Closing Radiators

Mike T., Swampeast MO

Assuming the heating system is original to the house, it most likely operated via gravity circulation. The easiest way to tell a gravity system is the size of the pipes near the boiler. With three originally heated floors you'll probably see four HUGE pipes nearly the size of sewer lines that gradually get smaller as they work their way around the basement.

If so, the heat via gravity circulation naturally wanted to ZOOM to the 3rd heated floor and the dead men who piped them went to extraordinary measures to balance such systems.

Presuming it was gravity and it's been converted to forced flow (you'll see a rather large circulating pump right by the boiler), everything they dead men did now has a nearly opposite effect.

The hand valves for hot water systems have a little hole that prevents them from EVER shutting off fully--under gravity you could "shut" the valve without much fear that the radiator would actually freeze... This tiny hole alone is often enough to make room temp regulation via the valve nearly impossible once the system is converted to forced flow. This is especially true for ground floor radiators which are fed by the largest branch lines in the system.

Often, a single branch riser would serve both a 2nd and 3rd floor radiator in a 3-floor gravity system. This essentially broke the rule of "each radiator in a two-pipe gravity system has its' own dedicated supply and return branches", but it was done for a reason... The smallest 2nd floor rooms--say a bath or hall--were most likely to serve the heated attic space as well. The dead men would somewhat oversize the 2nd floor radiator on such a "dual" branch because they were intentionally creating a two-temp branch with "more than its' share" of flow going to the 3rd floor. In other words they INTENTIONALLY made the 3rd floor attic radiators <I>with the greatest heat loss--the <B>essentially uninsulated</B> roof</I> hotter than 2nd floor rads served by the same branch.

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You have one and only one reasonable option: Install thermostatic radiator valves (TRVs) on the 3rd floor. Once you've found what they do, you'll likely want them everywhere...

Joshua Sunshine

Hi,
I just moved into a house built in 1930 with a hot water heating system. The boiler is in the basement and there are radiators on the first, second and finished attic level. Before I ran the system, I paid a local company to inspect the system and bleed the radiators. After the system ran for a few hours it was about 15 degrees hotter on the attic level than it was on the first floor. I tried to turn of the radiators in the attic and a few on the second floor to improve the situation which helped (the difference is down to between 4-8 degrees). The radiators I turned off on the second floor are completely cool now, but the radiators in the attic are still hot. Am I doing something wrong? Am I not turning hard enough? Do the valves need to be replaced? Is it impossible to turn the radiators off for some reason?

Thanks in advance for the help,
Josh