Heater Help.. Pilot Light

[oldcpecdr]

Hi all

I have an EMPIRE direct vent hot air 35000 btu propane furnace on the first floor of the shop. It is insulated and drywalled and I block off the upstairs section with a heat curtain so am only heating about a thousand SF. The heat has worked flawlessly for almost 14 years, I have replaced the thermocouple twice , about every 5 years.

On Monday I noticed the heat wouldn't fire so I checked the propane
tank..half full and pressure at the furnace. I re-lit the pilot manually and
it cycled several times but when I went out the next morning it was out.

So down to the store to get a new universal thermo-couple... replace, re-lit
and all was fine....till Wed AM .. I re-lit and it was fine for one more
day...cycled just fine...but Thursday out again...

I took everything apart, blew out the pilot tube..vacumned out around all the heat tubes etc but I have to say it is very clean and not corroded. I re-lit again and it was fine till Fri morning (today) and went out again.

Any ideas...Should I try another thermocouple even though this works for 12
hours or so ? Pilot light and main burners are burning a nice blue and look
great...when they are lit....

Any input appreciated...

Thanks Mike B

 

[Richard Cranium]

It sounds like your thermo-couple is not making a good connection- Maybe some corrosion. I don't know if you could you a dioeletric grease

 

[zmaxmotorsports]

Hi all

I have an EMPIRE direct vent hot air 35000 btu propane furnace on the first floor of the shop. It is insulated and drywalled and I block off the upstairs section with a heat curtain so am only heating about a thousand SF. The heat has worked flawlessly for almost 14 years, I have replaced the thermocouple twice , about every 5 years.

On Monday I noticed the heat wouldn't fire so I checked the propane
tank..half full and pressure at the furnace. I re-lit the pilot manually and
it cycled several times but when I went out the next morning it was out.

So down to the store to get a new universal thermo-couple... replace, re-lit
and all was fine....till Wed AM .. I re-lit and it was fine for one more
day...cycled just fine...but Thursday out again...

I took everything apart, blew out the pilot tube..vacumned out around all the heat tubes etc but I have to say it is very clean and not corroded. I re-lit again and it was fine till Fri morning (today) and went out again.

Any ideas...Should I try another thermocouple even though this works for 12
hours or so ? Pilot light and main burners are burning a nice blue and look
great...when they are lit....

Any input appreciated...

Thanks Mike B

Is there a breeze blowing through the area where the heater is,Does the heater make any loud noises when it fires up?
Can you post a picture of the heater?
Maybe a bad gas valve.

 

[koditten]

Any chance you sealed up the structure and have negative air flow?

 

[oldcpecdr]

I'll try dielectric in the morning.. but last two thermocouples worked for five years each.

Gas valve seems to work fine and I can hear the solenoid click as it ignites the first few cycles.

The insulation and air flow haven't changed much in 14 years... I am going to check the outside vent in the morning...

Mike B

 

[zmaxmotorsports]

Watch the flame/burners when blower kicks on,Does it look like air is coming in and affecting it?

 

[RECox286]

Is the burner puffing when it shuts down, blowing

out the pilot ? Gas valve possibly ? Is there a

screw to adjust the pilot flame ? Maybe a weak

t-couple to begin with.

Uncle Bob

 

[oldcpecdr]

Thanks for all the suggestions...I took it down again today and installed another new thermo-couple and re cleaned the pilot and of course it fired right up and ran perfect for one heat cycle..about three hours and shop up to 55 and all was well....

Then it didn't restart and pilot was out again...

I am going to check the direct outside vent tomorrow for any sign of a missing baffle or whatever and then research testing the gas valve...I didn't think the gas valve would be intermittent but maybe when it heats up it sticks ?

Off to the internet to study up...

Mike B

 

[Caddybill]

does the pilot flame hit the thermocouple about 3/4 the way up and get it nice and red? If not maybe the pilot assembly is clogged or the gas pressure is NG. You can test the Tcouple using the millivolt feature of a DVM. should be around 30mv disconnected from the gas valve. about half that when connected to the gas valve( you will need a special adaptor to test this)

 

[zmaxmotorsports]

I dont think its a thermal couple issue,they tend to be more of a go or no go issue.(kind of like my wife on sat night! )

 

[Jackfre]

I dont think its a thermal couple issue,they tend to be more of a go or no go issue.(kind of like my wife on sat night! )

Only on Sat nite? You are a lucky man!

