Dayton 2NNR7 Thermostat to control 240v fan forced heater unit.

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AFJES

Member
Location
Penn US
Using this Dayton 2NNR7 Thermostat to control 240v fan forced heater unit (2000W).

Pictures show thermostat to be used and instructions for its wiring.

I basically understand how it needs to be wired but just would like confirmation as I have not wired one of these before.
Here is the link to the manual. I believe Figure 4 would be the way to go. Simple fan forced hot air heating unit; residential size being used in a laundry room common area for tenants to do wash. Two hots to thermostat. One hot wire nutted together and back out to heating unit and the other hot incoming to "R" and then back out to heating unit on "B" and ground the thermostat. Using 12/2 and 20amp 2 pole breaker, so far as we do not have the actual heating unit where the name plate may dictate otherwise. Would have preferred to use a two pole thermostat but this would work.

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qcroanoke

Sometimes I don't know if I'm the boxer or the bag
Location
Roanoke, VA.
Occupation
Engineering
Using this Dayton 2NNR7 Thermostat to control 240v fan forced heater unit (2000W).

Pictures show thermostat to be used and instructions for its wiring.

I basically understand how it needs to be wired but just would like confirmation as I have not wired one of these before.
Here is the link to the manual. I believe Figure 4 would be the way to go. Simple fan forced hot air heating unit; residential size being used in a laundry room common area for tenants to do wash. Two hots to thermostat. One hot wire nutted together and back out to heating unit and the other hot incoming to "R" and then back out to heating unit on "B" and ground the thermostat. Using 12/2 and 20amp 2 pole breaker, so far as we do not have the actual heating unit where the name plate may dictate otherwise. Would have preferred to use a two pole thermostat but this would work.

View attachment 13626 View attachment 13629
You are correct. wire in on red dot (1) out on blue dot (2). Close on temperature fall.
 

iwire

Moderator
Staff member
Location
Massachusetts
Because that thermostat is only a single pole unit and has no marked off it can only be used as a controller it cannot double as a disconnecting means.

You will have to provide a two pole disconnect in sight of the heater or you may be able to install a breaker lock at the panel.


By the way, normally with a fan forced heater you do not shut the power off to the unit with a T-stat, normally you feed the fan forced heater constant and there are terminals to add a thermostat to.
 

AFJES

Member
Location
Penn US
You are correct. wire in on red dot (1) out on blue dot (2). Close on temperature fall.
Thanks for confirmation

Because that thermostat is only a single pole unit and has no marked off it can only be used as a controller it cannot double as a disconnecting means.
Thanks for that. I could put a 4x4 metal box just before thermostat with a double pole switch in it to act as the disconnect as it will open both un-grounded conductors at one time. This customer likes to stay in the "economical" range.
 

AFJES

Member
Location
Penn US
UPDATE received heater finally.

UPDATE received heater finally.

UPDATE - the heater arrived a few days ago. Please see pic to see a drawing of how I wired it. If I turn the thermostat down to even -10 the heater stays on. Yes, the room is very cold but would think that at some point turning the thermostat down to its lowest setting should shut off the heater but it does not shut off, just keeps running.

I have looked this over several times and I believe I hooked it up properly.

Yes, the drawing does not show a disconnect to the breaker as the panel is in the same room.

I had to use a switch leg layout to the therm as the therm is in another part of the laundry room. I don't think this matters much as to how I wired it though. Am I missing something here or am I staring at this for so long I don't see the obvious.

Just another set of eyes on this would be appreciated. Thanks so much. 20160123_060422.jpg

NOTE: Model number and manual of therm is listed in my first post along with pics.
 

ActionDave

Moderator
Staff member
Location
Durango, CO, 10 h 20 min without traffic from wing
Occupation
wire pulling grunt
Just another set of eyes on this would be appreciated. Thanks so much.

