Boiler problems that HVAC company can’t solve

bewilderedboilerboy

WMno57 said:

catastrophy said:

So they replaced the old expansion tank and then the old boiler cracked and they replaced it with a new boiler that has since cracked. What was wrong with the old expansion tank? And what is the differences between the old and new expansion tanks?

The expansion tank could be a red herring. I'm thinking the two boiler failures 4 years apart were due to thermal stress. Caused by either incorrect bypass piping or dry firing.

It's worse, there were two boiler failures less than ONE MONTH apart! The first boiler failed when it was only 4 years old. Probably incorrect bypass piping (more like NO bypass piping).

bewilderedboilerboy

JUGHNE said:

IIUC, they already changed from a 30 tank to a 90.

This system would have had either a ceiling hanging compression tank, maybe 16" in diameter and 4-5' long. Perhaps connected to the old boiler.

Or an open top tank perhaps on top floor or even attic. This would have been connected to the piping system possibly anywhere. It may still be in place.

A real grasping of straws is that one of these tanks is still connected to the system somehow.
Almost an impossibility, but stranger things have happened.

IMO, worth a little research.


Do you have any other air vents other than the one shown in the picture?

Maybe a small one on the bathroom floor radiant heating?

It seems air is getting sucked into the system somewhere.

Thanks for the thoughts! I'll check with the boiler tech when he comes back tomorrow. Is it possible that air is getting sucked in through the cracked heat exchanger? The same thing happened when my last heat exchanger cracked.

bewilderedboilerboy

Matt_67 said:

You should also make sure the pex on the infloor loop has an oxygen barrier.

Thanks--do you know whether there's an easy way to figure this out without ripping out the floor?

sjchalela640

First thing you need to do is disolve yourself from your current contractor. You want a company that works on boilers. Your paying them they should not need advice . if they have good reviews with heat, make sure its boilers not furnaces, heatpumps . u will know hes a boiler guy if he tells you to stop touching ****, sit back and he"ll tell you after a series of methodical steps, your problems and the way to solve them. It will probably start at your water feed to expansion tank maybe even a pressure test throughout the system  

WMno57

bewilderedboilerboy said:

Matt_67 said:

You should also make sure the pex on the infloor loop has an oxygen barrier.

Thanks--do you know whether there's an easy way to figure this out without ripping out the floor?

Is there any text printed on the red pex shown in your boiler room photos? If you post a close up photo, someone may be able to answer.

JohnNY

To me, the size of those pre-formed headers and the number of branches suggests something about high water content and the thermal mass of that system.
The boiler looks too small to meet a high demand and so I'd say all the leaking is actually condensation.

That said, the real problem here is that hydronics is a specialty trade and it'll always be an issue that it years ago got mixed up with air conditioning and plumbing.

Rich_L

BBB, it really sounds like your current company just isn't up to the task of addressing your hydronic system's issues. You'll do yourself a big favor if you find a company with a guy or two that knows their way around hydronics.

I see you have a Spiro-top on your system. That's not a Spirovent and simply acts as an air vent, not an aggressive air remover. That's not the source of your problems though. You're sucking air in at some point in your system and its most certainly piping related. The piping around your boiler is a mess. I'm wondering if a previous homeowner did some of that, though I've seen "professionals" do worse. I've retrofit a few former gravity heat homes around here and I can assure you they didn't look like that when I was done.

You shouldn't need any more than 12 psi in your system, unless you're more than a 2 story home.

A boiler bypass is crucial on your system. That Weil McLain is a great little boiler and should last a long time but it will condense if return water temps of less than 130 - 135 F are coming back to it for any length of time. That will shorten its life drastically. It can be as simple as a connecting line between the supply and return with a valve to regulate flow, but the best setup would be a 3 way valve with a temperature sensor on the return line.

I live in East Central Iowa, unfortunately a little far away for a service call or I'd be happy to stop by and help!

frankmarr

Do you still have the cold water and expansion tanks in the attic? It seems like that cold water being drawn back into the boiler would cause some thermal shock issues. I also do not understand how you are "bleeding" the system without an auto feed. Are you manually opening the feed at the boiler and then going up to open the coin vents? Otherwise you aren't really bleeding anything correct? You are actually just introducing more air?

You also have a radiant floor? is there sufficient flow going through that manifold? I installed radiant floors at my house a few years ago and had a real tough time getting all of the air out and maintaining the flow.

Sorry if I sound like kind of a dullard here, I am more of a hobby plumber, not doing this for a living.

