View Full Version : Dayton Heater - Check the Thermostat Wiring

Don Jarvie
12-12-2010, 4:40 PM
Everyone who has a Dayton G73 or similar model needs to open the case and check the wiring from the thermostat. The thermostat is defective and is causing one of the leads to burn up.

See Mike Cruz's thread below with more pictures and how he ordered a replacement.

I have added a picture of mine below.

The serial number of the bad thermostat is: 5813-11002-000


Rick Moyer
12-12-2010, 6:03 PM
I checked mine earlier today and everything appears fine. Now that you posted a serial number I'll go look again. Are you comfortable that all the ones with a problem will likely have that serial number? Or is that merely YOUR serial number? If the defective ones all have the same serial number it should be an easy check. What does Grainger/Dayton have to say about all this? btw, thanks for posting the serial number. I'll again look at mine and post the number, too.

mine says 5813-2050-000

Incidently, the wires are both black, not red, and they are 14 AWG.

Ian Wormsbecker
12-12-2010, 7:55 PM
I had the same issue. They sent me an entire new heater (after 6 months of waiting :( ).


Rick Moyer
12-12-2010, 8:09 PM
Ian, would you mind checking your thermostat serial number? I'm curious if it is like mine or the other ones that have had a problem.

Don Jarvie
12-12-2010, 8:30 PM
Rick, seems like the thermostat you have is OK so we should assume its the serial no I posted above that is defective.

Rick Moyer
12-12-2010, 9:21 PM
Hope so to both counts. It would be nice to know that that serial number was the problem for anyone involved. It would also be nice if we knew WHY there was this problem.

Don Jarvie
12-12-2010, 9:40 PM
If a few more come forward with a bad thermostat with the same serial no then we know it was the lot. Hopefully it was a bad lot. We'll see what others post.

It amy be wise to check the wires every few weeks to see if there is any issue. The manual does indicate it has a shut off if the unit malfunctions.

Ian Wormsbecker
12-12-2010, 11:45 PM
I returned my Dayton heater in March or so this year for repair. The Acklands-Grainger took FOREVER to get it back to me. Eventually I got a new heater in mid October. They told me it was the 'new model' (looks exactly the same from the outside, as well as the inside. perhaps the only difference is in fact the thermostat?)

My serial number on the new thermostat is 5813-11002-000. There is also a number of ATC-26B as well as L57C. All are on separate lines on the back of the thermostat. Unfortunately, I do not have the old unit that was problematic :(

I _think_ the new heater has thicker gauge wiring from the junction block to the thermostat and into the heater.

My heater had the exact same issue as other peoples: the contact point on the thermostat burned itself off the connector.

For what it is worth, I re-attached this after it happened and it burned off again.

My new heater I have had running on low for about a month with no issue.


Ian Wormsbecker
12-12-2010, 11:49 PM
Well, this isn't good. I didn't think to _actually_ compare my serial number with that of the faulty ones. Sure enough, mine is the same :eek::eek::eek:

I will have to keep an eye on it.

Also, both of the wires attaching to my thermostat are 14 gauge red wires.


Chris Mahmood
12-14-2010, 4:31 PM
I posted this in Mike's thread but probably should have just put it here, sorry for the duplication.

I contacted the manufacturer, Marley Engineered Products, about this and sent them your pictures Mike and they called me back within a few hours. The person I talked to was very interested in the problem. He explained that they've had some problems in the past with the supplier not crimping the terminals properly and the arcing eventually destroys the wire. I asked if soldering the terminals would help and he said probably not and judging from discoloration on the side of the thermostat there may be a problem with the riveting as well. Anyway, he asked that the defective thermostats be sent to him so they can try to narrow down the date ranges of the bad ones and offer replacements:

Marley Engineered Products
Attn:Mike Phi
470 Beauty Spot Road East
Bennettsville, SC 29501

Rick Moyer
12-14-2010, 5:22 PM
Thanks Chris for taking the initiative. Hopefully there will be some resolution at some point.

Thomas Short
12-26-2010, 2:17 AM
Hey all-

New guy here, came across this thread and thought I'd add my experience.

