Viesmann vit 100

[dave1967]

Good evening.

I had the boiler installed last year and have been losing pressure on the heating side without any trace of leaks. Also had two overnight drops in  ch water pressure causing the boiler to fail to operate about 4 months ago. I have removed the condensate line tonight to see if it could be a passing valve. Ive noticed i have a 15mm bend to the boiler from 22mm gas supply which i believe may be undersized. The flue also drips as it is not angled correctly . Does anyone have similar issues with this boiler or suggestions.

Thanks

[JohnMo]

It's likely to be the expansion vessel has a leak or needs a recharge.

[dave1967]

Thanks. Is the 15mm elbow ok?.

[Huckleberrys]

Viessmann 100w come with a 15mm elbow I believe...pre bent. Or at least a 15mm connection. I forget. I always increase in size immediately after that.

[dave1967]

Thanks

[dave1967]

Ok. Still loosing pressure and water present in the expansion tank when shreger valve tested. Dont have any high pressure issues apparent as is normal.  I think something may have happened in the  summer as shower wouldn't get warm one morning an found the system pressure was zero from about 1.3 bar a few days before.

[MJNewton]

41 minutes ago, dave1967 said:

Ok. Still loosing pressure and water present in the expansion tank when shreger valve tested. Dont have any high pressure issues apparent as is normal.  I think something may have happened in the  summer as shower wouldn't get warm one morning an found the system pressure was zero from about 1.3 bar a few days before.

 

So, you've found the issue. From what you've written it sounds like you're still looking though? 

[dave1967]

Ok. Still loosing pressure and water present in the expansion tank when shreger valve tested. Dont have any high pressure issues apparent as is normal.  I think something may have happened in the  summer as shower wouldn't get warm one morning an found the system pressure was zero from about 1.3 bar a few days before.

[dave1967]

Maybe, just insure why im osing pressure when inam ot getting the telltail high pressure associated with u/s expansion tank.

[MJNewton]

As the water heats and expands in the sealed system it'll increase in pressure and cause the PRV to open. This loss of water will result in pressure loss once cooled. 

[dave1967]

Thanks but i don't get a pressure increase.

[MJNewton]

Does the PRV outlet show any signs of passing? 

[dave1967]

The grey drain hose drips but i believe it is shared with the condensate drain so im not sure.

[MJNewton]

Put the heating on max and watch what happens. The pressure increase without expansion capacity will happen without having to wait too long. 

[dave1967]

Will do.

Cheers

[dpmiller]

if there's water coming out of the schrader valve then the pressure vessed is FUBAR. Simples. Replace it before you try to hunt down any other ghosts...

[JohnMo]

14 hours ago, dave1967 said:

Still loosing pressure and water present in the expansion tank when shreger valve tested

You expansion tank, has a diaphragm in it, water side and air side. The Schrader valve is on the air side - t should be dry.  As stated on Monday it is likely to be an issue with the expansion tank. Order new part, replace, done - or call your plumber to have him do it. But strictly speaking, as the expansion vessel is within the boiler casing, you should be having a gas safe plumber doing the job.

[dave1967]

Viessmann doing it next week under warranty after I explained the issue.

Cheers all

[dave1967]

Ok they came out. 

Said water in expansion tank is not always an issue with viessmamm 100. 

It was pressured up again with a pump.

Prv was ok. Not sure what else he did but said it was not set up correctly for external control which he fixed. Not Sure how that was the main issue as it been fine for 10 months but seems ok now and no pressure loss.

So all good.