reznor unit heater

[mike grab]

i am having a problem with a reznor unit heater. i dont have the model #. 125,000 btus. on me but here goes.
its newly installed last week. the unit tripped flame rollout. when i returned to find problem it would lock out on flame sensed while gas valve is not energized.

there is a lingering flame when the gas valve shuts off for about 10 seconds. this is what the sensor senses.
the unit is vented horizontally about a 4 ft run max.
it does it with the flue conected or not. it does it at any gas pressure.
is the draft inducer motor not alowing enough draft?

[Diceman]

Many unit heaters do not draw well, they are hung close to the ceiling and there isn't enough vertical height for proper draw, also the bldg may have some negative pressure in it. I have seen many old unit heaters operate under those conditions, and no one knew cause older ones didn't have the rollout sw. On new reznors I sell and install I go with the better models with built in draft inducers, just installed a 250K one last week. I have no problem with those.
2 things ya can do at this point.
1- Possible cheap out method, add a whirly bird spinner cap on top of the flu, they can really help sometimes.
2- Install a small additional Tjerland draft inducer, with a time delay run on it or rewire the one you have to stay on for a period of time.


[Edited by Diceman on 01-31-2004 at 10:37 AM]

[cynic]

Still having flame 10 seconds after the valve is supposed to be closed sounds like a problem with the gas valve.

[Diceman]

True, I missed that, valve could be bad.
I thought he was talking about residual heat still lingering.

[hvt]

Reznor= junk

I have found more cracked heat exchangers on reznor equipment than on all others combined, I really dont know how they can still be in business, maybe in some areas a couple of small cracks are OK when installed in garages and warehouses.

[bradjmx4]

Check the polarity of the incoming power. Reznor setups react bad to reversed polarity.

[airmax]

Most UH I worked on had 24v to the stat.
On a call for heat it would power up the flame sensing device, which in turn would power up pilot, sense the flame if there was any, and power up main gas valve.
Call ends, you lose power to flame sensing device, gas valve included.
No lock out.
Roll out switch should be wired in series with the stat/ flame sensing device.
Change the gas valve, most likely problem.

[mike grab]

the gas valve is closing 100% closed. i can put my ginger over the orfice and the flame still lingers. i also checked with my magnahelic no pressure at the orfice when the valve looses power
maybe a better way to discribe it is simular to an old ribben burner when the gas valve shuts of it takes maybe 3 seconds for all the gas to burn off in the burner.

m# UDAP 125
S#BBE79Y2N63979X

i havent taken the burner apart to see whats inside but i will try to explain what it looks like.

from the orfice it goes into about a 1.5 inch tube that goes into a rectagular box at a 90 deg angle. from there i asume its diverted into each heat exchanger cell

[troyorr]

Is this on LP? If so, did the individual doing the conversion install the adaptor on the inlet venture tube? IF not on lP, sounds like a bad gas valve. How does the vent terminate after 4 feet? Find the instructions, you may need to increase the vent lenght to a minimum of 5 feet.

[troyorr]

Call a qualified service technician. Don't burn your building down working on something you are unfamiliar with.

[Diceman]

Yeah, now I know what ya mean, just like the one I put in last week, very weird design huh? I noticed mine had a good draw on the vent already. That seems to be your problem, put a spinner cap on it or wire the draft inducer to run for a time after the flame shuts off. The Reznor I got had 2 nuts missing from the fan motor, it was hanging down, new in the box like that. Thats an odd size too, lucky I had a few of em laying around in my misc collection of junk.

[mike grab]

i am the qualified service mechanic who installed this thing. i can assure you its not the gas valve. just read my last post.

whats this spinner cap you are talking about diceman? is it like some of the older roof vents that spin with the wind or hot air rising thru the attic?

the inducer runs for about 30 seconds after the gas valve turns off.

[Diceman]

Yeah, that's what the are but you need to really investigate the flu and all that, you did check it on the roof right? Do you have a good draw on the flu, you need to find out. 30 sec of extra run time should clear out any heat, not sure what is going on here, something weird. Start with the flu, draw, etc.

[valvndamperguy]

Spinner caps are not accepted be the AGA.

[Diceman]

Who cares.

[sirtab]

I didn't think those spinner caps are legal on a flue. Because of the fact they can sieze up in a high wind or if a pigeon or something fly's into them. If they can't spin there are a hazard. They do work good though. But my neighbor had a squeeky one. It went squeek squeek squeek squeek squeek squeek squeek squeek squeek squeek squeek squeek so now I hate em. Crawled up on his roof myself and "SHOT IT" with WD40 worked fine ever since.

[Edited by sirtab on 02-03-2004 at 10:42 PM]

[valvndamperguy]

If we don't care, who will? You can't put a moving device in a flue unless it's mechanically interlocked with the combustion cycle (tjurnlund, field, etc.). This is life safety stuff.

[customheating]

i dont know if this will help., but i put in the exact same model, same size brand new, about 2 months ago. it was a bad honeywell valve. hard to keep pilot lit, and it would burn for a few minutes, then kick out. i think you have a bad valve. are you sure its kicking out the rollout. there is a pilot cut off that goes in the back of that valve, shaped like a triangle, i would lean toward the valve. but not completly sure.

