I have an air handler in a large building that's heated by a central boiler. I would like to confirm that the correct wires are in their places on the thermostat. The main problem right now is that in fan mode, the air handler circulates hot air, not cold air. (It seems as if the hot water solenoid doesn't shut off when the fan is on and the thermostat set low.)

I have a multimeter and can test continuity with the circuits off, or can measure voltage coming from the air handler with the furnace on and the thermostat body off. I tried to follow the wires back to the air handler, but it's a real mess inside the air handler. (I have photos I could post if this would help you answer my question.)

The air handler is controlled by a standard mercury Honeywell thermostat. Four wires are connected in what I am told is an unusual setup.

In the transition and cooling seasons, emergency electric heater coils within the air handler can be activated. In the heating season, the only heat available is from the boiler. There's a heat/cool switch on the thermostat. You can smell the electric heat if used, as it tends to be dusty and this dust burns when the electric heat is on.

Thank you for your consideration and answers. I need to determine if the solenoid is broken, the wires are crossed, and if something needs to be replaced (complete handler or solenoid). Also, if any of this can be done DIY.

Start with some info on the zone valve (brand/model). Post some pics with cover removed if possible, try to get an image of the wiring.

Here are six photos of the inside of the air handler:

Image of cover plate - Photobucket - Video and Image Hosting (http://s711.photobucket.com/albums/ww114/ubusum/?action=view&current=coverplate.jpg)


And one video (dark):

http://s711.photobucket.com/albums/ww114/ubusum/?action=view&current=MVI_1879.flv

Love the music. LOL What youn have here is a cluster f***. I would have a hard time telling what wire went where let alone what they did exactly.

Looks like it has pipe sensors to sense the heat, a Erie water valve, and a small 2KW electric heater which might be there to prevent freezing of the hot water coil if this unit is subject to freezing temperatures like in a warehouse during a boiler failure.

The only thing I can tell you to do is check the circuits and each individual control and device to be sure they work. If a defect is found then replace the parts. Since this looks like a home brew setup and no actual electrical drawing is available for the complete set up you have your work cut out for you.

You are probably correct on the valve leak. The only way to test without removal is to remove the wires and see if the hot water still flows. If it flows without power then it is leaking.

Thanks for your response. It's gratifying to read your reaction because I've had a hard time with this thing! Glad you liked the music. (Next time I make a video like this I'll know to add some light.)

So, if the valve needs replacing, can a do it yourselfer manage that (or even get the replacement part)? Do you need to solder onto the copper, or are there fittings available for repairs? (I believe the company that made these units is no longer in business or has been bought out so I would seek a generic 24volt valve somewhere.)

====

(From the furnace)
LANCO

Model ER-08-WS-B30

Your skill level will determine what you can and cannot do. In this particular case it will be difficult for a do it yourselfer since the system the system contains many different parts that must be activated at different times. In other words it is not like you are replacing a on and off switch. Most of the parts should be available or replaceable but the clip on pipe sensors of the correct temperature and size might be difficult to find.