Persistent AIR issue

[teejay246]

Hi Guys
I am a newbie on the site. Q: I have an "air problem in the HW circuit. Pump gets very swishy noisy. I vent the pump, quiet for a while, then builds up again. Also get overflow occasionally though from the F&E.
Open vented fully pumped, large ( 18 rads ) very old but sound system ( professional opinion received here ) New Grundfos basic pump installed 2 winters ago, had "air" probs ever since. Did a complete system clean ( X400 for 5 weeks ), thorough drain and flush, refilled ( x100 added ), spent a week or two chasing the air around and venting etc. Still have "air" and just realised it's the HW circuit that seems to be the culprit. Have an AAV at a high point in the CH circuit and 2 open vents for the HW circuit - diagram of system attached, the AAV protruding through the roof are lead joined to the copper pipework inside the loft space. My pro CH guy ( who was a "lackie" for the guy who fitted my system 30yrs ago and well remembers the system AND who is and now a highly recommended CH engineer in his own right ) advised me on the clean, drain, flush etc. If probs reamined, told me that a simple modification to pipework might be required. Can't remember what that was though. CH sytem works and heats great.
Cheers :smilewinkgrin:

 

[mountainman]

Hi Teejay
Wouldn't it be easier if you asked the engineer who advised you previously to explain the required modification.
Got to be so much easier as he had previously worked on the system and therefore his advice would be much better than a speculative enquiry on a forum.

 

[tamz]

Your drawing is a bit wrong but,

Cut off the ch open vent and fit an auto air vent to it.
Tee another vent off the feed
Keep pump set to lowest speed setting the system will operate on.

 

[teejay246]

Many thanks Tamz, greetings from rainy Ayr. very helpful. What was the error on the diag? Direction arrow on feed from f&e perhaps? I am keen to make the correction. Would a partial drain down to below level of highest rad below the pipes to be worked on, work or....Thank you again.