Empty Expansion Tank, Pressure Relief Leaking

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Old 10-12-09, 09:42 AM
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Empty Expansion Tank, Pressure Relief Leaking

Hello everyone. I just had my house inspected for sale and, wouldn't you know it, there's an issue with the heating system. When the heat is turned on, the pressure soon reaches 30psi and the relief valve starts to leak (as it should). The boiler and expansion tank are old and I've never had anything serviced. The inspector told me I probably need to "bleed the expansion tank." He instructed me on how to drain it - close the valve (C, below) to isolate the tank, then attach a hose to the drain and open valve (D) and that should take care of the problem. Well, I tried this but the expansion tank is completely empty so I'm at a loss.

Here's a pic for reference:


To date, valves A & B have always been CLOSED. Valve C is open. Valve D is the tank drain and that is also closed.

Can someone tell from the picture if valve A is an "auto-feed" valve? Should either A or B be open?

Any other advice as to how to solve the over-pressure problem would be greatly appreciated. If you need more info, just ask!

(If it matters, the boiler is made by American Standard.)

Thanks!
 
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Old 10-12-09, 02:36 PM
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Expansion Tank draining

I'm just a homeowner and have no real expertise with boiler's but I do have a couple of thoughts. It looks like the drain valve is on a 3/8" or 1/2" iron pipe on the bottom of the tank. I would think that the drain piping could be plugged with rust and scale. If you do connect a hose to the drain, try tapping the pipe elbow with a hammer. I'd wear gloves and hold the end of the hose 'cause if there's anything plugging the line or valve, then there's pressure trapped in the tank and anything that comes out will be under pressure and will flash to steam at the hose. Is there a vent valve above the tank you could crack open to check for pressure and to allow air into the tank if there is water in it? Be careful.
 

Last edited by Grandma Dee; 10-12-09 at 03:13 PM.
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Old 10-12-09, 02:48 PM
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There is no vent valve that I can see. The ceiling is plastered around the tank but it is open 5 feet or so away. I'll stick my head up in there and see if I can see anything. But I'm pretty sure there's nothing there.

As for the valve being clogged, I suppose that's possible too but some water did trickle out so it's not totally seized up. I expected the tank to be FULL though so I would think water would keep trickling out (it did not).
 
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Old 10-12-09, 04:14 PM
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You say A and B have always been closed? No, neither of them are an auto-fill, both appear to be shut-offs... and you've NEVER had to add water to the system?

When the relief valve opened, what came out? hot water? or STEAM?

I wonder if you've got any water in the system at all!

When the boiler is OFF and at room temperature, what does the pressure gauge read then?

How long have you lived with this system? Long enough to know that it has worked properly in past winters? IOW, it's not a 'flip'?

Unless you tell me that the boiler pressure is zero when cold, I'm going with Grandma's suggestion that the valve is plugged.

You might be able to unblock it with a shot of air from a compressor into the end of the hose... I think I would first let the pressure off the system and then close valve C before I tried that... because if you do blow the sludge out and there is pressure, you could end up with a mess...
 
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Old 10-12-09, 05:22 PM
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Not a flip - I've lived in the house almost 10 years and there is definitely water in the system. I bleed the radiators a couple times over the winter and I've never had any problems. The valves aren't blocked as you'll see if you read on.

Several years back, one of the valves on a radiator leaked (I had it shut off for a very stupid reason that I won't get into now). So, last year, I decided maybe the system needs some water so I opened the shut off valves...very briefly and very "gently" as I was afraid of screwing something up. I know it was ill-advised but I thought, like you, that the system HAD to need water after all of this time. When I did this, it didn't seem to do anything. I heard no water flowing or anything like that. I was afraid of back-flow so I stopped messing around and just left it as it was. So, it's possible that I added water and didn't even know it.

