Arduino powered home environmental system

[Daggy67]

I hope to reveal for myself, and others who have interest in this venture. The process at which the following is transformed into Homeseer to be used for making decisions to run the fresh air heat exchanger that brings fresh air into the house and exchanging the fowl air. By stripping from that air the invaluable heated or cooled entropy from the discharging volume of air back onto the fresh makup air as it is returning into the house.

When and for how long is bases on indoor and outdoor conditions that include temperature and relative humidity, perhaps including indoor air quality measurements and weather information too. Changes in the house when cooking, cleaning or working require the air to be drawn from the affected areas using home made dampers that I have and will be crafting using servos.
By using some of the existing duct work that may also require running new ducts to areas to extract the offending air at its source. I have not worked out the logic yet but for the climate I am operating in, it is very different seasonably and acute when weather patterns change.

For starters I'm trying to get relative humidity values with a mix of an analog signal from a 0-5 volt sensor that is nearly linear however the response from the sensor has a starting value that is above 0 volts so this introduces a voltage offset to the output, and it has a slight non linear response that gives it a slope as the voltage goes up the output tends to be less positive not straight towards the top 5 volt.
This sensor would be the Honeywell HIH400-003 analog sensor. These calculations to its final presentation will give you the humidity at 25*C.

If I want to measure humidity at different temperatures and create a result with a more familiar scale such as relative humidity (RH) the co-efficient of the DS18B20 1Wire temperature sensor needs to be introduced and the math worked out and a new result presented as a whole in Homeseer.

The experience gained here can be applied to other sensors doing other tasks, but for me this is home automation, and I could have easily purchased a humidity sensor, but that is not what I have to work with and the lessons hear will be invaluable to other exploits.

My experience with writing strings and such begins here, and for some others I would imagine the same.

I hope to catalog my experience here because home automation, to me, is creating an environment that improves ones feeling and health aside from greeting you home and setting in motion your desires. For this one aspect it is with indoor pollution and activities building up with in the envelop called home and then having set in action the heat recovery unit, allowing the crisp clean air from outside to permeate the house on a cold winters day makes for an invigorating boost to the senses. You can smell it like crisp linen.

As I stated with the changes to seasons the use of air conditioning and the summers humidity and heat will also, if not monitored with the logic of homeseer, suck energy and adversely make the indoor experience uncomfortable.

Please help me in reaching my goal and with my past experience with HVAC and electronics I will share. I hope you will be able to help me over the hump of code and strings that I do not understand to make the reality of Homeseer the robot that I do wish to create by way of the Arduino pluggin and more, to be the servant that make home automation what it is. This is but one of my pursuits and I hope others will take interest in doing the same.

I hope to supplement my progress with video and this thread.

[Daggy67]

[Daggy67]

Isolation HRV air damper Arduino servo powered

I made this isolation damper to inject the fresh air into the furnace make up air duct(see attached).
Best practices is to isolate it from the indoor system If it is connected right into the duct it will draw air through the make up unit and pull air from outside when the fan of the furnace is running. It opens when the event runs, and closes for regular furnace heating and cooling operations are not concurrent to the fresh air request, but that might be a good time to initiate it and Homeseer can do that.

So I built an Arduino powered damper using a servo and provided an air gap to isolate the 2 different air streams.

To power the servo I'm using a parallel 5 volt power supply I built from an old PC power supply and used a regulating switching power supply on the 5 volt rail to keep it at 5 volts.

Right now I have homeseer running the event every 2 hours. When the event runs it opens the make up air valve to 90 degrees, and turns on 2 digital outputs that activate each of the isolated relays that switch the furnace fan to high and turn the make up air unit onto high. I need to update this in Winter.

I just found that the valve stopped working and the servo has burnt out. I think it is because I'm getting jitter every time the communication light flashes on the Ethernet connected Arduino the servo spasms. I will need to put a relay in to only power the servo when it is in operation to open the valve unless there is something in the code that can be fixed so it is not always re-positioning itself or so called jitter.

I have the make up air unit running on low when there is no call for fresh air, it switches to high when the event runs and the relay calls for it, but with winter coming I will need to put an isolating relay on the power plug of the make up air unit to turn it on and I will need to make an event to run it on low from time to time and only turn on the fast when I have a reason too like too much humidity, cooking or a lot of people in the house.

I built the damper from parts I had kicking around, and since this was a transition from 6" to 5" it was a challenge due to the off set. There is lots of power in the servo to overcome the plastic bushing I used to tighten the hole around the stud on the do it yourself type valve you buy in any hardware store.

The biggest problem in the winter is when the heat exchanger freezes up due to the moist air inside freezing. The HRV (heat recovery ventilation) senses this and only runs the output fan to defrost. The 5 pipe does it different.

There are other models available that have an extra vent to circulate indoor warm air to defrost the heat exchanger. It has 5 pipes that connect to it. The one I'm using has 4.

[ServiceXp]

Please don't take this the wrong way, but your posts are too difficult to read.