I'd throw in a new thermocouple. Cheap, easy, you know how to do it and should tell the tale. Otherwise you get into the gas valve or possibly your tank regulator.

 

[FullRaceMerc]

I'm with most of the replies above, it sounds like it could be a caused by an airflow issue. I'm not familiar with your specific heater, so these are more general things to check. Sometimes a bad exhaust baffle allowing a breeze could be the problem. And in a fan forced heater, blower air sometimes can leak in a way to blow out a pilot. Or poor exhaust allowing CO backflow to kill the flame. Or fresh air supply blocked enough to suffocate the flame. Sometimes a pilot a little out of position will be affected by the burner turning on or off in a way that snuffs the pilot.

I'd watch the pilot thru several on & off cycles. Watch for odd blowing of the flame. Can you see the pilot without removing any covers? Using a mirror? Airflow can be different with a cover off & cause the problem to not show up.

Is it more likely to happen after running undisturbed for a long period of time? That can point to supply air issues. Or possibly an exhaust blower that overheats & cuts out over time.

And a gas valve, as it fails, can have intermittent spurts. But usually you will have lighting issues as well if that is the case.

 

[jambottle]

i had to modify my thermocouple mounting to put it more directly into the piolet flame to fix the same problem with my burner. worth a try.

 

[dreasoner]

You are able to see furnace relight thru several cycles? A cracked heat exchanger will cause crazy airflow patterns. Have also seen a crack blow the pilot out. Can you check CO levels easily in the conditioned air? Have you verified LP gas pressure on inlet and and manifold? Just throwing out ideas.

 

[zmaxmotorsports]

You are able to see furnace relight thru several cycles? A cracked heat exchanger will cause crazy airflow patterns. Have also seen a crack blow the pilot out. Can you check CO levels easily in the conditioned air? Have you verified LP gas pressure on inlet and and manifold? Just throwing out ideas.

Thats why I asked about funny noises when it fires up and flame blowing around when running.

 

[crankshaftdan II]

Does this unit have a flame sensor? If so, maybe it needs cleaning?

 

[zmaxmotorsports]

Does this unit have a flame sensor? If so, maybe it needs cleaning?

It has a thermal couple and a standing pilot.

 

[oldcpecdr]

Hey all

Thanks for all the additional suggestions.. I spent the day in the shop and did a lot of cleaning while watching the heater cycle on and off..

It worked most of the morning and finally the pilot died after lunch... I relit it and it was fine for several cycle... I then turned the thermostat up and down watching the main burner light off and then shut off....
on ONE occasion it did make a rumbling puff and the pilot blew out on a relight... I don't see any visible cracks in the combustion tubes but a lot of that is hidden...short of taking apart all the sheet metal it would be tough to inspect.

I did relight it after the blow out and it ran fine the rest of the day. I shut it off about 7 PM as I was a little leery about leaving it running all night with no supervision.

Any chance the gas valve is sticking occasionally ? The thermocouple seems fine as the pilot starts as soon as I let it warm up.. I can hear the gas valve solenoid pull on as soon as I raise the thermostat..

Does a gas valve fail slowly?

Thanks
Mike B

 

[oldcpecdr]

Pictures with front cover off

 

[Champ128]

Some gas valves open slowly and others just open. Often times the valves that are a slow open do not open as fast as the did when new, which causes some of the symptoms you describe, like the rumbling puff. This could also be caused by dirty burners that need to be cleaned and the air adjusted.

 

[zmaxmotorsports]

Hey all

Thanks for all the additional suggestions.. I spent the day in the shop and did a lot of cleaning while watching the heater cycle on and off..

It worked most of the morning and finally the pilot died after lunch... I relit it and it was fine for several cycle... I then turned the thermostat up and down watching the main burner light off and then shut off....
on ONE occasion it did make a rumbling puff and the pilot blew out on a relight... I don't see any visible cracks in the combustion tubes but a lot of that is hidden...short of taking apart all the sheet metal it would be tough to inspect.

I did relight it after the blow out and it ran fine the rest of the day. I shut it off about 7 PM as I was a little leery about leaving it running all night with no supervision.

Any chance the gas valve is sticking occasionally ? The thermocouple seems fine as the pilot starts as soon as I let it warm up.. I can hear the gas valve solenoid pull on as soon as I raise the thermostat..

Does a gas valve fail slowly?