Tonight, I ran the heat again and got the same result (of course). The temp got up to about 130 F and the pressure almost reached 30 so I shut it down. After it cooled a bit, I decided to try the advice of the inspector. I isolated the tank, and opened the drain...some water came out. Not a lot but some. I closed the drain and opened the isolation valve...and the pressure went down a bit (visibly via the gauge and audibly as I could hear some kind of flow). I repeated this a few times and took out maybe about a half gallon of water and the pressure dropped each time. I fired up the boiler again and it got up to 130 quickly and the pressure was somewhere around 15. So, tomorrow, I'm going to fire it up again and see what happens. Am I on the right track?
 
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Old 10-12-09, 07:18 PM
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Am I on the right track?
No, somehow I don't think so...

You still need to tell me what the pressure is when the boiler is COLD. That's important...

What you are doing is letting water out of the system, and that's why the pressure is going down, but you aren't actually doing what you need to do to get the tank to do what it needs to do.

Understanding the function of the expansion tank is key to 'fixing' the system.

When your system heats the water in it, that water expands, as much as 4% or so... that expanding water needs a place to go.

Water can not be compressed, but AIR can.

Your expansion tank when serviced properly should be about 1/2 full of AIR. That air provides the 'cushion' that is compressed when the water expands, giving that expanded water someplace to go.

What you need to do is empty ALL the water out of the tank, and make sure that the tank is full of AIR.

Then, when you open valve C water from the system will enter the tank, but the AIR will STAY in the tank, and be compressed by the system pressure.

Lastly, you then need to check the boiler when it is COLD (room temp), and ADD WATER until the pressure in the boiler is 12 PSI, and close the water valve.

Now, when you heat the boiler, and the water expands, it will further compress that 'bubble' of air that is trapped in the tank.
 
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Old 10-12-09, 07:21 PM
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BUT... on the other hand, maybe you DO have the correct amount of air in the tank, and maybe when you added that water you increased the COLD pressure too high...

So that's why I need to know what the cold pressure is.

It might be as simple as opening a drain and letting that extra water out.
 
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Old 10-13-09, 07:31 AM
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The cold pressure is definitely zero. I'm afraid to add water to it. I'm going to fire it up today at some point and see how it runs after I removed some water yesterday.
 
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Old 10-13-09, 09:22 AM
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OK, same result...pressure rose almost to 30 but the temp only got up to 130.

I will try adding water to the system as per your suggestion below. It definitely makes sense because, like I said, water has come out of the system over the years and I've never put any back in (outside of the half-hearted attempt I made last year which I really don't think did much).

Bottom line is this - if there's supposed to be pressure in the system when it's cold, then I need to add water because it is most definitely ZERO. I'll snap a picture when it cools down from this morning's test.
 
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Old 10-13-09, 09:40 AM
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I think NJ Troop is right on target. Pressure cold must be between 12-15 psi. When you stated:

So, last year, I decided maybe the system needs some water so I opened the shut off valves...

Is it possible you let full "house" water pressure into the system? If so, you bumped up the pressure above normal operating pressure. The pressure relief valve should not "leak". If it does, it means that the system pressure is too high, or the valve is bad.

Also, since it appears the expansion tank is a bladderless steel expansion tank (not the bladder type) the tank is almost certainly waterlogged. Does the expansion tank have a sight glass for water level?

When opening valve D, you need to allow some air to enter the system, otherwise "air-lock" will prevent water from draining out of the tank (much like filling a drinking straw with water and holding your finger on one end. If you don't take your finger off, the water will stay in the straw). If not, the quickest way (without having to introduce pressure into the tank at the expansion tank drain valve to "push" the water out through the boiler drain) would be to drain the system down and drain the expansion tank.

Follow NJ's lead - you need to get the excess water out of the expansion tank, otherwise the system pressure when in operation will always exceed the pressure relief valves design pressure - and the relief valve will do what is designed to - relieve the excess pressure.
 
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Old 10-13-09, 10:08 AM
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Originally Posted by PinnacleGC View Post
I think NJ Troop is right on target. Pressure cold must be between 12-15 psi. When you stated:

So, last year, I decided maybe the system needs some water so I opened the shut off valves...

