Hello All,
Bear with me please while I explain my issue. In the meantime I have been trawling this forum to seek answers to my issues and am well aware that the Vaillant 428 has problems.
We have the Vaillant 428 EcoTec plus installed for about 15 years. Its an extended bungalow (we have an upstairs) - 13 rads and a mixture of microbore downstairs and 15mm upstairs. Its open vented and HW is via a Megaflow. I know the boiler is oversized and we have had D.0 set to 18 since the instal. Pump is a Grundfos UPS 15-60. By and large its been fine until recently. About a month or so back we noticed that the pump was a bit noisy and the heating seemed to be less efficient. I bought an Alpha 1 15-60 as a replacement but wasn't happy with the performance - best we found was PP3. I managed to source a new old stock identical UPS pump and fitted that - still quite noisy and I still felt the system wasn't working well.
This week I bit the bullet, and drained the system, cleaned the F&E tank, fitted a Magnaflow Pro filter on the CH return, added some X400 and refilled. Its been a nightmare ever since - couldn't get the rads to heat last night, but seem to have hot water. Today it did eventually warm the rads but they were not hot so I drained again - flow through the hose is pretty decent - flushed through and refilled. Same issues. There seem to be insufficient flow as the boiler is constantly cycling so never runs long enough to get the heating hot.
Either I have a blockage in the system somewhere (seems unlikely as my drain flow was strong and all rads heat albeit very slowly), or an airlock, or the heat exchanger matrix on the boiler is clogged and thats been the root cause of my issue all along.
Contemplating a 25-80 pump to see if that will fix it.
Any help much appreciated!
Bear with me please while I explain my issue. In the meantime I have been trawling this forum to seek answers to my issues and am well aware that the Vaillant 428 has problems.
We have the Vaillant 428 EcoTec plus installed for about 15 years. Its an extended bungalow (we have an upstairs) - 13 rads and a mixture of microbore downstairs and 15mm upstairs. Its open vented and HW is via a Megaflow. I know the boiler is oversized and we have had D.0 set to 18 since the instal. Pump is a Grundfos UPS 15-60. By and large its been fine until recently. About a month or so back we noticed that the pump was a bit noisy and the heating seemed to be less efficient. I bought an Alpha 1 15-60 as a replacement but wasn't happy with the performance - best we found was PP3. I managed to source a new old stock identical UPS pump and fitted that - still quite noisy and I still felt the system wasn't working well.
This week I bit the bullet, and drained the system, cleaned the F&E tank, fitted a Magnaflow Pro filter on the CH return, added some X400 and refilled. Its been a nightmare ever since - couldn't get the rads to heat last night, but seem to have hot water. Today it did eventually warm the rads but they were not hot so I drained again - flow through the hose is pretty decent - flushed through and refilled. Same issues. There seem to be insufficient flow as the boiler is constantly cycling so never runs long enough to get the heating hot.
Either I have a blockage in the system somewhere (seems unlikely as my drain flow was strong and all rads heat albeit very slowly), or an airlock, or the heat exchanger matrix on the boiler is clogged and thats been the root cause of my issue all along.
Contemplating a 25-80 pump to see if that will fix it.
Any help much appreciated!
