Line voltage thermostat options?

[LaurentR]

Hi all,
I have an old radiant heat system that uses a line-voltage thermostat. What are my options to control it from a HA system (ideally, it would plug somehow into an Elk system or z-wave).
I assume that since there is not much to it, I can just use a switch/relay module, but that would lose the "normal" thermostat interface on the wall, which I'd like to keep if possible.

Thanks in advance.

Laurent

 

[dBeau]

I had two zones out of six that were baseboard electric and controlled by wall mounted line voltage thermostats. After looking around a bit I realized automation friendly line voltage stats were not very common. Besides, I really wanted to use Aprilaire 8870's on these two zones just like the four hot water zones in the house.

The trick was to use a couple of Honeywell R841E relays mounted at the breaker box. Luckily each zone had it's own breaker so the installation was simple. Back upstairs, I replaced the line voltage thermostats with a couple of wire nuts and a blank face plate. Next to that I mounted the 8870 and ran the control wires to the basement where they connected to the R841E for the zone.

Hi all,
I have an old radiant heat system that uses a line-voltage thermostat. What are my options to control it from a HA system (ideally, it would plug somehow into an Elk system or z-wave).
I assume that since there is not much to it, I can just use a switch/relay module, but that would lose the "normal" thermostat interface on the wall, which I'd like to keep if possible.

Thanks in advance.

Laurent

 

[AO-Brandon]

Unless I am mis-understanding what you mean, wouldn't the HAI relay isolation module allow you to bypass the line current and put a standard type T-Stat on the wall?

If I am incorrect, please post more details, such as a model number or a link and I can look it up.

Thanks!

 

[mustangcoupe]

Brandon - I dont beleive these will work as I think these are ment for 24 VAC not 220 VAC which electric heat usually is (I cant find a manual for them so this is only a guess from the photo)

I beleive the only option is using contactors (note I said contactors not relays as the high current would butn up most standard relay) You could 1- parallel a set of them with the thermostat connection so wither one would turm the system on. But you also might want to also add a set before the thermostat so you could have a HA overide....


connect the coil of the contactors to relays connected to the ELK optputs connecting to a a powersupply so you can open anc close the relay (output) which will work the contactors[/code]


This is just my current thought, and may not work 100% you may need more/less parts depending on you actual setup.....

If you are not comfortable doing this type of work STOP and so not do it as this is high voltage! Hire a professional!


edit removed ASCII drawing as it got all screwed up on upload......

 

[AO-Brandon]

ahhhh ... missed the 220v part, I hear "line voltage" and assume 120v.

What about something like this?

 

[LaurentR]

ahhhh ... missed the 220v part, I hear "line voltage" and assume 120v.

What about something like this?

In my case, this is driving a radiant heat furnace, which uses gas, so it's just the pump that's electric. AFAIK, it's 110V and reasonable amps (not like an electric heater).

So the Honeywell things mentioned above should do the trick although I am a tad confused about the wiring.

Thanks all.

Laurnet

 

[pete]

In my case, this is driving a radiant heat furnace, which uses gas, so it's just the pump that's electric. AFAIK, it's 110V and reasonable amps (not like an electric heater).

So the Honeywell things mentioned above should do the trick although I am a tad confused about the wiring.

Thanks all.

Laurnet

what type of radiant heat do you have ? ? electric (best guess w/ line voltage stat), hot water (next guess, but you said furnace, did you mean boiler?) or hot air (which is what a furnace makes) . .

line-voltage stats are usually just used w/ electric heating . . if yours is line voltage, but running a furnace or boiler that'd be odd . . if this is the case, you should determine if the unit actually is using line-voltage from the stat or if there's a transformer in the circuit somewhere . .

how hard would it be to run a new wire from the stat to the heating unit ?

Pete C

 

[mustangcoupe]

In my case, this is driving a radiant heat furnace, which uses gas, so it's just the pump that's electric. AFAIK, it's 110V and reasonable amps (not like an electric heater).

I guess I don't understand how your heat is configured, is it forced hot watter with a pump? Does the thermostat just turn the pump on and off? What about turning the furnace on or is that controlled by the water temperature (aquastatic thermostat in the furnace) Do you have 120 Vac going from the feed into the thermostat then going DIRECTLY to the pump?

if so the Honeywell R841E looks to do what you want....

Per Honeywell, the R841E (or what they refer to as a R841E1068 - 24 V Electric Heater Relay with Spst switching)
Has these ratings: Electrical Ratings, Contacts (resistive) 22 A @ 120 Vac, 208 Vac, 240 Vac


So watch out with the size of pump it is controlling......

 

[LaurentR]

In my case, this is driving a radiant heat furnace, which uses gas, so it's just the pump that's electric. AFAIK, it's 110V and reasonable amps (not like an electric heater).

I guess I don't understand how your heat is configured, is it forced hot watter with a pump? Does the thermostat just turn the pump on and off? What about turning the furnace on or is that controlled by the water temperature (aquastatic thermostat in the furnace) Do you have 120 Vac going from the feed into the thermostat then going DIRECTLY to the pump?

if so the Honeywell R841E looks to do what you want....

Per Honeywell, the R841E (or what they refer to as a R841E1068 - 24 V Electric Heater Relay with Spst switching)
Has these ratings: Electrical Ratings, Contacts (resistive) 22 A @ 120 Vac, 208 Vac, 240 Vac


So watch out with the size of pump it is controlling......

I am not in my house now, but yes, there is a pump, and the furnace is likely directly controlled by that too (need to check - I am not at home right now). There is no tank, so there is no real point in having the pump and the furnace not running at the same time. But I'll check.

What I know for sure is that the thermostat has 3 wires: neutral, line and load, all 110V, so the R841E looks like what I need. I just need to figure out how it is wired to the low voltage thermostat (haven't explored these since I have always owned houses with line voltage tstats).

Thanks again.

Laurent

 

[mustangcoupe]

it looks like there is a line and load connections (for both hot and neutral), and a seperate set of wires or contacts for the 24 VAC side of things which would go to the low voltage t-stat.