I have a Dayton G73 in my workshop. Bought the first one December 2009; failed in the exact same way as those above about 5 months later. Received a replacement through Grainger, installed it, and didn't run it until this winter (late Oct). It failed in the exact same way.
Mine has the same numbers / markings: 5813-11002-000 as well as ATC-26B and L57C. Unfortunately I don't know the numbers from the first unit that failed.

I have emailed Marley ... will see what happens. I like this heater, it does a good job keeping the shop comfortable. Hopefully I can keep things from freezing until this gets fixed.


Don Jarvie
12-26-2010, 6:39 PM
Thomas, I pried out the burnt out wire and recrimped a piece of 10g wire in its place and put it back in. It has been working fine. I'm going to wait until the warm weather and get a replacement part.

Anthony Diodati
12-26-2010, 7:15 PM
I had the same issue. They sent me an entire new heater (after 6 months of waiting :( ).
6 months, OMG. Well at least you can buy a new T-Stat and have a 2nd. heater almost free.
TY, Tony

Casey Scott
12-27-2010, 1:03 PM
I just bought a Dayton 3UG73 on 12-3-10 Ive had it running almost 3 weeks. Was in the shop last night painting and noticed it would run for a short period of time and shut down. So I figured the tstat was cutting it out. I opened the bottom and saw the wire going to the tstat was burnt somewhat.
http://img130.imageshack.us/img130/4210/tstat.th.jpg (http://img130.imageshack.us/i/tstat.jpg/)

Anthony Diodati
12-27-2010, 2:09 PM
"I opened the bottom and saw the wire going to the tstat was burnt somewhat. "
May want to call/e mail the CO and maybe send them the picture and get another one sent out, (
heater, or replacment T-Stat).

Just wondering, how does the replacement Y-Stat get wired in? Does it have a length(s) of wire(s) already attached to it that you wire nut in?

As stated on another thread, I just got the Air&Water version of the G72, Got it for $238.99,free shipping, with some kind of free little space heater, (that I did not get yet, e mailed them) looks to have the same specs as the Dayton, except for the fan CFM, 200/Air&Water, 270/Dayton. Don't know if the Air&Water brand had any problems with the T-Stat. Was still kicking around how to wire it, plug, No plug, read about the one plug catching on fire, so don't think I'll use a plug. Maybe wanted some type of shut off, cant tell from the book weather the T-Stat turns it *OFF* or sets it to it's *LOWEST SETTING* . Also they spec. a M/C, or A/C type of cable, or "whip" from a box to the heater,but my local home center did not know what I was talking about, and I did not see such a thing. Here is a page from the manual, TY, Tony

Don Jarvie
12-27-2010, 3:35 PM
The other thread by Mike Cruz has more info from Marley who make the heater for Dayton and where to send back the thermostat for a replacement.

My theory is the 14g wire can't handle the load and is burning up. I replaced the line with 10g and it's worked fine so far.

Anthony Diodati
12-27-2010, 11:52 PM
I will be running 10/2 NM from my breaker to a J box ,and from the J box to the heater, as per my manual, I got about 5 feet of 10/2 with ground, Alum MC cable. I am assuming the Alum pertains to the jacket, as the wire is copper. It has a separate green insulated ground wire.
I forgot to ask the fellow at the elect supply about this, but do I need these
anti short bushing's I read about in another thread, and if so, might a hardware store have them? What holds them in, as there is no "bonding wire"
run along this cable, as referred to in the other post.
Also what about the cable clamps, can I just use the same kind I have for NM, or does the MC take a special one?
Here is the other post, and a picture of the anti short bushing's
Thanks, Tony

Don Jarvie
12-29-2010, 10:02 PM
They make cable clamps for use with metal covered wire so you dont crush the alum when you tighten it. I don't know anything about the anti short bushings.

Anthony Diodati
12-29-2010, 11:29 PM
Thanks Don.
I got this type pictured, but not sure if I like them or not, as it seems this style could crush the MC also. I am looking for the type that screw on, but my local ACE did not have the right size.
From what I have read, the NEC does not require the anti short bushings for MC cable, but some
of the manufactures recommend them. However the NEC does require them on AC cable.
Here is a good PDF on AC and MC cable.
Thanks, Tony

Thomas Short
01-03-2011, 7:52 PM
Another update.
The retailer I bought the first two units through sent me a replacement via Grainger.

