Our Solar Hot Water

Posted by on Jun 6, 2007 in Life Support Systems | 5 Comments

This project is still in the planning stages;

Here are my specifications, open to public comment and quote. We hope to have it installed shortly, as winter is upon us.


Click for High Resolution:

The fireplace is fitted with a wetback. The flue rises up through the mezzanene floor and then through the roof between our two photovoltaics. The solar hot water panel and tank is at least 500mm (50cm) lower again on the roof. The pipes will act as towel warmers as we make our way to our steaming showers.

Kirrah is concerned about the pitch of our roof, the tank is very heavy and we want to use experienced, harnessed and insured workers. This extends our time from glory and increases the cost – money well spent i’m sure.


We have revised our plans in the interest of expediting the works. We now have a winter plan and a summer plan, to be phased in accordingly.

This is the winter plan. Again the hot water out line is brief.



  1. Brett
    June 7, 2007

    I too am keen to incorporate a wetback system to my solar hot water, I have checked out you diagram, are you concerned that the water may boil in the wood fired heater causing steam pressure to be injected into , what appears to be, a closed system? This is a real delima i am faced with, i want to use a heat exchange system that can, if needed , vent to open air. I am finding it very difficult to find some useable diagrams and advice on Wetback Systems on the internet, can you point me in the right direction?

  2. [email protected]
    June 9, 2007

    The diagram actually got a bit too cluttered so I left out the vent and the tap/shower line.

    You are absolutely correct that a relief is needed.

    The hot water out line from the tank is tee’ed and an open air shepherd’s crook of 1/2″ copper is run up above the height of the header tank.

    I’ve got some very usable diagrams that i’ve copied from other sources. However I am not sure about reproducing them on the website – sorry but i’ll show you the ones that i’ve done myself and try to answer any questions to the best of my knowledge.

    The distance between the bottom of the tank and top of the panels should be at least 200mm – this prevents reverse flow at night, cooling your water down again.

    The tank should be placed as high as possible and as close as possible to the collector.

    All cold water pipes should flow down all the way from the bottom of the tank to the bottom of the collector.

    Similarly all hot water pipes should flow up all the way from the top of the collector to the tank entry point. This prevents any air locks forming which will defeat the thermosyphon.

    I’ve uploaded another picture and an update which might help you with regards to the vent.

  3. Ann
    June 9, 2007

    Dear Guy,
    I like the idea of 2 phases for the introduction of your hot water system. It gives you some more time to refine your final plans and there does seem any point rushing into a big project on the roof when you won’t get the full benefit of it over winter,

  4. chris kennedy
    August 19, 2007

    Dear people, found you by accident. Spent 25 years in Alaska, and what you are doing sounds similar to things we did up there. Congrats!! I am going to install a used residential Solarhart up here in Sydney, and am also trying to devise a way to provide building heat either from the sun, (but not through windows, as house faces wrong way, or from the excess water in the air, as we are also much too humid all the time. Couldn’t read the diagrams you have shown, however.

  5. [email protected]
    August 20, 2007

    Hey Chris,
    Thanks for the feedback;

    I’m studying orthographic drawing at the moment, so my designs are getting clearer all the time.
    In fact it was subject of my latest post:

    We are currently using a nectre bakers oven as our sole source of hot-water. We live in a forest though, so keeping the firebreak clear and cutting up some of the dead ones provides the fuel. It also warms our house, bakes our bread, dries our clothes, cooks our food and keeps us happy without a tv.
    Not so in the city. I commend you on designing for some intelligent heating and cooling.

    As for your design situation – Radiant heat, perhaps through a in-floor system is the most comfortable. If there is good solar access on the roof, but not to the windows, it could be possible to at least preheat the water.
    If there is a slab in place already then it isn’t really a possible retrofit.

    Good luck, do you have a website?

    Regards, Guy