REZNOR gas shop heater WHOOMP ! on ignition - DIY Chatroom

Wildcat355 · 10-27-2009, 01:23 PM

I have a ceiling hung REZNOR natural gas shop heater in my 800 sq ft garage. It’s 10 yrs old now and two yrs ago, the pilot light would not stay lit. Sometimes I could relight it and it’d be OK for a while, but I ended up replacing it. Same thing at the beginning of the ’08 heating season, then again at the end of the Spring ’09. I replaced the thermocouple, three times now. In itself, that seems like a problem.

Before starting up the heater this Fall, I put in a new Honeywell thermocouple. Over the last several days, the heater started making a WHOOMP sound when the burners ignite and a small gas ignition flash was visible at the bottom of the unit. Clearly not good. Carrot Top’s career would be ended if he were standing underneath when it lights

. I’m in no such danger as my head is free of hair being at risk of being singed.

I did some research and found this forum, but I’d read, and it may have been somewhere else, or here, to check and clean the burners. I shut off the heater’s gas and power, dropped the burner tray and swept out the very small amount of crumbs/debris that had accumulated over the years in the tray. The five burners are stamped (stainless?) steel and I blew them out with compressed air, noticing that virtually nothing was dislodged. The burners look very clean, but I used a wire brush to brush the tops, as one tech advised in one of the forums I had found online.

I also probed the five orifices in the gas manifold to check for obstructions. All were clear. I blew a little compressed air into the manifold for good measure.

I started the heater back up and the first ignition was smooth and quiet. The flames are even, without gaps and consistent blue flame color. I turned the thermostat back down, let it cool, then turned it back ON. I hear the call for heat switch, but there seems to be maybe one second of delay to ignition. The second ignition made a small whoomp sound, then the third, WHOOMP

and a visible flash under the heater.

I blew compressed air into the burners again, relit the pilot and turned the heater back ON. Quiet, no frills ignition….the first time. The second, WHOOMP. Very notable ignition flash.

The next test I did was to cycle the call for heat ON then OFF without letting the unit cool all the way down, meaning I would turn the thermostat back up while the fan was still running and blowing hot air out the front. Doing this resulted in repeated, quiet, reigniting of the burners. Hmmm.

I checked the heat exchanger for cracks, rust, etc and the exchanger looks to be in great shape. I remember a few years a go seeing the exchanger in my parent’s 40 yr old furnace. Now that was BAD!

The last test I did was to check the flue and draw. There’s no logical reason for the flue not to draw suddenly after 9 heating seasons, unless a squirrel took up residence, but the critter cage on the cap is intact and a smoke test with some burning newspaper proved the flue was drawing just fine.

Obviously, there is a gas buildup before ignition. If it was a problem with the burners, then why would they ALL have a clean, blue flame front to back? My suspicion is the valve (what else is there?) partly because the pilot light issue the past two seasons. Maybe that was the warning the electronics were starting to go.

Since this was first detected, I have shut the heater down unless I was right there to closely observe burner ignition. My shop is everything to me and I won’t risk it getting distributed like the contents of a piñata by letting the problem worsen.

Like a lot of people, I’m broke and on a fixed income. I hate paying a “professional” to do what I can do. The only difference here is that I may see this situation once, where they see this and have had training (I hope) in diagnostics to be able to know fairly quickly what it is. I can’t afford to throw parts at it until everything is new but the name plate.

yuri · 10-27-2009, 06:16 PM

Post a pic of the pilot flame. If it is the wrong size/dirty orifice etc that may be burning out the thermocouple. You are getting delayed ignition and that is VERY dangerous. Need to get a tech to check the manifold pressure of the gas valve. May be too high or low and causing a problem, not a DIY task. Or the gas valve is sticking. Or the burners need to be physically removed and the crossover slots cleaned and or wash out the burners with hot water running in a sink. Carrier TUAs are bad for that.

Wildcat355 · 10-27-2009, 08:07 PM

Yuri, I completely GET "VERY dangerous", hence why I am trying to get this diagnosed. Valves are not servicable nor would I try monkeying with the internals, adjusting pressure, voltage or whatever is not considered a DIY.

