I have a two year old system. Weil McLain Ultra 155, with 4 zones(radiant, baseboard, 6 rads, 6 rads). Been noticing a puddle around the boiler in the moring and identified it was coming out of the relief. Called my HVAC tech and he replaced the valve, ran the system and everything seemed fine. Next day, had the same problem. New tech came during the next day, spent 2 hours and couldn't figure it out because he said he couldn't replicate the problem. All he accomplished was telling me that the backflow and pressure reducing valve are installed backwards- which is correct. Said my expansion take seemed ok. Day after that, I woke up early and found the boiler leaking through the relief. Pressure was at 27 psi when it typically runs 15. Seems to be happening during a recovery period in the morning. Any ideas would be welcome. Others have clued me in that I may need to move to a Extrol 60. Thanks, pics below..

Boiler pictures by dgr68 - Photobucket

 

This is just saying the obvious, but the relief valve is dribbling because the system pressure is too high. Did this problem just start or has it been going on for two years?

From your description, I think your pressure reducing valve may be leaking past its seat, causing the pressure to rise over time. I don't think the expansion tank's size is the problem. See the yellow-handled ball valve in the domestic water supply, ahead of the pressure reducing valve? Shut it, and restore the correct system pressure (say, 15 psi cold or a few more psi hot) by draining from the boiler drain valve. Leave that valve shut, and see if the pressure stays OK. If it does, then that points toward the pressure reducing valve leaking past the seat.

From what I see in your pix, I don't think the back-flow preventer or the pressure reducing valve is installed backwards.

 

There are three main causes of wild pressure excursions; the pressure reducing (make-up or auto fill) valve, a leaking coil in a tankless coil or indirect water heater and the expansion tank. The expansion tank is the most common problem and usually comes from a conventional (no bladder) tank being waterlogged and a diaphragm tank having a leaking bladder or originally sized too small.

Drop the pressure on your system to zero (close the make-up water hand valve and drain just enough water from the boiler to cause the pressure gauge to register zero or below) and then check the pressure in the expansion tank bladder. If there is ANY water from the air valve (tire valve) on the bottom of the expansion tank the tank needs to be replaced. If the pressure is merely low (it needs to be 12 to 15 psi and the make-up PRV needs to be set to the same pressure) you can try adding air. Be sure to not over pressurize the bladder or you will buying a new expansion tank.

If the pressure IS normal and this problem has been going on since original installation the expansion tank was incorrectly sized and either another tank may be installed with the original or a larger tank installed instead of the original tank.


The pressure reducing valve and backflow preventer are installed in reverse order, not backwards. The backflow preventer should be on the supply side of the pressure regulator.

 

Before you change the tank, definitely try recharging it.

Here's a handy 'step by step' instruction for doing so:

=============================

1. Shut off boiler and allow to cool to under 100°F.

2. Shut off water supply line to boiler.

3. Drain only enough water from the boiler drain to drop the system pressure to ZERO.

4. With an ACCURATE tire pressure gauge, check the air charge in the tank on the air valve opposite the end of the tank that's connected to the system. If ANY water comes out of the air valve, the bladder inside the tank is shot and the tank needs replaced. *see note below* If no water comes out the air valve, and the pressure is less than 12-15 PSI, continue to step 5. If the pressure is OK, turn the water supply to the boiler back on and repressurize the system, turn the power back on to the boiler, no service is necessary.

5. Using a bicycle pump, or a small air compressor, add air to the tank until you have 15 PSI air charge.

6. Check the boiler pressure gauge again, and if it has risen off ZERO, drain some more water from the boiler drain until it is again at ZERO.

7. Check the air charge on the tank again. If it is below 15 PSI, add air to the tank until it is at 15 PSI.

8. Repeat steps 6 and 7 until the boiler stays at ZERO and the tank stays at 15 PSI. At this point, the tank is properly recharged and the water supply can be turned on to re-pressurize the system, turn the power on to boiler and return to service.

