This thread is a bit old and may be dead, but it is an issue I have been fiddling with for a few years.
We have owner built a house 5 years ago and at the time installed a Solarhart with no electrical backup. As a backup in the winter we attached a wood buring heater, with wet back and because it is a high pressure closed system were told you must use an open vented heat exchanger on the Solarhart. This turned out to be quite inefficient. With the heater burning for 5 - 6 hours a night there wasn't really enough hot water for a family of 4. Lots of luke warm showers on winter mornings.
I bypassed the heat exchanger and circulated the hot water directly through the Solarhart tank. This improved efficiency and we could all have quick hot showers but no long hot baths and I'm still not happy with it.
I am now adding a flue hot water jacket to try and increase the amount of hot water. I'm also thinking of adding a pump to circulate the water through the system.
Would this increase efficiency over just relying on convection?
A few questions/comments re the previous posts.
I was under the impression that reverse thermosyphon/convection isn't possible. If the hot water tank is at the high point, then once the fire is out, cold water settle at the bottom and without heat to circulate it, hot water rises and nothing happens.
Regarding connecting a wood heater to a closed system - the solar collectors are connected to a closed system. With hot WA summers the sun gets the water much much hotter than I've ever managed with the wood heater. And is it a closed system if it has a pressure blow off valve?
The other problem is that the cold water entering the hot water system when you turn on the tap on those chilly winters mornings is only 3-4 degrees.
Any feedback greatly appreciated.
Posted Sunday 11 Mar 2012 @ 8:13:05 am from IP #