The pilot light is strong, fan shaped, and blue but I had noticed the tip of the thermocouple is glowing red. If that is too hot then I'd suspect that is another problem and the pilot tube/burner needs cleaned or replaced, yes?

The first Photo of the pilot light shows the red tip of the TC. The next is one of the burner tray with burners in place and one of just the burner tops.

If my assumptions are correct, low or high manifold pressure, or sticky valve equals replacing the valve, right? There's no real fixing in there, is there?
Since ignition seems to be the dangerous symptom, then a tech checking pressure will do what besides adding an overpriced service call to the overpriced cost of the valve and its replacement which IS a DIY fix? Maybe not for most folks, but I feel technically capable. I have also passed the City/County building dept's homeowner exams in both electrical and mechanical contracting, and I have a lengthy list of techno-mechanical skills that I can brag about somewhere else. If the answer is just to call someone, then DIY wouldn't be DIY now would it? It'd be CS (call someone)

I do appreciate the advice, but I'd rather the service tech go to the homeowner who thinks the pilot light is that Honda (Pilot) coming towards him and his gas orifice is well...you know where this is going.

In the meantime, I'll remove the burners once again and wash them out thoroughly with a brush and hot H2O.

Would the conclusion then be to replace the valve, or.....?

yuri · 10-27-2009, 08:26 PM

Most folks and DIYers seem to forget one important factor. An EXPERIENCED tech like myself or Beenthere, Houston 204 and some others can spot problems, find the REAL problem, setup the burners and pilot flame and position properly. That may not have been correct from the install date. I don't tell my doctor my problems after doing internet research and expect him to agree. I let him do the diagnosis. I would recommend if you can find an experienced tech it is worthwhile. We have had posters throw $1000 worth of parts into a furnace only to find out the problem was blocked venting. Gas valves are not adjustable/fixable and most of the time set correctly from the factory. Your pilot looks too strong and a glowing thermocouple usually burns out. If you don't have the proper shape of pilot flame that can cause ignition problems. I would recommend try find a tech that has done good work for your neighbors/friends and get a 2nd opinion before you throw parts in. Reznors have always been finicky units.

Wildcat355 · 10-28-2009, 12:24 PM

I apologize if I offended you. I just didn't expect the first expert advice to be to call somebody. I'm sure there are great techs out there but my luck has been less than the best when I've hired contractors and even HVAC companies to do work for me. In one case, the HVAC tech turned the filter sideways (without my knowing) to allow about half of the incoming air to bypass the filter altogther for "improved" air flow. He also left the pull-out breaker/plug out at the AC condensor and hours later, I found the house just gettig hotter, but the blower still running. After a walkaround I discovered his "expert" work. Let's not forget the leftover screws laying on the ground. That was just one incident with an HVAC tech. I can relate absolute true stories with similar dufusses from the telcomm, plumbing, building/construction arenas. Maybe Denver just has mostly incompetent contractors and service techs. I don't have a lot of confidence in most of them as I have found their work sloppy and less than "expert".

Now back to the problem. You have an excellent point of the unit maybe not having been setup correctly from the beginning.

I also concur that the glowing TC is bad. when I saw that, I thought "that can't be right". Do I need a tech to dial that pilot flame down a bit?

All I needed to know is what the value add would be of having a good tech come out. I'm not looking for someone to just agree with what I might suspect to be the problem. The point I'm tryinig to make is that if by haviing someone come out and just swap parts, then I can do that myself and NOT spend the $1000... that I can't afford. I'm trying to avoid throwing money at this, whether it be through having a service tech come out, or by my replacing parts.
If there is truly "setup" involved in the valve for proper manifold pressure, pilot operation, then I can see the value in having an experienced tech do that. I admit that is beyond my scope of experience. I don't know that the manifold pressure was tested and setup when the unit was first installed. It would have been my naive position that the valve is a valve and the pressure is what it is out of the pipe. Pretty ignorant, right? I also don't recall any specific setup of the gas prssure when Ihad my new GFA/AC unit installed about 8+ years ago.

