We have received City approval to install vertical GFX heat exchangers like the Power-pipe. They will recover 50% of the heat in the hot water used for a shower. The only problem is that they are 5 or 6 feet tall (there are shorter ones but they aren’t very efficient), and they have to be installed vertically. That means we can’t recover heat from a shower located on grade without pumping the drain water.
Today, my horizontal wastewater heat exchanger prayers seem to have been answered. EcoDrain claims their 30″ long horizontal heat exchanger will recover up to 40% of the energy in a shower. My first thought was “well, that’s going to clog immediately,” but EcoDrain thinks I should relax:
The contact area of the horizontal EcoDrain drain is coated with a very slippery environmentally friendly non-stick coating. This prevents anything from sticking to the device and makes it self cleaning. For further assurance, it is possible to purchase a hair cover for the drain which dramatically reduces the amount of hair that ends up in the drain.
A 4″ diameter vertical GFX heat exchanger can be installed on the main gray water drain leaving a house to recover heat from all showers, the washing machine, and dishwasher, but the EcoDrain is sized for a single shower at a time:
A single EcoDrain can be used for multiple showers provided the showers are rarely used simultaneously. There is a limit to the maximum flow on the supply side and also an optimal flow on the drain side. If multiple showers drain at the same time, there will be diminishing returns in terms of savings because the heat exchanger capacity may be exceeded resulting in some water just passing through the heat exchanger without transferring any heat.
That’s fine with me. Our clients should be washing clothes with cold water anyway, and the dishwasher doesn’t use a lot of hot water. The clothes washer and dishwasher are also non-coincident loads. They fill with hot water. They do their thing, and they drain later. You wouldn’t be recovering heat unless you happened to be running some water while one of them was draining. Showers are what we need to recover every time. The other fixtures are good to pick up if it’s not any trouble.
The horizontal EcoDrain fits in a box 30” long by 6” high by 2” wide. It is designed to fit between a p-trap and a main drain line under the floor of the shower.
The vertical EcoDrain is a tube of diameter 3” and length 30”.
Pressure drop is about 5 psi.
The larger GFX heat exchangers are probably the way to go if we have a basement because they’re more efficient, but EcoDrain will come in handy when we have a shower located in the basement.