I am trying to understand how to turn the heater on in our unit.

There is a thermostat on the living room wall that looks like this:

enter image description here

And there is a trapdoor below the heater in the wall looking like this (yes, it's upside down in the wall):

enter image description here

So far I have tried to turn on the [B] button, and turned the black know 1 to either "on" or "pilot" and pressed the button 2 but I'm not sure what to look out for to show whether or not I'm doing the right thing, and I'm also not trying to blow up the apartment or gas myself, so I turned everything back to "off" until I know what's what.

  • 1
    Have you verified that there isn't a closed valve outside of the fireplace? Dec 25, 2020 at 0:41

2 Answers 2


Looks like:

System "on" at B.

1 to pilot, 2 should either press or turn (and will need to be held, if it's what I think it is) and 3 should be pressed in (and will make a "clunk" sort of noise) one to three times.

There should be some place you can see the pilot light - you might need to move a flap, you might not. When you see it light, stop pressing 3 but hold 2 for (typically 30 seconds, but it varies.) If you don't see it light after a few presses of 3, or can't figure out where to look, re-evaluate.

1 is the gas valve, I believe that 2 is the over-ride that allows you to light the pilot, and what it over-rides turns off the gas if the pilot is out, and 3 appears to be a spark igniter (you may have seen them on gas barbecue grills) to light the pilot.

When the pilot has ben lit for long enough it will stay lit when 2 is released - at which point you can move 1 to "on" and proceed with heating.


I'm also not trying to blow up the apartment or gas myself, so I turned everything back to "off" until I know what's what.

The good news is, it's hard to cause any trouble with these because they're designed to be safe. Also, small amounts of unburnt gas will quickly mix into the air and be no longer concentrated enough to burn. I used to have similar worries, but advice and experience showed me that the conditions for actually burning gas are quite specific. The "blow up the apartment" case is if something leaks lots of unburnt gas into the room, usually over a long time, but the valve you've got is designed to prevent doing that by accident.

Just to get more familiar with what all the parts are, have a look at this part of your picture:

Closeup of second picture in question

  • The large pipe on the left is the pilot's gas pipe. You might be able to see the burner end of it through a hole or window to see when the pilot is lit.
  • The white wire in the middle must be the igniter, because it goes off to the separate red button on the right which has the shape of one, and doesn't connect to the valve.
  • The coppery pipe on the right is the thermocouple, or thermopile: it detects the heat of the pilot light and signals the valve, and the valve will not let the gas continue to flow if the pilot goes out, for safety. (In gas appliances which don't have an electrical hookup, a similar device might actually provide power to operate the gas valve, solely from the heat of the pilot.)

Now as to lighting it: there may well be lighting instructions in the information sticker visible on the right side of your picture. If not, or if they're unclear, here's how it might go:

  1. You usually do not need to turn the thermostat on to light a pilot light, so I'd recommend leaving it off: set the switch to "system off" (B), or turn the temperature setting (A) down, or both. That way, you can't be startled by the main burner lighting while you're working with the valve.

  2. There might be a manual gas valve on the other end of the yellow flexible pipe, wherever it goes. Make sure that valve is turned on (handle in line with the pipe).

  3. You need to get gas to flow so you can light the pilot, even though the abovementioned safety sensor doesn't see a flame. This is done by some combination of turning the knob (1) to the PILOT position and holding down the red button on the valve (2) — it looks like the button moves to the side, but I haven't personally used this style of valve to check. You might also have to push in the knob (1) to turn it. In any case, there will be something that must be held down for gas to flow (this is for safety, so it can't continue to flow unattended).

  4. You may be able to hear the gas flowing as a faint hiss. In any case, it'll take a few seconds for the gas to flow through the length of the pipe and flush out the air.

    Wait a couple seconds, then press the red button (3) firmly until it goes “snap” — this creates a spark which can ignite the pilot light. If you can see where the pilot light burns, just do this until you see the flame; if you can't see it, give it something like 10 seconds, trying every couple seconds.

    No need to frantically press the igniter — as I mentioned above, any gas that doesn't get lit will quickly dissipate and there won't be a dangerous fwoosh even if you're “late”.

  5. Now the pilot is lit, but the thermocouple will not instantly heat up enough to keep the gas valve flowing. So, keep holding down whatever you started holding down in step 2 for several more seconds. If you let go too soon, the pilot will go out and you'll have to start over.

  6. Once the pilot is lit, turn the knob (2) from the PILOT position to ON. The heater should now be controllable from the thermostat.

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