I think the auto- bypass on my Glow Worm 30CXI boiler is stuck open and I would be grateful for some advice on the consequences.
Hopefully the boiler will be replaced later this year so I would sooner not pay out on repairs I don’t have to. However, just in case the boiler replacement happens later rather than sooner I’d don’t want to damage it and force a replacement.
Why I think the bypass is stuck open: -
I recently topped up the central heating on the boiler after refitting a small radiator. To do this I used the in-built Filling Loop Tap accessed through the bottom opening of the boiler.
After topping up the system to 1.0 bar and running it for a while I found that the pressure had risen to 1.6 bar, normally it does not rise above 1.1/1.2 bar when hot. Thinking I may not have closed the in-built Filling Loop Tap properly I checked it. The tap was fully closed, however, I noticed that the pipe from the in-built Auto Bypass was hot; something that I had not noticed before and would not have expected as the heating was nowhere near up to temperature.
The boiler has recently had its heat exchanger changed, system cleaned and refilled with inhibitor. All the radiators get hot with no cold spots; therefore, I don’t think there are any system blockages.
To check if the bypass is stuck open, I’ve removed all the TRV heads and fully opened all the lockshields to ensure there is no restriction causing the bypass to open. Then I used a digital thermocouple thermometer through the bottom of the boiler to monitor the bypass pipe temperature against the flow pipe temperature just below the boiler. The bypass temperature pretty much follows the rise and fall of the flow pipe as it warms up and cools down.
I’ve been running the boiler at 60 to 65 degrees dependent on outside temperature to try and achieve the required condensing temperature. With the not so cold weather we’ve been having these boiler settings cope with the heating requirement. Typically the temperature difference between the flow and return is less than 5 degrees. I've been advise that the boiler is oversize
From what I’ve written does the auto-bypass appear to the stuck open?
Any help would be much appreciated
Hopefully the boiler will be replaced later this year so I would sooner not pay out on repairs I don’t have to. However, just in case the boiler replacement happens later rather than sooner I’d don’t want to damage it and force a replacement.
Why I think the bypass is stuck open: -
I recently topped up the central heating on the boiler after refitting a small radiator. To do this I used the in-built Filling Loop Tap accessed through the bottom opening of the boiler.
After topping up the system to 1.0 bar and running it for a while I found that the pressure had risen to 1.6 bar, normally it does not rise above 1.1/1.2 bar when hot. Thinking I may not have closed the in-built Filling Loop Tap properly I checked it. The tap was fully closed, however, I noticed that the pipe from the in-built Auto Bypass was hot; something that I had not noticed before and would not have expected as the heating was nowhere near up to temperature.
The boiler has recently had its heat exchanger changed, system cleaned and refilled with inhibitor. All the radiators get hot with no cold spots; therefore, I don’t think there are any system blockages.
To check if the bypass is stuck open, I’ve removed all the TRV heads and fully opened all the lockshields to ensure there is no restriction causing the bypass to open. Then I used a digital thermocouple thermometer through the bottom of the boiler to monitor the bypass pipe temperature against the flow pipe temperature just below the boiler. The bypass temperature pretty much follows the rise and fall of the flow pipe as it warms up and cools down.
I’ve been running the boiler at 60 to 65 degrees dependent on outside temperature to try and achieve the required condensing temperature. With the not so cold weather we’ve been having these boiler settings cope with the heating requirement. Typically the temperature difference between the flow and return is less than 5 degrees. I've been advise that the boiler is oversize
From what I’ve written does the auto-bypass appear to the stuck open?
Any help would be much appreciated