Is it possible you let full "house" water pressure into the system? If so, you bumped up the pressure above normal operating pressure. The pressure relief valve should not "leak". If it does, it means that the system pressure is too high, or the valve is bad.
If I bumped up the pressure above normal, wouldn't the gauge tell me that? It's at 0 cold. The pressure relief valve is only "leaking" when the furnace is on and the pressure gets up around 30, which I assume is correct and indicates that the valve is working properly.


Originally Posted by PinnacleGC View Post
Also, since it appears the expansion tank is a bladderless steel expansion tank (not the bladder type) the tank is almost certainly waterlogged. Does the expansion tank have a sight glass for water level?
No sight glass. It's definitely bladderless.

Originally Posted by PinnacleGC View Post
When opening valve D, you need to allow some air to enter the system, otherwise "air-lock" will prevent water from draining out of the tank (much like filling a drinking straw with water and holding your finger on one end. If you don't take your finger off, the water will stay in the straw). If not, the quickest way (without having to introduce pressure into the tank at the expansion tank drain valve to "push" the water out through the boiler drain) would be to drain the system down and drain the expansion tank.
OK, I was thinking air lock might be a problem as well but would it really prevent water from coming out at ALL? Is the
"negative pressure" in the entire system enough to keep the water in the tank without a drop coming out? Seems unlikely but I'm just guessing.


Originally Posted by PinnacleGC View Post
Follow NJ's lead - you need to get the excess water out of the expansion tank, otherwise the system pressure when in operation will always exceed the pressure relief valves design pressure - and the relief valve will do what is designed to - relieve the excess pressure.
I'm skeptical that there's excess water in the system just because I know that water has come out of it over the years. I know I said I tried adding water but I really don't think that it made any difference.


Here's a question - is it possible for there to be too much water in the expansion tank and at the same time have the cold pressure be zero?

And another - if there is not enough water in the system, what would the symptoms be? Would they match the symptoms I'm having now?


I appreciate the help, everyone. I'm sorry if my questions come off the wrong way (like I'm questioning the logic behind what you're saying) but I'm just trying to understand what's happening. I am indebted to the members of this forum for helping me with several issues over the years and I don't want that to be lost because of the cold nature of typed conversations. Thx!
 
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Old 10-13-09, 03:20 PM
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I don't get the 'cold' at all... yer doin' fine, just askin' questions trying to understand!

Here's a question - is it possible for there to be too much water in the expansion tank and at the same time have the cold pressure be zero?
Yes, absolutely.

OK, I was thinking air lock might be a problem as well but would it really prevent water from coming out at ALL? Is the "negative pressure" in the entire system enough to keep the water in the tank without a drop coming out? Seems unlikely but I'm just guessing.
Yes, if when you opened that valve, there was zero pressure in the tank, you might get just a trickle. Pinnacles drinking straw analogy is right on, put your finger on that straw and lift it out of the glass, how much comes out? none...

Do you own an air compressor?

And another - if there is not enough water in the system, what would the symptoms be? Would they match the symptoms I'm having now?
Yes... but maybe 'not enough water' isn't the correct wording to use. Your system is probably FULL of water, but what you don't have is enough PRESSURE.

With the boiler cold, and ZERO PSI, and FULL of water, when you heat that water, and that water expands, it MUST have somewhere to go, else the pressure will go crazy. You can not compress water... remember that... if you take a closed vessel full of liquid, and heat it up, the pressure will very quickly go SKY HIGH... like that time when I was a kid that stupid Bosco threw an unopened can of tomato soup into the campfire... KABOOM!

The captured air in the expansion tank serves as the cushion to absorb the expanding water, because you CAN compress air.

So, even if you have ZERO to start, if you don't have the air trapped in the tank, and the tank is full of water, it will take very little heating of that water to run that pressure off the Richter Scale...

If you were to plug the relief valve (DON'T DO IT! EXAMPLE ONLY!) and try to heat the boiler to 180, you would probably have THOUSANDS of PSI in the boiler... but, you wouldn't have known that, because the boiler would have exploded long before that happened...

