Boiler was serviced but problem not resolved

Langdon

Back in January of 2019 our boiler pressure relief valve kept dumping water about once every night. We had a repair person come out and they replaced: the pressure relief value, the expansion tank (previously we had an old no bladder type) and the water pressure regulator valve. (The house is a cast radiator hydronic system from the 60s)

The problem went away until this spring when the new pressure relief valve began to drip constantly even when the boiler switched on. It was enough water to fill a bucket about every 5 hours. I replaced the PRV myself and kept an eye on the pressure gauge on the boiler and even checked it was reading accurately.

The drip went away but when the boiler was on the pressure was building up within an hour to 30psi at which point I would shut if off.

Last week we had a different repair tech come out to the house after not being able to figure out the problem myself.

He replaced:

• Pressure relief valve
  
• Expansion tank
  
• Reducing vlave
  

In addition he reoriented how the expansion take was mounted and stuck around until the boiler came up to full temperature and then bled all the radiators for 5 min until there was no trace of air in them.

But as you can see from the pics below the problem was not really solved since the boiler is still building up pressure but now it takes a couple of hours rather than the 1 hour before.

(brand new 5 gal expansion tank)

STEVEusaPA

Maybe the expansion tank is just too small, or maybe all the air isn't properly purged from the system. The other problem may be the near boiler piping is incorrect.

Do you use your boiler for domestic hot water?

Langdon

no the boiler is strictly for home heating

The piping hasn't changed since the boiler was installed in the early 90s and we never had a problem before. The only change has been going from a ceiling mounted tank to the bladder tank but that used the same connection point just shorted since it did not have to reach the ceiling.

HVACNUT

Is there a tankless coil in the boiler or an indirect water heater connected?
Could be a domestic leak forcing it's way into the boiler water.
Is the new expansion tank pressurized to 12 psi?
Is the new expansion tank large enough. Assuming by 5 gallon you mean a #30 extrol. How many floors? Maybe it needs a #60.

Jon_blaney

How do you make hot water? Could you have a coil leak which is allowing domestic water pressure to pressurize the boiler?

Jamie Hall

The most likely problem is that either the expansion tank simply isn't big enough, but it's also possible that it wasn't set up properly.

When it was installed was it precharged, while empty, to the system pressure? It should have been brought to final system cold pressure before it was attached to the system...

That said, it could also just be too small. Large cast iron radiators have a lot of water in them, and thus need a good sized tank. The old overhead compression tank which you had was, in all probability, much bigger.

Although it shouldn't be related to the pressure problem, what kind of air relief do you have on the system, and where is it located in relation to the boiler and the pumps?

Langdon

The hot water for domestic use is from a stand alone 50 gal gas water heater.
other than the fact they are both fed from the house water main they are not connected.
And the heating boiler has a new reducing valve after the branch from the water main away from the domestic water heater.

Its a 2 story house with a ground level basement.
The expansion tank he just installed is a Zilmet Cal-pro ZHT 4,8 gallon
But he did bleed air from it after he installed it, how much I don't know but the photo above is the reading I got when I checked it today with a cold radiator - about 14 PSI

Assuming I have the terms correct:
There in no coil in the boiler which is my guess since there is no access panel for one anywhere on the boiler

EBEBRATT-Ed

Sounds like the expansion tank is too small

Langdon

Jamie Hall said:

Although it shouldn't be related to the pressure problem, what kind of air relief do you have on the system, and where is it located in relation to the boiler and the pumps?

none other than the ones on the individual radiators themselves. The repair guy was discussing how newer systems have a valve that sits adjacent to the bladder tank to auto-bleed any air in the system but we have no such thing on this.

And I was not downstairs when he installed the bladder tank so I don't know if it was pre-charged. But like I said I did see part of when he was bleeding air from the new tank once he was testing the boiler as it was hot. All I can go on now is the charge my air gauge shows when the boiler is cold.

Jamie Hall

Oh dear. Well, with a bladder tank you do have to have and air release valve, and it should have been installed. Also, if he was bleeding air from the new tank when he was testing the boiler... as I say, oh dear.

For starters, someone needs to check the precharge on that tank. To do that you have to disconnect -- valve off or whatever -- the tank from the system, empty all the water out of it, and set the air pressure through the Schrader valve to the desired air pressure, and then reconnect it. You cannot check the precharge with the tank connected to the system.

Jon_blaney

Supplyhouse.com has a pressure tank sizer. You are on the cusp for that smaller pressure tank. I would go larger. Ask the tech how he sized the tank he installed.

JUGHNE

Cast iron radiators hold a lot more water than the typical system.

