Balancing system to help out an uninsulated room?

bipbap

We have a one-pipe steam system and there is one radiator on the top floor that just doesn't do the job for the room. It does heat up properly, but that room has very poor insulation (if any) so while the rest of the building gets to about the 70 degree thermostat setting, that room is still hanging out in the mid-50s.
So it's not really the radiator's fault that it can't keep the room warm.
Short of insulating the whole space and new windows, is there any way to adjust/balance the system to help this issue?
We have good main venting already if that's helpful to know.
Thanks for any ideas.

BobC

Seal up any air leaks at the floor, ceiling and and door to help stop heat from escaping

If the radiator is on a exterior wall or a wall that is shared with an unheated space try putting a shield between the wall and the radiator. That will cut the amount of heat being sucked out of the room. Try putting a fan or two underneath the radiator to get more heat out of that radiator, the fans should be thermostatically controlled so they only run when the radiator is hot.

Bob

bipbap

Ok I’ve tried some of those except for the fan.
Any ideas of venting or changes to the system which could be altered to help?

mikeg2015

Find the room that gets warmest and put a smaller vent on it or a cover on it. Just some pieces of sheet metal under the sections to reduce airflow might make a difference.

Or increase vent size on this one. But warning, venting radiators too fast can cause some weird imbalances.

Best solution it looking at overall balance and possible venting all but the coldest rooms slower. It’s a slow methodical process. Took me a a month and a hundred vent changes later of trial and error.


Is this radiator fed near the end of the main? If so, you may need to vent the main faster. Are radiators at the start of the main get hot a lot faster? If so you need to vent the main quicker.

Jamie Hall

A heating system, particularly a steam heating system, is a system. Not a collection of parts flying in close formation. If the heat load in one room (such as the one in question here) is seriously out of balance with the heat input to the room (the radiator) when compared with the rest of the building, it's almost impossible to fix (that is to say, if the rest of the house has radiators sized to make things comfy at 10 below, and this room has a radiator which can't keep up at 32, for example).

Bottom line: a radiator better matched to the heat loss of the room, or fix the room so the heat loss is better matched to the radiator.

PMJ

I don't think a bigger radiator really fixes the problem of one room with dramatically different insulation characteristics than all the others. A bigger radiator might more than cover the heat loss when it is heating, but the way these systems are run today there are long off periods between runs. An uninsulated room will see it's temperature drop must faster than the others when the radiator isn't doing anything - which ends up being a lot of the time. So unless you overshoot the target considerably each cycle, the average temperature in that room is going to be lower than the others. The temperature swings are going to be greater than the others no matter what you do.

Now, if you install a bigger radiator and spread all the runs out over many more cycles things will improve considerably. Vacuum would improve it even more.

On the other hand, if the system were coal fired and radiators continuously heating, the bigger radiator would actually work quite well.

nicholas bonham-carter

Remember that the pipe size may not be big enough for a larger radiator.
I also vote for checking the main venting. It should be allowing the air to escape at less than 2 ounces of back pressure.
That way, the steam will rise into all the rads at the same time.
Thermostat location may have an effect as well.—NBC

PMJ

This is where the lost art of vacuum used to help out considerably. The pipe may be too small to make use of a larger radiator with steam being delivered in pressure conditions. In vacuum, however, that radiator being in a colder area will end up commanding a significantly bigger share of the total steam produced - even with that small pipe.

bipbap

FWIW, The radiator in question is actually a pretty big one- maybe 13 fins wide- and probably already the biggest size in the whole building.

PMJ

bipbap said:

FWIW, The radiator in question is actually a pretty big one- maybe 13 fins wide- and probably already the biggest size in the whole building.

Does that rad ever fill enough to close the vent? I'm guessing not. In that case I suggest trying to just use a check valve there instead of the vent and let that rad go into vacuum in the off cycle. It will continue to pull steam from the main then while no other ones will. You can get some additional balancing that way. You will need one with really low cracking pressure - perhaps one of the ones others here say they removed the spring inside.

gfrbrookline

What vent do you have on the radiator. If you don't already have it I would put a Gorton C or even a D to heat it up fast. You will never overcome the cooling effect unless you insulate the room.

bipbap

Yeah it’s got the biggest Gorton on it already.
It is capable of fully heating up and getting the room somewhat decent, but as some suggested, when it cycles off, the heat loss in that room ruins it.