Another relief valve question...

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Old 01-19-14, 09:42 PM
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Another relief valve question...

Hi all, I have read the previous posts, and did some troubleshooting, but still having a problem with my relief valve on my oil burner with constant leaking water.
1. Replaced the relief valve
2. Replaced the expansion tank.
3. Closed the shutoff valve right after the pressure reducing valve. (As I hoped this was the problem and I could troubleshoot it w/o replacing valve.)I guess I could have a bad shutoff as well as a bad reducing valve but that seems highly unlikely.
The leak continues pretty significantly with my psi hovering around 25-30.
I'm not sure it's worth mentioning but after I replaced the expansion tank, the psi was right as rain at 12-15, but only lasted a few hours before pressure built up.
I have read it could be the coils, or some other internal problem, which I'll have to call someone out.
Anyone have any final ideas or thoughts on what might be causing this? NJ trooper you seem to be dead on, help please! Lol
 
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Old 01-19-14, 10:41 PM
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Do you have a hot water coil, either in the boiler or indirect. If all the above are as should be, that's where it may be coming from.
 
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Old 01-20-14, 06:42 AM
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Hi Jake,

In other words, what is your source of domestic hot water?
 
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Old 01-20-14, 10:39 AM
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I've attached a few pics, If I'm understanding the question, I just have a standard oil burner, with no hot water heater. Still leaking at a good rate, maybe like 3/4 gallon per hour. If any other pics would help let me know, thanks in advance.
 
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Old 01-20-14, 11:10 AM
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That round plate on the front of the boiler with the gauge and the gray Honeywell box also has two pipes coming out of it.

Those two pipes are connected to your domestic water system and the boiler is providing your domestic hot water.

There is a coil of tubing behind that plate which is immersed in the hot boiler water.

That coil may have a leak which is causing the undesired over-pressurizing of your boiler .
 
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Old 01-20-14, 11:56 AM
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How fast does the pressure build once you lower it? Do you have a way to isolate the coil with valves?? You may have to turn the water off to the house to test the theory if it is leaking. You could do it during the day while at work for less inconvenience
 
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Old 01-20-14, 12:15 PM
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I believe it took 2 hours or so for pressure to back up. I'n the picture I think the valve on right would shut off incoming domestic. So I'm thinking if I turn off burner, let it cool down, drain it until 0 psi, close that incoming domestic valve, and fire it back up, that would let me know if it is the coil. If I do that but pressure doesn't rise, that's my problem? Let me know if my logic makes sense..
 
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Old 01-20-14, 04:15 PM
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You would only want to drain it to 12 to 15 psi if you run the boiler. The PRV/auto fill would bring it back up to 12 if drained to O. If you did drain it to 0 I would not run the boiler, just let it sit.

I would just shut the INCOMING DHW valve and drain down to 12 and wait and watch. Although I do not recommend it due to potential burning, no need to let the boiler cool to drain off a little pressure as long as you are careful (I would also close water supply to boiler in case you drained to much as to not send cold water into a hot boiler) .
 
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Old 01-20-14, 04:53 PM
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I would say that if the boiler is HOT only drain to say 18 PSI or so, if COLD, go to 12-15.

You can continue to run the boiler during this time, but when you close that valve you will not have domestic hot water to the home, and a BIG CAUTION is in order...

IF it is a leak in the coil inside the boiler,

AND you cut the incoming supply to the coil off,

AND you open a hot domestic tap,

THEN the pressure in the domestic hot water piping will be LESS THAN the pressure in the boiler,

AND this means that the boiler water will enter the hot domestic piping under pressure inside the boiler.

In fact, if you left the hot tap open and there is a leak in the coil, you would eventually get boiler water out the tap. If the water feed to the boiler was OFF during this time, you would see the boiler pressure slowly DROP.

Water will ALWAYS flow from higher toward lower pressure.

If you do this, be sure to thoroughly flush the domestic piping when finished, and DO NOT use any hot water for cooking or anything really, until this is repaired.

It actually is good practice to NOT use hot water for cooking or consumption in ANY case. Grandma never would, and she was a smart lady!
 
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Old 01-20-14, 09:24 PM
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Ok, so I shut off the incoming dwv, drained the psi to about 10 , and then turned back on burner. It popped right back up to 12, but then after about 3 hours went back to 25-30 so I'm guessing it's not a coil problem. I'm at a loss, even though I troubleshot the prv /auto fill by turning off that valve on an earlier test maybe I'll just go ahead and replace it. I'm not really sure what my other options are...thanks
 
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Old 01-21-14, 06:47 AM
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Hi Jake,

2. Replaced the expansion tank.
And before installing the tank you verified that it contained a pre-charge of 12 PSI, correct?

What is the make/model of that tank? If you replaced it with one that was intended for use with a potable water system, it is likely that there was a FORTY PSI pre-charge on the tank, and a tank with a 40 PSI charge on a boiler system operating at 12-30 is as good as having no ank at all.

This may be your problem now... fingers crossed.

If you need to reset the pressure in the tank, you MUST drop the boiler pressure to ZERO or you will not get a correct pressure reading.

See:

http://www.doityourself.com/forum/bo...sion-tank.html
 
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Old 01-21-14, 11:21 AM
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Looks like this is the right tank although I did not verify the psi before I replaced it, however the tank appears to be working properly. Any other ideas trooper? With this snow and single digit temps is there any dangers or the boiler being like this for a few days? It seems the leak has slowed some but the psi remains between 25-30. Thanks again,
 
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Old 01-21-14, 01:29 PM
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OK, good... they DO pre-charge the tanks at the factory and they are USUALLY pretty darn close, so it's 'probably' OK.

From what I can see in the pictures it appears that the water feed manual shut off valve ahead of the pressure reducing valve (the green thing) is what we call a 'GATE' valve, and these are notorious for NOT shutting off 100%. But even if it's a 'STOP' valve with a washer in it, those often don't work well after decades of being open either.

Same can probably be said of the valve for the hot water coil shut off I guess...

So we still really don't know if it's the pressure reducing valve leaking through along with a leaky gate valve, or if it's the coil leaking, along with a leaky shut off for that!

Unfortunately, to change that pressure reducing valve, because there is no valve between it and the boiler, it means that to change it you will need to drain the boiler... when you replace that reducing valve it would be a wise move to install BALL VALVES on BOTH SIDES of it so that future service can be done without having to drain boiler system.

Because we still can't conclude 100% what the problem is, it would seen that you need to start changing parts. It's far more likely IMHO that the reducing valve and the gate valve are both leaking, rather than a leak in the coil, so I would start there.
 
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