IntelliCenter with multiple ETI Heaters

[dw886]

So I was reading the installation manual on the ETI 400 heater, and it states that you can install multiple heaters in parallel:

The question that I have is about control via the IntelliCenter. It doesn't look like the ETI 400 heater has an RS485 connection, so it would have to be the fireman's switch.

Assuming a single temperature sensor connected to the Intellicenter and heaters are hooked up in Parallel as outlined above heating a single body of water, and that for control the desired outcome is that both heaters turn on together until the setpoint is reached, is it "ok" to connect both heater fireman switch connections to the Gas Heater (J2) port?

Later on in the ETI 400 manual, it has this cryptic statement (highlighted), and I'm trying to understand what it means:


I'm assuming that one side of the fireman's switch has voltage, so polarity would matter in this sitution, otherwise the power from one heater may be completing the fireman's switch circuit for the other heater...

 

[ajw22]

They are saying to wire up two external relays that are closed by the IntelliCenter heater connector and each relay closes the "Fireman's Switch" on one heater.

 

[dw886]

They are saying to wire up two external relays that are closed by the IntelliCenter heater connector and each relay closes the "Fireman's Switch" on one heater.

So are they saying to route this wire into the high voltage area of the box, and use those relays to activate it, or is there a better way to do this?

I was also thinking that since one of the sides of the fireman's switch is effectively going to have voltage (aka, be "hot"), only one connection from a single heater would be needed to the J2 relay, and the non-voltage side of both heaters would need to be connected to the other J2 terminal. Thinking this would do the same thing as well?

 

[ajw22]

So are they saying to route this wire into the high voltage area of the box, and use those relays to activate it, or is there a better way to do this?

No. You use two external relays and a transformer to power the coils connected to the J2 terminal.

Each heater connects to a relay.

I was also thinking that since one of the sides of the fireman's switch is effectively going to have voltage (aka, be "hot"), only one connection from a single heater would be needed to the J2 relay, and the non-voltage side of both heaters would need to be connected to the other J2 terminal. Thinking this would do the same thing as well?

That is not how it works.

Each heater had its 24V that needs to be kept separate.

 

[dw886]

No. You use two external relays and a transformer to power the coils connected to the J2 terminal.

Each heater connects to a relay.

That is not how it works.

Each heater had its 24V that needs to be kept separate.

OK, so in other words, add something like a RIB double throw relay, the J2 will tell the external relay to close, and the external relay will switch both fireman switches independently at the same time.

I'm guessing that depending on the relay, a person could use the 24v coming off of the intellicenter fused output that is provided for the valves? Maybe something like this: RIBM2402D - Functional Devices, Inc.

 

[ajw22]

OK, so in other words, add something like a RIB double throw relay, the J2 will tell the external relay to close, and the external relay will switch both fireman switches independently at the same time.

Correct.

I'm guessing that depending on the relay, a person could use the 24v coming off of the intellicenter fused output that is provided for the valves? Maybe something like this: RIBM2402D - Functional Devices, Inc.

My only concern with using the 24V from the actuators is that the relay specs do not indicate the current draw when the relay coil is energized.

There is the 24V DC 160ma connector used by the wireless antenna.

An actuator runs on 24V AC at .75 amps.

 

[dw886]

Correct.



My only concern with using the 24V from the actuators is that the relay specs do not indicate the current draw when the relay coil is energized.

There is the 24V DC 160ma connector used by the wireless antenna.

An actuator runs on 24V AC at .75 amps.

This is listed on the datasheet for that relay - would I be incorrect to assume that these specs are for when the coil is energized?

 

[ajw22]

This is listed on the datasheet for that relay - would I be incorrect to assume that these specs are for when the coil is energized?

View attachment 524137

You would be correct.