Still not right

Hi there. I have visited this site a few times & followed the advice for intermitent hot water. I.E fitted new HWS sensor,,no luck so fitted new heat exchanger,, no luck removed right hand heat exchanger circulator pump & stripped down & found to be perfect. Removed non return valve under pump just to try, no luck. Speed of pump sounds to be behaving properly. My problem is that there seems to be air in the pipework just before the pump , If i place a short hose to the drain cock just before the pump & after the heat exchanger & hold in a bucket with a small amount of water in, I open the drain & get a small amount of air out. After bleeding like this the system works great for 2 or 3 days & then the same happens again, so i repeat the process & it,s ok again. I was even thinking of fitting a self bleed valve in the pipework but i cannot understand why air is getting in. My header tank is full. Any idea,s Steve. LEEDS
P.s My heating works great & I always have a tank full of hot water, the system is aprox 5 yrs old.

Hi Steve,

Odd. This is a not a 'normal' fault. It sounds to me as though the store is not properly full of water. Try loosening the compression coupling where the vent pipe exits the top of the appliance. Do you get water out? Or nothing at all? If water then the appliance must be properly full, if nothing, then this indicates a blocked cold fill pipe. I've seen one or two recently on Boilermate 2000s.

Cheers, Mike

I drained the cold water header tank & took off the expansion pipes & cold fill pipe which are married together as you know. 15mm into storage tank + 22mm. The 22mm has a 1 way valve fitted , ie lets air out of tank but none back in. The valve was completely blocked with crud. I took it out & gave it a good clean & refitted it. Immediately on refill i noticed air was coming out as the store was refilling, & now i have hot water at any speed of demand. The pump is now almost silent as before it was wooshing all the time. It must have had a large air pocket at the top with the water level being just where the heat exchanger inlet came from the store causing the pump to suck air. Many thanks for the help & keep up the good work. Steve Edwards. LEEDS

Hmmm the one-way valve is NOT a standard fitting! I suggest you remove it should the system play up again.

Best to leave well alone while it is working now though. Glad you got it fixed and thanks for the feedback - always helpful to know what fixed a problem!

Cheers Mike