It was nice that our roofing crew took care of the roof tear off. That gave me the space and time to focus on the little side projects, like the roofing vents.
Let’s start with the main roofing vent, or the main drain-waste-vent (DWV) stack, if you want to call it that. It services the laundry room, main bathrooms, and kitchens.
Back in 2011 we decided to slightly rearrange the bathrooms. That meant we had to move the main vent stack over by about four feet in the plumbing wall.
Rather than punching a new hole into the roof to surface the vent stack, I put a kick into the stack right under the roof so that I could surface it through the existing hole of the old vent stack.
That was meant as a temporary solution, and now was the time to discharge the temporary and build the permanent.
With the roof torn off, it was easy to cut out the temporary stack. We abandoned the awkward kick right under the roof and filled it with insulation. We cut a new hole that was centered right over the main DWV stack and reconnected it. This way the stack runs in a straight line from the basement slab to the roof – the way it should be.
And then there was the need for a whole new vent stack, which services the 2nd bathroom on the 1st and 2nd floors. We again cut a hole that was centered right over the stack and connected it.
These are the kind of connections you want to do while you are re-roofing. This way the roof penetrations become part of the waterproofing system, rather than another patch to your roof.
The troubleshooting of our busted boiler (a Trinity LX150 by NTI), led me to the fact that mineral deposits inside the heat exchanger led to partial or complete blockage.
I knew that I had to clean out those mineral deposits, but I wasn’t able to get my hands on the recommended Fernox DS-40 descaler and cleanser – at least not quickly.
My next best option was to use widely available cleaning vinegar. But for this to work I had to isolate the boiler. In other words, I needed to just flush the boiler with the cleaning vinegar, but not the whole hydronic heating system, because that would take gallons upon gallons of cleaning vinegar.
Isolating and flushing the boiler should have been a cake walk, if our boiler had been installed with the drain and isolation valves as shown in the nifty manufacturer-issued plumbing diagram.
The reality of our boiler plumbing required a little creativity, because I only had one isolation valve and did not have drain valves as shown in the diagram.
I isolated the boiler by turning off the isolation valve on the outlet side, and turning off the isolation valves for the boiler pump on the inlet side. Removing the boiler pump was the best substitute available for the missing drain valve.
I then proceeded to remove the pressure relief valve on the outlet side and replace it with a simple ½ inch riser.
By pouring about one gallon of cleaning vinegar into the boiler through the riser, I was able to displace the water in the boiler and heat exchanger.
I added about another gallon or two into the bucket below the boiler pump, set my small sump pump into the bucket, and connected it with a vinyl tube to the riser on the outlet side. With this setup I was able to start flushing the boiler in reverse (outlet to inlet) with almost pure cleaning vinegar.
I also added a small wire tray to monitor the debris discharge. It took me three days of boiler flushing to get the mineral deposits out of the heat exchanger. I actually flushed for four days, but had no more debris discharge on day four.
And don’t be fooled by the rapid flow rate in the video, which I took on day four. On day one, I had a fraction of that flow and the sump pump was cranking pretty hard.
How did we get by without a boiler for three days?
That was thanks to the resilience of our system. We didn’t use any hydronic heating during the three days of boiler maintenance, but instead relied on our minisplits for heating.
I sat with the boiler during the flushing process and manually turned it off to let it cool down once there was a hint of hammering. It was time consuming but it worked.
I also noticed during the three days that the boiler operation got increasingly more quiet. Not only did the hammering and banging cease, but so did the hissing of flowing water. With the obstructions in the heat exchanger removed, our boiler ran almost silently and very efficiently once again.
Our Trinity LX150 by NTI (NY Thermal Inc.) started hammering and banging and eventually shut down. When I checked the boiler display, I found an error message saying: “Lockout 81 – Delta T limit”.
At the time I had no idea what the cause of the problem could be. So I started with the troubleshooting chart in the operation instructions, which was pretty straight forward:
I tested “Fuse A” and it was fine. I checked the pump, and it was running. The plumbing was correct too and I had water pressure of 20 psi. That left me with the dreaded last option: a fouled heat exchanger. Dreaded, because I wasn’t quite clear on what it meant and what the implications were. After some research and scouring through YouTube, I finally was able to put the pieces together.
A boiler doesn’t just break. It usually has a good reason, such as deferred maintenance. And I am embarrassed to admit that I am guilty of such deferral.
Our high efficiency boiler (Trinity LX150) takes care of our domestic hot water and hydronic heating system. I wrote about our mechanical system and how it functions in a previous blog post, which makes for good reading.
The boiler has a modulating capacity from 25,000 to 150,000 BTU and a stainless steel heat exchanger.
It is that heat exchanger that makes these boilers so efficient. In our case, we have small tubing (probably 3/8″) that surrounds the burn chamber. The ratio of the small water volume in the heat exchanger versus the relatively large surface area of the heat exchanger allows for efficient heat transfer.
