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gslittleus · May 3, 2007, 12:20 PM

I have a Burnham V8 Series oil-fired boiler and two ADP multi-position air handlers, one in the basement and one in the attic. All the units are approximately six years old. The boiler/air handler combo in the basement works fine, but the attic air handler is not producing warm air.

The boiler and attic air handler both turn on and off accurately as I adjust the 2nd-floor thermostat up and down, yet it appears that hot water is not being sent from the boiler to the attic air handler as per the following.. . One of the copper hot water pipes leading from the boiler to an air handler does NOT get too hot to touch when I crank up the 2nd-floor thermostat to activate the boiler and air handler. The other hot water pipe (presumably from the boiler to the basement air handler) DOES get too hot to touch, and that air handler produces hot air. Further, the thick vinyl hot water tubes running into the attic air handler also don't get hot.

I've tried turning the air handler and boiler off and on with the toggle switches located on each unit, but that hasn't helped. I'm stuck after that.

Can anyone help me with a diagnosis and required action?

Thanks very much,

hvac1000 · May 3, 2007, 01:16 PM

There is a water valve called a zone valve on your units. The valve may not be opening to allow the water to flow. Usually this is a 24 volt vakve that is controlled by the thermostat for that area. You need to check the valve to see if it is getting 24 volts. If not then the thermost and connecting wiring will need to be checked.

You could also have lost some water out of the boiler not allowing it to have enough head to reach the upstairs coil.

There could be air in the lines going to the upstairs unit.

These are just three ideas it could be other things.

JackT · May 3, 2007, 01:23 PM

There should be some kind of device that controls the water flow to the upstairs air handler. It should have it's own circulator pump or a small zone valve. Have you heard any air circulating through the system? Is there a automatic water fill device for the boiler and is it working? If your system is low on water, the upstairs unit will be the first one to stop working. Some of the automatic filler valves also have screens in them that may need cleaning.

gslittleus · May 3, 2007, 06:16 PM

Thank you for your ideas. Regarding checking the valve to see if it's getting 24 volts, I'll have to leave that to a professional. I haven't heard any air going through the system. We just bought this house, and it was empty through the winter, so it was "winterized". I'm speaking to that company tomorrow to find out what they did to "winterize" it and if they did anything to the boiler. How can I as a layman determine if there is insufficient water in the system (or is that best left to a professional also)?

Thanks again, gentlemen.

JackT · May 3, 2007, 07:29 PM

There should be a pressure gage on the boiler that will indicate what the pressure is in the system. Sometimes they aren't to accurate, It's possible they shut the water off to the boiler and drained it for the winter. If the heat was off all winter, they even drained it or added chemicals to prevent it from freezing. You should check with the company who winterized it for you.

gslittleus · May 4, 2007, 08:21 AM

The gauge reads 28psi and the boiler is rated at 30 psi MAWP (maximum average water pressure, I assume). Would that indicate that it ISN'T a low water situation? Also, the heat wasn't off for the winter because the house was being shown to prospective buyers. The water to sinks, toilets, showers, and faucets was off, however.

Thanks.

JackT · May 4, 2007, 12:58 PM

28 should be plenty and maybe too much, I never have much trust in the gages. Sometimes you can tap the side of it and it will change. Did you find any zone valves or have any idea what controls the water to the up-stairs unit? A zone valve usually looks like a box attached to the pipe with low voltage wires coming out from it.

gslittleus · May 4, 2007, 01:53 PM

There are three zone valves, one for each of the two air handlers and one in line from the boiler to the indirect-fired water heater. The vertical slide switch on the zone valve for the basement air handler (this is the one which works) is set to "open" (down position). The slide switches for the water heater and the attic air handler are both set to "auto" (up position). I didn't try sliding the zone valve switch for the attic air handler to "auto" because I'm a novice and I don't want to screw up the system.

JackT · May 5, 2007, 09:48 AM

Have someone turn your upstairs thermostat to the heat position and set it high enough so you know it's calling for heat. As someone else turns up the thermostat, you can watch the zone valve. Depending on what make and style, you should be able to see it move or hear it open. You may also be able to remove the cover and move it manually to see if that will give you hot pipes upstairs. Sometimes when they haven't been used for a while they will stick.