Radiator vs. A/C: Whichever wins, we lose.
May 24, 2016 7:33 PM   Subscribe

The radiators in our new home are going rogue and destroying our attempts at using A/C. How do we turn off our radiators for the season?

We moved into a house in March that was built in the early 1930s. The owner in 2009 installed central air for A/C and kept the existing radiators for heating. The radiators are gas with electric ignition and are recessed into the wall with a cover that is flush with the wall so we don't have easy access to the individual units.

We've never had radiators before and are having trouble figuring out how to control them. They don't seem to be controlled by our Honeywell wall thermostat, which is currently set to "Cool" so the A/C can counter this week's 80 degree temps. In fact, the radiator system seems to view our attempts to cool the house as a challenge and kicks in to counter the cool air from open windows on nice days and A/C on the muggy days. It's not on at all times, it only starts up when there is flow of cool air in the house.

How does one usually go about turning on and off their radiators?
posted by Luminiferous Ether to Home & Garden (8 answers total) 1 user marked this as a favorite
radiators transfer heat by running either hot water or steam through them. you most likely have a gas furnace/boiler in the basement heating water that's pushed through bunch of pipes running up into the walls with radiators in them.

if it's kicking off and on that means you have a separate thermostat somewhere connected to your boiler. you'll be able to either turn it off at the thermostat or the boiler.
posted by noloveforned at 7:47 PM on May 24, 2016 [1 favorite]

There is very likely a switch near your boiler in the basement that will turn it off completely. No harm in doing that if you can't find the thermostat that controls the boiler (which, yes, there is likely a separate one).
posted by ssg at 8:20 PM on May 24, 2016

Can you tell us more about your radiators? Are they set up to be individual units? You say that they're "gas with electric ignition," but is there a central furnace (which would be the standard setup) or are they stand-alone units (which would be unusual)?

How did you set the temperature the house should warm to during March & April? Was it using the same thermostat you're using now?
posted by Betelgeuse at 7:17 AM on May 25, 2016

You are getting answers from people in real cold weather regions (I am too) where heat is always centrally controlled. But, it sounds like you may be in a borderline region where you have individual gas wall burners strategically placed to warm things up. In that case each one has a control hidden under the cover. You will have to remove it to get at it. Some pictures would help you get more useful answers.
posted by no1hatchling at 12:44 PM on May 25, 2016

Response by poster: Here are some hopefully helpful pictures. First, our boiler and hot water heater system (Honeywell aquastat obscured by copper pipe). Second, a drawing of what the radiator looks like behind its wall cover. Third, a picture of one of the many radiators that are behind covers. More info: we just noticed this was a problem yesterday after we set the AC on and then left for 7 hours. When we returned to the house the radiators that were closest to the AC-blowing vents were very hot and fighting the AC.

A couple hours ago we tried turning a valve to prevent water from getting into the radiator: it seemed to work but then we lost all water upstairs so we turned that valve back on. Right now we cannot be sure how long it takes for the radiators to activate (it seems to take longer than two hours).

noloveforned, there is an aquastat back there in the basement. How do we know if that's just for the radiator system or for all our hot water? And if it is just for the radiators, it looks like a pretty common Honeywell aquastat, how do we adjust it or turn it off?

ssg, there is indeed a lightswitch that has sign taped over it that says "FURNACE IGNITION - LEAVE ON." I had assumed that was for all the things the furnace does and not just the radiators.

Betelgeuse, the radiators are old. Possibly from the early 1930s. They're recessed into the wall. My wife and I haven't been able to find any pictures of radiators that look similar to how ours do behind their covers. They were blasting when we toured the house and during the inspection (25 degrees outside, 74 inside). When we moved in it was warm enough that we turned the thermostat upstairs to the "off" position and haven't had it on "heat" since, but evidently that had nothing to do with whether the radiators would kick in automatically. We live in the middle of the East Coast and the weather has neither been tremendously cold or hot since we moved in.

"Gas with electric ignition" was the description of our "heating fuel type" in the home inspection. Besides the fact that our home has radiators, nothing else was written about it. I was told to bleed the radiators if they weren't working properly.

No1hatchling, as far as we can tell everything is centrally located though the radiators seem to work more if they're getting blasted with cold air.

Thanks for all your help everyone!
posted by Luminiferous Ether at 7:45 PM on May 25, 2016

Best answer: OK, all you need to do is turn off the boiler. The boiler supplies hot water to the radiators based on a thermostat somewhere (not the aquastat, which controls the temperature of the hot water itself). If you can't find the thermostat that does this, then the easiest would be turn off that switch. I'm not clear why it would say "FURNACE IGNITION" as you don't seem to have a furnace, but it is very likely to be the right switch for the boiler. If you are worried, follow the wires coming out of this switch and see if they go anywhere other than the boiler. That hot water heater doesn't even need electricity. Alternately, you could turn off the gas to the boiler, but that would be more complicated.

You have a hot water tank to heat water and the A/C to cool. The boiler performs no other function than supplying hot water to the radiators, so there is no problem turning off the boiler until you need heat again. The radiators can possibly be adjusted individually, but that's not how you stop all heating - you turn off the boiler. I don't think the recessed radiator do anything different than normal radiators. Don't worry about the radiators.

You can follow the thin wires from the boiler to find the thermostat, if possible, or at least get a better idea where to look upstairs. You can also look on the back of the thermostat that you do have and check if there is a wire connected to the heating terminal, in which case that thermostat is probably supposed to control your boiler, but isn't for whatever reason.

So, in short, turn off the boiler from a thermostat connected to it or at the switch. Don't do anything to the radiators themselves. Don't turn off the water to anything.

You may want to get an HVAC person out to have a look at the whole system before heating season and have them explain to you how everything works.
posted by ssg at 8:37 PM on May 25, 2016

sounds like you've got your boiler turned off in one way or another... a few last things, should you still be interested-

listen to ssg's good advice about having someone come out to look at it in the fall before the winter and show you the basics. just as a heads up, a lot of HVAC people will not work on old boiler/radiator systems.

when you have the person come out, have them show you the silt trap on the boiler. basically it catches all the dirt/mud/etc and let's you flush it out. i'm heard some people do it weekly, i'm more of a monthly kind of guy.

you mention an upstairs thermostat- is your AC system in the attic? are there vents for the ac on the first floor? with older houses it's somewhat common to install separate AC for each floor of the house or just one floor of the house (quite often the second). if you don't actually have vents (or anything else pushing cool air) on the first floor, than any thermostat you find on the first floor will likely be the one for the heat.
posted by noloveforned at 11:45 AM on May 27, 2016

I'm no expert, but I would be surprised if there weren't some kind of thermostat somewhere controlling your heating system. It is possible that this is either the same or a different thermostat than the one that controls your cooling system.

So, if you're the adventurous type, I'd do what ssg suggests and follow the thin wires that go into your furnace to the place where they disappear up into the house. That may give you some sense of where to look for your heating thermostat.

If you want some help, definitely get an HVAC person out. Your system may need cleaning before the heating season starts and, in the mean time, that person should be able to show you where your thermostat is. This is important because it will allow you to control the heat better during the summer. I suppose there's some possibility that there's some weird cross-wiring in the thermostat that doesn't totally turn off the heating system when you turn your cooling system on, but these are all questions a HVAC person should be able to answer.
posted by Betelgeuse at 8:50 AM on June 1, 2016

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