Here's what ya do...

Open the feedwater valve and put 25 PSI of pressure in the system. Hook up your hose to the tank drain. Close the valve between the tank and the boiler. Open the drain. You should get an initial burst of water from the drain at 25 PSI, and it will then trickle off and stop. If that water that comes out is all muddy and gunky, close the drain, and open valve C again, and repressure to 25 PSI. Close C , and open D ... again you should get a flow of water... and if it's still all gunked up, you know you have 'mud' in the bottom of the tank that's obstructing the drain. Repeat the above steps a few times and see if the water starts to clear a bit...

Bottom line is that you need to drain that expansion tank, and get it FULL OF AIR, then close the drain, and open C, and then open the feed water valve to put 12 PSI in the boiler cold.

Using a long skinny hose on the drain valve isn't going to help you... the shortest, fattest hose you have is what you want. Even better is no hose at all, and the bucket right under the drain.

Maybe you have an old crappy hose laying around? CUT IT... just long enough to reach from the drain valve to the bucket, or floor drain, or laundry tub...

Sometimes when the flow stops, it helps to partially unscrew the hose at the drain valve and let it suck air and empty the hose.

The air compressor would come in real handy for this... blowing air back into the drain will break that vacuum lock, and also blow the 'crud' outta the way.
 
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Old 10-13-09, 04:31 PM
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NJ just types faster than I do, but that is exactly the exercise I was thinking of.

I did want to point out though that those posting advice on the forum are doing so to solve a problem - yours, and those that may read the forum with the exact same or similar issue. No appologies necessary. If one of my assumptions are incorrect, I would want, no expect, someone to correct me. I'm a big boy -I can take it. No one knows it all.

As a side note - this forum helped me through my issue - yes I have issues too!

Do what NJ Trooper suggests, and let's see where we stand.
 
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Old 10-13-09, 07:35 PM
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Thanks guys. I will give this a shot in the next couple of days or over the upcoming weekend at the latest. I'll report back my findings.
 
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Old 10-16-09, 09:36 AM
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OK, guys I think I'm on the right track now. Here's what I've done so far...

First off, I didn't mention this because I didn't think it was relevant, but when I bought the house 9 years ago, there was an old coffee can hanging from the tank drain. I just assumed that the valve maybe leaked once in a while so I just left it. Well, when I went to open the valve for the first time last week, the whole "internal assembly" of the valve turned as I turned the handle. I tightened up the nut and worked the handle loose so the valve would function properly.

So, today, when I went down there to give this whole thing another try, I did exactly what NJT said above. I closed off the tank (valve C), pressured up the system to 25, then opened up valve C. When I opened the tank drain valve (D), I got a little water out but that was it. At that point, I decided to just take out the internal part of the drain valve that I mentioned above. I did this VERY slowly since I didn't want a shower of dirty water. Well, what ended up happening was interesting. With the valve open this way, air was able to travel back into the tank to displace some water and let it out. It started to drain very slowly. It sounded like an office water cooler. I placed a 1 gallon bucket under the drain and when it filled, I screwed in the valve assembly back in to stop the flow and emptied the 1 gallon into a 5 gallon bucket (? one of those large spackle buckets...I think it's 5 gallons). After a couple HOURS of this, I must have filled the big bucket about 3/4 of the way or so about 7 or 8 times. FINALLY, the water stopped coming out. Now, I wouldn't say I saw any "sludge" but it definitely got dirtier as it got to the bottom of the tank. So, I did it again. I pressured up the system, opened valve C and opened the drain only this time I had the drain valve back together and let it drain normally. I connected a hose and the water immediately came flowing out. I was thrilled! Also, it was a LOT dirtier this time. I repeated this process 4 or 5 times until the water wasn't as dirty. It's still gray but no obvious sediment.