NOTE: Model number and manual of therm is listed in my first post along with pics.
I think your problem may not be with the t-stat but with the way it is wired to the heater. I agree with what iwire said,
By the way, normally with a fan forced heater you do not shut the power off to the unit with a T-stat, normally you feed the fan forced heater constant and there are terminals to add a thermostat to.
I would check the instruction manual in the heater for t-stat instructions.
 

hbiss

EC, Westchester, New York NEC: 2014
Location
Hawthorne, New York NEC: 2014
Occupation
EC
Remove the thermostat and bring it inside to room temperature. Let it warm up. Take a continuity tester or an ohm meter on the lowest range and connect the leads to the R and B screws. Rotate the knob and see that the tstat opens and closes at around the room temperature. If set above the room temperature the tstat should be open, below it should close. You also should feel and hear a slight click as you turn the knob and the contacts open or close.

My feeling is that you have a defective thermostat.

-Hal
 

AFJES

Member
Location
Penn US
Thanks all for your replies.

Here is a link to the manual instructions. They shipped the 1000 watt heater instead of the 2000 watt heater but that should not matter as both are 240V. The model number is W2420 King; it does not have a built in thermostat.

I tried with the power off to turn the knob and do not hear a distinct "click" when it reaches room temp although it is quite cold in that room.

According to the instructions a single pole therm can be used which is what I have.

Urgh! this is driving me nuts.
 

iwire

Moderator
Staff member
Location
Massachusetts
How long did you wait for the heater to run?

Typically when you apply power to these heaters the fan does not start only the heating elements get power, once they warm up an internal temp sensor starts the fan. This is to keep the fan from blowing cold air.

Once the room is warm enough the heating elements shut down and the fan should run until the elements are cool so heat is not wasted
 

peter d

Senior Member
Location
New England
How long did you wait for the heater to run?

Typically when you apply power to these heaters the fan does not start only the heating elements get power, once they warm up an internal temp sensor starts the fan. This is to keep the fan from blowing cold air.

Once the room is warm enough the heating elements shut down and the fan should run until the elements are cool so heat is not wasted

I really wish this forum had the "nerd" emoticon. ;):lol:
 

ActionDave

Moderator
Staff member
Location
Durango, CO, 10 h 20 min without traffic from wing
Occupation
wire pulling grunt
How long did you wait for the heater to run?

Typically when you apply power to these heaters the fan does not start only the heating elements get power, once they warm up an internal temp sensor starts the fan. This is to keep the fan from blowing cold air.

Once the room is warm enough the heating elements shut down and the fan should run until the elements are cool so heat is not wasted
Which is why I think you were right when you said power needs to go to the heater first.

AFJES, what does the heater manual say about thermostat connections?
 

iwire

Moderator
Staff member
Location
Massachusetts
Which is why I think you were right when you said power needs to go to the heater first.

AFJES, what does the heater manual say about thermostat connections?
He posted the link to the instructions above, it shows wiring the t-stat into the supply as the OP is doing and I don't see a fan delay set up in the diagram.

I can only guess it is very budget conscience unit.
 

hbiss

EC, Westchester, New York NEC: 2014
Location
Hawthorne, New York NEC: 2014
Occupation
EC
If I turn the thermostat down to even -10 the heater stays on. Yes, the room is very cold but would think that at some point turning the thermostat down to its lowest setting should shut off the heater but it does not shut off, just keeps running.
Come on guys, read the original post. He has the tstat in series with the supply. It never opens it. Return that tstat and get another one.

-Hal
 

iwire

Moderator
Staff member
Location
Massachusetts
Come on guys, read the original post. He has the tstat in series with the supply. It never opens it. Return that tstat and get another one.

-Hal
Maybe, but those T-stats are pretty much rock solid unless he shorted it and blew out the micro switch in it.
 

peter d

Senior Member
Location
New England
I thought this forum was for industry professionals only? I just read a bunch of the OP's prior postings in other threads and it's obvious he is doing DIY projects.
 
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