=================================

The 'pros' couldn't figure this out? hmmmmmm... or maybe they are the same ones who improperly installed all the circulator pumps with their butts up in the air? That installation is only recommended by the manufacturer if the system pressure is ALWAYS over 20 PSI. They should all be turned 90 degrees. yeah, pros... right.

After checking/charging the expansion tank, the pressure still climbs, then as the others have said, the reducing valve...

 

Thanks all. I appreciate the help! The water from the relief started about a couple of weeks ago. A year ago, I began hearing a loud water hammer sound when the boiler shut off and the original installer (guy stopped working for himself and went to work for a large outfit so he's out of the picture) replaced the orig exansion tank and fixed the problem. New company, which has a fancy name, sent two different kids and they both had no clue.

1. If expansion tank is bad, any coincidence that I have two bad ones in two years?

2. Will system automatically refill itself once supply is opened? Should I open valve, wait till pressure builds then fire boiler? (I'm assuming supply shutoff to boiler is the valve to the right of the primary circ pump)

2. Do you think it is safe to shut the domestic water off to isolate whether the problem is the feed valve?

2. Does the fact that the backflow and feed valve are in wrong order make enough of an impact that I should swap them?

3. Obviously a little late re: the orientation of the circ pumps. Why do they need them horizontal? Will it give longer life to motors? Is this something that can be left alone, or can the system be set to 20 psi?

 

It may not be a "defective" tank so much as just lost its air charge.

If the PRV is working properly it will refill the system to the correct cold pressure. You will need to turn off the make-up water by use of the valve in the water piping going to the PRV. I can't see enough of the piping (left side of picture is cut off) to see if you have purge stations on the various zones nor what you have in the way of a shut off valve on the boiler return.

The PRV and the backflow preventer should be swapped but you can wait until summer for that job.

The motor bearings in the circulator pumps are made of carbon or ceramic materials and are lubricated by the water. Having the motor vertical allows air bubbles to collect at the top and this would cause the water to be displaced from the bearing on the outboard end. When the pressure is higher the size of the bubble is smaller but in reality the pumps really do need to be changed to a horizontal configuration. I wouldn't mount the motor vertically even if I had fifty psi pressure. This is another job that can wait until summer.

 

The symptom you quoted as "a loud water hammer sound when the boiler shut off" typically isn't something that would be caused by the expansion tank being bad...

A little bit more about the pump orientation... I believe another reason for the manufacturers recommendation is the nature of the design will allow the pumps to CAVITATE more easily in that position. There's all kinds of technomumbojumbo terms that can be thrown out here, but I'm not going to because I don't understand them well enough to explain. Gravity also plays a part in this... I'm thinking that with the impeller horizontal, and the lowest pressure point inside the pump in the middle of the volute, it's just that much easier for the cavitation to occur in that position. Also, because of the decreased density of the water when HOT they will more easily cavitate at that time... When pumps cavitate they can make "a loud water hammer sound", and actually destroy themselves. Coincidentally, this is when you report having heard that noise. Furd is also correct about the bearings, but I think that's actually a secondary reason.

Why changing the tank seemed to 'fix' that problem is a mystery to me.

Air permeates through the bladders in those tanks at the rate of 1-2 PSI per year. This is NORMAL... tanks should be checked/charged at a MINIMUM of every 2 years. From what I've seen, most systems can tolerate a loss of 5-6 PSI in the expansion tank before there are complaints of the relief valve popping. I guess most systems have enough 'headroom' in the tank to tolerate that low of a charge in the tank. Keeping the proper air charge in the tank minimizes flexing of the bladder, and promotes longer life. (mine is over 20 y.o. - touch wood).

Another failure point with the tanks is the schrader (tire) valve. They sometimes leak air slowly. You can test with a little spittle, or soap solution. Make a bubble on the end of the valve and watch for it to grow. Sometimes they need to be snugged up or replaced. Real easy to do using standard tire valve tool. Pep Boys has tire valves.

