Help with Modine Hot Dawg Heater

[jsears]

I have a problem with my 45,000 BTU Hot Dawg heater, and I can't find anyone who can help. It is an older 102 series heater.

PROBLEM: When the heater comes on initally, the exhaust fan runs for a couple of minutes. The burners light and burn well. A short time later, the circulating fan comes on. So far, so good. Now, the heater will burn for a while, maybe even come up to where the thermostat is set, and then the burners go out. But the circulating fan continues to run, and will not shut off. To get the heater to light again, I have to shut the electric off to the heater and let it sit for maybe 1/2-3/4 of an hour. When I turn the electric back on to the unit. It repeats the same cycle.

WHAT I'VE DONE SO FAR: Called the service guy (because I don't know jack about this stuff). He checked the gas pressure before it lights and after it lights. All is good there. Replaced Terminal Board w/time delay relay (at Modine's suggestion). That didn't work. Contacted the factory sales rep. Was told that Modine is familiar with this problem and there is a problem with the wiring harness. They sent me one at no charge. Didn't work.

There's not a lot to these things. Somebody ought to know what's wrong. About the only other things to change is the gas valve (at nearly $200), the pressure switch ($55) or possibly the high limit switch ($30). The Terminal board was $70.00. I can buy a new heater for just over $350.

Has anyone else had a similar problem, or have any idea what the problem may be? I'm getting desperate here. I haven't been able to work in the wood shop all winter because I don't have any heat.

Thanks for any help you can offer.

Jim

[bonafide]

Make sure unit is level, check vent for blockage, GL

[jsears]

Thanks for your reply bonafide. I should have mentioned that this is not a new instalation. It's about 7 years old and has worked properly up until this winter.

[bonafide]

Thanks for your reply bonafide. I should have mentioned that this is not a new instalation. It's about 7 years old and has worked properly up until this winter.

Doesn't matter how old someone may have bumped it with forklift or something

[jsears]

The heater in in my woodworking shop at the rear of the shop. No heavy machinery in my shop. I am the only one that goes into the shop, and know that it has not been hit with anything.

[beenthere]

Did it do it while the tech was there.
Or did he just check a couple things and leave.

He should run it, and when it does it, he can trace the problem out.

Thats not an uncommon problem with some unit heaters.

PS: Your hreater needs cleaned.

[jsears]

Beenthere.. Yep, it did it when he was here. At first he thought it might be the gas valve. Then he thought it was the terminal board. He finally talked himself into the terminal board. So that's what we got. Maybe he was right the first time. Cleaning the furnace is one of the first things I do before starting the heater every year.

[dec]

shut power off and let it set for 1/2 to 3/4 hour of an hour before it will cycle that way again.

Thats the trick sentence here


Not in pro section ....sorry I have no opinion then ..... sorry

[jsears]

Do you not want to give me an opinion because I'm not a professional contractor? I'm not trying to stiff a pro by not giving him my business. I'll be happy to pay someone to do the work if we knew what the problem is. Problem is, I live in a small town and there is nothing in the phone book says "knowledgable techs". The nearest large city that is likely to have one is about 40 miles away, and I don't want to pay someone that far away for a service call just to tell me he don't know what the problem is.

[dakotakid]

PS: Your hreater needs cleaned.

This takes care of 95% of the problems with these heaters. As you said, there is not a lot to these heaters. A good tech should be able to isolate the problem. I am not familiar with the "hot dawg" although most of the different brands of unit heaters are set up the same. Does this unit have a diagnostic light on the control board? If it does this will point the tech in the right direction.

[Dog]

All I want to Know is where can you get a new one for three fifty just priced on out for a job and it was about triple that?

[airmn38]

ive got one of these in my garage its about 4 years old it has a control module is that what your calling a terminal board? The sequince tells the story i cant imagine if the unit satisfied the stat and the fan kept running it could be a gas valve . my unit i can hear the ignitor after the inducer motor pulls in the press switch.if you hear the ignitor and get no flame the valve could be at issue.or it could be fouled with sawdust . you my want ask the company for a more expierienced tech not a part changer . a 2 min inducer cycle sounds long to me inducer wheel may be full of crap (sawdust) check that too.good luck

[beenthere]

Beenthere.. Yep, it did it when he was here. At first he thought it might be the gas valve. Then he thought it was the terminal board. He finally talked himself into the terminal board. So that's what we got. Maybe he was right the first time. Cleaning the furnace is one of the first things I do before starting the heater every year.

He has to use a meter to trace out which device is opening.
If he;s just guessing, he's going to be installing a lot of parts until he guesses teh correct one.

This site has rules against giving technical advise to home owners. Thats why most of us won't tell you the most likely part that is doing this.

How did he confirm the limits weren't tripping. Did he use a meter. Or just a guess.

[jsears]

Dakotakid..Yes it has a diagnostics led. But it's not on the board, it's on the gas valve. It flashes bright/dim which indicates "normal" operation.

Dog.. OK maybe $350 is a little on the light side. But I know I can get one for $450 with no problem. If you have to pay more than $1000 for a 45,000 BTU Hot Dawg, you're shopping in the wrong place.

airmn38.. The terminal board is located on the inside/bottom of the unit cabinet. The new one has the time delay relay built on the board itself. The old board had a TDR seperate from it and mounted on the inside/bottom of the cabinet beside the board. Since Modine uses what they call a "Smartvalve", maybe the control module is built into the valve itself. I don't know. The problem with the more experienced tech is that, like I said in an earlier post, there is none. I live in a small town with very little support locally. I'd have to call a tech from about 40 miles away. Can't imagine what the service call alone would be. I have no problem paying for someone's service call. But I need to be realistic about if the servcice call plus parts and labor is worth the value of the heater.

beenthere..He did use a meter to check thingss out. But since I don't know much about these units, I really don't know what he did check. I do know that he bypassed the HL switch and the heater acted the same way. I didn't know that there was a rule against giving advice on this board. But I guess I understand. You have to be careful and not leave yourself hanging out there when some idiot does something stupid and blames you for it. I'm a retired Deputy Sheriff. I know that we had to be careful about giving legal advice. The question we always got was "If someone comes into my house, can I kill 'em?" I'd always tell them if they do, they'll probably go to jail for awhile and let 12 other people decide if they should stay there or not. Sorry. I got off on a rant.

To all who responded. I appreciate it. My email address is in my profile if you wish to contact me.

Thanks again...Jim

[Jon Brown]

Here's a handy troubleshooting guide. A good tech. can use this to isolate the problem. Best of luck:

http://store.h-mac.com/mohetrgu1.html

[DanW13]

You say everything runs ok and then the burners go out..... You can try a couple of things one is to reverse the polarity blk wire hot, wht wire netural, green ground. Or it could be you lost your ground connection, or your flame sensor has a bad connection and is not sensing properly. You can also check your gas valve at the orfice could have a build up of dust in the orfice and changed the size of it, You could have also developed a negitive pressure in your shop as well as the venting got blocked or plugged with a dead bird or squirrel. These are some of the things you can check yourself and I bet you fix this yourself. Come on your a wood worker you should be able to fix this unit !!!!