Honeywell Mercury Switch Relay 1950-60?

Hello,

Thank you for having this forum.

I have a old electric base board heat system, with 3 heating units, attached to a Honeywell Mercury switch relay and thermostat.

I would like to update the mercury switch relay, with a newer modern Honeywell unit.

Enclosed are some pictures as I dont have the model number of the honeywell relay.
The specs would be compatible with the current unit.

If someone could identify or suggest a replacement based on the system.
I am not sure if its 120/240... I need to pull the panel cover.

Thank you in advance.

K.

 

Welcome to the forums.

The circuitry looks to be 240v.
That would mean you have one 2P breaker that controls the heat.
Probably a 2P20A breaker.

Did you want to change the thermostat too ?
Are all three baseboard heaters on this controller ?
Please supply the linear footage of the three so we can calculate combined current.

The Aube controller is good for 22A at 240v........ Aube RC840T-240

 

Hi Pete,

Thank you.

the room is 14 x 12 and there are 3 windowed walls each with a 7’ electric hydronic unit at the bottom.

Main wire come to the first unit, the unit is wired and another wire goes off from the main wire to the next unit.

The thermostat is an old dial type. I would like to change that to a digital w program as well.

20 Amp dbl break with 2 wires coming off either side

I don’t know the watt for the units, the company was purchased from cadet I believe.
thank you for your help with this.

based on the unit size, I would say at 7’ long, they are the 1500/1125 watt models; we’re at 240 volts so 1500 watts x 3 units, 4500 watts

6.5 amps each

Kurt

 

So you're actually just over the limit of the circuit.
4500w = 18.75amps
Code now requires electric baseboard heat to be figured at continuous load which means a max of 16 amps on a 20 amp circuit.

Does that mean 4 wires on a two pole breaker ?
I see one switching relay.... where would the second set of wires go ?

The Aube unit would replace what you have at that location and give you a C connection for a programmable thermostat.... not a wifi thermostat. I only see two wires to the thermostat so you could use a battery programmable.

 

Sorry, only 2 wires total coming from the breaker; it’s a old pushmatic, which somewhere down the line I want to address with an electrician.

i could try running 2 units to deal with the code requirement. We just want to get the draft out of the room when it’s colder out. Another possibility would be to have a 30 amp breaker installed when we get the service updated. We have lived here for 30 years and all the homes being sold now are being torn down and replaced with 2 story homes. We plan on moving in the next 5 years.

this gives me enough to update the relay, and safely have heat in the room for now.

thank you Pete👍

I will post an update.

Kurt
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If your system has been running ok.... don't fix what ain't broke.
Pray the Pushmatic doesn't crap out.

You can use the Aube. You can gut your relay box and put it inside or replace that box with a 4" deep square box. I can draw you a diagram for which ever you want to do.