I installed a system ( Vaillant system thermocompact 618/2 and Vantage cylinder) for customer about three years ago. System was flushed with X300 followed with inhibitor.
Got called his morning and ( customer just lives down the road) both heating and hot water is not working.
Went to have look and the boiler is cycling. It fires up and the flow gets very hot within 10s of seconds, return is cold.
So I
1. looked at the pump, works fines, i.e spins, resistance 160 ohms across the windings.
2. There are two NTC's on the flow and return near the heat exchanger The Resistance on the NTC on the flow is 3Kohms. The NTC on Return only has terminal, haven't come across this type before. Don't know how to check whether is working.
3. Suspect the heat exchanger is likley to be sludged. Took out, looks OK, Clean water came out both from the flow and return inlet.
4. Suspeced a blockage in the system somewhere but the autobypass on boiler is cold.
I am thinking it's the primary exchanger what's the best way of checking it. I don't do many boiler repairs mainly installs.
Thanks
Got called his morning and ( customer just lives down the road) both heating and hot water is not working.
Went to have look and the boiler is cycling. It fires up and the flow gets very hot within 10s of seconds, return is cold.
So I
1. looked at the pump, works fines, i.e spins, resistance 160 ohms across the windings.
2. There are two NTC's on the flow and return near the heat exchanger The Resistance on the NTC on the flow is 3Kohms. The NTC on Return only has terminal, haven't come across this type before. Don't know how to check whether is working.
3. Suspect the heat exchanger is likley to be sludged. Took out, looks OK, Clean water came out both from the flow and return inlet.
4. Suspeced a blockage in the system somewhere but the autobypass on boiler is cold.
I am thinking it's the primary exchanger what's the best way of checking it. I don't do many boiler repairs mainly installs.
Thanks