fatboise wrote:-

> I have recently moved into my new house and need to install a shower > pump on my gravity fed system. I also have a solar panel attached to > the roof which will be plumbed through the HW cylinder to provide hot > water (not operational yet).- > > Hang on. I'll take a guess the panel was there when you mvoed in. If > so... > > First the solar panel will put out lukewarm water unless you pump it > very slowly. These are not fast devices. Also most are not freeze > proof, and require a separate antifreeze circuit. Many home made ones > are direct heat and need draining down in winter. A few are freeze > proof and can be run direct with no extra issues. > > How to plumb it depends on the type of panel, and to some extent the > type of HW setup. But I would not simply assume that pumping tank HW > through it is necessarily the right thing. We'd need more info, e > what > size is it, is this a small commercial panel or a big home made job, > etc > > - > The problem that I think I may have is that the temperature of the > water in the cylinder cannot be regulated when the solar panel is > operating and it may rise over 65 celcius on a hot day.- > > If its a big panel, yes. Not going to happen with commercial panels. > Even if it does, its not much of a problem. > > - > The only thing > that I can think of doing is adding a thermostat that would shut off > the water supply/power to protect the pump but then nobody can have a > shower until the water temp goes dowm!!!- > > that doesnt seem to make sense. > > - > Does anybody have any > suggestions how I could runthe pump if the above sutuation occours??- > > it wont. Not unless someone's gone solar crazy and installed 10m2 of > high efficiency home made panels. It has been known, but is rare. > > > NT

Thanks for all the replies, I think that the idea with the temperin valve is the best option .... I'll have to look into this a bit more.

"The solar pump would be controlled from a differential stat such tha it only run when (a) the water in the tank colder than the set poin temp, and b) when the water available from the solar panel is hotter tha the tank water. (A) takes care of the water in the cylinder not gettin too hot, and (B) stops all the heat accumulated in the tank from being pumped back outside again as soon as the sun goes in!"

John..Thanks for the input but I don't think your on the right trac with the control of the solar panel. The only control that I'm going t put on the solar panel is a thermostat. When the temperature of th water in the panel gets to x degrees celcius the pump will switch on It doesn't matter what temperature the water in the cylinder is becaus to stop any dammage to the solar panel system the pump needs to run whe the sun is shining on it. I should also mention that the solar pane loop is closed system. Basically, if the sun is out and the pump isn' running the water in the panel will get to hot and the pressure ma cause a rupture in the piping (Get Out!!!! It's going t blow....................)

"You may also need a anti convection valve in there as well to sto any gravity circulation."

Don't know why I need the anti convection valve...please explain????

I'm going to add anti-freeze to the circulating water which shoul prevent any issues during the winter months

-- Fatboise

Reply to
Fatboise
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So a sunny day and a power cut could work out quite expensive then?

Sounds like you need an expansion vessle in your closed circuit to prevent any possibility of damage (the same sort as used in a pressurised central heating system).

If you had a differential control that ensured you only got a net flow of heat into your cylinder, you would still have the problem that even with the pump turned off, you could get heat passing from the cylinder to the solar panel by gravity circulation (i.e. convection). Much the same was as an old non pumped hot water system would be heated. The anti convection valve is a simple spring loaded flap valve that is easy enough to push open with the force of pumped water, but strong enough to keep itself shut against convection circulation.

Reply to
John Rumm

Sounds like you need a solar powered pump as well - then you wouldn't have to worry about power cuts.

Reply to
Set Square

You're overcomplicating things. A solar panel is not going to overheat the tank water, so all you need is a diff stat, nothing more. When panel temp > tank, pump on, otherwise pump off. Simple as that.

This also takes care of the collector boiling, which would indeed be possible if youve got an evacuated tube collector. It wont happen with a flat panel.

NT

Reply to
meow2222

meow2222

Thanks for the input but if I'm reading your post correctly I thin that what you advise is pretty much what I had in mind. If you explain to me what a diff stat does then I'll know for sure

Just so that nobody's confused we're talking about two pumps in the original post, the pump on the solar panel circuit and the pump for the shower being fed from the HW cylinder

You've been a great crowd, thank you and G'night

Reply to
Fatboise

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