Yes, of course. Standard practice, in fact, Bell & Gossett recommends that the systems be run with the manual valve CLOSED all the time, except when adding water. Just keep an eye on the pressure, which you will be doing anyway for diagnosis. If the system is water-tight, there is no reason to not be able to run with the valve closed. ( I do )

There's a long standing debate about to open, or not to open, with good arguments for both cases... it will never be resolved. I think the happiest medium would be to install a "Low Water Cut Off" (LWCO) control to prevent the boiler from firing with low water, and to run with the manual valve CLOSED.

As furd also said, wait until Spring... the backflow preventer relies on higher pressure at the inlet side in order to function properly. In the position yours is installed, it simply won't do anything. It's just 'there'. I don't think there's any impact on the reducing valve though. There are MILLIONS of systems out there with JUST the reducing valve, and no backflow preventer. There is a check valve also built into the reducing valve. One last thing... the ONLY time these backflow preventers or check valves do ANYTHING is when the pressure in the boiler is higher than the water supply pressure... which happens how often? the twelfth of never?

 

Furd- There are boiler drains at each zone return and shutoffs after the drains before they come into the primary loop. There is a shutoff on the primary, which is at the bottom left of the photo.

NJ- I remembered the installer had to make a few calls before he swapped out the expansion so who knows? Also, last night I was reading the manual and was looking for what internal protections the boiler has. Seems like its only a high temp shutoff. Mentions that some locations require a low water cutoff be installed. Funny thing that a $3,500 boiler can't have this as a pre-installed feature.

 

While not standard equipment, most of the manufacturers have taken steps to include information on LWCO in their manuals. While it's not a 'new' piece of equipment, neither is it 'old'. Building codes are slowly being amended to require them. Probably won't see it as standard equipment until there is a federal regulation...

Can you snap some more pics? I'd like to see what's to the left of the bank of circs if you don't mind.

 

Something else I feel should be standard equipment that I like to bring up whenever there's talk of expansion tanks:



Consider setting up your system like this when you swap the position of the backflow/reducing valves.

Perhaps the reason that expansion tank air charges are a neglected issue is because of the PITA involved in having to depressurize the system just to check the air charge on the tank. With this setup, it is not necessary. Just close the water feed and the isolation valve, hook a hose to the drain and drop the pressure off the tank. Check/charge/change is SO easy with this setup I can't understand why it's not always done... anything to save a buck I guess.

Interestingly, Watts has 'appropriated' my idea and combined all this stuff into one neat little package:

What's New | Model RBFF Residential Boiler Fill Fitting

I'm still waiting for my royalty checks.

 

Well, at least according to Watts' literature, they haven't patented their contraption.

The one additional feature that would make servicing the expansion tank easier: an air gauge permanently installed to measure the pressure on the air-side of the bladder. That would eliminate the need to find and futz with a tire gauge.

It would also be nice to have a way of pumping up the bladder that is less awkward than a bike pump. My bike pump is designed to be placed on the floor and it has a short hose - so it has to be stroked while being held in mid-air.

 

I guess I should file the patent then?

A gauge on the air side would make it easier, but remember that gauge will only be accurate when the water side of the tank is at atmospheric pressure. For example, say the real air charge was at 5 PSI, and the boiler pressure was at 12 PSI. The gauge on the air side would read at or near 12 PSI because of the pressure on the bladder from the boiler. This might lead one into a false sense of 'everything is just fine'.

 

OK, then suspend the expansion tank from a load cell, or electronic scale, like used for BBQ-grill propane tanks to indicate their weight and, therefore, percent fill. (Connect the exp tank to the hydronic system with a flexible hose so that the load cell measures the correct weight of the tank.)

The load cell would thus indicate the inflation of the bladder. The load cell would be connected to a 24-V alarm system that would activate when the weight of the tank is abnormally high, indicating that the the bladder had lost too much of its air charge and that the tank was flooded. Or, instead of an alarm system, it could start a tiny, 24-V, air compressor that would automatically recharge the air-side of the bladder (while simultaneously opening a small, solenoid-operated, water bleed valve to maintain the correct system water pressure).

patent pending, M. Speed, 2/21/10

 

What do they say about great minds? I was out in the shop today and while I was working, I was having the same thoughts! No kidding...