So...here's my next question:
The next step in the process according to what I've read from you guys is to pressure up the system to 12 PSI with valve C open. Here's how I went about it:

1) close tank drain D
2) open valve C
3) open fill valves (A & B)

It's the same process as before except valve C is open. When I did this (and I tried it a few times) the pressure is NOT increasing in the system. What is happening is the water is just flowing into the expansion tank and the pressure stays at 0. What I'm assuming is that if I leave the fill valves open with valve C open, the pressure won't start to rise until the tank is full again. Am I correct?

Right now what I did was up the pressure to around 12 with valve C CLOSED. I then opened valve C and the pressure went down to about zero as the water flowed into the tank. I just fired up the furnace to see how she runs. I'll let you know how it goes...but I'd like to get clarification on this just for peace of mind.


Lastly, I just want to say thanks again, guys! I really appreciate the help. If this works out, you probably saved me a good $300-$500 at least.
 
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Old 10-16-09, 10:00 AM
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Quickly... at my 'day job' now... do NOT run the boiler with valve C closed!

When you turn on the water feed, it may take some time for the pressure to build...

The expansion tank will PARTIALLY refill with water during this process, and compress the air bubble that will be trapped in the tank.

But, you MUST have valve C open, and the system and pparticularly the BOILER MUST be full of water.
 
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Old 10-16-09, 10:53 AM
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Oh, I know...valve C is open. Thanks though.

I will let it cool down and try opening the fill valves again to get the pressure up.


I have another question though. Here's what I did so far today...

The thermostat read 65 degrees (ony 1 zone) when I turned it on. I set the heat temp to 72. It fired up. It ran for a while and I kept checking the pressure to make sure it didn't spike again. It only got up to around 8 PSI max so that's good. Temperature, however, got up to 160...and then the furnace shut off. Temp at thermostat was only 68 so it didn't receive the signal to turn off from there. I left it alone, the water temp cooled a bit (140ish) and it turned back on. So, I'm assuming it was cycling on and off by design, right?

I'm asking because I don't think it ever did this while I've been living here. It could be that this system wasn't ever set up correctly or at least wasn't set up correctly by the previous owners of the house. This makes me kick myself because I've probably been throwing money away all these years.
 
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Old 10-16-09, 03:12 PM
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OK guys, it looks like I am good to go. I let it cool down and added water until the pressure got up to 14. The water was still warm (100ish) so I figured a few extra pounds would compensate for that. I ran it again for a while and it seems to be running like a champ now. I'll let it cool down fully and give it another test tonight or tomorrow morning but at this point I think the problem is solved.

Once again, I thank you all for taking the time to help me out. I couldn't be happier with the results thus far and I'm excited to tell the prospective buyer that the furnace is in good working order.
Beer 4U2
 
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Old 10-16-09, 03:19 PM
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Originally Posted by dinologic View Post
The thermostat read 65 degrees (ony 1 zone) when I turned it on. I set the heat temp to 72. It fired up. Temperature, however, got up to 160...and then the furnace shut off. Temp at thermostat was only 68 so it didn't receive the signal to turn off from there.
What type thermostat do you have? A photo would help.

If you have a mechanical 'stat, it'll probably have a bi-metalic element, a heat anticipator, and a little dial thermometer. The thermometer doesn't necessarily show the same temperature as the bi-metalic element senses.

Digital 'stats, on the other hand, have temp displays that usually track with the on-off settings.
 
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Old 10-16-09, 04:25 PM
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Good Deal!

Regarding your thermostat issue, and playing off of Mike Speed 30's post, if the thermostat is a mechanical type (mercury bulb with contacts), there should be a heat anticipator on the thermostat base. This determines how long the burner stays on, and is normally adjusted to the amp rating on the gas valve. The anticipator helps in stopping over-shoot of the boiler (setting the thermostat at 72, the boiler continues to operate, and temp increases in house to 80).

You need to let the system run and stabilize, and then make any anticipator changes - IF REQUIRED.

If you set the thermostat at 72, and the boiler stopped with the temp at 68, you're probably OK - DON't CHASE the THERMOSTAT.

