Bosch Singular 4000 leaking from fill valve

markwl

I installed a Bosch Singular 4000 in January, it worked great until yesterday when it started leaking pretty constantly from the fill valve, pressure valve, and a lot of water coming out of the condensate drain.
It still heated domestic hot water but not space heating (and would fill a 5-gallon bucket every 20 minutes or so). I had turned the space heating as low as it would go due to warmer weather, could this have caused some issue?

Big Ed_4

On most boiler feed valves there is a lever to fast fill which over rides the adjustment . Check the lever and make sure it is off .

markwl

Thanks, I unscrewed the valve all the way and took it out, screwed it back in and it went in further than I could get it before - now water is only coming out the condensate drain.

After I fill the system I get an A5 error 'low water pressure'. It will run for a minute or two and start heating, I can also get DHW, then water continues to flow out of the condensate drain for about 5 minutes and the low water pressure error occurs. Any thoughts?

JUGHNE

Does the water pressure gauge on the boiler work?

Can you post a picture of the entire boiler showing the cond drain and pressure gauge?

Big Ed_4

What did you unscrew ?

markwl

There is no physical gauge on the boiler, I can use the display to show pressure. When filling it will go to almost 30 psi, then when turned off drops to 15 and stays there.

I unscrewed the actual plastic fill valve knob (see picture). Also, see below for an overall picture of the installation.

Big Ed_4

I don't see a thermal expansion tank , Is there one inside ..

markwl

It's below just out of the photo....this one

https://www.supplyhouse.com/sh/control/product/~product_id=102-1

with this on top

https://www.supplyhouse.com/sh/control/product/~product_id=VJP075-TM

fenkel

check the internal pressure sensor.. red-black (DC 5V) input output should be the same.. White-black
whats the pressure in the expansion tank? should be 12-15lbs..
How do you fill the system?
Do would you have a pressure reducing vale on make-up pipe coming into boiler?
I think you might have a pressure issue with the make up water.. Send pictures of how you add water...
Also, if water is coming out the condensate line. it indicates that the boiler is flooding out. and it will shut down..

fenkel

Say, it doesn't appear that you used Oxygen barrier pipe for your install. you need larger supply lines for the space heating system.. cause you need to move the heat( btus)away from the boiler. this too could cause you some issues with pressure.. I just worked a singular boiler that had the same size piping and it over heated all the time.. it too leaked water out the condensate line......
Are you using primary/secondary for you space heating system?

Big Ed_4

Shut off the boiler feed as a test . If it continues ,you might have a bad plate heat exchanger .It takes the feed out of the equation . If the pressure rises on temperature rise and settles when it cools , you have a expansion problem .