using sewer system as geo thermal as heat transfer

[grizzzlle]

Does anyone know if anyone has ever tried to use a sewer system as the source for transferring energy just like a river?

[AiResearch]

Interesting concept.

There may be several issues to overcome.

-municipalities would probably reject the idea
-septic tanks are not large enough for the required footage of pipe
-piping could cause blockage of sewer flow

However the idea could be efficient , considering the gray water flow at a consistant temperature. Dont think the sludge would be a problem either , as it would probably aid in heat transfer , coating and surrounding the pipe , mixed with water.

Service on the loop could be bad though.

Dont know if this would be going "green" or going brown.

[dijit]

Give it a try and let us all know how it works out. I know I will not be installing the loop.

[grizzzlle]

Airesearch thanks for your ththoughts. As far as the municipality is concerned I think the biggest problem will be making contact with the right person who is open to new ideas. As far as plugging the line at this point I am not to concerned with that problem right now. I would be looking at using larger diameter pipe to keep a larger GPM flowing over the loop so should be plenty of room. I figure the number crunching as to pipe size and required GPM would come later depending how receptive people are to the idea.

Dijit lol. I make my living working in or around sewage. Let me tell ya for the most part it is not bad then probably just like other jobs there are days you can't take enough showers.

[dijit]

What kind of sewer temps are we talking?

[grizzzlle]

There are variables to temp but for the most part in my area 55 would be average. It has been a while since I have looked at temps for I usually am looking at depth and velocity. I can get solid numbers this week if you would like.

[terawatt]

One issue with using your sewage system as a heat source - removing too much heat could lead to an increase in viscosity of the sewage, interfering with flow and ultimately making it easier for the system to have freeze problems.

Not being familiar with sewers or septic, I also wonder if reduced temperatures in a septic system could interfere with the natural bacterial processes that break down the organic materials in the sludge (or whatever you call it).

[AiResearch]

Dont think you could fit 3,400 ft of poly pipe in a septic tank.

[grizzzlle]

I was thinking of using the main lines of the municipality. Is there a rough rule of thunbas to how much pipe you would need per a ton of heating or cooling.

[DeltaT]

There were some studies and actually homes modified so that all of the waste heat from the drains were tied into a heat exchanger that preheated the water going into the hot water heater and it really saved a bit of money/energy.

But the costs for installation were pretty high. Still, one heat exchanger located inside the home at the main outlet of the home sure would extract some heat from all that hot water going down the drain, I would think. That would elimanate all contact with the local sewer authorities but would bring you face to face with plumbing inspectors.

[thes]

i'd just throw this out there. with all that crap and crud on the pipes, i'd wonder about longevity of the piping system, just a thought, but interesting idea!

[trouble time]

Try to get the pipes coming out of City Hall, I am sure you will get the right amount of excrement you need to heat the planet.......

[DeltaT]

Try to get the pipes coming out of City Hall, I am sure you will get the right amount of excrement you need to heat the planet.......

Not anymore. I think it's all backed up these days.

[mahlv]

i seem to remember either reading or hearing about planned geothermal communities doing this very thing with a specially developed 'coaxial' sewer pipe. It may have even been overseas, but it would be very interesting to see it work. I wouldnt do the septic thing as freezing your tank, inlet, outlet, or leach field would really be $hitty times.

[ga-hvac-tech]

Seems like a reasonable idea to me...

I am looking at a piece of property to purchase ne3xt year. It is in the back of a neighborhood and has a house with 5+ acres. There is room for Geo on the property... I am interested in how to set up a Geo system.

[whatsthat]

i seem to remember either reading or hearing about planned geothermal communities doing this very thing with a specially developed 'coaxial' sewer pipe. It may have even been overseas, but it would be very interesting to see it work. I wouldnt do the septic thing as freezing your tank, inlet, outlet, or leach field would really be $hitty times.

The community you're thinking of is in Sudbury, Ontario. It's a couple of years old at this point but I have not heard any results.

I agree on keeping away from a septic system. That can be pretty messy if you're in a heating dominated climate and you freeze things.

[glennac]

How in the world would you get your "heat exchanger" into a main sewer line? I'm sure if you asked permission to "tap" into it with your lnes they would say no but hell no.

You would be occupying space in their "hydraulically engineered sewer pipe and thus reduce it's capacity. Plus they would be opening Pandora's box for all kind of folks wanting special favors for this or that. I'm curious if you actually thought any about those issues. Thank you very much

[whatsthat]

How in the world would you get your "heat exchanger" into a main sewer line? I'm sure if you asked permission to "tap" into it with your lnes they would say no but hell no.

You would be occupying space in their "hydraulically engineered sewer pipe and thus reduce it's capacity. Plus they would be opening Pandora's box for all kind of folks wanting special favors for this or that. I'm curious if you actually thought any about those issues. Thank you very much

I wasn't involved in the project, but the geo lines were fabricated into the concrete sewer pipes. It's not impacting the flow... at least as long as it's not freezing the water. I too hope the engineers involved thought of all of that.

If you google "sudbury geothemal sewer lines" the second link down gives some info on the project.

[glennac]

I wasn't involved in the project, but the geo lines were fabricated into the concrete sewer pipes. It's not impacting the flow... at least as long as it's not freezing the water. I too hope the engineers involved thought of all of that.

If you google "sudbury geothemal sewer lines" the second link down gives some info on the project.

Understood. My post was really directed at the OP. Thanks for the reply.

[grizzzlle]

Please calm down glennac. Yes the OP (me) has thought about some of those issues. First you must know my backroud. Working with and designing those hydraulically engineered sewer lines is how I make a living. To say something that is occupying space in a line would deminish capacity is a blanket statement and is false. It is not unusual for a 21" pipe to only have a couple inches of flow in them for most of the year. During heavy rains yes flow might increase to half or more flow in the pipe. It is something that would have to be evaluated when looking at a line.

As far as not being allowed to tap into a system I have already asked about the idea and some interest has been shown. I need to get more information but am busy doing something else at the moment.

Pandoras box was opened years ago. Currently there are agencies that do rent (for a lack of a better way to describe it) there sewer infrastructure out to other utilities as a way of not having to dig up streets.

I am also not to conceded at the moment with how to install something in the sewer pipe. That would be a discussion farther down the road when trying to figure out different methods for the transfer of heat. Currently you would be surprised what gets shoved into a system on daily basis. There is an entire industry centered around it.