How much load could a load cell cell...

 

1. What is above the drain valve under the expansion- a regular shutoff?

2. Do you thing the following statement is accurate (from another poster):

"dgr68, there's several obvious errors in this installation, in this particular forum I'm not allowed to get into it, I hope you didn't pay too much for this."

"Though the piping and soldering looks decent, many of the parts are installed in the wrong location, and incorrectly, this is either a DIY install, or a very inexperienced contractor."

3. Here are the pics:

Boiler pictures by dgr68 - Photobucket

 

1. Yes, a shutoff. Ball valve is probably best.

By the way, if you didn't have to swap positions of the backflow and the reducing valves, I would say to leave the water tee right where it is. My graphic shows it on the other side of the isolation valve, on the bottom, but it would work the way you have it now if you just came off the bottom to a ball valve, tee with drain, and then the tank.

The way I show it would also allow you to adjust the reducing valve 'off line'.

2. I'll look at the new pics now...

Other than the pumps and swapped BF / RV positions, I'm a little curious as to why the boiler loop is the primary, and the CH loops the secondary. I think normally it would be the other way around... offhand, without spending a lot of time thinking about it, I don't see why it wouldn't work fine as built though (it is after all working now!)... but I'm tired and doped up on cough medicine right now... maybe rbeck, or TO (or anyone else for that matter) can take a look and comment?

 

Thanks NJ. Hope you feel better.

Sunday morning after the relief emptied, I turned off the make up water shutoff. This morning during recovery new water was in my bucket and boiler was running 27psi at 190 deg. I'm assuming if I see the same thing tomorrow then the feed valve is not the culprit. Should I increase to a Extrol 60?

Not sure why he built manifolds for supply and return off the primarly loop. I would have connected straight into it. It does work fine except for these issues.

 

Did you also lower the system pressure to 12-15 psi (cold) by draining water out of the system? To verify your conclusion, that needs to be done.

 

It returns to about 14-15 after the morning.

 

Are you absolutely sure the shut-off valve doesn't leak through? I've seen that happen more than once. If the pressure reducing valve is working fine but the preceding shut-off valve leaks it could still be a combination of the expansion tank and the shut-off valve causing your problem.

 

It was leaking for three weeks and I just shut the valve yesterday, so what's the chance of it going. I may just throw in a new PRV since I have to move it downstream of the backflow.

 

The only thing you did was close the makeup valve, correct?

If your expansion tank is low on charge, you will STILL see the extremes in pressure swing. It may not open the relief valve though...

Go through the steps to recharge the tank.

(step by step posted earlier in this thread.)

Reset the system pressure cold to 12 PSI and close the feed valve. Then keep your eye on it and see if the pressure stays in control.

Then, re-open the feed valve and see if the pressure slowly creeps up again. If it does, replace it.

I think that's 'jumping the gun' and I doubt you have that much water volume in your system to require the larger tank.

First get to a known state... service the existing tank properly and THEN evaluate the situation.

 

Yeah, I just closed the shutoff upstream of the prv. Question is, why would expansion tank get low on pressure? In my mind if a bike tire gets low it's because it has a leak and will leak again if reinflated. Also, boiler drain under expansion tank really needed? Thanks again, all.

 

No, not necessarily. Bike tires lose air over time due to diffusion of air directly through the rubber inner tube. Pump up your bike tires in the fall, and well before spring they will have lost much of their air.

A bladder-type expansion tank loses air the same way, but it takes longer because the air pressure is lower and the bladder is thicker than a bike's inner tube.

I would quit fighting it and go ahead and recharge the bladder per the procedure that has been recommended to you.

 

Air molecules very small.

Spaces between rubber molecules a teensy bit bigger.

Smaller air molecules squeeze in between rubber molecules to be free.