Thanks
Mike B

A rumbling puff/boom when the furnace kicks on is a good reason to have the heat exchanger inspected in my book.

 

[dreasoner]

The furnace has enough age on it to suspect a heat exchanger. Pilots were on the way out in '92. A high CO reading with the gas train cleaned would also suggest a crack. The typical location would be where the flame pattern hits the shells and around welded joints. Do you have a CO detector in your living space that is near the furnace.? A crack won't instantly kill you,but it is something to take very seriously. I don't know of any other way to be sure of the heat exchanger but a thorough visual. Smoke candles are an option but they can be very messy. Any ideas

 

[dreasoner]

Date code is usually in the serial number. That is probably 7 month of '94. Wall furnaces are not hard to install or exspensive to buy. Can that unit be pulled from the cavity in 1 piece to look at the heat exchanger?

 

[oldcpecdr]

Hey all

It's in a separate shop NOT attached to the house or any living spaces... looks like there is a panel that can be removed to inspect the exchanger... I don't see any VISIBLE cracks or problems with the exchanger but a lot of it is hidden.. I will take a look later today.

Mike B

 

[rharman]

A new RobertShaw valve is probably only about $50. I had to replace mine on a fireplace but the symptoms were different.

 

[oldcpecdr]

Hey all

Pulled off the inner panel and inspected the exchanger... all looks good and no corrosion or obvious leaks anywhere. Went over to my friends shop and borrowed his smoke machine they use for finding emission evap leaks and it all is coming out the exhaust. Ordered a new pilot light assembly and will try that when it arrives. Off to sunny California till Monday so the cars will have to shiver for a few days.

Thanks for all the suggestions so far

Mike B

 

[mygarageone]

We just dealt with this kind of problem , believe it or not the pilot we had was was to strong ( you could hear it roaring ) and the least bit of air movement would blow it out , so we adjusted the flame down so just the flame tip was hitting the thermocouple , it is a lazy flame compared to what we had but that was the problem for us and it" s been 3 wks and no pilot outages .

 

[oldcpecdr]

Pilot seems just about perfect.... the owners manual says there is only adjustment for natural gas, not LP (propane) but I am thinking for 14.00 I will try a new pilot assy.

 

[zmaxmotorsports]

Hey all

It's in a separate shop NOT attached to the house or any living spaces... looks like there is a panel that can be removed to inspect the exchanger... I don't see any VISIBLE cracks or problems with the exchanger but a lot of it is hidden.. I will take a look later today.

Mike B

Normally you remove the burner assemblies,then look up inside each chamber of the heat exchanger with a small flashlight and an inspection mirror on the older clam shell heat exchangers.

 

[mygarageone]

Pilot seems just about perfect.... the owners manual says there is only adjustment for natural gas, not LP (propane) but I am thinking for 14.00 I will try a new pilot assy.

I have yet to see a non adjustable pilot on any gas valve . But I have'nt seen everything .

 

[oldcpecdr]

May be adjustable.. but definitely says LP does not require... off to California for a few days..wont need heat there.. I hope

Mike B


The correct pilot flame (Figure 11) will be blue, extending past the thermocouple. The flame will surround the thermocouple just below the tip.Natural gas pilots require adjusting when the inlet gas pressure isabove 5" w.c. (1.245kPa). Remove the pilot cover screw on the control valve (Figure 3), and turn the adjustment screw clockwise to reduce flame. Replace pilot cover screw to eliminate gas leaking at that control valve opening.

LP gas (Propane) will not require adjustment.After use, cleaning may be required for the proper flame.




Related Manuals for Empire Heating Systems DVC-35-1SPP

 

[zmaxmotorsports]

Many cracks dont open up till the furnace gets hot,did you take a picture of the heat exchanger when the cover was off?

 

[oldcpecdr]

Hey all

Flew back from LAX last night 85 and sunny and got to DC and got grounded, flight to Providence cancelled....

So just got home... the way to fix the furnace would have been to stay in California.

But instead I will install the new pilot assy that arrived while I was gone..
Hope to have good news and heat end of day tomorrow....or maybe a ticket back to Ca....

Nothing more fun than snowblowing a foot of snow after getting home a day late !!!!

Mike B

 

[dreasoner]

It builds character.

 

[oldcpecdr]

New Pilot light installed for 24 hours and so far so good....

With single digit temperatures coming up the next few days it should get a good

workout!!!!!

We will see if I actually get to work out there this weekend...

Mike B