Oil furnace - Cycle water


Old 05-21-07, 03:21 PM
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Oil furnace - Cycle water

Hello all,

I have a forced water (baseboard) oil heater which also does hot water. I need to do some work upstairs on the baseboards, and I need to drain the water and then refill it back up. How do I go about it?

Old 05-21-07, 05:42 PM
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Draining Boiler

If you can supply us with some pictures of the boiler & nearby piping, explaining the drain/refill process will be a lot easier. You can post the pictures on photobucket or similar photo sharing web site & post a link here.
Old 05-21-07, 08:49 PM
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That's not actually a boiler. It is an oil furnace for my heat that also heats the hot water. Sorry if I wasn't too clear. Anyway's here's the pictures:


Furnace again:

Baseboard upstairs:

Thanks again.
Old 05-21-07, 11:34 PM
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Yes, it is a boiler

You have your terminology incorrect. In domestic heating systems a unit that heats water to be used elsewhere in heating a home is called a boiler. If the unit heats air that is distributed by ductwork it is called a furnace.

To be REAL technical, all (fuel fired) boilers have a furnace which is the place where the fuel is burned to release heat to the water contained inside the pressure vessel. In a forced air furnace the fuel is burned and the heat is released (via a heat exchanger) to air that is delivered through the ductwork by means of a blower.

Anyway, you have a boiler and while I do see a valve on the return piping (from the baseboard heaters) I do not see a valve on the supply piping. This means that you will have to shut down the boiler and drain down your entire heating system. You will not have any hot water service while the boiler is shut down.

Turn off the switch on the front of the boiler. I strongly urge you to also turn off the circuit breaker supplying power to the boiler and tape it in the off position along with a note that the boiler is open for service.

Connect a garden hose to the drain valve on the right hand side of the boiler at the very bottom. Lead the other end of the hose to a drain.

Turn off the "make-up" water valve. This is the valve in the horizontal pipe directly above the boiler cabinet and approximately in front of the smokestack. Closed is when the yellow handle is perpendicular to the pipe.

Open the drain valve that you previously connected the hose to. You will get an immediate gush of water and then almost no water. This is because you need to let air into the piping system. Open the little key-operated vent valve on the baseboard unit and air will be sucked into the system allowing the water to drain from the boiler. You may want to CAREFULLY remove the vent valve completely to allow the air in (and the water out) faster.

You do not need to drain any more water than to have the water level below where you are going to be cutting the pipes. How to determine this is not always easy. If your house has only one story or has all the baseboard heaters on the same floor you won't need to drain as much water as you would if you have a multi-story house with heaters on all levels.

To refill, after you have finished your work, closed the drain valve, replaced the vent valve (if you removed it) and closed the vent valve with the key you will open the make-up water valve and wait. The boiler and system will fill until the cold pressure has been reached and then stop.

At this point you will need to vent the air from the baseboard units by opening the vent valves and allowing the air to escape. You will probably need to do this several times.

Now you can remove the sign and the tape from the circuit breaker, turn the breaker on, turn on the switch at the boiler and it should start the oil burner. Turn up your thermostat to start the circulator pump (it may not start until the boiler temperature comes up to a minimum temperature, perhaps 140 degrees) and then start on another round of venting the air at all of the baseboard heaters.
Old 05-22-07, 09:42 AM
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Thank you!

Great response! I'm sorry again about my limited knowledge on this matter.
Thanks again!

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