posted 4 hours ago
So a heat pump works better when the gass or liquid it is stealing heat from is warmer.
A brief search shows that the average temperature of municipal sewage is 50° to 70 ° F.
I'm gonna guess that the air in the system is a similar temperature.
This gives me some crazy ideas.
-An air sourced heat pump that gets its air source from sewage vents.
To avoid breaking the liquid seals in the traps we would put in as much air as we extract.
-A liquid sourced heat pump that draws heat from grey water heals in an insulated tank.
Held greywater tends to turn into to black water, but aeration can prevent that.
-A liquid sourced heat pump that draws from a counterflow heat exchanger.This could be the least efficient.
I think the air sourced pump could be better because it will get cooler temps overall which will help for cooling, plus no tank of dirty water to deal with.
In a house that has city sewage but doesn't use it, there is way more leeway for such a system.
In house with a septic system, there is already a giant underground container of dirty water.
This could be a place to put a coil.