But this efficiency comes at a price. Because of the small diameter, the tubing can be prone to clogging by lime and other mineral deposits. And once deposits build up inside the heat exchanger tubing, the efficiency of the boiler goes down and the banging and hammering starts.
If the water in the closed loop hydronic system would be treated properly, the risk of mineral deposit formation would be greatly reduced.
When our installer first filled the hydronic system, he added an additive that depletes the oxygen in the water and reduces the risk of corrosion and mineral deposit formation. From that point on, the closed loop system was supposed to run almost maintenance free, as long as no new water (i.e new oxygen and minerals) was added to the system.
But I did add new water. First when we filled and started up the radiators on the 1st floor, and again later when I partially drained the buffer tank to service a sensor. I did not think about the newly introduced water at the time, and it came around to nip me in the butt!
The first symptoms were the hammering and banging in the boiler. I assume what happened was that the tube diameter was decreased by mineral deposits to the point where the flow volume was so small and slow that the water turned into steam. That’s a very unnerving thought!
The boiler has an amazing array of safety sensors and mechanisms. It recognized the dangerously high temperature in the heat exchanger and automatically shut off.
That is good for safety, but it is not good for maintaining domestic hot water and keeping the radiators running.
This winter, we have being using our minisplit as our primary heating source. It is rated to provide heating down to an outside temperature of -5 degrees Fahrenheit (-20.5 degrees Celsius).
But once we were railroaded by the Siberian express and temperatures dropped below -5 degrees Fahrenheit on January 29th, I turned the minisplit off and fired up the boiler to power our radiant heating system.
Even though everything seemed to be humming along just fine, I heeded the recommendation by the City of Chicago to proactively check on the mechanical systems. It held the promise of soothing my nervousness that arose from the record cold temperatures that remained below (and sometimes far below) 0 degree Fahrenheit (-17 Celcius) for 49 straight hours.
That’s how I discovered that our Trinity LX 150 boiler must have shut down sometime during night #2 of our polar vortex. Because of the insulation, our building takes a long time to cool down, and it may have been another half a day before we noticed that the heat was off.
One of the safety features on our boiler is a combustion sensor, which jumped into action because it detected insufficient airflow into the combustion chamber (see image above).
Outside I found some ice build-up on the exhaust, which is expected because of the water vapor that is in the exhaust. What I did not expect was to find that the air intake pipe had frozen up. It is a little hard to see, but you may be able to make it out in the image below.
That ice build up literally choked our boiler and shut it down.
I whipped the hair dryer out to warm up the pipe and melt the ice, which was a completely futile exercise at -20 degrees Fahrenheit (-29 degrees Celsius). I didn’t even get the ice on the pipe to melt, let alone the ice in the pipe!
Cathy had a better idea and handed me our heating pad, a towel, and a bungee. That did the job within a few minutes, and the relatively thin ice block in the pipe collapsed so I could scrape it out.
Hunting for the cause
With the boiler up and running again, I started to search for the probable cause of the ice blockage, and was handed a “duh” moment.
The wind blew the exhaust loaded with water vapor across the fresh air intake, where it froze up. Cathy pointed out that this installation (having the exhaust blow across the intake) did not make any sense. I checked with the installation manual, and she was right!
The recommendation is a minimum 18 inches vertical separation between exhaust and intake. I used a short piece of PVC pipe and duct tape for a quick fix.
And it makes perfect sense, because the hot exhaust fumes tend to rise up fairly quickly. Having the air intake at least 18 inches lower almost eliminates the risk of exhaust fumes being sucked back into the boiler. I just have to come back and make this fix permanent.
What really bothers me is that I had assumed from the time the boiler was installed that the exhaust and air intake met the manufacturers recommendations. God knows how many times I had the boiler run inefficiently because southerly winds blew the exhaust right across the air intake!
It’s that fine line: Do you micro-manage installations by your contractors, or do you trust that they know how to do things right?
We pulled all the wires, but I was still left with a messy spaghetti bowl at the breaker panel. What looked like a bad hair day needed some serious combing.
Percy, our electrician, was an excellent mentor, so I got a shot at untangling the wires and connecting them to the breakers and bus bar.
Two elements made this task straightforward:
Have a plan
Before we started with the electrical installation, we had laid out the number of circuits we need across the apartment, which also helped us to plan the home runs from the breaker panel.
Having a good wire labeling strategy was more than half the battle. It eliminated the guesswork on what wire to connect to which breaker. It also allowed us to trace wires from the breaker panel back to the point of use.
If done correctly, wiring the breaker panel can substantially help with EMF (Electric and Magnetic Fields) management. The key is to run the hot and neutral wire of a circuit next to each other for as long as possible. I accomplished that by connecting the neutral wire to the bus port closest to the breaker. You can read more about this best practice and EMF in one of my previous posts.