Control Central A/C Units

Other Devices & Integrations Climate Control & Temperature Sensors
1

Hello,

I am interested in the control of central air conditioning A/C units using zwave.

Can you tell me how it would be possible to control several central A/C units in a house (3 floors house with 1 or 2 in each floor) ?

I was thinking of the SRT321 thermostat in combination with the SSR303; however, I was checking with an aircon specialist here and he was saying that the SSR303 would not work since central A/C units here are powered by 24V and they use some transformer to get that, but I think he was lying and just claiming that because of fear of competition of some sort. I really do not know anything about airconditioning and central A/C, can you tell me how practical it would be to use this SRT321 and SSR303 combination to be able to do this?

If it is not possible, what other option is there ? I do NOT want just to turn on and off, I want full temperature control.

Regards,

2

I am not sure I understand your question, because there are many thermostats that are controllable from the Vera (using Z-Wave or other means) that can all control central A/C. A typical thermostat (in the U.S.) does use 24 volts AC (alternating current). If you have several typical central AC units in this house, then you have many many options. If, however, you have some atypical central A/C system, or if it’s not actually central AC but instead individual, isolated units, then there are different, often less straightforward options. Please provide more detail and I’m sure someone here can give you more useful information.

Regards,
watou

3

I am really sorry for not being very clear but as I said my A/C knowledge is very limited, I just quoted the aircon guy with what he said but let me try and explain how this is setup in our country usually.

In the floor of each home, depending on the size, there would be one or 2 A/C units (not window ones), big large units that are usually hidden in the false ceiling above the bathrooms or kitchens and ducts go from it to the several rooms in that floor and you can change the temperature from local thermostats on the walls. These thermostats are connected to receivers that controls a contactor that in turn controls the main machine, usually the contactor is 24V alternating current powered and they set up a transformer from 220V to 24V to do that.

The SSR303 receiver operates at 230V so I dunno if it can be used with this setup in combination with the or not and I do not know any other european standard products exists to do so, this is a very important thing for me and I hope someone can advise on how to solve this…

Regards,

4

No worries – there are many different combinations of equipment and vendors and it can be confusing for anyone. I am not the most knowledgable person to give you input, but I expect that someone here will chime in if they have firsthand information. I hope you can Z-Wave-ify your setup! All the best, watou

5

Your Aircon guy is NOT lying to you.

The SSR303 needs Line Voltage (250 V) for power. It has and independent (isolated) relay so it can control your 24V Central Air.
But you will have to get LINE power to the theremostat … Since the Aircon guy indicated that only 24V is run to the thermostat (Which is typical).

The SSR303 is really designed to be a Line Voltage HEAT thermostat.

6

There are 24 V Z-Wave thermostats … I am not sure if they run on the Z-Wave frequency for your country.
Maybe a NEST thermostat (Wifi) … but I do not know if NEST supports NON US clients.

7

[quote=“RichardTSchaefer, post:5, topic:178569”]Your Aircon guy is NOT lying to you.

The SSR303 needs Line Voltage (250 V) for power. It has and independent (isolated) relay so it can control your 24V Central Air.
But you will have to get LINE power to the theremostat … Since the Aircon guy indicated that only 24V is run to the thermostat (Which is typical).

The SSR303 is really designed to be a Line Voltage HEAT thermostat.[/quote]

Thank you for your reply, can you please tell me how can that be done if i manage to get the 230v (as per the manual) to the SSR303 ? If you can sketch up a diagram of some sort I would really appreciate it, the aircon guy is refusing to check it he is just saying it is not possible, he thinks the SSR303 does not give back 24 V, does it? Documentations says nothing I cannot really tell …

8

from the sound of it, SSR303 will not work for you. What brand name is your Central AC? Trane? do you operate it using a thermostat (what model?) Which country are you in (because Z-Wave frequencies are different in different countries)?

I suspect you have a 24V Central AC, if that’s the case, you need one of the Z-wave 24V thermostats like Amazon.com, however this uses US Z-Wave frequency, which may not be right for your country. So more info is needed from your part.

9

I am in the middle east so I lie within the european region and would need something working at the 868 MHz frequency, I am not able to find any and when I got the SSR303 I was not aware of the 230VAC and 24VAC issue (no A/C knowledge whatsoever) and I was told by the zwaveeurope person that it can work but maybe he did not even know of the 24VAC issue.

The temperature range on the SSR303 is 5 till 30 celcius so it can support cooling I reckon; however, the power issue remains.

There is no specific brand of central AC that I might have to work with, it is probably mixed so I cannot really know but I do know they always have a thermostat to control them locally in the rooms or sections of the house at least.

10

If this is AC Only, Not AC and HEAT … then the thermostat will work. It can be used for either.
But you will have to run power wires (230-250 V) to the thermostat as well.

11

You probably need something like this: http://shifrasmartdistribution.com/product_info.php?cPath=24&products_id=74

disclaimer: I personally haven’t used this type of thermostat but based on the assumption that you have a Central AC with 24VAC, the specs for this thermostat seems to match what you need well.

12

You probably need something like this: http://shifrasmartdistribution.com/product_info.php?cPath=24&products_id=74

disclaimer: I personally haven’t used this type of thermostat but based on the assumption that you have a Central AC with 24VAC, the specs for this thermostat seems to match what you need well.[/quote]

Thanks capjay; however, I had already come across that products and as you added that disclaimer, you would know that it does not seem like a very legitimate products, no information is mentioned, no datasheets, no certificates of conformity, no mention on zwavealliance as an accepted product, nothing and to top that, it is ridiculously expensive. I would not risk getting a product that is probably just assembled in china without any proper testing, A/C is critical in a country where most of the summer days are 40+ celcius .

[quote=“RichardTSchaefer, post:10, topic:178569”]If this is AC Only, Not AC and HEAT … then the thermostat will work. It can be used for either.
But you will have to run power wires (230-250 V) to the thermostat as well.[/quote]

Thank you again for replying, and please excuse my ignorance but I really have no knowledge regarding this and I am a bit confused with what you said.

First of all it is just A/C, no heating is required, heating is usually just in very rare special cases that I will handle separately in that case.

As for the confusion, it is just that when you refer to the thermostat, do you mean the SSR303 or the SRT321, since the latter is battery power and from my understanding just offers an interface for the users to choose temperature from but the SSR303 is the one that needs power wires (By the way would 220V be okay?) and it communicates with the contactor of the machine in place of the old regular thermostat.

Regards…