Gravity boiler system – stay or go?
I am getting ready to renovate a 1928 house that has a gravity boiler system. I’ll be installing central air so obviously a new furnace could replace the existing hot water heating. I like the comfort of radiant heat so I’m considering leaving the boiler and using a heat pump to handle summer cooling and spring/fall heating, then kick the boiler on when the cold weather sets in.
If any of you have experience with boilers to advise me on the PIA factor of owning and maintaining such a system I would appreciate it. Also concerned about the energy consumption. Previous owner was burning as much as 80 MCF in February. Their level-pay plan with the gas company is $390/month. Ouch.
House & boiler data: 2 story colonial, 3700 sf with minimal attic insulation and I’m guessing no wall insul. I plan to strip all the plaster and insulate the exterior walls (2×6 const), replace the original windows with insulated, low-e double hungs, and insulate the attic. The boiler is “Ideal Gas Boiler – American Radiator Company”, but I couldn’t read the rating data on the nameplate. It was 15 degrees and windy yesterday so I went over to see how balanced the heat was. Temps were even in all rooms.
Replies
" It was 15 degrees and windy yesterday so I went over to see how balanced the heat was. Temps were even in all rooms."
Thats says it all.
It adds to the overall cost, but I would replace the boilier and add the a/c system.
the folks over at heatinghelp.com will also have good advice
Thanks for the suggestion on heatinghelp.com - - I'll try to glean more info on the subject from that site. I would like to replace the existing boiler with a high efficiency boiler but depending on the cost, I may have to settle for forced air heat.
I was impressed by the comfort of the existing HW system. On such a cold day I expected to some chilly rooms - - maybe that's because I'm used to my current furnace!
My opinion, forced air is never as smooth and even as radiant. My skin is 98.6 degrees, so even 110 degree air blowing over it gives me a chill.
A very rough and ready measurement of efficiency is the temp of the flue gases.
An old boiler like that might be producing flue temps of 500 - 600 degrees.
A modern high efficiency condensing furnace (not boiler) will have flue temps of 110 - 120. (I don't see many boilers so I don't have much diret experience with them, but each degree of temp going up your flue isn't doing anything to keep the house warm.)
Is the boiler as old as the house? If it is you are wasting money trying to keep using it. Compared to a modern system you could be burning three times the fuel. Sorry for the negative.
I don't know how old the boiler is but I assume that it's at or near the end of it's useful life, thus here's the alternatives I see:
1. Replace the old boiler with new high efficiency. Plus add central air conditioning.
2. Demo the boiler, pipes, radiators and brick chimney. Use the 20"x20" chimney space as a chase to run new ductwork to the 2nd floor. Add central air with A/C & FAG heat.
Here's another question you might be able to answer: If I end up keeping the HW system, when I drain it to replace the boiler and remove a few radiators (due to wall demo) will I get a bunch of corrosion in the pipes? I'm thinking the exposure to oxygen might cause those old pipes to oxidize pretty fast. I could see it taking a few months to get all the mods made and refill the system.
Unless the pipes are in a bad condition when you disconnect the radiators, [you will know if the pipe starts to crush] you should not have a problem. [FYI a gravity system is not the best.] The rest of the post is your call. Lots of luck.