Watch your boiler gauge when the burner shuts off - the boiler temp will always rise - and that relates to additional temp rise in house.

If you have to adjust the anticipator, the higher the number, the longer the burner runs. Adjust in 1/2 increments, and wait 2-3 hours for the system to stabilize before making further adjustments. I really don't think you'll need to do this.

As a final note, the thermostat (if mechanical) has to be level (remember, there's a mercury bulb in there with electrical contacts). If not, the burner can run longer or shorter (depending on which way off-level the thermostat is), and can make the temp swing either way.

Good Luck on the home sale!
 
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Old 10-16-09, 04:45 PM
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Temperature, however, got up to 160...and then the furnace shut off. Temp at thermostat was only 68 so it didn't receive the signal to turn off from there. I left it alone, the water temp cooled a bit (140ish) and it turned back on. So, I'm assuming it was cycling on and off by design, right?
Yes, probably. The aquastat control on the boiler has a high limit setting. When the water temp reaches that limit, the burner will shut down, but the circ may continue to run if the heat call is not satisfied. When the boiler cools below the control's 'differential' and if the heat call continues, the burner will re-fire up to the high limit again. This will continue as long as needed until the t'stat is satisfied.

Good Luck on the home sale!
ditto... and,

We'll be expecting our usual commission checks in the mail!
 
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Old 10-16-09, 04:55 PM
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Originally Posted by PinnacleGC View Post
Good Deal!
Good Luck on the home sale!
Thanks! We're about 90% of the way there actually. This was a sticking point from the inspection so it was paramount that I get it fixed quickly and, from my perspective, cheaply. Nothing cheaper than DIY!


Originally Posted by NJ Trooper View Post
Yes, probably. The aquastat control on the boiler has a high limit setting. When the water temp reaches that limit, the burner will shut down, but the circ may continue to run if the heat call is not satisfied. When the boiler cools below the control's 'differential' and if the heat call continues, the burner will re-fire up to the high limit again. This will continue as long as needed until the t'stat is satisfied.
Yes, that's what I believe is happening. The thermostat is actually a digitally programmable one. There's a little image of a flame in the btm right corner when it's "on" so when I saw that the furnace had shut off while the flame was still there I knew it wasn't the t-stat that told the furnace to shut down.

Originally Posted by NJ Trooper View Post
ditto... and,

We'll be expecting our usual commission checks in the mail!
 
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Old 10-17-09, 10:40 PM
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Looks like I celebrated a little too soon. I'm still having a problem.

It's late but I'll post a quick summary of the events of the day:

Before I went to bed on Friday night, I set the thermostat so that the heat would go on at 8am on Saturday morning. I woke up around 8:30 and my wife said there was water in teh basement. The pressure had once again spiked up to 30. I waited all day until the system cooled down completely and flushed it out again using the method described above. When I was sure the tank was empty, I opened up the tank valve (C) and the fill valves to pressured it up to 12 PSI. I ran it again and it seemed fine. When I shut it down, the pressure was somewhere around 16 PSI. I planned to let it sit overnight and manually fire it up on Sunday morning. Before I came up for bed I checked the meter (about an hour ago) and the pressure is at 20. It had been off for several hours at that point. Not only that, the tank seems pretty full judging by how it feels when I push up on it.

So...what can I do now?
 
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Old 10-18-09, 08:27 AM
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OK, this is really weird. Maybe, maybe not. But this morning I went down to drain the tank again and the pressure was at 30! So, overnight, with the system completely off, the pressure increased from 20-30. The relief valve opened and about a gallon of water leaked out (I had a bucket under it just in case). AND...get this...the water was warmish in the tank. I know you're going to say that the system must have fired up overnight but I assure you it was off. Is it possible that the pilot light could have introduced enough heat to raise the pressure 10 pounds? I may have had the tank valve closed...I can't remember. But even still, the fact that the water in the tank was slightly warm is very strange.
 
