I got called today to a Glow Worm Betacome 30C with hot water problems. Water would only get lukewarm and fluctuate between lukewarm and cold. This is a typical symptom of a blocked plate to plate heat exchanger. I also noticed a Magna Clean magnetic filter incorrectly fitted to boiler flow. It should have been fitted on boiler return pipework. Picture below show the boiler with Magna Clean fitted on the flow of the boiler. In this configuration filter is only catching what has already gone through the boiler.
I inspected the filter to find out just how dirty this system was. There is no doubt that with this amount of sludge (with the filter on the flow) the plate heat exchanger must be blocked.
The next step was to drain the boiler and remove the heat exchanger and either clean or replace it. If you ask manufacturers they suggest that it should always be replaced.I choose to clean them and have done so for years without any problems. It is worth noting that cleaning a heat exchanger is only a temporary measure and does not fix the root problem of sludged heating system. If you clean or replace heat exchangers on dirty systems sooner or later they will block again. The only proper solution is to power flush the system, protect it with inhibitors and clean or replace plate to plate heat exchanger. I must also say that I regularly clean heat exchangers on systems protected by magnetic filters (all brands). Those filters are great but on very dirty systems they simply will not cope with catching all sludge.
Removing plate to plate heat exchanger on Glow Worm Betacome is a pain for 2 reasons:
– those boilers are not fitted with draining points, so when isolated on flow and return the only way to drain them is by activating the pressure relief valve. If you look into Glow Worm Betacome 30C manual this is exactly what it suggests. This is the last thing you want to do on a dirty system. Once activated those valves with drip water and will have to be replaced in 90% of the cases. It is best to find an alternative method of draining the boiler. Luckily in this case I could use isolating valves on Magna Clean for the flow and boiler’s return isolating valve to drain it. If it was not for a Magna Clean being fitted on this system a full drain down would be my preferred option.
– heat exchanger is located at the back of the boiler and at a first glance it seems impossible to remove it without having to remove other major components. I managed to remove it by disconnecting hot water outlet pipe from the boiler and moving it slightly out of the way.
Pictures below show the heat exchanger removed from the boiler. Note blocked right hand side port.
Second picture shows cleaned heat exchanger.
System will get power flushed and Magna Clean filter moved to the boiler return pipework next week.
Update on 11/07/2015
It took a while for tenants to move out of this property and I just got a chance to go back to flush the system and move Magna Clean filter to boiler return pipework. Hopefully this will end hot water problems with this Glow Worm Betacome combination boiler. See picture with correctly installed Magna Clean below.