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Hot Topics: Adjust old radiators

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Original Post: How do I adjust these old radiators?

OceanicEyes ̵

1; Member

My house was built in 1958 and has these old radiators for the hot water systems. The majority of the house is perfectly heated, but I have two rooms that really need to be adjusted, one room gets cold and the other gets warm. The size of radiators seems appropriate based on other rooms in the house.

Whoever gets cold just doesn't feel as hot as the others and the hot one feels warmer than the others so I feel there should be some way to adjust them. I was really expecting to find some kind of bud when I removed the panel, but look and see that there are no buds. I have attached several pictures, two on the right side, two on the left and the whole thing. I appreciate all the help.

 old radiator

 old radiator control

 old radiator foil and controller

 old radiator left side panels and controls

 old radiator controls left side

mockup Member


What you have called convectors and generally there are no adjustment knobs.

Since the lids are off, you can feel the pipes for the difference in water temperature between the hot and the cold. Feel the tube to the right (without the silver air valve) and the one to the left which is the return to the boiler. If the supply is warm but the return is cool or cooler, it may need to be drained by the silver air valve. There is a screw or nut on the top that you release to let air out until a stream of water comes out and close it and see if the convector heats all the way again.

Any debris or dust in the fins will inhibit air flow which gives less heat. How these work is that air comes in from the bottom, over the coils and from the outside so that anything that blocks the air flow decreases with your heat supply.

The water temp should be about the same through all units so they should all heat the same. Walk around and feel the pipes that go to the units for all temporary wiring.

Hope this helps a bit.

Andrew Member

For the "too hot" convector, if there are no control valves under the floor, one thing you can try is to place a carton over part of the coil to partially block airflow.

beelzebob Member

Do you have an installation with one or two pipelines? In a single pipe, both ends of the heater, the source and the return, are connected to the same pipe. In a double tube, one end of the heater is connected to a source pipe and the other end of the heater is connected to a return. The installation can best be seen in the basement.

tomf63 Member

They definitely need a good vacuum to help with their heat output. I would probably do them all considering their age. As suggested, cover an area with fins in the room that is too hot, I would use aluminum foil over cardboard, but it's just me trying to soak the unit that is cooler.

gilmorrie Member [19659005] My Crane cast iron baseboards (aka convectors) are 1951 vintage on a monoflo hot water system. The units in the bedrooms have adjustment valves. Ground valves can be installed, possibly in the basement, by a plumber for units that go too hot. For units that are too cold, check for air blocking suggested by Spott.

 an old radiator ventilation

OceanicEyes Thread Starter [19659005] It is a single pipe system. There's definitely no air stuffing on the cold, it's the one I photographed (after vacuum, lol). I will try to bleed the cold unit. Should the system be on or off when I try to bleed it? It does not matter?

Grady Forum Topic Moderator

I prefer to bleed when the system is running. For those who are too hot, I prefer to use hard aluminum foil to wrap some of the found area. It takes some trial & error to get the amount covered correctly.

beelzebob Member

You experience the classic disadvantage of a pipe system. The first cooler in the loop gets the hottest water while the last cooler in the loop gets the coldest water. Measures such as wrapping the fins, flow control installation, etc. Can help but it does not solve the problem. In my opinion and if there is access to the pipeline. the best solution is to split the loop into two loops.

OceanicEyes Thread Starter

I appreciate the help. Thanks everyone.

doughess Member

Mid 1957 a pipe system has the same enclosed elements as those in OceanicEyes images and is fed from below with monoflow / venturi tee's

in this system all elements are air traps and the solution is Watts auto valves. After replacing the manual ventilation openings on elements in pictures with Watts, my system works well.

I eventually divided the system into zones so that the area was only heated when it was occupied. Not because of lack of heat problems. Now in the morning, only the kitchen is heated, not the living room or dining room.

Here is my latest post on the system.

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