Furnace and water heater seem to have low pressure

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  #1  
Old 02-06-18, 01:33 PM
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Furnace and water heater seem to have low pressure

Hello. I just had my water heater go out due to the pilot not staying on. I replaced the thermocouple/pilot assembly, but the pilot still wouldn't stay lit, so I called in a professional who checked my work and replaced the gas valve. He wound up with the same problem, pilot wouldn't stay on, in fact it was pretty hard to get it to light at all. Unfortunately he didn't know much about testing the thermocouple voltage, line pressure etc. so we agreed to pay him for the part and part ways. Nice guy, but no more skilled than me.

That got me to thinking that I had to replace the thermocouple on the wall heater just a month before that runs off the exact same gas line extension (water heater is in the basement right under the wall furnace on the ground floor which is 24 feet from the 1" service line to the house). Since I got the wall heater working I had imagined that it was burning a little low (it's a Valor portrait fireplace). Could I be having some sort of localized low pressure area off this extension? The water heater worked until yesterday and is only just 6 years old.

I have never done a pressure test, always had the local utility to do that, but it takes a week to get an appointment. Could anyone point me to the kit I'd need to buy to do this at home? (if the idea isn't totally absurd) I'd really appreciate any suggestions.
 
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  #2  
Old 02-06-18, 02:16 PM
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You need a manometer to test the pressure.
 

Last edited by PJmax; 02-06-18 at 08:01 PM. Reason: swapped a for o
  #3  
Old 02-06-18, 08:04 PM
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Pilot won't stay lit...... It goes out immediately or some time later ?
In other words..... does it go out while you are holding the button or when you let it go.
 
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Old 02-07-18, 03:31 AM
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What size is the gas line from the meter , through the house with all reductions if any and the pipe size feeding all gas appliances. Include the approximate length of the pipes. and the gas input of all devices. For a test kit you can buy one at amazon or "GOOGLE" gas pressure test kits. If you are not sure of what you are doing, seek and wait for professional help. Natural gas is explosive and will hurt you. You could also contact your gas supplier and ask what the gas pressure is at the meter and ask if they are having any problems with gas pressure or gas supplies in your area. Also, what type chimney is the heater connected to and does the heater have a draft diverter mounted on the flue pipe. A picture of the whole water heater would be helpful.
 
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Old 02-07-18, 04:27 AM
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Pilot goes out after letting go of the gas valve button. Whether it's right away or a minute. That said, I can't get it to light at all now.
 
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Old 02-07-18, 04:30 AM
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There is minimal gas consumption when just the pilot is burning so I doubt you will see a pressure problem when it's just the pilot. If you did have undersized piping or a failing gas meter it would likely present itself when both the furnace and water heater burners were running. Even then you'd likely have a lazy or low flame.
 
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Old 02-07-18, 04:32 AM
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Steamboy, the line coming into the house is one inch. It runs about 40' from the service into the house before branching off (1/2") to a gas furnace on the second story (10' up) then down to a gas dryer (about 20' run), then another 3/4" branch right off the end of the 1" pipe, it ges up about 3" to get over a supporting beam the crosses 24' to get to the other side of the property. One 1/2"branch forks 3-4' up to the gas stove then another 1/2" forks up and down to the above mentioned furnace and water heater. Water heater is the lowest on that end of the line.
 

Last edited by variable; 02-07-18 at 04:38 AM. Reason: corrections
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Old 02-07-18, 04:43 AM
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Here are some pics. 1st is above the water heater. Second two shows the gas line on left and right side of heater. Last is gas line coming from the street, leftmost one showing tees. The path that goes up into the subfloor is what leads to the water heater/furnace.
 
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Old 02-07-18, 08:57 AM
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I would call the gas supplier and ask if they are having pressure or supply problems in your area and could they check your gas pressure and the gas meter. Explain your problem and they should respond as necessary.
 
  #10  
Old 02-07-18, 09:16 AM
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Unfortunately they will not connect me to a human. I've scheduled an appointment for two weeks from now, so we'll wait and see.
 
  #11  
Old 02-07-18, 10:03 AM
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V,
Is this a new problem or existing, has any new work been done.

I see you have other appliances coming off the gas line also.

How are they working as far as the gas pressure goes.

If it's the meter or the main pressure I would imagine all of the appliances would be effected.

Just a thought, hope this helps a little.
 
  #12  
Old 02-08-18, 12:21 PM
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Thanks everyone for all your help and feedback. I ended up taking the advice of the original plumber (and the 3 that I called to test the pressure) and replaced the whole water heater. While I was doing that I discovered that the whole gas line down to the heater had 2 elbows, each of which tilted the line about 10 degrees so there was a gradual slope the whole way down to an incredibly kinky hose and no sediment trap of any kind. I rebuilt the whole line and installed the water heater.

After a terrifying false start in which I completely forgot to install the relief valve (and much mopping) the new heater fired up right away.I appreciate everyone who took the time to listen to my ideas and respond.
 
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