Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.
Question # 2 for Glenn Harrison & others
On a call for no heat by a new tech he finds that the gas valve has 24 volts to the valve. He has gas up to the valve. He determines that the gas valve is defective and he replaces the gas valve. He now finds that with the new valve he has the same problem it will not operate with 24 volts to the valve. He calls for a more senior tech to help him out. The senior tech rechecks everything and takes a gas pressure at the inlet of the gas valve which measures 7" W.C.(SORRY FELLAS NO 3.5" W.C. I WAS LOOKING AT THE NEXT PROBLEM I AM GOING TO POST WHEN TYPING LET US TRY THIS AGAIN) He also finds 24 volts to the gas valve and it will not open. He decides that the new valve must be defective out of the box.
Do you think it is the gas valve?
If not what could it be?
How could you prove it?
Do you think it is the gas valve?
If not what could it be?
How could you prove it?
0
Comments
-
If the gas valve will not open...
how is there 3.5" on the outlet side of it (manifold pressure)?0 -
Yah
And why does Jim's post say 2:22pm?
Interesting.
Mark H
To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"0 -
I know Timmie is waiting for something...
So here's something really stupid: The first tech only knows there is some sort of pressure there, but not the value. The second tech got himself a brand new gage, but it's not a U-tube, and he didn't calibrate it. So 7" is really 3.5", and 3.5" is really zero, there is a low gas pressure condition, and both valves are good. Nah, you wouldn't do that to us, would ya?0 -
The obvious answer is
They need a new heating system!!!!!!
Mark H
To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"0 -
Ya thats the ticket
But seriously folks, if there is 24 volts and 3.5 inches after the vavle than the valve is opening but not lighting at the pilot ? Do we have spark igniton and a bad module ?
Scott
To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"0 -
spider web
I have seen a spider web or soom kind of cocoon substance in the orfice or manifold pipe block the gas flow. The valve works fine the gas can't go anywhere0 -
Good point Jim my
mistake I corrected the problem. I have another problem I am going to post and I was typing from it. There is no 3.5" W.C. pressure as Jim says because the valve will not open. There are no tricks here just good troubleshooting to find the answer.0 -
Rob that is sure a possibility
and I also have run into that. That is not however the correct answer.0 -
Darn, tricks are more fun...
So, what type of ignition system? You gotta give us one now, to make up for driving us crazy!0 -
What type of ignition is this unit?0 -
Could it be.....
...that the gas valve is in the "off" position??
(not that that's ever happened to me :-0 )
Starch0 -
No John
the valve is not in the off position. Say you must be the only one who ever did that.0 -
Rob and others
this is a simple 24 volt standing pilot system with a thermocouple and Honeywell VR8300A gas valve.0 -
What....
Is the reading from the thermocouple?(did they check?)
O.K. Tim, I guess I REALLY have to ask this question.Has the pilot proved and is it in the right position?
Maybe this is the bigger question..... Is there a call from a thermostat or an aquastat? (I may have missed this once or twice, but with 24V at the valve ,I'll assume there is)
Maybe an improperly placed pilot flame? Inquiring minds would love to know.
Chris0 -
Good voltage but not enough
current? Years ago I had a solonoid valve that would not operate. After hours of troubleshooting I found only two strands of the stranded wire were in the stakon connector. The wire connector would not carry the current needed to operate the "load" but the voltage was there.
hot rod
To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"0 -
If
If he has 24V on a standing pilot and the pilot is operating, one would have to suspect the t-couple not providing enough MV to operate the pilot safety. Hot Rod named another "quirk" that I have run into only once. (thank goodness) Correct voltage but not enough current. I didn't know how to find it with a meter, I just happened to lay an eye on an 80% broken wire on that one.0 -
Let me see now
The pilot is lit, thermocouple is okay, voltage and amperage are okay. The thermostat is calling. You have all given some very good answers but no one has hit the jackpot yet.0 -
-
Tease!0 -
Timmie
I'm confused, what is the inlet gas pressure? is it 3.5 or 7.5 ?
You know I am an oil man and out of my league here, but, will a gas valve open against too much inlet pressure?0 -
24 volts TO the gas valve??
Voltage AT the gas valve?? How about voltage across the gas valve? The answer can't be as simple as a missing wire on the gas valve...
Howard Hansen..back without popular demand0 -
Safetys
You say there is 24 volts to the valve but is the common leg open? safety's installed on the common leg? and reading 24 volts to ground from the valve maybe?
S Davis
Apex Radiant Heating0 -
beat ya to it by 1 minute
Subject: 24 volts TO the gas valve??
Howard0 -
Let me make sure I understand...
There is 7" water column pressure at the inlet of the valve, while there is 24 volts at the valve coil, and there is 0" manifold pressure coming out of the valve, correct?
I ask this as my first thought is the 7" of pressure drops to nothing when the valve is energized with 24 volts. Is this the case?0 -
S Davis you got it
there is 24 volts to the valve but the common leg back to the transformer has a break in the wire.
The way to check a gas valve is this:
Place one test lead of your multimeter on the "C" (common) terminal of the transformer. Then place the other lead on the TH terminal of the gas valve you should read 24 volts if all the switches ahead of it are closed (they are) now move your test lead from the "TH" terminal to the "TR" terminal on the gas valve you should read "0" in this case with a broken wire back to the transformer you will read 24 volts.
