Viessmann Vitodens 222-F Water Discharge

kjr

This weekend, our Viessmann Vitodens 222-F boiler malfunctioned and flooded the basement. Water was discharging from the overflow pipe and the pressure release valve was all the way up. Our entire basement was flooded. Photo is available here -goo.gl/jgJivf

Over the last few days, water has continued to discharge overnight from the pipe but only approx. 1-2 cups and only at night between 2 am and 6 am--no water is discharged at any other time. We think the discharge is happening around the time of the DHW individual setting start time of 5 am - maybe 30 minutes before that start time, which we understand is when the boiler fires up and tries to reach the set temperature.

Our water temperature is set for 140 degrees. The boiler temperature on the unit display varies throughout the day from 88 F all the way up to 183 F.

We are wondering if the problem is either or both: broken pressure valve, broken boiler sensor? The original installer has said that these parts will not be covered by the Viessmann warranty.

Also, we purchased this home with the boiler already installed. Is it typical for the overflow pipe to discharge onto the floor? There is no floor drain. Should it be piped outside?

Our plumber has reached out to Viessmann, to no avail. We would be grateful for any ideas you have.

Robert O'Brien

Is it the boiler relief valve or the DHW?

kjr

Robert O'Brien said:

Is it the boiler relief valve or the DHW?

It was the TPR valve on the DHW tank that was stuck in the "up" position.

Jamie Hall

If it's the TPR valve on the hot water tank, the first question is -- is there a check valve or pressure reducing valve or backflow preventer anywhere on the domestic water system? And, if so, is there also an expansion tank on the system?

As part of the fix, that valve should probably be replaced.

kjr

Jamie Hall said:

If it's the TPR valve on the hot water tank, the first question is -- is there a check valve or pressure reducing valve or backflow preventer anywhere on the domestic water system? And, if so, is there also an expansion tank on the system?

As part of the fix, that valve should probably be replaced.

Yes, there is a check valve. It deteriorated (crumbled) so we removed it and it is running without it until a replacement can be found. There is also an expansion tank that I assume is attached to the hot water tank.

Jamie Hall

The check valve crumbled? That's a new one...

Can you describe the sequence of piping and fittings for your domestic water? Or post a sketch? What is the source?

Paul Pollets

There is an internal boiler expansion tank on the left side of cabinet. There needs to be a potable expansion tank (ST-5) installed on the CW feed to the DHW.

HomerJSmith

If the expansion tank has an air charge on one side, be sure that it is at the proper charge and that it is not water logged. A water logged expansion tank will open the PRV and discharges water as the water heats up as the water has no other place to go.