It appears to be the exact same; the wiring to the t'stat is the same red 14GA wire, the t'stat has the same numbering, etc.

I have installed it and as before it is running fine so far. It is a little concerning, as there appears to be no difference. I read the above about putting a 10GA jumper to the t'stat, but am not sure I am comfortable with this, as I do not fully understand the nature of the problem - is it not a little unusual for the t'stat to carry the line voltage and load? I am going to keep a close eye on this unit; if it fails in the same way then I am finished with the Dayton unit until the issue is resolved. I feel OK about the fire risk; there is nothing combustible in the bottom compartment, and it is surrounded by pretty heavy gauge steel.

Any other thoughts?


Mike Cruz
01-11-2011, 11:19 AM
Thomas, yes the replacement looks pretty much the same, but I think these came from a different "run" or something. My understanding is that the problem wasn't anything directly with the thermostat, but with the connections. If there was a bad crimp, or loose contact, then it overheated. I agree with you that I wouldn't change the wire size. Why? Two reasons: There might actually be a reason to have a smaller gauge wire for these runs. I don't know what it might be, but there might; Also, IF I have another problem, I have a leg to stand on with a complaint. If I tamper with the thermostat in any way, well, there goes my case.

Mine has been working just fine since the swap out.

Don Jarvie
01-11-2011, 11:59 AM
After talking with an electrican friend he said the stranded wire can hold more amps than the solid core wire so that could be the reason they put the 14g wire in the unit.

Mine has been running fine with the 10g I put in.

Bob Winkler
01-11-2011, 12:20 PM
I have the same heater, but different problem. My thermostat sticks closed, resulting in my heater running continuously. Luckily, I monitor the shop temp from my house and then go out and turn off the breaker. What a PITA. I bought a line-level Honeywell thermostat and will install it this weekend or sooner if I can get to it. My plan is to bypass the existing troublesome thermostat and use the remote mounted thermostat.

Mike Cruz
01-11-2011, 1:06 PM
Bob, that is EXACTLY what mine was doing before it melted. I would replace that pronto!

Anthony Diodati
01-11-2011, 1:37 PM
I bought a line-level Honeywell thermostat and will install it this weekend or sooner if I can get to it. My plan is to bypass the existing troublesome thermostat and use the remote mounted thermostat.
Bob, is that a SPST T-Stat, So you would just wire the 2 contacts on the T-stat in place of the
factory T=Stat?
Thanks, Tony

Bob Winkler
01-11-2011, 1:41 PM
Tony, that's my plan.

Anthony Diodati
01-11-2011, 2:25 PM
Thanks Bob

Rick Moyer
01-11-2011, 2:54 PM
Seems like so far everyone of these that failed, the ones we have the info on, have the same numbers on the thermostat and also have two red wires. As I stated earlier, mine has two black wires and a different thermostat number. SO, is it the wiring or the thermostat? I guess we still really don't know. I am inclined to believe it is either bad crimping, as the color of the wire certainly doesn't matter, or a malfunctioning thermostat. But, I don't understand how a bad thermostat would cause the arcing/burning so my limited knowledge would make me think a bad run of crimping the connections. I don't suspect mine will be a problem but it would still be nice to know the cause.

Bob Winkler
01-11-2011, 4:10 PM
I don't know or care about the root cause at this point. In my mind, poor wire crimps would not cause the Tstat to stay closed. I inspected the Tstat and saw no evidence of heat or arcing, yet sometimes the heater stays running. For me, the location of the tstat is also an issue, since I don't believe that you can accurately sense the correct temp at the unit. My solution is to eliminate all the problems by installing a remote Tstat 15' from the heater.


Rick Moyer
01-11-2011, 6:34 PM
I do care about the root cause of the problem so I can prevent a problem for myself. I agree that your solution of a remote thermosat is a good idea. I am hoping that since mine has been working fine for two years I should not have a problem, but it would still be nice to know for sure.

Bob Winkler
01-11-2011, 7:13 PM
Rick, I understand. What I meant to say is that given the uncertainty of the reliability of this Tstat, I'd rather just replace it with what I hope is a better solution. I have enough to worry about in my life, and don't want to add thermostat to the list.


