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Strange Radiator Problem

Hi, I have radiant heating system that has been acting strangely this year. I have been living in my house for 5 years and this is the first year that there is a distinct temperature difference between the main & 2nd floors, about 3 Degrees celsius difference. We have an old cast iron system that was installed in the 1920s with the boiler located in the basement and it was replaced in 2003, 2 years ago we renovated the basement and installed 2 new style radiators to replace the electric heating down there, which the boiler has the capacity for and these worked fine for a year. We also have the original expansion tank that was installed in the 1920s, however every single valve in the system is seized open as long as I've been here, except the fill valve and one which I replaced 3 years ago because it cracked (Power outage caused it to freeze). I have been draining, refilling & bleeding the entire system each year since we moved in and every spring I drain it the water that comes out is black, however all the rads heat evenly top to bottom so I don't think there is a massive build-up of sediment. I am wondering why all of a sudden this year the 2nd floor is much colder than the main floor, the rads on the 2nd floor get warm, but not hot like the ones on the main floor. I am wondering do I need to do an overhaul on this system next summer? (replace all the stuck valves, flush the pipes & rads, clean the pump out) Do I have an airlock somewhere? Unfortunately every technician I've had come in is fundamentally useless and just messes around in the basement for an hour or two then says I need various different unnecessary repairs and proceeds to leave the system in pieces which I have to put back together myself so I have heat, the last technician completely unhooked all the circuitry and said I needed to call an electrician. I have lots of experience with electrical & plumbing and can perform almost all maintenance tasks as long as they don't involve touching gas lines. Any help, thoughts or insight would be greatly appreciated.


  • vibert_c
    vibert_c Member Posts: 69
    Gidday @nick_TD Welcome to this forum.
    Reading your posting brings a smile to my face when I remember the story of the lass that telephone the local plumber and said "I have got a leak in my basement". He replied "go ahead madam, Its your basemenet"

    Are you savvy enough to post pictures of the new radiators you installed in the basement as well as a picture of the boiler and the overhead expansion tank. Without these pictures, I am at a loss to realize how your system is configured.

    To drain the system every spring for five years allows oxygen into the system with the fresh water causing "rust" just to look at the black water? The black water is as efficient as the clear water at transferring heat. If it takes a year to get the oxygen out of the system, it is not prudent to allow it back in for no "good" reason.

    Did one of the usless service guys install a circulating pump on your old gravity system by chance?

    I get the feeling that you might reside in Montreal; am I correct?

  • unclejohn
    unclejohn Member Posts: 1,833
    Pictures a must and pressure and temp readings and stop draing and filling system.
  • nick_TD
    nick_TD Member Posts: 2
    Sorry I'm currently out of town and this is what I could find on my laptop, I hope it helps. These pictures were taken when the system was drained for installing the new radiators, so the pressure reading was 0. It usually likes to sit around 17-20 PSI, only ever seen it go higher than that when we get our -20º weather with a wind chill and the system is basically hot all the time.

    Here is one of the old cast iron radiators

    Here is one of the new radiators in the basement.

    Here is the boiler off to the left with the expansion tank in the ceiling

    Here is the piping just above the boiler, the pump is behind the boiler on the return (Down arrow) pipe just before it goes inside pumping water through the boiler. The blue circle is a leak I had for a while when I first moved in, only to find out that there was no solder on that joint.

    Here is the pump behind the boiler.

    From my understanding the pump was installed the same time the boiler was installed (2003), unfortunately because the valve on the expansion tank is seized I have to drain the whole system to drain off the tank, and I simply haven't gotten around to replacing that valve yet, I am hoping to do that this summer. I am in downtown Toronto where almost every house (at least in my area) has been renovated with either forced air or subfloor radiant heating. There was one tech who I had come in the first year we moved in who was fantastic and understood the system quite well, but he retired and I can't find anyone who even seems like they've seen a system like this before, which I though would be easy living in a big city.