HVAC in NZ / Australia

[Kiwi]

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[rirvine]

Hi David,

"Most" HAVC systems work on a very simple relay type connection. On a HAI Omnistat RC80B (that I run) it's simply R and W = Heat on. R and G = Fan, R and Y = Cooling.
There are heaps of different brands and models, just have a look at the Thermostat you can get with the system. Forget the "Computer Controlled" ones as the smarts are in the thermostat. Find the most basic thermostat that'll work with the system you want. Have a look at the back of it. There could be any number of connectors but for a heating system look for R and W terminals.

I don't think you're going to get a "list" as there are too many variables. Don't take "Oh, you MUST use our $500 thermostat on this system" line as they're probably just trying to sell their own stuff. You really need a good HAVC person who knows this stuff.

For my house I was lucky enough to still have the Heating manual which included a wiring diagram. So with that and a multimeter I was able to work out what I needed.

If you have a separate heating and cooling system and want to use one thermostat you'll need an isolation module so one 1 system powers the Thermostat, while still allowing it to control both systems.

Doesn't really answer your query, but might be some useful info.

Ross.

[andymorgan1]

Hi Ross

Could you explain how these thermostats work? I would be looking to only use it for heating. Is the thermostat all you need? Is it just a straight swap over with the existing thermostat or is other hardware needed?
Any advice much appreciated!

Andrew

[rirvine]

Andrew,

I sort of did explain in the previous post. I knew nothing about HAVC before I decided to purchase an HAI Omni system and replace my thermostat with a HAI one.
I was lucky in a way, my existing thermostat was an old mercury switch manual type. I also had the wiring diagram for the heating unit, so with that I was able to work out what did what, and how to make it work.
The biggest problem you face is the concept of a "common" wire. The RC80 thermostats "steal" power for the wires going to the thermostat to power itself (they are not normally externally powered, however they can be if needed).
I could go into detail but, every install would be different. If you don't want to take the chance to blow up your heating unit or you're not too good with a multimeter then get a HAVC person to do this for you.
There is nothing "special" in a way, how the HAI Thermostats work, Eg Thermostats are Thermostats. (Communication to them is a separate serial connection). The only thing to keep in mind is the ability of it to "steal power" if there is no common wire. Worst case, you can power the thermostat via an external power supply with a bit of messing around.

Send me your email address and I'll email you the User and Install manual for the HAI RC80's. Just reading through them will allow you to get a better understanding on how they work even if you don't use an RC80 in the end and go for an RCS Thermostat, you'll have a better understanding.

Regards,

Ross.

[andymorgan1]

Thanks Ross

I also had a mercury thermostat but I replaced it with one which had a timer from RS Components which is good, but nothing like being hooked up to Homeseer!!! Hopefully the theory is the same....
My email address is andymorgan1@iprimus.com.au
Again, thanks fir your help..its invaluable

Cheers

Andrew

[applecity]

Hey Kiwi,

Since you mentioned the RCS brand thermostats I assume they are available in New Zealand. If so then you might find it helpful to know that the ELK-M1 does support RCS thermostats. You can inteface with up to 16 thermostats. Hope this helps.

[nscott]

Andy,

I think I have a very good understanding of what you have and how to hook it up.

Get in contact with me directly and I will step you through how to set this up.

Cheers

Nick.

[andymorgan1]

Thanks mate...once again I'm sure you will come up with the goods!!!

Andrew