If you still have the first replacement bladder on site, you can put both bladder tanks on your system. They just have to have matching air pressure before they are installed.

You still have to have some automatic air bleed method....and not out of the bladder tanks.

Your old hanging compression tank is probably OK. Just that most younger people do not understand how it works. It lasts forever or until it leaks....whichever comes first.

Langdon

I should have used some common sense..... I closed the valve and then removed the bladder tank which was obviously a water cannon. So after cleaning that mess up I took a reading from the air gauge.

the tank came back as 4 PSI. I used bike pump to bring it up to 12 and reinstalled it, reopened the water valve and will report back. I don't have the old bladder tank so I can't test that theory.

But it sounds from what you are saying that its is still too small and the system needs an air release valve. I paid them $x00 to fix the original problem so I don't know how generous they will feel about doing all that at a discount.

JUGHNE

Can you show some pictures including the old tank and where it was connected.

Back up to show floor to ceiling.

Langdon

first off, thanks for your help

So the update is after 90 minutes of the boiler being on:

* The re-precharged expansion tank went from 12 PSI to 22 PSI
* The boiler pressure went from 14 PSI to 26 PSI

I shut it down since its clear the direction is headed back to pretty much where it was since they did the repairs on Thursday which is not much different from the situation that made me call them in the first place.

JUGHNE said:

Can you show some pictures including the old tank and where it was connected.

pecmsg

That appears to be some large piping combined with the pump being on the return........... from here I’d get a larger expansion tank. 

Alan (California Radiant) Forbes

.......obviously a water cannon. So after cleaning that mess up......

It's nice to have a drain between the valve and the x-tank for that reason. It's happened to all of us. Consider it your baptism.


Everything seems to be pointing to a larger x-tank at this point.

EBEBRATT-Ed

Yes you need a larger tank or another smaller one. I question if the techs know what they are doing. The new tank only had 4 psi on the air side. Either it's a bad tank or they bled air out of it which proves they are clueless

JUGHNE

Your old "compression" tank was probably just water logged and lost it's head of air and simply needed drained.
That old system would collect any extra air in the system and hold it in the upper half of the tank, the bottom being full of water.
That method must have no air bleeders on the system or that tank gets water logged.

The newer "expansion" tank system must have some form of auto air remove device.

Plus you need a larger or second expansion tank.

The company would do themselves and you justice by learning how this old system works and reconnecting it as was.

Alan (California Radiant) Forbes

The newer "expansion" tank system must have some form of auto air remove device.

I'm less likely to install a microbubble air eliminator on a radiator system because I figure the air will accumulate in the rads where it can be bled.

Langdon

I suspect that when they come back they may eat the cost of a larger bladder expansion tank since they failed to repair the problem but if the system now needs a valve to bleed the air out on its own that they will not be doing that work for free.

From what you guys said then the problem started 2 years ago when the other company changed us from the compression tank to the bladder type and failed to put in both a bigger tank and the air valve. (or fix the compression tank) And that was why the PRV failed in such a short period of time.

And this new tech who came last week just took his cues from the work before him and repeated the mistakes. And that the reducing valve was probably fine and did not need to be changed. So I am LITERALLY paying for their mistakes.

pecmsg

I disagree, you should pick up the extra for the larger tank but not any labor.

EBEBRATT-Ed

@Langdon

The expansion tank issues have nothing to do with the PRV failed Prv or not

Alan (California Radiant) Forbes

The problem with rising pressure is often not an easy one to fix. Most often, it's the x-tank. If not the x-tank, then the fill valve. Replacing them both usually does the trick, but an obvious lesson from this example is that you have to size the tank properly. As far as the fill valve, it's a 50% chance that it doesn't work anymore as they fail often, so if yours was old, it's probably not a bad thing that it got replaced.

Matt_67

On cast iron radiator systems I have seen where partially air bound radiators act like an expansion tank. I had one call where the owners came back from a trip and went around and bled all their radiators and then called at midnight when the relief valve tripped. The existing tank was undersized but had worked ‘fine’ for quite a few years. It’s really not that likely that a tech will calculate the volume of an existing system when replacing a tank that had been there for a long time. When replacing a recently replaced tank in that type of system I would.

HVACNUT

Will a #60 extrol even fit in that same location?
Where's the tech from January of '19? 
You might be able to work something out with the service manager of the company. 
Or, you seem pretty handy even though you took a bath. Order a #60 and do it yourself. You don't need to drain the whole system, just drop the pressure to 0 psi. If the piping needs to be altered to make a #60 fit, close the 1/2 in. ball valve and add what you need. Get a means to support the piping to the extrol because when the diagram bursts on a #60, she heavy.
Then of course you'll have to go around and check/bleed the rads.
Since there's no means of air elimination right now, you might need to periodically bleed the rads.
When you replace the boiler in the future, you'll be sure the contractor follows the 'pumping away' principle. 
 