The garage furnace issue does beg the question of why it operated without any problems for first eight years before the pilot/TC started showing signs of malfunction. The gas pressure would have had to increase tio make the flame stronger and burn out the TC.

I ran the heater last evening after posting the pilot photo and got a shot of the five burners all lit. I'll post those this morning. I did shut down the heater so it would NOT turn on overnight. I'm going to wash out the burners this morning too.

Did the burners look OK from the photo, or is the resolution not high enough?

Lastly, I do appreciate expert advice. While I can do most things myself, I do know when something is HAS to be done by an experienced pro. I just try to avoid the unnecessary expense whenever I can.

yuri · 10-28-2009, 07:52 PM

A proper installation is where a tech checks the gas pressure, temp rise, safeties etc. Most of the time that is not done. We had brand new Smartvalve gas valves out of the box overfirng at 4"WC and burned out a lot of new furnaces so anything is possible. Now getting older HWell valves that the regulators are failing. The orifice in the pilot burner may be plugging and distorting the flame. May need a new pilot burner as they can warp. Will wait and see if cleaning the burners helped.

Wildcat355 · 10-28-2009, 10:39 PM

Yuri, thanks. I called a HVAC tech referred by a close friend who's also a master electrician (

yes I let him do the big electrical stuff). And I'm still waiting to hear back after several hours

. I washed out the burners using very hot water a new engine block brush (18" long, 1" or so diameter, stiff, but not scratchy bottle brush) and a new nylon scrub brush for the outsides. Nothing visible came off the burners. I'm headed out here shortly to put the burners back in but with a bright light I inspected every burner tube before and after and saw nothing that could possibly obstruct the gas. The metal looks clean.
I pulled up the reznor site and found my heater model - F 100 (100k btu ?) with 80% efficiency. pretty big for my 800 sq ft garage. Probably could have had one half the size and been more than fine.

These are the standard specs-

Orifices for natural gas
Aluminized steel heat exchanger
Aluminized steel burner rack with stainless steel insert
Manual match-lit pilot with 100% shutoff
Single-stage combination gas valve (field adjustable for high altitude operation)
115/1/60 supply voltage
115 volt fan motor with internal overload protection
Fan and limit safety controls
Energy cutoff (ECO) device
Blocked vent shutoff system
24-volt control voltage transformer
Individually adjustable horizontal louvers
Full safety fan guard
Terminal strip connector for 24-volt field wiring
Convenient bottom burner access
2-point 3/8"-16 threaded hanger connections
Horizontal/vertical vent outlet

The control valve is a Honeywell V8200 7003, which I can find virtually no replacement info on, execpt a product manual link to the Honeywell site which won't let me access the page. I'm not an "authenticated" user.

http://customer.honeywell.com/honeywell/ProductInfo.aspx/68-0281
http://customer.honeywell.com/honeywell/ProductInfo.aspx/69-0234

Where I'm presently at with this is that I'm willing to adjust the pilot flame a little and see if I can get that dialed down. I'm not sure how to do it and I'm feeling that you probably don't want to instruct me on how and would rather I have someone else do it. I'm also in that same mode with adjusting the manifold pressure. I don't have a manometer and I'm not sure what the correct WC pressure shouold be and if one that says its for LPG ( vs. Nat Gas ), is OK to use. A $50 tool for a single or 3 time use isn't too bad. I can also resell it. I'd like to adjust them both downward a little bit and see if things get better, but it's also clear now that a new valve is imminent. The elevation here is right at about 5400ft, which is danged close to the "high altitude" reznor makes reference to in the manual for ".....field adjustment". A new valve will need to be setup properly I'm sure.

You probably hit it right on the mark about the initial setup. I think the old guy just didn't do it. I did a lot of the physical work, from digging 60ft of trench for the gas line, to actually hanging the heater. I think I'd have remembered if he did some setup on the gas pressure.

Here's a question though- why, when I cycle the heater ON, run it for 2-5 minutes, then turn the thermostat back down to end the call for heat, wait a minute ( fan still running) then turn the thermostat back up, the relight is smooth and without any dramatic flash and WHOOMP?