Children's baloons. Blow up. One week later, flat! No leak. Why flat?

The drain below the shutoff is to release the pressure on the tank after you close the shutoff valve above it.

 

All:

Tuesday morning I decided to check the expansion tank. Shut the supply and return on the primary loop and then emptied the boiler. When boiler wouldn't drain anymore the pressure still read 2-3 psi which was a surprise- gauge out of calibration?

Checked the expansion tank- no water came out but it would barely push the rod out of my pressure gauge. Took your advice beenthere and installed a new 60. Read about 12 psi out of the box and charged it to 20 psi before installing. (Didn't have time to install shutoff as wife was looking at me like I was crazy doing this when the house was getting cold. By the way NJ, can I just install one of those ball shutoffs with the little bleeder in it?)

Had a hard time trying trying to get the system filled with water. Tried to depress the auto feed lever but the increased pressure would just blow the relief. Three hours later it showed 12 psi so I fired the boiler. I took notes on the psi/temps but don't have them here. Long story short, next morning there was no water in the bucket under the relief. Seemed to be running 20-21 psi when hot (180). At night, seems to show 14-15 psi when cold (80). This morning again no water. PSI 21 at 190.

I was not able to adjust the auto feed because it was taking so long to fill the system. I noticed the relief seems to start to open when the pressure shows 24-25- which seems low to me. Appreciate your thoughts. Thanks again...

 

OK... nobody said anything about emptying the boiler... and you didn't need to. If you were only checking and/or charging the existing tank, all you had to do was drop the pressure to zero. (I understand you were probably waiting for your probably inaccurate gauge to go to zero... but you should have stopped when it was obvious that it wasn't dropping any more.)

Since you changed the tank even though you didn't need to, you would have to have drained a little bit of water... but certainly not the whole boiler, because your tank connection is above the level of the boiler...

But that's done... so fuggedaboudit, and just remember it for next time. (if there's a next time.)

Why did you do that? The proper air charge in the tank is supposed to MATCH the cold fill pressure. Adding MORE air than necessary is defeating the purpose of an expansion tank.

You need to drop the system pressure as low as it goes... 2-3 PSI if that's as low as your gauge reads, and reset the tank pressure to match the cold fill pressure.

By putting more air in the tank than needed, you are DECREASING it's capacity to accept the expanded water. It won't take any expansion until the system pressure hits 20 now. You want it to begin accepting the expansion as soon as the water starts expanding... that's why they are pre-charged to 12 PSI. MORE IS NOT BETTER!

Sure you could... but you don't WANT to... what's gonna happen to the water that comes shooting out that little bleeder when you open it? It's gonna spray all over the place. By using a proper drain valve, you can put a hose into a bucket... it may not be a LOT of water (but it COULD be if the tank had failed)... but still, why make life difficult?

I don't understand? You only hold open the fast fill until the pressure in the boiler is 12-15 ... why would you let it go until it popped the relief?

Also, because you emptied the boiler, you should also have vented the air out of it as you were refilling it...

Why would you want to? It should already be set at 12 PSI.

Based on what you've said about pumping the new tank up to 20 PSI, this is what I would expect to see. If you were to drop the tank pressure back to where it belongs, you will likely not see the system pressure go much over 16-17 when the boiler is hot.

More evidence that your gauge may not be accurate.

I wish before spending the money on the new tank you had just followed the instruction for recharging the existing one... a 60 size would only be called for on systems with a LOT of water in them, which yours is not... but I guess some folks just like to tinker!

 

Changed to a 60 because two guys (one online and one in person) recommended it based on the amount of water in the system and the fact that I'm on my second one in two years. I've also been told by people in person and online that a 30 is fine, so I erred on the side of the larger one.

Increased the pressure to 20 on the new expansion tank because I was planning on running the system at 20 psi so that I would be in the range for the taco circulators. I don't plan on re-working the entire piping system. Is there any problem with running the system at this pressure?

How much water could be in the little bit of line above the expansion tank? I'm used to getting soaked when I bleed the radiators!