Don Jarvie
01-11-2011, 9:02 PM

Could you give a run down of how you install the thermostat when you do. I have a Honeywell Tstat ready to install but I'm not sure how to by-pass the old thermostat.

I bought mine before I replaced the wire but it will be worth installing it so I don't have to go up and down the stool to turn it on and off.

Bob Winkler
01-11-2011, 10:30 PM
Sure, I hope to get to it installed either tomorrow if the snowstorm is as bad as they say and I stay home from work, or else this weekend. I plan on disconnecting the two stat wires in the heater and run 10 awg wire to the thermostat. The one I bought is a DPDT so it has 4 wires, but I will only use 2 of the 4 tstat wires. The extra wires will be unused and capped.

I'll let you know how it goes, but expect success.


Rick Moyer
01-11-2011, 11:50 PM
You know you got me thinking that I might like to have a wall mounted t-stat too. Since my heater is on 9' ceilings, it would be much easier to use. Plus, as you said, it would be better to set a temp rather than guessing what the thermostat postion will give you. Thanks for any insights.
btw, it's been snowing pretty steadily here since about 4:00 this afternoon. Have about three to four inches so far and pretty slippery. You should probably stay home from work ;):p.

Don Jarvie
01-12-2011, 10:42 AM
I have a digital thermometer in the shop new the heater so I can monitor the temp. I usually run it on high till it hits 58 degrees and then cut it to half way so it holds the temp.

Mines about 10ft in the air so I have to go up and down.

I'm not sure how to wire the thermostat in so I look forward to the tutorial.

Bob Winkler
01-12-2011, 10:42 AM
Rick, I grew up and Allentown and my wife is from Carlisle, so I know it snows there too :) So far, here in CT we have 18" on the ground now and it's still coming down. I can't even get to the shop until I clear a path with the snowblower.

Thomas Short
01-13-2011, 5:03 PM

I agree. For now my plan is to keep a close eye on it. When I go out to the shop I just turn off the breaker, open the unit and check the wiring for evidence of overheating (including feeling the wire to see if it is warm to touch). So far so good, but the last two units that failed also were OK for a month or so before keeling over. Unfortunately, I don't know what the wiring did before the failure - i.e. did it just suddenly / immediately fail or were there signs of overheating before. I wasn't checking the other units beforehand.


Bob Winkler
01-15-2011, 2:47 PM
In case anyone is interested in my addition of the remote thermostat to my Dayton workshop heater, let me give you an update. Perhaps I should provide the caveat that I'm not a licensed electrician, so please consider these comments using your own good judgment based on your particular skills. I AM an electrical engineer and have been doing my own wiring for over 30 years including my own shop, and I'm pretty confident in my abilities.

In any case, I installed the tstat a little while ago and all appears to be working well. Here's what I did.

- First I bought a heat-only Honeywell tstat at Lowes for $20. This happens to be DPDT, but only SPST is needed for my needs.
- After shutting off the breaker to my Dayton, I opened the bottom door and cut the wires about 2" from the built-in thermostat. My wires were red.
- I stripped the wires that the tstat used to connect to. One goes to the Line In terminal block and one goes to the watt-selection terminal block. My plan is to wire-nut my new tstat wires to these existing wires.
- I ran 10 awg wire through a Daytom enclosure knockout to a post in the middle of my shop. Make sure to use a cable clamp in the knockout.
- Inside the Dayton enclosure, I connected the Tstat ground wire to the green ground screw, and used wire nuts to connect the wires I stripped from the Line In terminal block and the watt-selection terminal block. U connected the black to the Line In and the white to the watt selection wire.
- I mounted a double junction box on the post because I wanted to have lots of room for the large awg wires. I mounted a single gang mud ring to the large box to make it a single gang with lots of wire room.
- I did not use the 2 double pole wires, so I capped them with wire nuts. On my tstat they were red and labeled L2 and T2. I also capped the ground wire which is not used.
- I connected my black Dayton feed wire to the tstat L1 input and the white to the Tstat T1 output.
- I closed all the enclosures and turned the breaker back on. I set the Tstat for 52, the heater came on, and went inside for a cup of coffee.

