Can I run my boiler with all radiators closed on main level with only pipes heating in basement?

sneilsen08 · November 21

we have a very old boiler system (100 yr old boiler still in perfect shape!) with steam radiators on the main level of the home and exposed radiator pipes in the basement. We are getting a furnace that will heat the main floor of the home as well as a new addition. Can I put a thermostat downstairs to control the boiler with all the radiators closed upstairs so the exposed pipes can heat the basement? Or do I need to leave one or more open upstairs?
Is there possible damage to the system if I leave them closed for a long period of time?

EBEBRATT-Ed · November 21

You can try. The old radiator valves may not hold tight so if any rads start banging you will have to open them up or disconnect and cap the pipe. The boiler will be oversized for just the basement and will probably build steam pressure so keep an eye on that. You may have to adjust the pressure control.

It's not going to be very efficient to run a large boiler for a small load.

Jamie Hall · November 22

Well,. as @EBEBRATT-Ed says, yes you can. It will be wildly inefficient since the boiler will be extremely oversized for the load it is powering.

May I ask why you don't want the steam to continue heating the first floor?

sneilsen08 · November 22

we are adding 700sq ft onto our home and putting in furnace/ AC into the addition as well as the main level of our home but don’t want to have to lower the basement ceiling to put duct work in the basement and get rid of boiler. Confusing but basically we need to heat our addition and can’t find anyone to add radiators to our system so our choice was furnace. And we wanted AC through the whole house which we currently don’t have.

ethicalpaul · November 22

it would be ludicrous to heat only the basement with a 100 year old boiler sized to heat a whole house.

Sorry for the direct language but this is a no brainer

Jamie Hall · November 22

I'll be even more blunt that @ethicalpaul . You have been given very bad advice, most likely from a very plausible salesperson.

I dare say that it's too late now—but you would have been much better served, for a good deal less money, to install a heat pump for your addition, with ducting to provide both heat and cooling to the rest of the building in what are called the "shoulder" seasons when a heat pump can provide heat for considerably less energy use and hence operating cost than a furnace, and to maintain the steam for the coldest times of the year when it is more economical.

Which leaves the question of how to heat the basement. Doing it with the existing boiler and the steam mains alone will be astonishingly expensive, as well as quite unsatisfactory (although you won't actually damage anything). You don't mention the fuel for your new furnace, but I'd imagine natural gas (I hope…). If that is the case, or even if it is LP (very expensive, but works) your best bet is going to be to install a small boiler to provide hot water heat for baseboard or panel radiators in the basement.

Can I run my boiler with all radiators closed on main level with only pipes heating in basement?

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