A Leaky Ceiling, Huh?

Back in April 2024, I wrote a PHC News column titled “The (Mechanical) Middle Class is Dying” (https://bit.ly/3DhLXmg). The column referenced a boiler installation at a high-end residence that I walked away from because the customer found a cheaper bid.

Do you think that was the last time I heard from the homeowner? No. It was not.

Little more than a year later, he called me to fix the new system — the one that was “cheaper.”

To set the scene, this is a two-story, 100-plus-year-old farmhouse. It’s poorly insulated with bad windows, a rubble foundation and an ancient masonry chimney. The boiler is in the basement, and the entire home is served by a single zone of high-mass, cast-iron radiation. Yes, every radiator in the home is part of a basic single-series loop. No fancy two-pipe, reverse-return, monoflow or venturi system here! Who needs closely spaced tees, anyway?

My son, Richard, and I arrived at the site to find that the handyman who provided the cheaper bid had converted the existing oil system to propane. The LP-fired boiler was certainly new and shiny. Alarm bells rang in my head when I saw that the unit was a conventional, atmospheric boiler.

The year before, we had planned to install a condensing boiler because the owner didn’t want to spend money to break the radiation into several small zones. We knew that a condensing boiler would be unaffected by the (very) low return water temperature coming back from the giant single zone.

We tested the supply and return water temperatures and found a 30-degree delta-T in April.

The massive, bugling, stamping elephant in the room, however, was the fact that “water” was leaking through the plaster of the second-story ceiling. After further inspection, it turns out that the atmospheric boiler was condensing so much that it interfered with the atmospheric boiler’s draft. To make matters worse, the old masonry chimney had never been properly lined during the low-budget oil-to-LP conversion. 

Combustion gases traveled slowly up the chimney and condensed on its interior surface as the chimney passed through the attic. It had nowhere to go but through the old mortar joints and down. Condensate began pooling above the second-story ceiling and, eventually, through the plaster and into the house.

We also knew — from previous experience at the house — that the home’s well water was extremely high in iron with a low pH. That explained the owner’s complaint about replacing water heaters every few years. 

A blank slate

The owner asked us to “fix” the system. I told him nicely that I wouldn’t touch it unless we tore the boiler out and started with a blank slate. I can’t assume the liability that someone else created.

We completed the evaluation and provided an estimate to install a condensing boiler. That estimate included water treatment and magnetic separation, both of which would be critical for the health of the new hydronic system going forward. This time, our bid was accepted.

We installed a K2 boiler in October of last year. Again, due to cost, the owner did not want us to break the single large zone into multiple smaller zones. That said, with a condensing boiler, it was no longer a mechanical concern; it was a comfort consideration.

After tearing out the old boiler and abandoning the chimney, we thoroughly flushed the radiators and piping.

Next, we looked at ways to balance the temperature across the radiators to whatever degree we could without completely repiping them. To begin, a three-speed circulator was installed as the system pump. This moves water through the radiators more quickly than the undersized single-speed pump that had been installed during the recent retrofit. By pumping faster, system fluid reaches the last few radiators on the loop before losing too much thermal energy. 

We also reversed the original direction of water flow. Water used to go from the boiler to radiators on the south side of the home, passing through the north side radiators right before returning to the boiler. The north side typically needs more heat than the south, so by changing directions, we improved comfort. There was only so much we could do without rezoning. This was a nice little trick.

To ensure that the aggressive well water couldn’t continue harming the system, we installed two magnetic separators: one on the return side of the boiler and one on the main loop. A three-gallon Axiom system feeder isolates the boiler system from the poor-quality well water. Adey MC1 heating system protector was added to the system’s 80-gallon water volume to halt further corrosion.

Richard and his team used Centrotherm polypropylene flue pipe to sidewall-vent the 100 MBH high-efficiency boiler. They also added stub-outs for the eventual addition of an indirect-fired water heater. This wasn’t installed at the time because the homeowner thought it best to leave the existing electric tank in place until it failed. 

Because heating season was ramping up during the time of the retrofit, we installed the entire new system in parallel with the existing boiler. Once it was all piped, we switched heat sources in a single day. 

We now have a 15-degree delta-T across the radiation, meaning that the radiators maintain much more consistent temps from one end of the loop to the other. If I was a betting man, I’d wager that the customer will hire us later to break new zones out, at which point we can broaden the delta.

Homeowner looking at deeper energy savings

A few months after the project, the homeowner called to say that the comfort in the home was much improved, and the new system used a lot less propane than the other boiler had the previous winter. He’d also read about air-to-water heat pumps and asked if a hydronic heat pump would be suitable for his heating system.

In his words, the cost of electricity fluctuates less than LP, so he wanted to explore the possibility of a heat pump. 

Richard and I explained that the above-average heat loss of his home would mean that the heat pump would be an advantage during the shoulder seasons and milder winter days, and the boiler would run on colder days. That said, southeast Pennsylvania has pretty mild winters, and he already had a condensing boiler, so a dual-fuel system would work well if he wanted a heat pump.

After considering it, he hired us to add a heat pump to the new boiler system. We chose a five-ton Ambient air-to-water heat pump, which can supply up to 140-degree water and continue operating down to an outdoor temperature of -13 degrees. That supply water temperature is adequate, but we suggested that if a heat pump was added, the radiators should be broken into at least two zones. 

The heat pump is now in place and the dual-fuel control provided with the heat pump is hung on the wall, but we’re waiting for the weather to warm up before piping the heat pump to the existing boiler system. 

I expect that next winter, we’ll get another call from the owner to tell us about even deeper energy savings.