ADP hydronic air handler blowing cold….sometimes

mindym

Hi - homeowner here. We have an ADP hydronic air handler installed horizontally in the attic space with a Lochinvar instant heat boiler and hot water system installed in the basement. The ADP air handler is model BSA9230D3WMOR30267. The air handler randomly blows cold. This has been going on for 3 years since we had the attic insulated and the Lochinvar installed. Prior to the those events, it worked perfectly.

Thing is, I can take my shoe and beat on the outside panel nearest the hot water inlet pipe and the hot water will start circulating. I’ve called technicians and they say they need to wait for whatever is causing it to fail completely before they can do anything. More info - until this month, it would blow cold if the outside temp got above ~50° and then dropped overnight. Now, there is no pattern for when it stops. Does anyone have any ideas as to what might be causing this?

pecmsg

Does this attic space get below freezing?
Is there glycol in the boiler?

mindym

The attic is heated and cooled. It is mostly finished.

No glycol in the boiler.

pecmsg

Can it go below freezing?

mindym

Our outside temp does go below freezing but it does not affect the randomness of the needing to beat the air handler. The air handler is in an insulated, climate controlled place in the attic. Until the last month, when the outside temp was colder, the unit performed correctly.

pecmsg

OK My point is If or When you lose power, a pump fails, something goes wrong you chance freezing and bursting that coil.

As far as your problem it just sounds like there an air pocket that's stopping flow. If that happens during freezing weather, then you could freeze the coil.

You need to have that line purged properly.

I Highly recommend glycol for any unit that can be exposed to freezing conditions like attics.

mindym

I’ve wondered about an air bubble and the installers not properly purging the system. I have tried banging on that pipe instead of the air handler but it never got the water to circulate. There is a hose bib on the pipe going into the air handler. Would I purge it there or the one nearest the boiler?

I only stumbled upon the banging “fix” a couple years ago when I was so mad, I kicked it, and it started working. I’ve tried different areas on the outside panel but it only works in a specific area. We now call it the “kick it Charlie Brown!” method.

mindym

Re losing power - we have a whole house generator so we never lose power for more than 30 seconds before it kicks in. The air handler for the 1st floor is located in the finished basement and (fingers crossed) works perfectly. Honestly, at this point we would replace the mis-functioning air handler but it is behind a knee wall the previous owners built. Given the air handler’s size, I’m pretty sure I will have to take part of the wall out for it to be replaced which would be a giant PITA

Thank you for trying to help!

pecmsg

I don't advise Banging on anything.
Without seeing it it's difficult to explain how to properly purge the system.

One thing I do on attic installs is let the circulator run and have the thermostat control the fan.

EBEBRATT-Ed

@mindym

Beating the poor thing will only cause damage. It could be air, it could be a sticking zone valve etc.

You know what you need? A technician with a brain. When something doesn't work it can only be a few simple things.

If they show up and go DUH they will never find the problem unless they LOOK for the problem.

And replacing the air handler is not a good idea.

How would you like to go through the nightmare of replacing it and then end up with the same problem?

Post some pictures so we can see what is going on. Pictures of the ahu and the boiler

HVACNUT

Seems like a relay is hanging up and the Fonzie trick closes it.

mindym

EBEBRATT-Ed said:

@mindym

Beating the poor thing will only cause damage. It could be air, it could be a sticking zone valve etc.

You know what you need? A technician with a brain. When something doesn't work it can only be a few simple things.

If they show up and go DUH they will never find the problem unless they LOOK for the problem.

And replacing the air handler is not a good idea.

How would you like to go through the nightmare of replacing it and then end up with the same problem?

Post some pictures so we can see what is going on. Pictures of the ahu and the boiler

Agreed about the technician with a brain. If you know of one in the Boston area, let me know. They are in short supply or at least the places I’ve called. Pics below in a few minutes.

mindym

The green outline on the air handler is the area you have hit to get the water to circulate. I understand banging on it is not ideal and as you can see, it has no damage after 3 years of banging.

pecmsg

https://heatinghelp.com/find-a-contractor/

neilc

shoes stay on your feet,

shut the boiler and any circulator off,
at the airhandler,
try cracking open that bib / high vent,
air? or water?
any air?
if there's air, let it out,
turn the boiler and circs back on

Jon_blaney

I would also check that the plug on that valve has not detached from the stem.

HVACNUT

Replace the heat sequencer in the coil cabinet. 

mattmia2

Is the coil not getting hot or is the blower not coming on when it does get hot? It looks like there is a snap disc thermostat right where you whack it. Perhaps that is sticking.

mindym

mattmia2 said:

Is the coil not getting hot or is the blower not coming on when it does get hot? It looks like there is a snap disc thermostat right where you whack it. Perhaps that is sticking.

The hot water doesn’t circulate. The blower starts blowing as soon as the thermostat calls for heat.

SuperTech

I agree with @HVACNUT about the sequencer. They are a part with a high failure rate and your Fonzie trick to get it going describes the way they malfunction. 

EBEBRATT-Ed

I don't see a zone valve so I guess it has a dedicated circulator.

I agree about the sequencer but the op mentioned the fan starting as soon as the stat calls but no water circulation. Says it blows cold air so it's the circ pump not starting

It's not air bound because it works when everything starts

I could be wrong but I am not seeing anything in the AHU that will prevent the circ from starting

I looked up and read the manual and you can buy this ahu with a multitude of options so it's impossible to figure out the wiring from here

So the question is Is their something in the AHU preventing the circ pump from coming on.

Your tech needs to figure out how the circ pump starts and troubleshoot that circuit

If the stat wires go to the AHU then their must be stat wires running to the basement to start the circ pump. That's what needs to be looked at

@mindym

mindym

Woke this morning to it blowing cold air. Took the panel off and held the panel switch down. Waited until blower motor was running and verified no hot water circulating. Gently (very gently 😀) tapped the relay sequencer twice with an insulated screwdriver and viola, hot water started circulating. I ordered a new one and it should be here tomorrow. Will post again after I install it.

Thank you all for your help!

HVACNUT

mindym said:

Woke this morning to it blowing cold air. Took the panel off and held the panel switch down. Waited until blower motor was running and verified no hot water circulating. Gently (very gently 😀) tapped the relay sequencer twice with an insulated screwdriver and viola, hot water started circulating. I ordered a new one and it should be here tomorrow. Will post again after I install it. Thank you all for your help!

That's more than likely the cause, but make sure there's full 24v to the sequencer coil and secure connections. Less than 24v might not be enough to close the contacts.

EBEBRATT-Ed

@mindym

You did better that some HVAC techs who can't see a problem unless it smacks them in the face.

mindym

Part came in - thank you RepairClinic.com - We have heat! Took less than 10 mins to replace it. Thank you everyone for your help!!!

EBEBRATT-Ed

glad it worked out. nice to have heat for Christmas