That's it. I remotely monitor workshop temp from my house with a wireless thermometer and it appears to be holding temp well. Let's hope it work better than the cheap tstat they built into the unit.

Take care,

Don Jarvie
01-15-2011, 6:08 PM
Thanks Bob, I'm going to tackle this peoject this week.

"Patrick G Rainsberger"
01-16-2011, 12:24 AM
178246 I had the same problem with my Dayton 3UG73 heater. It lasted about a week before the thermostat went out. (both wires were red) I took pictures of the burnt wires and sent pictures to Greenhouse Megastores where I bought it online. They told me to throw it out and they would send a new one. When the new one arrived, the thermostat looked different and both wires were black. This was in January 2009. I took the old heater apart and noticed that the fan delay control was not connected to the head element and was dangling from its wires. I reconnected it using the clips. I than purchased a new thermostat from Grainger. It looked different than the others and had two black wires. Since then I have not had any trouble with either of the heaters. On a thread back in Nov. or Dec. 2009 there was a thread discussing this same heater. Someone had put a switch between the breaker and the heater and had they not been in the shop when the switch caught fire it would have burned their shop down.

Anthony Diodati
01-16-2011, 1:23 AM
Yeah, I would have "thrown it away too". Good deal.
Are you sure that thread was not about an outlet catching fire, or was there another one, and it was a switch.

Anthony Diodati
01-16-2011, 3:04 AM
Man, might have saved some money, Oh well, here is a 5,000 watt Fahrenheat one for $187.49
If you recall, This is the one I got. I paid about $239.00 for it.
I'm just wondering if the Fahrenheat one for $187.49 would be a better heater, plus I can save about $50.00.
I think I can still send this one back, with free shipping, or maybe it will be best to just leave
well enough alone.
You know sometimes you try to make something better, and you just cause problems.

OK, here are some things, fan CFM is 70 CFM higher on the Fahrenheat one.
Also, says

Automatically delays fan action until heating element is warmed up
Fan continues until heating element cools off

See I notice my fan starts running as soon as you turn it on, and I don't see where it it is
stated in my Owners Manual that the Fan continues until heating element cools off.
Don't know what to do now.


"Patrick G Rainsberger"
01-16-2011, 1:29 PM
Are you sure that thread was not about an outlet catching fire, or was there another one, and it was a switch..

Tony, You're right, he had wired it to a plug and the outlet caught on fire. It was from a thread by Augusto Orosco. "Heating Shop: Electric Alternatives" 10/12/2009. I found the thread in a google search
but am not sure how to attach it yet. I'll get there. Thanks for catching that. Pat

Anthony Diodati
01-16-2011, 1:49 PM
Yeah, I read that one. Turned out it was some RV plug and outlet.
But I don't know, I installed a L6-30 locking plug and outlet on mine, and a lot of guys either have a L6-30 locking plug and outlet, or a plain 6-30 plug and outlet.
Still trying to decide to stay with the little NewAir, or go the FahrenheatFUH5-4.:confused:

I just thought maybe a switch caught on fire too.................

Thanks, Tony

Bob Winkler
01-16-2011, 4:51 PM
I liked the high airflow of the Dayton (Fahrenheit clone) because I wanted to move a lot of air around. Except for the wimpy built-in thermostat, I think the Dayton is a good heater at a reasonable price.

And my opinion is that its rarely a good idea to use a plug on a high-wattage heater that will be running unattended. Most manuals recommend against it.


Justin Freund
01-16-2011, 10:26 PM
I don't understand the desire to keep replacing the thermostats on these units. Mine has been working fine but I saw the potential problem as soon as I opened the door when I installed it. IMO its a flawed design on an otherwise great heater. I'm putting in a remote thermostat on mine. It'll be one that actually has a temperature setting. I kept it on high when I first got it then realized that just above half kept it comfortable without running constantly (my shop is not completely insulated yet, so it was a big unnecessary waste to have it on high as it was never going to get to the "high" cutoff).

