I an new to this group and am writing to ask for some input to assist me in deciding whether or not to replace my existing boiler. Each spring I think about this, but haven't done anything yet. I'd hate to be without heat due to a winter failure, but I'd not like to discard a boiler if it is expected to last longer. My wife and do not know how long we will remain at this house. Our guess is it will be about 5 or 10 years until we're too old to maintain it and have to go.
My background experience is that I'm a master electrician by trade (Industrial & commercial is my only experience- I never could learn residential. Those guys work magic! ).
I got lucky- the company I worked at assigned me to work in tandem with some of the heating, cooling, pipe fitting & plumbing tradespeople for many years. I learned quite a bit about hydronics and refrigeration during that time. We were fortunate that we could actually work together and we each learned from, and sometimes apprenticed to, the other. I learned enough to get a mechanical contractor's license and a plumbing journeyman's card. But, I have not practiced in those fields for over 10 years, so my knowledge is fading fast. (As is everything else at my age...)
I apologize that the post is going to be long, but I thought it wise to provide as many system & equipment details as possible.
What I Have At My House-
I have a hydronic system with one pump on the return and 3 zone valves on the supply manifold. The house has a mix of fin tube baseboard radiation units and cast iron radiators. Each zone valve is a Honeywell motorized valve with end switches. The control is by a zone valve controller I built many years ago. Basically, the end switch closes and this allows the burner and pump to operate- assuming safeties are satisfied.
The boiler is a Bryant Model 26 cast iron sectional boiler from the early to mid 1950's (per Bryant). It is natural gas fired.
Years ago, when I called Bryant, the technician told me that boiler operates at 80% to 82% efficiency when new. (Amazing, if true)
It has a Thermiser on the 6" vent. It vents into a masonry chimney with a clay tile liner. (And shares with a water heater.)
The Radiation piping is a mix of original galvanized and type L copper tubing. There is some HePEX where I've added or moved radiation over the hears.
The house is from the late 1890's, but the basement was added in 1952. There are two additions- one from the 20's & one from the 40's. Based on clues from the monoflow tees and a few other parts, I believe this heating system was built in the 1950's.
Modifications I Did When I Bought The House About 35 Years Ago-
The boiler's gas system didn't have any pilot safety. If the pilot went out, gas was allowed to flow on a call for heat.
I installed a baso valve with an 24 volt gas valve after it. I also installed a new pilot burner & thermocouple as part of the project. I also made & installed a few baffle plates that lay on top of the heat exchanger between sections. Some were missing.
Additionally, I installed a flame roll-out safety in the boiler's jacket, just outside the burner area and a high water temperature cutoff. There is a carbon monoxide detector above the unit as well. There is a separate temperature control which starts the pump when the water reaches 110-F. (I probably didn't need to install this.)
I also put in a bladder type expansion tank to replace the original horizontal tank, as well as a low water cut-off device.
The system uses a Spirovent (installed about 12 years ago) for air removal, along with individual coin vents and Maid-O-Mist style vents on the upright radiators.
Basically, everything about the boiler- except the actual heat exchanger, the boiler's jacket & its burner are no longer original equipment.
The only problems I've encountered since I made stuff safe is once I replaced the thermocouple and one zone valve motor.
Every year I take the top off of the boiler and clean the sections with the long wire brushes. The furnace cement around the perimeter is inspected, but never cracked. I also vacuum everything in sight & check the flame for proper combustion. I can't think of anything else to maintain.
I keep the system water treated with sodium molybdate at 150 ppm. (GE Corroshield)
Since the boiler is cast iron and the controls are all newer, would it be wise to replace this boiler during the off-season, or do these boilers actually last a very long time?
I've read that cast iron boilers have a life expectancy of 10 years, 20 years, 30 years and forever. So my research do date is quite inconclusive.
If I Keep The Boiler-
Would it harm the system to change to an electronic spark ignition, or does the pilot have to stay burning all summer to protect the cast iron?
Assuming I convert to spark, would it be OK to remove the Thermiser and put in a vent damper, tied to the controls so the boiler can't fire unless the damper is proven open? (I tried to find a link to explain what a Thermniser is , but came up empty. A Thermiser is basically a box with a flap in it. The flap has a hole that is smaller than the vent diameter. The idea is that it keeps the heat in the vent longer, thus saving energy. If there is an explosion, the flap will open- allegedly open...)
If I Replace The Boiler-
Ideally I'd like to use a more efficient & probably lighter weight (wall hung?) boiler, or any efficient unit, which invokes a direct vent type.
Longevity concerns me: I remember many years ago installing various brand fin tube boilers and some Hydropulse boilers at work. These were used for indirect domestic water heating. Those would usually fail in 5 or 6 years, but I'd assume the products have improved. You all know more than I ever will about longevity.
Part Two is that venting a direct vent boiler will be a challenge.
On the boiler side of the basement, the rooms above cantilever 2 feet past the foundation. If I exit there, the exhaust would run under the overhang and terminate on a patio and right behind the condensing unit for the air conditioning and at the intersection of another wall. Air intake will also be a problem because the dryer vent is within 10 feet of that wall. (There's no where to move that & stay within the manufacturer's maximum length mandates.)
The basement wall on the other side of the heating plant adjoins a 12 foot wide crawl space, so I don't think I can run a vent that long, through the crawl space & out.
And, of course, there is no floor drain nearby for condensate, although I think could use a condensate pump if they are allowed.
Assuming they fit, I am wondering if a high efficiency boiler can vent into the existing masonry chimney if I put 2 liners in? One will be for the water heater & one for the boiler. The liner is 12 x 9 tile. If that's not an option, I'd go with a natural draft unit.
Thank You all for your advice on whether or not to replace a functioning boiler.
Your advice & guidance is certainly appreciated.
Enjoy This Day!