DIY ventilation heat exchanger

TimSmall · 12-14-12, 11:58 AM

So, as far as I can see, this problem can be split broadly into two different areas:

1. Heat Exchanger (plus housing, condensate drainage, duct ports etc.).
2. Fans
3. Control system (fan balancing, condensation control, CO2 control, noise control, freezing mitigation etc.).

There are quite a few different possibilities for the heat exchanger and enclosure, and the fans - and the optimum solution for each project will vary according to quite a few project-specific factors, it should be possible to make a pretty good universal (and I would prefer open-source) modular control system.

I'm thinking of buying an off-the-shelf exchanger, and doing the rest myself.

Why?

At the moment, there are hundreds of companies worldwide making their own units (a few big players, and many small ones). They all write their own control systems (or don't have on at all, just "dumb" speed setting). This sort of reminds me of the market for "small" computers in the early 80s - they all came with their own software, and overall the cost was high and the quality poor. Unless you were a big customer, modification of the operating system was expensive (and possibly difficult / inconvenient, or even impossible).

Here are just a few of the features which I think we could all have with a good open source system, some of these are present in the best commercial designs, but none of them have all those features...

. Automatic fan speed balancing to overcome external wind conditions, duct resistances etc.
. Intelligent condensation control (based on dew point calcs)
. Speed adjustment to minimise energy usage and noise

Those would be an excellent start, and you can quite easily spend lots of money on units which don't do all of those. Once you have that, you could add in:

. Internal air quality control via CO2 sensors
. Freeze control and recovery
. Realtime efficiency calculation
. Error alerting (fan failures, efficiency loss etc.)
. Remote dampers or auxiliary fans
. Noise control (based on time of day)
. Multiple sensor options (built-in, or remote, wired or wireless)
. Filter / duct cleaning reminders based on volume
. Summer cooling (over-night heat exchanger by-pass options etc.)
. Decent user interfaces (control panels or Android, iPhone, Web) and data logging options

Some of the higher-end models have some of those features, but I bet that none of them have all those features, and if the software became good enough (and was correctly licensed), then commercial manufacturers (especially the smaller ones) may well even pick up the software and begin using it themselves...

Any thoughts (overly ambitious maybe?

)

Tim.

12-14-12, 11:58 AM	#11
TimSmall Geek about the house Join Date: Dec 2012 Location: Brighton, Great Britain Posts: 17 Thanks: 0 Thanked 0 Times in 0 Posts	So, as far as I can see, this problem can be split broadly into two different areas: 1. Heat Exchanger (plus housing, condensate drainage, duct ports etc.). 2. Fans 3. Control system (fan balancing, condensation control, CO2 control, noise control, freezing mitigation etc.). There are quite a few different possibilities for the heat exchanger and enclosure, and the fans - and the optimum solution for each project will vary according to quite a few project-specific factors, it should be possible to make a pretty good universal (and I would prefer open-source) modular control system. I'm thinking of buying an off-the-shelf exchanger, and doing the rest myself. Why? At the moment, there are hundreds of companies worldwide making their own units (a few big players, and many small ones). They all write their own control systems (or don't have on at all, just "dumb" speed setting). This sort of reminds me of the market for "small" computers in the early 80s - they all came with their own software, and overall the cost was high and the quality poor. Unless you were a big customer, modification of the operating system was expensive (and possibly difficult / inconvenient, or even impossible). Here are just a few of the features which I think we could all have with a good open source system, some of these are present in the best commercial designs, but none of them have all those features... . Automatic fan speed balancing to overcome external wind conditions, duct resistances etc. . Intelligent condensation control (based on dew point calcs) . Speed adjustment to minimise energy usage and noise Those would be an excellent start, and you can quite easily spend lots of money on units which don't do all of those. Once you have that, you could add in: . Internal air quality control via CO2 sensors . Freeze control and recovery . Realtime efficiency calculation . Error alerting (fan failures, efficiency loss etc.) . Remote dampers or auxiliary fans . Noise control (based on time of day) . Multiple sensor options (built-in, or remote, wired or wireless) . Filter / duct cleaning reminders based on volume . Summer cooling (over-night heat exchanger by-pass options etc.) . Decent user interfaces (control panels or Android, iPhone, Web) and data logging options Some of the higher-end models have some of those features, but I bet that none of them have all those features, and if the software became good enough (and was correctly licensed), then commercial manufacturers (especially the smaller ones) may well even pick up the software and begin using it themselves... Any thoughts (overly ambitious maybe? ) Tim.