Sun, 24 May 2026 00:34:12 +0100 https://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2466&Focus=31638#Comment_31638 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2466&Focus=31638#Comment_31638 Tue, 02 Sep 2008 17:09:46 +0100 galway83
Problems might occur with a layer of slime forming over a heat exchanger however. Any opinions would be appreciated.

Also, along similar lines - I know of a few people who have combined their horizontal ground loops (geothermal system) with the leach field/percolation area of their wastwewater treatment systems. I think in the long run,they're asking for trouble. I think a biomat will form around the ground loop piping, that will hinder thermal transfer. However, they will in the short term invariably gain improved heat transfer rates due to the additional moisture in the soil surrounding the ground loop. Anyone have any horror stories?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2466&Focus=31642#Comment_31642 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2466&Focus=31642#Comment_31642 Tue, 02 Sep 2008 18:04:51 +0100 ludite https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2466&Focus=31655#Comment_31655 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2466&Focus=31655#Comment_31655 Tue, 02 Sep 2008 19:49:19 +0100 fostertom https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2466&Focus=31660#Comment_31660 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2466&Focus=31660#Comment_31660 Tue, 02 Sep 2008 20:05:44 +0100 Paul in Montreal
Paul in Montreal.

p.s. same thing for compost heaps too]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2466&Focus=31661#Comment_31661 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2466&Focus=31661#Comment_31661 Tue, 02 Sep 2008 20:15:59 +0100 chuckey Frank]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2466&Focus=31734#Comment_31734 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2466&Focus=31734#Comment_31734 Wed, 03 Sep 2008 12:42:09 +0100 galway83
the wrapping of a ground coil around a septic tank is definitely a worthwhile measure I think, just look at the fact that a snow cover will dissapear from the area around a septic tank far quicker than the surrounding area. definitely far higher temperatures. any estimates?

as for a heat exchanger in a septic tank, i don't think you could categorically state that it would be detrimental to the breakdown of waste. i don't think sufficient amount of heat would need to be extracted to cause worry in this area, especially if combined with a heat pump.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2466&Focus=31737#Comment_31737 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2466&Focus=31737#Comment_31737 Wed, 03 Sep 2008 13:21:35 +0100 Paul in Montreal Posted By: galway83as for a heat exchanger in a septic tank, i don't think you could categorically state that it would be detrimental to the breakdown of waste. i don't think sufficient amount of heat would need to be extracted to cause worry in this area, especially if combined with a heat pump.

Sorry, but it's time for a reality check as there is a lot of confusion here between "heat" and "temperature". Where do people think the heat in a septic tank comes from? Obviously its primary source is the excrement that goes in there in the first place. So the maximum amount of heat that could be generated is equal to the food intake of the occupants that "feed" the tank in the first place. Let's assume there are four somewhat lardy adults who consume 3000 Calories per day each. And, for the sake of argument, let's assume that their excrement also contains 3000 Calories each (i.e. they each digest about half of what's available in the food). 4*3000 Calories is 13.96kWh. Not a huge amount of heat. A more realistic figure is probably half this. Since a heating system probably requires 5-10x this amount, the septic tank would be rendered pretty cold pretty quickly and this would, of course, slow down the waste digestion. As for combination with a heatpump, this doesn't magically make more heat available, it just makes it usable - the heat still has to come from somewhere.

To cut a long story short, it's a waste (pardon the pun) of time to try and use the heat from a domestic septic tank and running refrigeration loops through such a tank would quickly degrade its performance - just in the way stuff in a fridge rots more slowly when it's cold.

Paul in Montreal.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2466&Focus=31754#Comment_31754 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2466&Focus=31754#Comment_31754 Wed, 03 Sep 2008 15:59:57 +0100 fostertom https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2466&Focus=31879#Comment_31879 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2466&Focus=31879#Comment_31879 Thu, 04 Sep 2008 21:15:49 +0100 galway83
Don't know about yourself Paul, but I don't produce 180 litres of faeces a day, even though with the cantankerous response left by yourself above, maybe you might have the disadvantage of emitting supplementary volumes from additional orifices to the ordinary person.

Also the majority of treatment of WW takes place in the percolation field anyhow, with relatively little breakdown occurring in the septic tank in the first place.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2466&Focus=31884#Comment_31884 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2466&Focus=31884#Comment_31884 Thu, 04 Sep 2008 22:37:56 +0100 Paul in Montreal
My intent was to merely indicate the magnitude of heat potentially available as I pointed out that many people equate heat and temperature when they're not the same thing at all.

Paul in Montreal.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2466&Focus=31892#Comment_31892 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2466&Focus=31892#Comment_31892 Fri, 05 Sep 2008 00:56:41 +0100 Kieran But I would agree that a tiny little domestic septic tank wouldn't be much use for anything.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2466&Focus=32036#Comment_32036 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2466&Focus=32036#Comment_32036 Sun, 07 Sep 2008 08:47:37 +0100 Dominic Cooney https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2466&Focus=32120#Comment_32120 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2466&Focus=32120#Comment_32120 Mon, 08 Sep 2008 08:17:16 +0100 veverett https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2466&Focus=32126#Comment_32126 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2466&Focus=32126#Comment_32126 Mon, 08 Sep 2008 10:04:52 +0100 fostertom Posted By: Dominic CooneyThat's why we called one of them 'Septic'Or is it 'Sceptic'?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2466&Focus=32128#Comment_32128 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2466&Focus=32128#Comment_32128 Mon, 08 Sep 2008 10:17:27 +0100 ludite https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2466&Focus=32129#Comment_32129 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2466&Focus=32129#Comment_32129 Mon, 08 Sep 2008 10:18:58 +0100 ludite