Heat Recovery Systems

[iPlug]

Wanted to start a thread on what others are doing, have done, or are contemplating with heat recovery/heat exchanger improvements within their homes. Also, ideas about building code improvements in this regard as a matter of public policy seems worthy of discussion.

Nothing to report on my end, but suspect at least a few here would have much to contribute to a discussion on this topic.

 

[nwdiver]

Wanted to start a thread on what others are doing, have done, or are contemplating with heat recovery/heat exchanger improvements within their homes. Also, ideas about building code improvements in this regard as a matter of public policy seems worthy of discussion.

Nothing to report on my end, but suspect at least a few here would have much to contribute to a discussion on this topic.

I installed the 'power-pipe' in my rental in WA state. It does work really well... BUT... when you look at the numbers it really doesn't pencil economically for a regular family of 4 especially if you're using a heat pump water heater. The ideal use for something like this would be a hotel or apartment where the drains are used far more often than in most homes. It's been a few years since I ran the numbers but if you have a HPWH the ROI is ~25 years. If you don't have a HPWH it would be <10 years. Obviously there are diminishing returns if you use less energy to heat water.

The use case is also somewhat limited. The showers need to be on the 2nd level. Essentially because of the physics of the way it works the water needs to drain downward vertically. Even a slight slope would negate much of the heat transfer effect.

 

[iPlug]

Seems like most heat recovery systems would be most cost effective to install during new construction. Renovations are doable in many cases, but ROI is often poor. For those handy and enjoying such projects, maybe not a bad proposition.

I’ve wondered why more has not been done with clothes dryers. After HVAC they may be the next most energy intensive device in the house, probably close to water heating.

It would be great to recycle much of the lost heat of a clothes dryer. In theory this all could be built into a dryer, but would probably compromise too much appliance space. Exit air condensate would also have to be collected and pumped to the washing machine or other drain if gravity drainage is not possible.

If the heat exchanger were built into a wall behind the dryer during new construction, that would be ideal. Not sure this is done standard anywhere. Still, there is no standard air intake on clothes dryers.

Over the years I’ve searched for add-on heat recovery clothes dryer products, but really only have been seeing large commercial and industrial applications. There are some web pages of guys who have built their own. Of these, most utility rooms probably do not have adequate space.

Waiting for full (American) size clothes dryer heat pumps to catch up with the quality of the smaller international sized ones.