Open vented CH - 2 port valve actuator replaced, now boiler overheating and pump noisy.

Joined
13 Feb 2009
Messages
143
Reaction score
9
Country
United Kingdom
Replaced the actuator/head on the 2 port valve that feeds the hot water cylinder coil two days ago. Tested HW and CH independently then tested with both HW and CH called for simultaneously - all seemed good, apart from a towel rad in the bathroom was hot only at the bottom half, cold top half. Said towel rad is part of the HW heating circuit. Couple of hours later, when system had cooled, bled the towel rad - loads of air expelled and I heard a gurgling sound from the loft (assume from the FE tank). Job done, I thought...

Now the symptoms are boiler overheating and locking out and pump very noisy. Up in the loft, at FE tank, I can hear air being sucked into the vent pipe when the pump is running. Can also feel a slight vacuum when put my thumb over the end of that 22mm vent pipe. Fortunately we have an immersion heater to fall back for the time being.

The FE tank water level is 2 inches below the overflow. Noted it was very difficult to remove the old 2 port actuator. After much prising the actuator was released and could see it had been fused to the valve spindle by white crud. Cleaned up the spindle, applied wd40 and rotated spindle back and forth a few times before installing the new actuator.

Trawling thru the forum, symptoms seem to point toward a blockage where the FE tees into flow pipe - is there anything alse I should examine to locate root cause, before I start cutting out sections of copper pipe?

Something else I noticed is that the pump was set to speed 3. I've been in the property (bungalow) for 10 months, everything worked fine up until now, so I'd never had cause to go snooping in the airing cupboard. Makes me wonder whether previous owner had the pump set at speed 3 to overcome an issue with the system. :unsure:
 
Something else I noticed is that the pump was set to speed 3. I've been in the property (bungalow) for 10 months, everything worked fine up until now, so I'd never had cause to go snooping in the airing cupboard. Makes me wonder whether previous owner had the pump set at speed 3 to overcome an issue with the systsystem.
What make/model pump is installed?
 
Bungalow!
All rads on drops?
Any AAVs at high level in loft space?
The CH pipework is under the ground floor floorboards. However, I did find an AAV in the loft this afternoon, fitted to a 22mm pipe which looks to be the flow pipe to the bathroom towel rad. So to heat towel rad, pipe goes up from airing cupboard, across loft floor, runs down vertically inside a stud wall to feed. Return from towel rad heads under floorboards on ground floor, eventually tee-ing back into main return pipe in airing cupboard. Anyway, that AAV had a white crust on it, cleaned it up a bit then opened the tiny black plastic cap and plenty air was expelled. Now when the pump is running all is quiet at the FE overflow pipe, which is a step forward. Pump also quieter (but still noisy) and boiler still locking out after a few mins. Maybe the pump has had it, can't push water through the boiler, or the boiler has air trapped in its heat exchanger.
 
Last edited:

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.


Are you a trade or supplier? You can create your listing free at DIYnot Local

 
Back
Top