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shutting off radiators

I live in an old barn of a home (150+ years old). I have a radiator type hot water heating system. The furnace is relatively new. There are 7 radiators downstairs and 5 upstairs. The 5 upstairs are in rooms currently unused.I have to admit that I am worried about fuel oil prices for next winter. It has been suggested by members of my family that I should completely shut off the water going to my upstairs bedroom radiators using shut off valves, and that this would lower my heating costs. Can this be done and would it help?

Re: shutting off radiators


You have a boiler there and not a furnace.

The coming winter promises to be very rough for those who use oil heat, from the looks of things now---they'll have to come a break somewhere along the line--many people have oil & have no access to natural gas, which is also rising.

That said, it would be a mistake to completely shut off the upstairs rads---there's a good chance the pipes would freeze, especially the ones running along any outside walls & you'd have a real disaster on your hands.

If you have shutoff valves on the rads now, you can try partially shutting them, so that at least some water circulates thru the upstairs rads---actually, even when these specialized valves that come with the rads are shut off, there is a little 1/8" hole in the valve that allows some water to pass thru so the rads don't freeze (installing aftermarket lower-cost ball valves would eliminate this safety feature, since BV's don't have the 1/8" hole).

Another procedure is to find out the type of piping you have going up to the 2nd floor---this would be either SERIES PIPING or PARALLEL/diverter valve piping.

In SP the rads are connected one after the other--so that if one rad is shut off, they all shut off---in PP/diverter valve, there are seperate supply & return lines going to each rad, so each one can be turned off separately (see the piping diagrams at the heating help site below---click onto "loop hot water heating" and "diverter-tee hot water heating").

If you have PP/diverter valve piping you can install THERMOSTATIC RADIATOR VALVES for ~$50 for each rad--they use no electricity & have their own t-stat inside that controls the temp of each rad.

Another option is to "zone off" the upstairs & downstairs rads by having zone valves or zone circulators installed---this is a good option that may cost $400-$500 to have installed.

This is done at the boiler & would give you a wall t-stat for each floor so that you could control the temp of the floors seperately.

If you have little or no insulation in the outside walls, you could decide to spend the money, ~$400, having insulation blown into the walls & attic to improve the heat-holding ability of the house.

You didn't mention how old the boiler is--if it's older than 20 years, you might consider a new boiler---if natural gas is available in your area, it might be a good move to have a gas-fired boiler installed---a new gas-fired boiler would be much more efficient that a 20 yr old boiler & would have you see a 30% drop in the amount of fuel you use.

Some people are replacing just the oil burner part of the boiler with a gas-fired burner, if they have NG available---this would be another option--call your oil dealer & ask them to take a look at it---oil dealers are licenced to install gas-fired equipment as well.


Re: shutting off radiators

thanks for replying and the links:)
I am sorry but I did not give you enough info. I replaced the old boiler with a new 6 boiler system 7 years ago. It cut my fuel oil costs in half at the time. My rad system is parallel: shutting down the upstairs rads as much as possible last winter did not affect the downstairs rads at all. We had planned to install the shut offs in the cellar and/or where the pipes come up through the first floor, so they should not freeze as both areas are heated. we are assuming that by shutting down 5 rads, less water will be in the system, and this should save energy as the furnace will have to run less. are we correct in this assumption? If we do install the shutoff valves, do we install them on both the supply and return pipes or just one?Thanks again for your help!

Re: shutting off radiators


Only one shut-off valve is used per radiator---always on the supply (incoming) side of the radiator (there is a supply pipe and a return pipe on each radiator).

The shut-off valves are always installed right next to the radiator it controls, on the supply side---and not in the cellar or 1st floor.

This is to avoid confusion and is according to code.

How much fuel you use & how much the oil burner consumes is actually controlled by the thermostat (and where in the house it is placed)

I assume you have one t-stat & it is placed on the 1st floor, with no t-stat on the 2nd floor.

The t-stat acts like an on/off switch---when the temp falls below a certain value, the t-stat closes, closing a circuit that turns on the oil burner flame & activates the circulator pump.

These components will keep going until the t-stat is satisfied & opens, closing down the boiler.

The boiler will circulate & heat the cold water sitting in the rads to 180 degrees & keep circulating it---if the upper floor 5 rads are shut off, the t-stat will be satisfied more quickly & shut down, so you would save some money on fuel---but there is still a danger of the stagnant water freezing.

Stagnant water also has the tendency to encourage the accumulation of iron oxide sludge in the non-circulating rads, and calcium & other deposits if you have hard water--this can cause circulation problems in the stagnant part of the system when you finally re-open the 5 rads.

You might get away with it without a freezup, but I would strongly recommend a zone system in this case instead of the plan you have in mind.

With a zone system, you could have the upstairs temp constantly set at 50 degrees, which would afford you good fuel savings.

Re: shutting off radiators

Thanks so much for your input! It was greatly appreciated:)

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