MikeL_2

Langdon,
                If you're attempting this repair / replacement, be sure to cover items below the tank that don't do well in water. We keep plastic contractor bags on our truck;  they make excellent rain coats & can prevent accidental drownings... 

Alan (California Radiant) Forbes

@Matt_67 That's a great reason to always leave a little air in your radiators. But even the radiators will eventually get waterlogged. Instead of bleeding the radiators in the Fall, drain them.

neilc

was the old tank leaking ?
I see it still hanging there, just begging to be piped back in,
post a picture of the opposite corner of the boiler

Langdon

The original compression tank never leaked. When the repair in 2019 happened they just said it needed a new tank and I didn't really question it.

I do not know if a larger #60 tank will fit there. I only have the one that is there now as a frame of reference. If its the same diameter and just longer it looks like it should but I am not positive. If they had to install a slightly longer pipe so there is space for a pipe clamp to provide more support that may be when the space in the area may not be enough.

I guess I would be able to install it myself but the one there now is only 4 days old and I feel like the sizing issue is something they should have known when they saw it. Two guys initially came to inspect the system and neither mentioned it was too small and one returned the next day to put the replacement in. As I mentioned I paid them x00 to fix the issue and its not fixed so them tacking on more charges makes me feel like I am getting ripped off. It honestly would have never occurred to me that the tank size was an issue if I had never gotten advice from your guys. I was cringing at the thought of them returning and saying I needed a whole new boiler because the pressure issue could not be fixed.

So I am a little confused about the recommendations above. Are you saying I don't need an air bleed valve and I can just get away with the current set up if I remove the air from the radiators periodically? Or do I leave some air in them?

Steamhead

If we had installed that boiler, it would have an air separator no matter what type of radiation the system had. We have the technology to eliminate or greatly reduce the radiator-bleeding chore, so we need to use it. I would have used a separator with a 3/4" connection on the top and hooked that to the existing expansion tank, with an Airtrol fitting at the tank. This setup is quite good at keeping the tank from waterlogging, and eliminates the bladder or diaphragm in the newer-style tanks that will eventually fail.

My next step here would be to completely shut off the water fill line and see if that solves the problem. If so, the pressure-reducing valve in the fill line is not closing properly- even if it's brand-new. If the house water pressure is excessive (over 70 PSI or so) a 2-stage reduction may be needed.

EdTheHeaterMan

I'm more likely to be of the opinion that most contractors are honest and want satisfied customers. That said, I would ask to speak to the service manager or boss or owner of the contracting firm. I would ask him if a satisfied customer is his goal. I would also ask him if he has any guarantee on the work his men do. Once you get him to agree that he has some kind of guarantee and that he likes satisfied customers, i would ask him if he paid $800.00 to make a repair and that repair did not solve the problem, What would he expect from the vendor? Like if he had to take a truck to the dealer for repair

Then ask him if he is interested in solving your problem, $#00 to solve a leaking relief valve and the relief valve still leaks.

Now I would be agreeable to pay a total of $%00.00 (additional $100.00) to get the proper repair done if the proper repair would have cost $%00.00 if it was the total cost to get it right the first time. This way you are not paying for the inexperience of the repairmen. Likewise, I would also ask for a refund if for example they installed parts that were not necessary, like the auto feed and relief valve that was new the previous year. This also would be like paying for the proper repair the first time. (This is the way I ran my company and my customers liked that about my guarantee)

As long as the relief valve does not pass when the water pressure is below 30 PSI then it is not defective. If it does pass below 30 PSI then the failure happened as a result of over use over the past year from the original problem not being properly resolved. Since the new company did not make the original incorrect repair, then you may need to eat the relief valve.

I can't speak for how other contractors operate, but I thought that we should get it right the first time. But no one is perfect and the customer should not pay for something that does not work.

We are not supposed to talk pricing of particular repairs and I was just using symbol in leu numbers for an example to drive home a point. What a contractor charges for a particular repair is not supposed to be discussed herein. It may be prudent to remove the $ amount and replace it with $$$

HomerJSmith

I didn't read all the comments, but that appears to be a #15 tank in the photo. A #30 might do. Also a low or too high an air charge would move the dial upward. You would have to remove the tank to check the air charge and set it at 12-15 psi. If you remove it, I would replace it with a #30 Extrol. They're cheap.

https://www.supplyhouse.com/Amtrol-102-1-30-Extrol-EX-30-Expansion-Tank-4-4-Gallon-Volume