As for the wiring, unless you have a properly rated twist-lok receptacle and plug to keep the plug in place, I'd highly advise against using a cord and plug. The constant cycling of the load with such high wattage is a recipe for disaster on a normal receptacle IMO. Personally I have EMT from the sub to a fused knife disconnect that I can shut off when I leave the shop. From the disco, it goes to the heater via a sealtite whip.

Anthony Diodati
01-17-2011, 8:58 AM
Here's the thing that got me, See I went to this link, (well it was a $40.00 off coupon then)
And it clearly shows the **DAYTON** heater, right?
Then if you click >>Get Coupon/Buy It>> It takes you to the Air-N-Water site, and sells you the NewAir G73.
Now I'm not saying there is anything wrong with the little NewAir G73, but The original Ad, *Clearly showing the DAYTON*,then switching to the NewAir one made me a little bit mad.
See I thought I was ordering the Dayton when I really was ordering the NewAir version.
Thanks, Tony

Bob Winkler
01-17-2011, 1:08 PM
Strange- perhaps this is their way of not having to deal with the Dayton thermostat issue.


Anthony Diodati
01-19-2011, 7:27 AM
Man, might have saved some money, Oh well, here is a 5,000 watt Fahrenheat one for $187.49
Of course, Now they are out of them........LOL

Ian Wormsbecker
02-07-2011, 9:43 PM
As an FYI, while I was away this weekend, my Dayton heater thermostat burned itself out again. GRRRRRRRRRRRRRR.

I will be making some phone calls in the morning :(


Myk Rian
02-10-2011, 10:53 AM
I have the same heater, but different problem. My thermostat sticks closed, resulting in my heater running continuously. Luckily, I monitor the shop temp from my house and then go out and turn off the breaker. What a PITA. I bought a line-level Honeywell thermostat and will install it this weekend or sooner if I can get to it. My plan is to bypass the existing troublesome thermostat and use the remote mounted thermostat.
Mine just crapped out on me last night. It wouldn't shut off.
I'll be calling a few places in town to see if I can find something to replace it with.
Number on the T-stat is 5813-11002-000

Mike Cruz
02-10-2011, 11:03 AM
Myk, if it is your thermostat that crapped out on you, and it is the thermostat you want to try to replace, call whomever you bought the heater from and they will likely replace the thermostat for free. If you just want to replace the whole heater, that is a different story. But it seems to me that these heaters are much like our shop equipment...4 different brand names that all look the same, probably all made by one manufacturer with the same parts but different labels.

Bob Winkler
02-10-2011, 1:51 PM
If it's an option for you, the line-level remote thermostat has been working great now for several weeks. It actually holds temp much better since it's located at eye level instead of in the heater. I'm glad I made the change, since I lost confidence in the reliability of the OEM thermostat.


Myk Rian
02-10-2011, 5:39 PM
I called a local electric supply this morning. They had an almost direct replacement for the OEM part.
It's a TPI Corp. Model TBS single pole. PCN 01054602. I only had to open the 2 mounting holes up with a next size drill bit to get an extra 1/16" between them.
I'm adjusting it for temp right now. Made in Tennessee.
www.tpicorp.com but the T-stat I have doesn't show up. This is actually a T-stat for baseboard heaters, in case that helps anyone looking for a replacement.
If this one doesn't hold up, I'll go with an external line control.

After removing the OEM stat I looked at the wires and terminals very closely. One of the crimps was starting to show darkening from heat. Hmmm.

Nick Sebastian
01-05-2014, 1:32 PM
I liked the high airflow of the Dayton (Fahrenheit clone) because I wanted to move a lot of air around. Except for the wimpy built-in thermostat, I think the Dayton is a good heater at a reasonable price.

And my opinion is that its rarely a good idea to use a plug on a high-wattage heater that will be running unattended. Most manuals recommend against it.


Bob. This is my first post and you had the cure for my issue with the 3UG73. It is about a year old and has been working fine until New Year's Day when I noticed it was stopped. No click from the thermostat. When I opened the bottom I saw the same thing mentioned many times in this thread... As you see from pic below
After trying to find the replacement/revised part I came upon this thread and your solution with a remote line voltage thermostat. Just wired as it were the original stat. Used a Honeywell 22amp single pole 2 wire and some 10/2. Works like a charm including all the pre warm and cool down features.