When trying to explain complex processes you might want to think about using more punctuation with good paragraph structure.

[S-F]

Please don't take this the wrong way, but your posts are too difficult to read.

When trying to explain complex processes you might want to think about using more punctuation with good paragraph structure.

I agree. I am particularly interested in this project from both a professional and personal stand point. I'll be installing an HRV in my house this winter.

[Daggy67]

I'm having trouble with the math to derive relative humidity.

I'll don't know how to get the math of 2 sensors to show as a new device if anyone knows how to do that. The servo burnt out and every time the light on my Ethernet board flashes the servo resets or jitters, it lasted for about 6 months. I can use a relay that will have to trigger first before setting the valve not a problem.

I'm going to build some more straight thru not reducer dampers. I'll post how I do that it is simple and cheap. You shouldn't hook up the HRV output (make up) air directly into the furnace it will draw air from outside when the fans are not running on the HRV and the fan on the furnace will chill the exchanger and it freezes sooner.

The filter gets real dirty on the furnace too, I built a pre filter box for the fresh air. Those are the things I've learned. Indoor humidity and outdoor humidity in the summer needs to be considered before running because it will swamp the house with humid air that is why RH is important.

I have 6 1 wire temperature sensors measuring the 4 different chambers in the HRV and the cold air return and hot air out on the furnace. I've used different lengths of wire with no problems. I want to graph the relationships so I can see the effects and that will help set the amount of time to run the HRV. I have another sensor that will measure CO and I want to see if I can actually see the change in fresh air and the air going out.

It is a mix of analog, digital and 1 wire information. I have a valve on my humidifier that dumps the water every week and allows fresh water to prevent harm to the water in the dish. I get an email to tell me so I can go check and make sure the float didn't stick.

I hope to expand on this with zones to target the source of offending air like cooking. I will have to run a return path thru the wall cavity to get at it. I will use Aduino powered servo damper to direct it to that source when called for. I have thought about this a long time and with the Arduino plugin being so rock solid I'm convinced it is the right platform to develop these ideas.

I can expand on any of these if you want. I'll take the time to show how I consider and do things as I build it. Feel free to comment and make this into an easy to follow how to. I'm not a coder, but electronics, home building and HVAC I'm very good with. Hardware is my thing, I need help with the software. Thanx for the comments.

[Daggy67]

HRV 1 wire data and filter box

This is a picture of the HRV plus the filter box for the fresh air, and you can see the one wire temperature sensors in the corners.

They are the silver 1/4" tubes I got from Bangood. Less than $4 with an 18" lead.

I have had no problems with 1 wire data. I have 2 others, parallel to the 18" runs that are 8 feet long collecting the furnace duct temperatures for a total of 6 that run back to the Arduino on a 12 foot cat5 cable. I put the resistor to draw current through the cat5 cable, to make the communications more reliable at the junction point where all the sensors connect, I would call it a star network. There has been some talk about unreliable communications and best practices for 1 wire. I have had no errors and the plug in has been rock solid.

I am going to build the isolated relay 120VAC plug switch box so I can plug the HRV into it and have Off-Slow and fast speeds to control the HRV. This will also travel thru the cat5 since it is a 5 volt isolated relay that uses 12VDC to trigger the relay (more on that principle)

I will need to add the humidity, CO sensors, to this ethernet arduino and I hope to place a remote outdoor temperature and humidity with another arduino outside. Hopefully the weather holds and I can get that remote station working before the snow. This is my very next project to do.

[kriz83]

Very interesting indeed.

But please add some paragraphs (enters) to your texts to group it a bit. It's just one bulk of data/text right now ...

[Daggy67]

I'll take that into consideration and it is a learning process and I will get better at it. I'm glad some people have an interest in this same en devour and we can work the problems out and share best practices.

I have a lot more to offer and some build video will help. I'm planning on building some more air valves.

I did a test last year with the condensate from the HRV and found I could use a 12VDC heat pad on an aluminum pan and almost bring that water to boil to re-introduce the moisture back into the air. The benefit is there will be no hard water deposits however this could cause a fire if it got out of hand. Figuring out when to run the heater by water level is a challenge I don't know if I should use an ultrasonic sensor or a capacitive level sensor. It took a lot less power than you would think. I also need to sort out a way to prevent spills if it didn't run.

Has anyone got anything to offer in regards to the math and RH? How do you do that get another device that displays the calculation.

I have never done that before. There is a analog math part in the Arduino plugin config and it seems as soon as I change the brackets on (value) the calculation goes impenitent, but there are certain steps that need to be taken in the calculation that needs the brackets. Besides another reference to the 1 wire temperature sensor.
From what I understand I need to reference that value some other place and by way of a string insert the calculation. I have a lot to learn about that.

[S-F]

Seems to me that using a heat pad to reintroduce your condensate to the house in the winter isn't a good idea. Why not get an ERV instead of an HRV? It will probably cost more to run the heat pad than you will save with the heat recovery. If you have low humidity in your house your house is excessively leaky and probably doesn't warrant either device.