And lastly, this v8200 valve must not be made anymore, so how do I select an appropriate replacement model? I find Honeywell standing pilot valves online and some at a great price, some at insanely high prices but is there a risk at just picking one ina 82xx series? One particular one i found is Mfg:HONEYWELL
Model #:VR8205S2296
Alternate Model #: 60-100394-01
SCL #:83428
Condition:New

24 VOLT GAS VALVE, 160000 MAXIMUM BTU, NATURAL GAS 1/2" X 1/2", REG. 3.5 ADJ 2.5 - 3.5 RANGE, US 396221 LP CONVERSION KIT, 5A, HERTZ:60, CLASS 2 TRANSFORMER, WEIGHT:1LB 7.6-OZ, DIMS:4-3/8"H X 2-3/4"W X 4-1/4"D.

I also found a VR8200. Also NEW but old stock.
Mine doesn't have the R in the model number-
VR8200 A 2132 Dual Valve Standing Pilot Combination Gas Control

yuri · 10-28-2009, 11:17 PM

I get all my gas valves: 1) OEM from Reznor/Lennox or whoever mostly for liability reasons and compatibility issues. 2) Cross referenced by my favorite wholesaler who I trust.
There are 3 types of valves; quick open, step open, slow open and you cannot just interchange part numbers. The reason it lights better when warm I suspect is the heat exchanger has expanded and the burners move or something else happens. All that backfiring is very dangerous and HARD on the heat exchanger and it is 2x the size you really need for your shop. If it has not been burning cleanly OR overfired/oversized you may have a partially plugged heat exchanger/cracked heat exchanger/damaged internal baffles etc which can affect the draft etc. Not much more I can help you with without actually seeing it for myself. We just had a poster change a igniter for no reason so swapping parts and guessing is not a good or safe way to go.

sutcha · 10-28-2009, 11:19 PM

This sounds like the same problem I had for weeks.Cleaned everything that I could think of.But when I would turn the furnace on there would be a small explosion inside. The force would blow my intake screen up an out of the furnace.My furnace is about twelve years old.I had it down to be the gas valve going bad. But I couldn't get a good cross reference over to the replacement valve.I finally called in a furnace repair man. He said he never seen anything like it.He had to do the cross reference threw heil.He brought over the new valve the next day.I installed the valve, an my problem was over.What a relief, it drove me crazy.After I installed the valve, I found the same valve on Ebay for 79.00. I gave 188.00 Good luck.

Wildcat355 · 10-29-2009, 01:00 AM

Well, there ya go. The HVAC guy sold me an oversized unit and another poster's pro HVAC guy "never saw anything like it". That's a professional who probably has his name on his shirt so he doesn't forget!
and now we're down to trusting a wholesaler who is an expert in what, catalogs? Has he ever even lit a pilot light, or has he always sat behind a counter selling parts? C'mon down Yuri! It shouldn't be more than a few days drive. Apparently their aren't any "experts" on the board south of Canada and since I know you won't come down, I should throw the whole danged heater out and spend a $1000 getting a new one? Or, should I hire a tech to inspect the heat exchanger because a lay-person like myself wouldn't recognize a crack in a heat exchanger from the crack... in the..... asphalt.
I'm glad I wasted all this

time trying to get some assistance and end up nowhere. Some advice. Let's rename the forum to Call a Technician, because the pros won't help you either for fear of liability or because when it comes down to the hard stuff, they don't know either.

Sutcha, Thanks. I just found a bunch there. I know that going down to the plumbing/heating supply warehouse, I'd pay about the same as you did. That 188.00 has to pay the guy to hold the stool down at the supply house. And, if the industry let too many facts out and didn't change model numbers every five minutes then more people would realize they CAN do it themselves and then put a lot of rip-offs and professionally employed idiots who "....ummmm, I never seen that before" out of business. Maybe we should bring back full service only gasoline stations while we're at it so the common person won't be endangering themselves by handling flammable fuels that only "professionals" in uniforms should be allowed to handle. Why we just might set ourselves on fire.

Oh the humanity!

Looks like I'm on my own on this one. See ya.