[hvt]

Originally posted by hvt
Reznor= junk

I have found more cracked heat exchangers on reznor equipment than on all others combined, I really dont know how they can still be in business, maybe in some areas a couple of small cracks are OK when installed in garages and warehouses.

[mike grab]

this unit does not have a pilot its direct spark ignition.
i am 100% positive it was the flame roll out cause the board flashed the code for it and also i had to press the manual reset to get the unit to fire.
like i said o know the gas valve is shutting off cause i can put my finger over the orfice to stop gasflow ( even if it had 2 pounds pressure i could stop the gas flow).
i was supposed to go there monday but didnt have time, and havent had time since. the only thing i have seen on the directions that i havent done right was a special reznor flu cap. ( in the picture it looks exactly like a high wind cap)

[Diceman]

Those spinner caps have enough of an opening, as much as any cap you see, that if they seize up the flu gas will easily escape. If you have major problems you need to address them, if it's marginal they are OK, that's my experience. Anything can plug up a flu, birds, broken flu pipe, etc. With regular maint and especially if you have a safety rollout sw on the draft diverter, they are safe.
As safe as any of this stuff can be.

[mike grab]

i went back today. unit says max horizantol vent 5 ft. i have 4 ft 6 inchs.
i reset gas pressure to 3.40 in wc spec is 3.5.
i took apart the burner and cleaned it out. was a lot of cardboard dust in it. man that thing is a P.O.S. a box about 16 inches tall by about 4 inches wide by 6 inches deep. has somekind of metal slots for the actual burner.
i also re enginered the flame sensor. ie. bent an offset away from the burner.

since i did this it worked fine. it still takes a while for the residual gas in the burner to burn off but instead of 11 seconds its 7 seconds. the website said the board gives it 10 seconds after the flame goes out for the sensor to stop sensing the flame.

crappy design if you ask me. i wont let the office order one of those again.
that makes 2 bad brands on my list
sterling and reznor.

[hvt]

Originally posted by mike grab


crappy design if you ask me. i wont let the office order one of those again.
that makes 2 bad brands on my list
sterling and reznor.

I always recommend lennox unit heaters, I rarely ever have problems with them. They are well worth the extra money.

[flipman2000]

This known as a soft lockout condition and for some reason, this only occurred on the 125,000 btuh unit. This is not a safety concern since the gas valve shuts off completely. The fix for this is to relocate the flame sensor. Reznor supplies a bracket which will can be used to relocate the sensor.

[slimwoodie]

well of course ... hecho en mexjico .... buy modine next time .....why do all carrier distributors sell reznor, anyways ??

[kb0vso]

If it is not wired wright it will act like senser. Check to see if lL1 and netural are correct and that it has a ground. It happened to me once.
I changed the cir board and the gas valve before I got smarter.

[acc]

i find spinner caps sieze to often

they have to be re-lubricated few times per heating season

ive only installed one and will not do anymore

when they do sieze,and the wind changes direction,there is a fine mess in burner/wiring/heatex area

especially on a older unit with no roll out device

this was for a rezenor rooftop heater and im sure a unit
heater would be the same

as for bird nesting debris problems,bird/chicken wire,or any other with small holes works good

[markwolf]

Originally posted by hvt
Reznor= junk

I have found more cracked heat exchangers on reznor equipment than on all others combined, I really dont know how they can still be in business, maybe in some areas a couple of small cracks are OK when installed in garages and warehouses. I agree instead of giving warranty heat exchangers they give a sheet telling you their burners are in a negative pressure so the cracks are ok-What a load of *hit!

[dg1976]

Originally posted by markwolf

Originally posted by hvt
Reznor= junk

I have found more cracked heat exchangers on reznor equipment than on all others combined, I really dont know how they can still be in business, maybe in some areas a couple of small cracks are OK when installed in garages and warehouses. I agree instead of giving warranty heat exchangers they give a sheet telling you their burners are in a negative pressure so the cracks are ok-What a load of *hit!

At least you got a response! Reznor is piss poor at customer service. They are great at the initial sale and as long as you don't complain, everything is good and they will treat you well. First time you have a problem, you are an a**hole. I work for a distribution company that sells Reznor so I feel qualified to chime up here. If you only knew some of the junk that has rolled into my warehouse from Reznor's Monterey Mexico facility and worse yet, being told to IGNORE THE PROBLEMS and ship it to my customers, or blame the installation....SCAREY STUFF! Thank God we are an independent distributor. I have all but told Reznor and our regional rep to stick it in their a**. Unfortunatly, one of the other owners of my company has a long standing relationship with Reznor and wants to give them "one more chance to work out their problems" He just found out Monday that we lost a huge project due to Reznor not fixing a problem with one of their units in the past. I have no faith in Reznor and would not be mad if I never sold another piece of T&B equipment again! It is only a matter of time before we change lines.

Let me put it another way: I have the opportunity to buy Reznor products at distributor cost. My garage and my personal greenhouse both got new MADE IN THE USA Modines this year ...enough said.