Pros and Cons of two Zwave networks within one HA installation

Configuration Z-Wave
1

Dear community, I have a 2 categories of Zwave devices that are running on one Zwave network. This are switches, dimmer, roller shutter, door strips and thermostats. However the thermostat are very chatty within the network (HeatIt TRM 3) and as a result they causing a lot of traffic and hence delay commands to switches and roller shutters.
While I couldn’t figure out how to reduce the traffic but also for network organization( I want to keep the “essential” devices like switches,dimmers secluded), I want to setup a second Zwave network to achieve the split. All devices are on EU frequency.
Seeking advice here if that would solve my latency issues experienced with the chatty devices.
From a “messing up” perspective, keep the essentials to themselves while experimenting in the other network, I can see the value.

Thoughts?
Note: I have looked up the posts but didn’t find a good answer. If I overlooked something pls link it her

2

The two networks may interfere with each other.

What model thermostat?
maybe replacing with matter thermostats or other zwave thermostat is better option.

zwavejsui has a poll feature. maybe limit to polling or maybe there is a setting to reduce the tx/rx of the thermostats.

EDIT
I see you posted the model of the thermostat

3

With some googling, I see that Heatit is active in some communities.

I specifically see them in community.homey.app threads. Found a couple thread where they were making changes based on communication in the threads. Maybe find a contact there to discuss your specific issues.

I don’t see a user for them here. Maybe hit them up on their website too.

I agree with @tmjpugh that a second network would also suffer from chattiness.

4

The two network will interfere, but that is not the worst.
The worst will be that the thermostat network will not have any router nodes, because they are all left on the other network.

1 Like
5

I have four z-wave controllers in my house. Two are used in Home Assistant, one is in a Ring alarm, and the other is on a test machine. I’d be curious how often their radios are transmitting when there’s not explicit traffic (related to change in state or reporting meter data).

I doubt having an extra controller would help in your case – if not make it worse – if the real issue is too much traffic already.

I have about 70 devices in Home Assistant, and traffic doesn’t seem very bad. I did have to configure my “meter” devices to send on larger changes and reduce periodic updates.

This is probably a worthless bit of info, but here’s how big my zwave log was yesterday, which might give an indication of level of traffic.

# zcat zwavejs_2025-06-28.log.gz | wc -l
160068

# zcat zwavejs_2025-06-28.log.gz | grep GetBackgroundRSSI | wc -l
5711

And on my secondary controller that only has a few nodes:

# zcat zwavejs_2025-06-28.log.gz | wc -l
35172

# zcat zwavejs_2025-06-28.log.gz | grep GetBackgroundRSSI | wc -l
5760
6

This was my opinion

Solve the thermostat problem vs create seperate network. Seperate network can work but may create new headache

On a side note. I added a lock yesterday and just happened to look at my logs. Noticed a switch was sending packets to controller every second. Didn’t impact network. The switch failed a year ago but it’s for unused room so never bothered to replace it. After seeing it constantly communicating I decided to unpower it. The chatty thermostat seems abnormal. I don’t think they are failed but if they are impacting network it seems really abnormal and maybe setting change can solve

7

From a radio point of view, having two networks will not cause any practical extra interference. The reason for this is that the protocol is already built around the standard “try to transmit, and if something else is transmitting then stop and wait” approach. This means the interference on a given frequency is a function of how often your devices transmit, not whether they are on different networks. You can put them on different frequencies to increase your total network bandwidth if you want.

There are two downsides to two networks: 1) nodes will not transmit through the nodes on the other network, so you will need to make sure each network has enough routers, and 2) the overhead of maintaining two zwave networks in Home Assistant.

I do exactly this with Zigbee: I have one network for about 60 lights that are often disconnected at the mains from wall switches and one network with about 40 switches and plugs. This means that when the lights get turned off, they don’t cause the network for the switches and plugs to lose connectivity. Both networks are on the same frequency, and it works fine.

-David

8

This is called collision detection and it is not the same as collision avoidance, so you will interference, but I agree the difference will not be big.

9

Okay, thanks for all the comment. I think I will try to solve the chatty HeatIt devices. Need to dig around a bit to find some good post how to do it.

10

You mean not enough repeater nodes to build a stable mesh network?

11

Yes.
The devices do typical not have the best antennas and can be a bit easy to disturb with interference, so what you see as the best route might not be the real life case.