Browse Forums Eco Living 1 Aug 06, 2011 10:19 am We were considering a combustion heater with a wetback system for heating water. However, they require a gravity fed hot water system. Are gracity fed systens even available any more? and is there much functional difference between them and the pressurised ones most people (including us) have now? Our HWS is old, so if it is worth it, we could replace it with a gravity fed when it gives up the ghost. However, the hearth space the wetback heater needs is quite big, so unless the wetback system is really worth it, would go with a smaller one. Does anyone have a wetback system and any feedback on them? Re: Combustion heaters with wetback water heating 2Aug 12, 2011 11:56 pm Basically the water jacket heats a water/glycol mix in a heat exchange boiler, which is unpressurised, you can use a small inline pump to circulate this solution (if it will not thermosiphon). The boiler has a 30_meter long heating coil that cold water runs in one end and comes out hot the other end, heat is transferred from the boiler solution to the water in the coil. The coil water is your hot water that you use. The boiler can also be boosted with solar panels, or with gas or electric. Very effective system as it uses the waste heat from the slow combustion. Steve Re: Combustion heaters with wetback water heating 3Aug 13, 2011 10:07 am Thanks very much for your answer. Should have prefaced my question by saying I am just a mere woman lol. However, have re-read your answer a few times and think I now understand it Family used to have a holiday house that was set up not to have mains power, and the hot water was fed from a combination of the combustion heater, solar and a chip heater. Worked well. But back then we had an in the roof, gravity fed hot water system. Can you still get gravity fed, and do they work as well as pressurised? Is there any wetback that will work with a pressurised hot water service? Is there any brand of combustion with a wetback anyone recommends?? Re: Combustion heaters with wetback water heating 4Aug 13, 2011 1:22 pm Most of the "mere woman" folk that I know are very capable... Sorry that it is a little confusing, try think of it this way, the water that you heat with the wet back (and/or solar panel etc) is not the water that you comes out of your tap...it is used to heat a great big storage tank (heat source) only. Cold fresh water then runs into this heat source (tank) in a copper coil , it comes out the other end heated...not sure if that will help? I really need to draw a picture. There are a whole buch of sytems that you can get/build and which will work for you depends on a whole other bunch of variables so it is hard to be specific and talk in general terms as each component has many + & -'s. Pretty much anything can be done but you need to find a decent plumber that knows his (her) stuff. tjilpi Can you still get gravity fed? Yes you can still get (build) such a system but there is no point if you are on mains water. If you have tank water then it requires you to have a header tank rather than a preasure pump. You need your water source to be up higher than your water oulet (ie a tank on a stand or up a hill) hence gravity creates water preasure. tjilpi do they work as well as pressurised? Depends what you mean by 'work as well'? They will not have as much preasure of course but you still get hot and cold water (ie no impact on temperature) tjilpi Is there any wetback that will work with a pressurised hot water service? The system I detailed in my first post (a heat exchange boiler) will...kind of. The water (solution) from the wet back is stored in an unpreasurised heat exchanger tank (so it does not explode) but the water that is heated by the exchanger is under preasure.... tjilpi Is there any brand of combustion with a wetback anyone recommends?? A hot water jacket on the flu is a good way to go as it fits on a standard flu that will go on a wide range of wood heaters. http://www.axeman-fireflue.com/ Nectre are Australian made wood heaters that can be fitted with wet back (that's what we have) very good effecient wood heater/wetback. This is the best site for alternate sustainable building stuff, this is the hot water section that may be on intrest. http://www.yourhome.gov.au/technical/fs65.html A good basic article on the subject http://www.insolar.com.au/wood-with-insolar.pdf Does anyone have a suggestion for a good hydronic in slab heating speacialist who may be able to help me with an existing system and wether or not it may need a seperator… 0 4882 18 90480 From what I know about water tanks (I've been working with a client on them for a few years now) is this - The concrete can last a lifetime if they don't crack for some… 2 10629 |