Convection Heater Problem


  #1  
Old 10-04-02, 02:13 PM
Taoduck
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Question Propane convection heater not firing

Greetings...

I am using a Universal Model 80-VCA propane convection heater in my woodshop. I have the tanks installed outside the shop, and the hose is routed inside through a small hole in the wall to the heater. The system worked very well last year, but when warm weather hit, I did not consider or perform any maintenance on the unit, nor did I think to disconnect the hoses.

Now, with cold weather approaching, I am running into difficulty getting the heater to maintain a flame. When I turn on the tank, there is an unusual amount of venting coming from the regulator assembly on the hose (this venting did not occur last year). The pilot light (piezo-electric ignition) works well... a nice blue flame with streaks of yellow... but it's been extremely difficult to get the main flames from the orifice to ignite. Last year there was no problem with this... the heater was ready and eager to light.

When the flames DO occur from the orifice jets, they usually begin with the one or two jets closest to the pilot light... then sometimes spread to the other jets (but not always). The flames are bright yellow. When the flames occur, the venting stops from the hose regulator assembly. After a short length of time... anywhere from 3 to 15 seconds... the flames abruptly cut off, and the venting resumes from the hose regulator assembly. After a few attempts at this, I shut off the tank and waited for any excessive fumes (both indoor and out) to dissipate before trying it again. And again..... I've removed the hose from the heater, and the propane flows OK through the hose. I checked all connections with soap solution, and they are all OK.

Could this be the hose regulator assembly? Or clogged orifice jets? This is my first foray into propane, and I'd appreciate some feedback. Thanks.
 
  #2  
Old 10-04-02, 04:58 PM
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good details

fist off, venting occurs to prevent excessive pressure. from what you describe, i would look at the burners and carry over area that transfers flame from burner to burner, etc. being a wood shop i would expect a lot of dust in these areas. this could prevent proper gas flow, therefore venting at the regulator, and as you describe not always light all burners. give it a good cleaning, that may do the trick.
 
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Old 10-04-02, 05:01 PM
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BTW

get the gas company to check the pressure at the valve, your regulator may need to be adjusted, or even could be throttling. also if you clean the burner assembly so not use a stiff wire brush, as it could damage it.
 
  #4  
Old 10-05-02, 11:07 PM
Taoduck
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Question

Thanks for the feedback....

I disassembled the heater. The main orifice jets were clean as a whistle. As I disassembled the main "plumbing" of the heater, I checked flow on various parts... both with air and propane.

The "divertor" button that sends propane to the pilot light assembly seems to work fine... no venting at the hose regulator assembly occured while the button was held in, but DID occur when the button was released.

There are no clogs after that area either... the ball valve was removed, and was clean, as was the piping leading to the orifice. It appears that there is some reason the propane will not flow past the divertor button as, I imagine, it should. Venting occurs at the hose regulator when propane is hooked up and the divertor button is NOT pressed in.

There is a spring-loaded assembly activated by the divertor button that could be the culprit... the schematics give no information as to what this part is... so I have no idea what to call it. When this mystery part is removed, everything looks clean.

There is still a faulty hose regulator assembly to be considered. I run two 10-gallon tanks... when one is empty, I switch the regulator over to the backup and refill the first... so I am dependent upon tank pressure. I did vent both tanks at the valve early on in this process just in case that might have made a difference. The regulator appears to be a standard type used with grills... and it DOES say that the regulator should be installed with the vent aiming vertically downwards (of course, I didn't notice that until now)... I don't know if that would matter... it's just been screwed into the tank valve all this time. Horizontally.

Any more thoughts would be appreciated....
 
  #5  
Old 10-12-02, 08:12 PM
Taoduck
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Talking Problem solved!!

It was the hose regulator.

It had been a struggle to find someone who was conversant enough with these heaters, but I was able to talk to a local heater shop mechanic who had dealt with one before.

The mechanic felt that the "mystery part" was one that rarely had problems associated with it, and a blocked hose regulator was more likely to be the culprit.

When I removed the regulator from the hose, there was 3/4 of a moldy gasket inside. Aha!!

Apparantly, the blockage didn't allow enough pressure to pass through the hose... there was enough pressure to maintain the pilot light, but not the full burner. The vent on the hose regulator therefore kicked in to prevent a buildup.

I couldn't find an exact replacement for the regulator, so I substituted a Mr. Heater one with a suitable rating as the heater. This new one has the advantage of having the vent on the side of the unit rather than the front... it was an easy matter to install it on the tank so that the vent pointed downwards.

Now I'm warm!!

Hope this helps someone else....
 
 

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