Mark @ Radiant Works Inc

I haven’t read all the comments but the three major things to look at would be number one expansion tank sizing, number two make sure your bypass is open so you don’t have stone cold water coming back to that boiler, what you’re seeing that’s leaking on the floor is most likely condensation if that bypass is not open enough and number three would be adjusting your expansion tank pressure. With all that water in the system, that’s a lot of weight which equals pressure at the expansion tank So your bladder may already be expanded halfway.  Take note of the static pressure of the system with the expansion tank isolated and then boost your tank pressure 12 pounds above the static pressure. If you’re finding you had to adjust your tank pressure to more than 20 pounds, add a second number 90 expansion tank so that your tank capacity is greater than what would normally be required. 

EricPeterson

I have to pipe in here (pun intended) on the subject of thermal shock.

After years of evaluating boilers I decided on a Burnham ES2 which I installed in the fall of 2010.
One of the selling points was this claim in the sales brochure:
"Designed to handle the kind of high water volume systems present in
most homes, the rugged ES2 cast iron heat exchanger can easily operate
with lower system return water temperatures than conventional cast
iron boilers. Most cast iron boilers require a minimum of at least 140°F
return water temperatures to prevent damage to the heat exchanger. The
ES2 has been designed to accept return water temperatures as low as
110°F without complicated piping or additional controls."

I was a bit flummoxed though when reading in the Installation Manual which very vaguely stated:
"Install a boiler bypass, system bypass,
or primary-secondary loop when needed
to avoid returning large volumes of cold
water directly to a hot boiler."

So to be on the safe side I installed a system bypass using a ball valve opened halfway so that potential returning cold water would always be mixed with heated water from the boiler. This seems to work fine and it is a simple solution but it is not a very intelligent one. I would be happy to go into the specifics (zones, radiators, piping, etc.) of my install in a separate post if I thought I could get some guidance as to improve on this setup.

But for now I just want to say that this whole topic is fraught with imprecision and confusion. A web search of "boiler system bypass" brings up a a collection of vaguely worded posts that do little to present a clear overview of the problem and solution. The Burnham I&O manual is a good example.
I suppose this is because there are so many different types of installs out there.

Thanks for reading,
Eric

Redchecker

I would make sure cracked could be condensation

BradHotNCold

Homeowner not a professional. Just a passing thought: As that is a Weil McLain boiler pictured, is there any possibility that the manufacturer has any Tech Services consultation available?

talon55

Hard not being in the room but ,safety valve, size of radiation and what ,kind, air elimanater , pressure when hot and cold.how many floors,also gate valves have a habit of sucking air when they cool

every time you bleed you ad more air in fresh water.

Danny_Jr

Are there any pipes running under the slab? You could have a leak being absorbed by the ground. If the water is being replaced continually this would explain why you have so much air. This would also contribute to colder water being injected into the boiler. If you had extremely hard water being injected into the boiler you could lime it up and have it crack within months. I have personally seen that scenario 4-6 times.

Darrell_4

Did anybody else hear him say that the system pressure gets to 60psi before the relief “eventually” blows?!!! If it’s getting to 60psi, that will definitely rupture the diaphragm in the expansion tank…no matter how big it is…and dump the captive air into the system. That needs looking into yesterday! If it was my project and his money…I’d haul it all out in the yard and start over with clean Primary/secondary piping and adequate zone pumping. Sounds like a lot a radiators on the main zone…I don’t see a pump big enough to do that. I see several mismatched zone valves…maybe the poor thing is just confused!

Danny_Jr

Does any one see a relief valve on that boiler. The home owner seemed to indicate that he did not have one. And I can't see one in any of the pics. If that is the case the installing contractor is culpable. although I doubt it was excess pressure that caused the boiler to fail, Regardless there is no excuse for the lack of a relief valve.

JUGHNE

HO/OP said he had a relief valve

bewilderedboilerboy said:

george_42 said:

I do not see a relief valve on boiler

Ah sorry, it's not visible because of the camera angle. It's there, and set to blow at 32 psi.

Do you see on the tag of that valve 32 PSI?
It should open right at 30 psi.

If you had a crack in the boiler and it always showed pressure, it would be peeing all over the floor. Isolate the water supply and see if it holds the same pressure.

Smitdy

Has anyone suggested you install a condensing boiler? Thermal shock wouldn't bother it at all.   

SgtMaj

your pump is making the air, possibly the wrong size pump.  Your near boiler piping is all wrong, no bypass, expansion tank is in the wrong location, I don’t see a relief valve.  Look at the installation instructions for your model boiler and the lightbulb should come on.