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Old 10-18-09, 08:53 AM
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It sounds to me as though either/both valves A and/or B are leaking through to the heating system. That would account for the slow increase in pressure with the system off.

I doubt the pilot would do it...

Did you close both A and B after you filled it? If not, give that a try. If you do have to service a valve, I would suggest replacing it with a ball valve.

You might be able to determine which valve is leaking... with BOTH A and B closed, open that drain valve between them, and put a bucket under it. If that bucket fills up, then ONE of them is leaking. If the bucket fills and the boiler pressure goes down, then B is leaking. If the pressure holds in the boiler, then A is leaking. There's no way to determine if BOTH are leaking though.

I don't know if we've asked this... how do you heat your domestic hot water?
 
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Old 10-18-09, 09:05 AM
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Reason I asked about the domestic hot water is because if you have a 'tankless coil' in the boiler for that purpose, if that coil is leaking, it could also account for slow pressure increase... but looking at the pics again, I see a water heater to the right, so presumably that is not the problem.

I would say that the solution to this is going to be replacing valve A with a ball valve. You may have to shut down the house water supply to do so, if you don't have another valve in the line to the boiler that allows you to isolate that line....
 
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Old 10-18-09, 09:10 AM
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Hot water is heated separately.

But a leaky fill valve would explain the gradually increasing pressure. I'll double check to make sure they're fully shut. If you look at the pics in the original post you'll notice that they are right up against the hot water heater. They're not easy to get at.

What do you think about the water in the tank being warm? Might it have just flown back from the radiators above and not have cooled down? It's not really cold here yet (NY State) but it is getting down into the high 30s at night.
 
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Old 10-18-09, 09:17 AM
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Another question - if I have to replace valve A, would it be a bad idea to just add a valve above it? With the hot water heater being where it is, it might be difficult to work in that area. It would be so much easier to just cut into the copper above and add a valve there. I'm pretty proficient with sweating copper but I haven't worked with galvanized pipe very much. I'm sure I could handle it but I'd prefer the path of least resistance...without "breaking any rules" of course.
 
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Old 10-18-09, 09:19 AM
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What do you think about the water in the tank being warm?
Hard to make a call on that one... residual heat ? gravity flow of the warmer water in the boiler up into the tank?
 
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Old 10-18-09, 09:38 AM
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would it be a bad idea to just add a valve above it?
Nothing wrong with that I guess... can't have too many valves!

But, valve A is threaded... and you can get a ball valve that's also threaded. In fact, you can get them threaded on one end and sweat on the other... or just use an adaptor the way it is set up now.

So, you could just cut the pipe above, twist the old valve off, twist the new one on, and splice the copper back together with a coupler... if you trust 'sharkbite' (why not?) you could use one of those to do the splice.

You could also consider using a compression fitting valve and not have to solder at all... which if you can't get the pipe dry, you know how that goes!
 
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Old 10-18-09, 04:25 PM
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Valve "A" was added because valve "B" leaks. If it were mine I'd pull everything from (and including) valve "B" back to the copper city water piping. Install a ball valve on the city water, a union, the proper pressure reducing valve, another union (unless the PRV has a union end) and a ball valve where valve "B" was. Then I'd remove the old expansion tank and install a diaphragm expansion tank. Total cost maybe $100 for parts, maybe $150. Pretty cheap in my estimation for not blowing the sale of the house.
 
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Old 10-19-09, 01:34 PM
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furd, I concur...and if I had unlimited time I would go ahead and do just that. But adding a ball valve above that mess will take me maybe all of an hour whereas replacing the whole section will probably take me the better part of a day. Plus, I'd be risking breaking something or some other stupid mistake. It's a tight area and it's old so...I'd rather not take the chance.

But here's yet another question - if the fill valve(s) were leaking, wouldn't the water meter show usage? I noted the water meter and waited about an hour and it didn't move at all. (I had to do this several times as I kept absentmindedly using the water elsewhere in the house). I also tried opening that spigot between A and B and it istrickling so...at least one of those valves is leaking. I'm going to run to Home Depot tonite and pick up a valve. If I can get it in there tonite I will. Will report back soon.

thx.
 