Is it unusual for a pressure gauge to be off by 3 psi? This sucker is under warranty and would be inclined to fix it.

Is there a vent on the boiler so I don't have to wait 2 hours for it to fill?

 

How much water is in your system? In your first post, you said "... 6 rads, 6 rads ..." do you mean 12 cast iron radiators?

OK, I think I understand what you are doing now... I didn't 'get' the fact that you didn't want to turn the pumps so are planning on running the system at 20 PSI cold, and that's why you want to adjust the regulator.

I guess there's no harm in that. Now that you have that large expansion tank, the pressure should stay under control...

It's not just what's in the little bit of line... it's what could be in the tank! you could end up having to drain a gallon or more depending on the circumstances.

Not at all unusual for a gauge to be out of tolerance.

Usually what guys do when they are filling a boiler that has been drained is they open the relief valve while it is filling... or any other valve you can open that is above the boiler. When water goes into the boiler, it will push the air out the open valve. When you get water out the valve, you know the boiler is full. A lot of installers will install a drain valve up high, above the boiler, called a 'purge valve' that can be opened to vent the air as the boiler fills.

 

Common pressure gauges are generally accurate to only 2% +/- of the full-scale reading so a 0-60 psi gauge would be considered okay if it read within 1-1/2 psi at any particular pressure. A 3 psi difference would definitely be outside tolerance but it also wouldn't surprise me in the least. Truth is, absolute accuracy is far less important than is repeatability, that the pressure gauge always has the same reading with the same pressure applied.

Yes, you can operate your system at 20 psi if you desire but it is still a band-aid approach to the incorrectly mounted pumps. You do need to adjust the fill pressure reducing valve to match the expansion tank precharge.

Most residential heating boilers do not have a vent valve. If you had used the valving arrangement Trooper recommends for expansion tanks you could use that vent valve to vent the boiler while filling.

 

In this case I'm not so sure that would have worked... for the same reason that the Spirovent might not have let the air out either... the water feed is 'right there' ... even the relief valve is sorta in the path of the incoming water. There's a check valve in the path of the return line, so the water couldn't go the opposite direction. Ideally there should have been a purge valve and boiler isolation valves installed when it was put in. I guess it's all these 'little things' that the person oldhouse quoted that was denigrating the install.

It seems that too often installers try to save a buck and leave out the 'convenience features' that make future service easier.

 

First floor has 6 radiators, three of which are real big. Second floor has 6 radiators, 2 of which are real big. Also have about 250 ft of radiant in my kitchen. I think my old system might have had twin 30s if I remember correctly. In any event, cold psi seems to be around 10-14 and hot around 20-23. Do I wait until system is cold and turn auto feed about a quarter turn to the right and wait a couple hours to see where pressure is? Any thoughts on that? Thanks..

 

OK, so you may have a fair amount of water in your system then...

Since you installed the new tank, have you watched the pressure gauge as the boiler heats up? If my guess is correct, what you would probably notice is a fairly quick rise up to the 20 PSI that you have in the tank, then a slower rise from that point. This would be because up to 20 PSI the expansion tank won't accept any water...

Yes, a quarter to half turn at a time... you might go a half turn the first few adjustments, giving the system time to stabilize in between adjustments... I don't know if it would need to be a 'couple hours' though... but by watching the gauge as you adjust you should be able to get a 'feel' for how much you need to adjust. Then, as you approach your setpoint, give it progressively more time to 'settle'.

Also, keep in mind that your pressure gauge may in fact be inaccurate... so you may want to keep the pressure a little lower until you can verify the accuracy of the gauge. You can pick up a 0-30 or 0-50 PSI gauge at a plumbing supply (or even pool supply) and adapters to screw onto a boiler drain fitting. This would let you compare readings between a new, supposedly accurate gauge, and the one on the boiler. Because you are now going to be running the system pressure so close to the relief valve pressure, you need to be more careful with that.

I would strongly urge you to consider turning the pumps.