Air seal your house so you save energy. Then the HRV will be necessary to, among other things, remove the excess moisture.

[Daggy67]

In the winter below freezing the air coming in has no moisture or very little -20 is very dry. Exchanging the heat to the cold air coming in is the H in RV. The air going out is laced with 72F moist air and when it contacts the freezing exchanger it will condense on the very cold exchanger and builds up. The HRV recognizes that and goes into defrost mode.

That is the difference between the 4 and 5 pipe system, the 4 pipe just pushes warm air out slow to defrost. The 5 pipe system you put the other pipe near a source of heat and it draws air through it instead of pushing air outside by way of a deflector valve.

I measured the current at 24 volts was 2 amps 48 watts started to steam in about 10 min. The only reason I considered it because I have very hard water with a softener but I still get a lot of scale in my humidifier. When running the HRV it will dry out the house in the winter in my area. The condensate will have no minerals. I was suprised how quick I could boil the water off 1 gal'n took less than an hour that is 48 watt hours. I can't remember if I bumped it up to 24 volt when I tested but I will use those values

Its just another process I considered Homeseer could do, but I'm not that desperate at this time, I have enough to figure out. When I switch to solar it could be a deal breaker.
The house is sealed very tight and is the reason for the HRV. The building code requires it because of air quality in the winter with the increased building envelope seal.

[ServiceXp]

Couple of questions:

1) Where do you live?
2) What type of heating/cooling system do you have?
3) What type of thermostat do you have?
4) What are your goals. (Winter RH reduction? Indoor Environment etc??)

I know you want to do this 100% Arduino, but there are a few items you really need to consider.

1) The biggest is the use of an HRV, vs an ERV. If you are in a colder climate you are fine using an HRV, but if you are in a warmer climate you really need to consider an ERV.

2) You need to use a manufactured gasket-ed damper. You can still control it via the Arduino and a relay. You are most likely going to burn up servo's and continually leak air with a homemade damper.

3) The ASHRAE calculations for fresh air exchange is no trivial matter. Please refer to this .pdf for help.

[ServiceXp]

In the winter below freezing the air coming in has no moisture or very little -20 is very dry. Exchanging the heat to the cold air coming in is the H in RV. The air going out is laced with 72F moist air and when it contacts the freezing exchanger it will condense on the very cold exchanger and builds up. The HRV recognizes that and goes into defrost mode.

The RH of 'winter air' is generally fairly high. It's only when the cold air expands (introduced into your warm house) the RH drops to unacceptable levels.

Even in homes where the RH is very low < 30% there will still be a need for a defrost cycle because with plate temperatures under 32F the moisture will freeze.

[Daggy67]

Couple of questions:

1) Where do you live? Woodstock Ontario, Canada
2) What type of heating/cooling system do you have? -Carrier
3) What type of thermostat do you have?- top of line with a serial t-stat
4) What are your goals. (Winter RH reduction? Indoor Environment etc??) I have had installed this when I moved into the house 9 years ago. I want to build a set of parameters that recognizes when and how long to run it for. Target the areas producing cooking smells and humidity at the source. so it wont spread in the house and have to run very long when it is very cold or humid outside by Channeling it to the HRV exhaust with the air valves.

I know you want to do this 100% Arduino, but there are a few items you really need to consider.

1) The biggest is the use of an HRV, vs an ERV. If you are in a colder climate you are fine using an HRV, but if you are in a warmer climate you really need to consider an ERV.

2) You need to use a manufactured gasket-ed damper. You can still control it via the Arduino and a relay. You are most likely going to burn up servo's and continually leak air with a homemade damper. CND dollar $90 v.s $20 a little leakage is ok. The exchange rate is a factor. The servos work fine, but the jitter should happen I think it is in the code. I can use a relay and make a global command when it needs to move to supply power by way of a relay. I'm not using a spring like the factory built ones.
The Link is you gave is for consideration in large buildings , I don't think I could do the math to fugue if I got it right or wrong. I have found if the HRV runs for the right amount of time under certain conditions outside it is a big difference in the home. I want to target those parameters and make Homeseer decide when and how long to run based on feedback from sensors. I will study it and gleam the factors that dictate those decisions Thank you

3) The ASHRAE calculations for fresh air exchange is no trivial matter. Please refer to this .pdf for help.

I use the furnace for humidity calls, because it has an outdoor temperature probe and make decisions about RH vs. outdoor temperature so my windows don't condensate. So I use a relay to know it is trying to restore humidity back to the proper level so the HRV shuts down, but certain calls will allow it to run. The furnace also has a de-humidify function that will use the AC, but I don't think it will run when it sees it is so cold outside for fear it will damage the AC unit I probed it and it never turns on, so I need to use Homeseer for that part.
Thank you for your help. Are you running a HRV-ERV?

[ServiceXp]

You are welcome. I'm an HVAC/R technician and have a fair amount of experience on the topic (USA), although using mfg products mostly Honeywell and EWC.

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