An easy way to remember when testing is that if you have voltage on both sides of a load from the load to ground then you have a broken ground wire.
I even fooled Carol Fey with this problem one time and she is the best electrical troubleshooter in the world.
Final test to get it to work just place a temporary jumper from the gas valve terminal back to the transformer the gas valve will open and the burner will light.0 -
Glenn that would be correct as the gas
valve is not opening.0 -
Howard you
are correct as there is not a missing wire but a broken wire going back to the transformer.0 -
Bill Nye
the inlet pressure to the gas valve is 7" W.C. which is normal pressure for a gas valve. The normal pressure coming out of a gas valve is 3.5" W.C. Gas valves can handle up to 1/2 pound pressure roughly 14" W.C. as it takes 27.6 " W.C. to = one pound of pressure.
In this case because the valve would not open the pressure at the outlet would be "0".0 -
So what your telling us is...
you have seen times where you will read 24 volts at TH and TR, even though it should be impossible as TR is not grounded and the common is open/broken??? I have had broken commons before and never read 24 volts at TH and TR when it happened. Please enlighten me.0 -
Timmie McElwain
Tim, I was at a car wash and they had a 2psi service at the meter, there was a 2 inch IPS main and No Regulator!
The building inspector didn't see it , the utility engineer didn't, a couple of other good people missed it. Finally me the oil man showed up. I put my gauge on it and it pinned the gauge. I thought I wrecked my gauge.
I called the gas service guy and asked him if maybe it needed a regulator, oh yeah! he said. Some times we miss the obvious.
The open neutral, how many times did I talk to a fellow tech on the phone at night that "swore it had 110 going to it". My answer was always , try disconnecting it and plug it into an extension cord. It runs, ok, you have a broken white wire. Check all of your wire nuts0 -
Timmie McElwain
Tim, I was at a car wash and they had a 2psi service at the meter, there was a 2 inch IPS main and No Regulator!
The building inspector didn't see it , the utility engineer didn't, a couple of other good people missed it. Finally me the oil man showed up. I put my gauge on it and it pinned the gauge. I thought I wrecked my gauge.
I called the gas service guy and asked him if maybe it needed a regulator, oh yeah! he said. Some times we miss the obvious.
The open neutral, how many times did I talk to a fellow tech on the phone at night that "swore it had 110 going to it". My answer was always , try disconnecting it and plug it into an extension cord. It runs, ok, you have a broken white wire. Check all of your wire nuts0 -
Glenn
with one lead of your meter on the common terminal of the transformer you should read 24 volts on one side of the gas valve coil and "0" on the other side. If the wire back to the transformer is broken you will read 24 volts on both sides of the gas valve coil.
It is easy to get fooled because you have 24 volts at the gas valve so the tendency is to think that the valve is faulty as it will not open.
If you have a broken wire back to the transformer and you put your meter directly across the coil on the gas valve what will you read? Answer "0" because there is no path back to the transformer.
It depends on how you are using the multimeter but if you follow my method you can not be fooled.0 -
You got it Bill
I carry a 25 foot extension cord with the alligator clips on one end. Hook it up to the motor and plug it in if the motor runs and it will not connected to the system then the ground is bad.0 -
Tim, I understand your testing method,
and I like it alot, as you said it is foolproof. I'm just saying I cannot see how you could put one probe on TH and one on TR and read 24 volts if the common is open. Now, if someone is in the habit of puting one probe on common at the transformer or contol board, and then hopskotching the hot side, then I see where false reading would occur. I guess I was always taught to test at the device that is supposed to be energized, in this case the valve coil itself.0 -
We had one today
that is getting a true 24-volt signal, yet not opening consistantly. It's sticking. Tap it and it opens. Works intermittently, which adds to a troubleshooters exciting travels. (Not the foist time - nyuk, nyuk, nyuk)
To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"0 -
Glenn next time you have a chance try it
pull the lead of the TR terminal which should be wired to the hot side of transformer. Then test each side of the coil and see what you have, should be 24 volts. Now put the lead back test again should have 24 on one side "0" on the other (the common side) All 24 volt gas valves are really just two wire valves the combined TH/TR is just a dummy terminal.0 -
Back without popular demand
> Voltage AT the gas valve?? How about voltage
> across the gas valve? The answer can't be as
> simple as a missing wire on the gas
> valve... Howard Hansen..back without popular
> demand
0 -
\"Back without popular demand\"
I like that.
Nice job of reading between the lines Howard.0 -
I will do that...
and I understand what your saying completely.
Thanks for the questions. Can't wait for the next one.
0
This discussion has been closed.
Categories
- All Categories
- 86.6K THE MAIN WALL
- 3.1K A-C, Heat Pumps & Refrigeration
- 54 Biomass
- 423 Carbon Monoxide Awareness
- 98 Chimneys & Flues
- 2K Domestic Hot Water
- 5.5K Gas Heating
- 101 Geothermal
- 157 Indoor-Air Quality
- 3.5K Oil Heating
- 64 Pipe Deterioration
- 931 Plumbing
- 6.2K Radiant Heating
- 384 Solar
- 15.2K Strictly Steam
- 3.3K Thermostats and Controls
- 54 Water Quality
- 42 Industry Classes
- 48 Job Opportunities
- 17 Recall Announcements