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Old 10-19-09, 05:43 PM
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wouldn't the water meter show usage?
I'm not sure the water meter would have that fine a resolution? It's been so long since I've had one that I just don't remember! I bet you don't need more than maybe a gallon at most to raise the pressure...
 
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Old 10-19-09, 05:57 PM
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My city water meter records usage in increments of 1 cu. ft. = 8 gal. (approx). And, then, I could visualize leakage of perhaps one gallon over several hours. Pretty hard to use the meter for such small leakages.
 
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Old 10-19-09, 06:51 PM
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Well, just FYI, I had both valves A and B shut tight and I opened the spigot between the two, attached a short hose, and dropped it into a large spackle bucket (5 gal?). It filled about halfway in a couple of hours. SO....this could definitely be the problem. I'll be adding a new ball valve tomorrow or ASAP.
 
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Old 10-19-09, 07:20 PM
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AND...it just occurred to me why there was warm water in the tank. The house water pipe is connected to the return side of the circuit so if there's constant pressure, albeit slight, the water is going to travel through the return and push the warmer water back down towards the furnace and eventually into the tank. I think. It makes sense.
 
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Old 10-20-09, 05:57 PM
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from: "Weil Mclain relief valve "exploded" open" thread

I just wanted to say thanks SO MUCH for the info in this thread!!!

I had the exact same problem, minus the leaky water feed valve. I thought my expansion tank was empty, just drips came out the few times we had tried to empty it.

I had just posted the "Weil Mclain relief valve "exploded" open" thread a few days ago. My pressure got too high and the relief valve was old and corroded and "exploded open" with a BOOM, spewing water, rust and sediment all over my basement walls.

After replacing the relief valve and still having a high pressure problem, I saw this thread today, and was finally able to empty out 15 - 20 gallons of water from the expansion tank, and get my boiler pressure to be more constant both when hot and cold.

(My whole story/reply is on the "Weil Mclain relief valve "exploded" open" thread)

Thanks again so much for the detailed descriptions, especially of the expansion tank emptying like a water cooler! That really helped. It took a long time, 45 min, for my tank to empty too.
 
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Old 10-21-09, 01:40 PM
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Silaurie, glad you got your situation worked out.
 
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Old 02-19-14, 08:53 PM
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just finished mine

Just came back to stay with mom, I'm 57 she is 82. Well having problems of this type and it is fixed. I fixed what caused it, but to see if what caused it was right, I had to drain the system. What happened is my back flow system, called a back flow Johnny, became my expansion tank. It can be caused by many things, if you can believe my electrical set up on my converted oil furnace with an exhaust fan caused it, well it did.

Anyway, when I relived the bladerless tank, 1919 boiler system converted from coal, to oil to gas. The back flow valve is right in front of the water line going into the furnace, it is set to run at 15 -25 or it goes through a 2 valve pressure relief system to equalize the pressure, it will not let water into the city system, the valve opens and dumps water.

The fix procedure on mine was:

1. Shut off furnace and it must be cold, not on and pumping.

1. after the back flow valve is the water leading to the pump, there (on mine) is a water valve that looks like a gas valve, a quarter turn one. 45 means closed, inline with flow means open.
 
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Old 02-19-14, 09:01 PM
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2. drain the tank and watch pressure gauge on furnace until it reaches 0, it will actually start to make noise like a water tank as explained in this thread.

3. At O stop draining, not 3 minutes after it hits 0 or 1 second after it hits 0, or you will start drawing from the system, at least the radiators on the second floor.

4. Turn on the quarter turn valve even with the pipe and watch the gauge.

It should stop well before 30, mine did at 18, I have a 3 story house.

It now operates at 22 psi-the blow valve on the furnace is set at 30. It was dumping at about 28 on the gauge from the backflow Johnny.

that it, I feel better now.
 
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