noisy vaillant 831

[g60rge]

hi,

I installed a Vaillant 831 ECO tech plus at my own house less than three weeks ago and this morning it started a humming noise on dhw mode, i lowered the temp which seemed to reduce the noise but id rather find the route of the problem. By afternoon it started doing so in heating mode.

il be calling vaillant in the morning but ive noticed its quite a common thing yet no definitive answers on this forum. Would be nice to have the answer for others. i will be posting progress.

for the record yes i am a gas safe engineer and have also been on the vaillant course, the system was flushed using fernox fx2, and 1 liter of inhibitor used, (10 rad installation). I believe the powerflush took me 11 hours all in so i presume i did a good job of it. (1 rad at a time, banged the life out of them and that)

what could this be?

 

[grahamgas]

What was the fga telling you?

 

[g60rge]

fg analysis was all within specs as was the inlet working pressures,gas rates etc even after mass confusion over the phone with vaillant.

for the record, you are allowed 4mb drop from meter to test point.

1mb on your pipework
3mb through to test point on the gas valve.

this doesnt meant if u have 22 at meter your allowed 16 at the test point which is whats most engineers think is acceptable due to a misinterpretation of the mi's stating 16mb is the minimum as this is a 6mb drop. - not good.

vaillant engineer said to me that test point is irrelevant really and to install a test nipple under the boiler in future installations to be sure.

thought id add that in as thats another grey area for most people..

back to my vibrating problem, all it was was air in the heat exchanger, quick draindown of the heat exchanger and repressurise and it was sorted.

but if you have rads you cant bleed you will have the same problem after a drain down so best to sort these out

thanks for your reply graham