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Originally Posted by jperigo

Ever find out what was the issue?...
What the issue was?...
Issue is?...

Yeah, valves were bad. This place has been neglected for a very long time. We changed all the valves and now everything is working fine.


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Ever find out what was the issue?...
What the issue was?...
Issue is?...

hit the valve with your kliens while holding the button and lighting. im bettin bad valves

I know its a long shot, but have you tried blowing out the pilot tubing and carefully inspecting the pilot orfice? Sometimes spiders will lay eggs inside the tubing, its not enough to stop the gas flow but enough to weaken the pilot and make you rip your hair out....

When I was a young tech I learned this after a couple call backs and was stubborn thinking that if the pilot is lit and how the hell would a spider get inside that tiny tube - but they do....

BTW, you have to use compressed air, simply blowing on the tube will not do it...

Good luck!

I use an old Baso switch I carry often for the magnet test

Magnet. That's what I was thinking.

Originally Posted by timebuilder

Maybe it's just a difference in terminology, so I'll ask...

What are you referring to as a "power unit?" Can you post a link?

Hi TM
Years ago when you could actually purchase sections of gas valves one was the magnet. It was termed "power unit" by Honeywell as well as other mfg.
I don't have link to post
Magnet has always been the accepted term.
Possibly it would be the same as saying Freon when speaking of refrigerants?

Originally Posted by mike3

The use of power unit(magnet from old valve) is not a conclusive test. Just because the tcouple holds the magnet only means the tcouple is producing at least 2 or 3 mv. You must use and adapter to take a load and dropout read. Usually you see around 12-15 mv under load and dropout should happen 2-3 mv. I've taken probably over a thousand mv test in my career and always used a meter. The suggestion of the power unit has merit only in a situation where you can't install the adapter into the valve due to position. I used my power unit with the adapter to check tcouple value. Of course this does not test the valve for dropout.
Wish you well

Maybe it's just a difference in terminology, so I'll ask...

What are you referring to as a "power unit?" Can you post a link?

The use of power unit(magnet from old valve) is not a conclusive test. Just because the tcouple holds the magnet only means the tcouple is producing at least 2 or 3 mv. You must use and adapter to take a load and dropout read. Usually you see around 12-15 mv under load and dropout should happen 2-3 mv. I've taken probably over a thousand mv test in my career and always used a meter. The suggestion of the power unit has merit only in a situation where you can't install the adapter into the valve due to position. I used my power unit with the adapter to check tcouple value. Of course this does not test the valve for dropout.
Wish you well

First observe then fix.

Also to note , you must have a strong blue pilot flame hitting the thermocouple tip, no lazy red flame.

If these are all old units , and or they don’t have drip legs in the gas line, the pilot safety valves maybe corroded or seized up. Try tapping on the gas valve before you release the pilot knob to free them up . Worked for me numerous times.
If that doesn’t work and you have 30 mv with no circuit Wires under the thermocouple, you need new gas valves.

Take the magnet out of a good gas valve(When you discard an old valve or furnace) Use the old magnet as a service tool.Take the thermocouple out of the gas valve you are working on.Screw the thermocouple into the Magnet(Tester).Lite pilot hold in the magnet.See if it holds in!!!If it holds in,Thermocouple is good.May have a bad valve.Make sure you don't have an ECO.Look for 2 wires coming out of the gas valve, going to a temp switch or fusible link.An ECO will break the thermocouple MV signal,If it is open,Preventing pilot from staying lit.

Well things did not go according to plan. I was called out to another job and the outside company went and did some troubleshooting. What they came back with is bad gas valves. The boss told them to change one and see if their theory was correct and if it is, then I will change the rest. If not, then back to square one.

I know it is unlikely that five valves went bad at the same time. What is possible is the site has been neglected for numerous years and the valves all didn't actually go bad at one time. Previous tech was fired for goofing off instead of working. It got so bad they put a GPS tracker on his truck and found him 45 miles away from where he was supposed to be at.

Originally Posted by Fender60

I am hoping to get back to that site tomorrow. I am fortunate that my boss isn't a jerk and knows that I am a rookie tech. He has called a local company that is owned by a former HVAC instructor at the college where I work to come and look at the units. My boss asked him and he agreed to let me be there to see what a seasoned tech finds wrong with the units. At least this way I can learn something for next time.

.

I am hoping to get back to that site tomorrow. I am fortunate that my boss isn't a jerk and knows that I am a rookie tech. He has called a local company that is owned by a former HVAC instructor at the college where I work to come and look at the units. My boss asked him and he agreed to let me be there to see what a seasoned tech finds wrong with the units. At least this way I can learn something for next time.

I have a solenoid from an old carier 60% gas valve i think it was. I just screw the thermocouple into it and if it holds then i call the valve bad.

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Originally Posted by Red Man

So this is a site with lots of unit heaters and only five have problems. These five are in different buildings. The problem is not common to them all. One possibility is they failed one at a time and no one complained for a while until a bunch had failed. One other thought is the original thermocouples were bad. When they were replaced they were over tightened, damaging the gas valve. Some gas valves are more sensitive to over tightening than others. I was taught to never screw in a thermocouple more than 1/4 turn past hand tight.

I have seen this many times. The call only comes in when enough people compalin and they can't keep up with the load.

I wouldn't replace anything yet. You have the adapter. A t'couple can't be properly tested w/o a load. Like a battery, the condition needs to be load tested. The test is two parts. The first with no load then with connected to the solenoid engaged. If the adapter didn't come with any charts you can probably find one an Honeywell. It shows the pull in/drop out graph where the t'couple should function.
But I don't think the pilot sensing is your problem. Hook up your adapter, lite the pilot and watch the readings when the burner is fired. It should remain within the range on the graph. If you don't have a graph you should not drop out. Most are OK at 8 mv.under load. A gas line with too much pressure drop is often the problem as you have 5 with the same problem I would suspect pressure drop.
Exhaust fans that bring in some of the make up air from the flues can create these problems by drawing the flame away from the t'couple.
The thing is, watch the flame to find if the problem is the pilot flame drawing back from the spot it needs to hit. That spot is 1/2-3/8 inch at the top of the t'couple. If the flame is too low the t'couple won't generate what's needed and will also fail soon.
My 2 cents.

I also will tell of pilot outages where some one, out of frustration probably, increased the pilot orifice hole to try to keep the pilot from going out w/o fixing the actual problem. This will burn out the t'couple fairly soon.

I say replace a valve on one and go from there.