Hydronic Heating System Blowing Out Cold Air In the Middle of the Night

SamInLasVegas

I have a very unusual problem. I have a hydronic heating system in my house. It functions perfectly fine during the day, but at some point in the middle of the night /early morning hours it starts blowing out cold hair and runs nonstop. If I shut it off and restart it, it will start blowing out hot air again and the house will heat back up. I keep the temp set at 70 at night when I go to bed and 73 during the day hours, but I'll wake up in the morning and it will be 65 degrees in the house. I can feel the cold air coming out of the vents. Once I restart it and it begins blowing air again it typically works the rest of the day until I wake up again the next morning.

I've had people out here four times now to look at it. They've drained the water heater and flushed out all the sediment. They've purged the air out of the system. They have also replaced the taco pump. The guy who was last here two days ago said he doesn't know what else he can possibly do.

Has anyone ever encountered a situation like this?

kcopp

Can you give us more information? # zones? Thermostats? Maybe a few pix...

MaxMercy

SamInLasVegas said:

Once I restart it and it begins blowing air again it typically works the rest of the day until I wake up again the next morning.

What exactly are you restarting?

The technician will have to actually be there when the problem occurs. Next time it does it, leave it blowing cold air and have him see why the water isn't circulating.

SamInLasVegas

kcopp said:

Can you give us more information? # zones? Thermostats? Maybe a few pix...

One t-stat in the upstairs hallway. No zones. Just one setting for the entire house. It's not a big house.

SamInLasVegas

MaxMercy said:

SamInLasVegas said:

Once I restart it and it begins blowing air again it typically works the rest of the day until I wake up again the next morning.

What exactly are you restarting?

The technician will have to actually be there when the problem occurs. Next time it does it, leave it blowing cold air and have him see why the water isn't circulating.

I'm restarting the unit in the upstairs hallway. There is what looks like a light switch next to it that controls the power to it. I flip that switch off and then turn the t-stat from heat to off. Then I restart them.

Here is a video I took this morning

https://www.dropbox.com/s/n0quy31t8bguwap/Heating.MOV?dl=0

Zman

Umm, The problem is rarely with the thermostat. What's under the hood? Is it a boiler feeding that in wall cabinet heater? Are the boiler pipes getting hot?
Pictures of the mechanical equip would help.

pecmsg

By turning it off and back on your resetting whatever is shutting it down.
What type of boiler?
Piping arangement?
Look for trouble codes.

unclejohn

Do you have hot water at the sink the times it quits working. Sounds like the fan starts but no pump. The pump relay is where I would start.

SamInLasVegas

Zman said:

Umm, The problem is rarely with the thermostat. What's under the hood? Is it a boiler feeding that in wall cabinet heater? Are the boiler pipes getting hot?
Pictures of the mechanical equip would help.

I'm attaching pics below

SamInLasVegas

pecmsg said:

By turning it off and back on your resetting whatever is shutting it down.
What type of boiler?
Piping arangement?
Look for trouble codes.

Attaching pics below. There haven't been any trouble codes on the water heater. The codes indicate it's running like normal

SamInLasVegas

JUGHNE

Pump sticking on early AM heating call, power off and back on might nudge it to go.
Or pump relay....or time delay relay .....both are visible in picture.

Jon_blaney

It is definitely an electrical issue. The pump is not starting when there is a call for heat after a cool down. Failing components can be effected by temperature.

HVACNUT

My money is on the sequencer on the right side in the air handler.