HVAC Diagnostics

I recently competed a HCAC Monitor kit and am trying to confirm that it is operational. I couldnt get it to be reccognized by any software that I have so I checked the board for problems. I found one solder bridge on the DS2450 and fixed that but still no recognition. I have tried the one wire viewer and MCSTemp using a DS9097 and DDE Server uswing a HA4B. Do you know of any other way to check that the DS2450 is operational? B)

The OneWireViewer should see it if it is on the network. You could try checking the solder joints again and check the wiring to the device.

I will try to give more tip later but I'm on my laptop at a local WiFi spot because hurricane Katrina has taken away my power and my battery is not going to last long. You would think being 200+ miles from the coast would keep me immune to hurricanes but this is the 3rd one on a year to take out my power.

Wow, what service; in the aftermath of a hurricane you are at a wifi spot answering customer questions. I got the HVAC monitor working.
I found I had reversed Diodes D1 and D2 and once that was fixed the HVAC monitor is up and running.
FYI, and for the benefit of other users, I can see it in One Wire Viewer but no values. On my HA4B using one-six DDE Server I get all the values. Finally Michael McSharry has implemented it on MCSTemp using a DS9097 and the values can be charted using his program, which is a plugin to Homeseer. The values don't equate to real voltages which is fine because I am only trying to look at the trends and differences. For example with no voltage applied the data reads .05+-, when I apply 5v DC the data reads .40+- and 12v DC reads 1.02+-

By the way the circuit board labels for the terminal strip don't correspond to the schematic labels, but it was easy enough to figure out using the schematic.
Thanks for your support and I hope you and your family were not too inconvenienced by Katrina.


Luckily we didn't get any damage at the house, just no power or Internet, so it could be worse (like New Orleans). Also when you sit without power or Internet too long you want to get out and go somewhere so why not a WiFi spot and check email :)

The values were never meant to equate to actual voltages. I created it originally for my own use since the RCS thermostat I have doesn't have a way to determine runtime of the HVAC unit so I wanted to just be able to tell if the thermostat was calling for heat, cool or fan. Glad you got it working.

I will have to check out the schematic, sorry about the confusion.

Out of curiousity, can you describe how you implement your HVAC monitoring.
I do heat my house with fuel, and with the cost I think I will start monitoring closer.

I'm curious about the hardware side, because it seems you manage it via windows, and
I'm on the dark side of Linux.

Thank for any pointer and feedback

Since moving to my new house I haven't had a chance to get mine going again. But as for the software, any software that can read a DS2450 would be able to get the values back from the HVAC monitor. If you hook the HVAC monitor in parallel with the thermostat, then when you see voltage then the system is not running and when there is not voltage detected then the system is running.

Does that help?

yes and no

I understand now how you detect if the system receive order to start, but
unfortunatly with my configuration, that cannot work. My thermostat is connected
to an electronic card, which do manage the docking fan. The fan is running at low speed
all the time, and will go to high speed if there is heating request for more than 5 minutes.
In that 5 minutes time frame, it inject hot water in the coil, to see if the temp will increase slowly ( I have a water/air exchanger in my dock ).

What I would like to monitor is the furnace burner. I know how many gallons/hour it does burn.
I'd like to count the amount of time the burner is running, to estimate my fuel consumption.
So if I could monitor if there is current running on a 120V line, this would do the job.

Any hint.

Well for your application it doesn't look like the HVAC Monitor will work. You could do a search for current monitoring and 1-Wire. I know that I have seen in the past some people doing current monitoring with 1-Wire but I can't remember where I saw it.

I will let you know if I come across it again.

That's what I'm looking for. Sadly, I just order them a link last week-end

I also found another solution.
What I need to know is when the burner is on or off.
I could put a light on the burner electric wire, and when the burner relay will be close, the
light should be on. With the solar sensor, I should detect light, and know when the
burner will be on.