modine how dawg & ecobee - isolation relay needed?

[upjeeper]

hi all,
i'm in the process of installing a modine hot dawg with an ecobee in my garage. it's a hot surface ignitor (not direct spark). i've seen some reference to guys using isolation relays as part of the process, curious if there's a need for me to go that route with mine?

please / thank you

 

[The Cobbler]

can't answer your question because I don't know ecobee, but I used an electronic stat on my Modine heater without issue, the only thing it didn't list was a fan only mode, but it does have the terminal , it's just not identified in the manual.
On that, I don't understand why you would need a relay

 

[dogdog]

if your heater doesn't have any low voltage controls like W,C and R terminals for normal 24Vac thermostats, then you will most likely need the isolation transformers. you have to look at your manual.

 

[PoorUB]

hi all,
i'm in the process of installing a modine hot dawg with an ecobee in my garage. it's a hot surface ignitor (not direct spark). i've seen some reference to guys using isolation relays as part of the process, curious if there's a need for me to go that route with mine?

please / thank you

I used to sell and install Modine Hot Dawg heaters. I can't think of any reason you would need a relay, unless the Ecobee doesn't play well with the Hot Dawg

if your heater doesn't have any low voltage controls like W,C and R terminals for normal 24Vac thermostats, then you will most likely need the isolation transformers. you have to look at your manual.

Why bring that up? It just muddies the conversation. It is extremely rare, perhaps never, that a modern gas heating unit doesn't have low voltage controls.
It may have been true in 1950, but not today.

 

[dogdog]

Why bring that up? It just muddies the conversation. It is extremely rare, perhaps never, that a modern gas heating unit doesn't have low voltage controls.
It may have been true in 1950, but not today.

Not sure how that will muddy the conversation.

 

[PoorUB]

Not sure how that will muddy the conversation.

It doesn't apply to the situation.

 

[upjeeper]

if your heater doesn't have any low voltage controls like W,C and R terminals for normal 24Vac thermostats, then you will most likely need the isolation transformers. you have to look at your manual.

thank you
yes i do have low voltage controls. maybe the relay was just for spark ignition heaters.

 

[fitter30]

Models HD & HDB have a terminal strip and 24 vac

 

[dogdog]

thank you
yes i do have low voltage controls. maybe the relay was just for spark ignition heaters.

Relay on the heater are for what ever they are doing. The relay on the thermostat are just for controls. Like connecting R to W to fire up heat and R to G to run the fan. C is purely there to power the thermostat.
Sometime system doesn’t provide enough power to run both the circuit in the heater and the thermostat. Then you would need the isolation relay and a separate transformer to power the ecobee. Or in some case like some heaters only have T1 and T2 connections then you would need an isolation relay and transformer to power that thermostat.
Maybe if you post the model, PoorUB might be able to tell you. Since he was a dealer for that brand of heaters.

As far as isolation relay, I think Ecobee have an article on how it works in one of their support forums articles if you just google “ecobee isolation relay” I think you can call them for support as well, they used to have good rating on support, not sure now though.

 

[upjeeper]

thanks. i have confirmed i do not need a relay

 

[D45]

Curious how or where you attached the tstat wires?

Normal low temp tstat uses 2 wires? How many for the Ecobee?

Also, what's the lowest temp settings on the Ecobee and what model you're using

I'm using a $21 Honeywell CT50K1028

 

[upjeeper]

the tstat wires connect to the board, on the top of the heater
i used 3 wires, R, W, and C
the ecobee uses Rc for heat and cool, that was part of the problem i had. it's internally jumpered.

looks like it will go down to 45*F
i plan to run my garage at 50 or 55*F

now i have to buy a new control board. evidently my time delay relay crapped out, and that's not a replacement part. i have to buy the new control board with the TDR integrated ($150)

 

[mikeyr]

my Hot Dawg is hooked up to a ecobee, I just wired it normal, no relays or anything. BUT my Hot Dawg is close to 20 years old, so that may make a difference on wiring it up.

 

[upjeeper]

thanks, it turns out this particular ecobee model uses Rc not Rh for heat. evidently it's jumpered internally. Ecobee tech support was able to help me in less than 5 minutes.