thanks
@Johntheo5. Things have been pretty hectic lately. I will look to find out the setting of d.05. What I have done since last posting is getting back the CORGI engineer who replaced 90% of my radiators in the house back in April this year together with replacing the old Grundfos pump with a new Grundfos UPS2 25-80 pump. He said that with the introduction of an UFH system and having 20 rads throughout the house, the new pump was necessary to ensure sufficient flow of water was being maintained through the heating system.
The engineer used a thermometer device which had clamps to connect to the flow & return pipework at the top of the boiler. When the heating was turned on, he could see the flow temp shoot up, the temp differential quickly go over 20C and the s.53 code appeared.
The engineer power flushed the 22/28mm flow & return pipework that runs from the Vaillant boiler (located in the garage) to the landing cupboard where the Grundfos pump, megaflo, and zone valves are located. He also checked to see if the Grundos pump was mechanically working by removing the screw at the front of the pump and slightly pushing a screwdriver into the pump while the pump was running. He said that if the pump stopped turning by the insertion of the screwdriver, the pump was defective. The pump did though continue turning so he does not believe there is a problem with the pump. He also removed part of the pump and he could rotate it freely with his hand.
After finishing the power flush, the heating ran successfully for about 3 hours. All the rads heated up as expected. However, after about 3 hours by which time the engineer had left, I noticed the temp in my lounge had gone cool and when feeling the rads, they were cool. When I checked the boiler, it showed s.53
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When I explained this to the engineer, he believes there is some blockage in the heating pipework. He spoke with Vaillant and they share the same theory. The engineer has ordered a new power flush unit which he says is more appropriate in power flushing the number of power rads I have. He plans to do a power flush on my heating system in a couple of weeks time.
One thing I have not got round to doing is running the UFH system on its own to see if this also triggers an s.53. In the meantime, I have reduced d.00 to 18. I currently find that the heating runs for longer and the nearest rads to the Grundfos pump are getting hot but the rads furthest away from the pump are cool/luke warm. I am not totally convinced there is a blockage
.
I think I mentioned before but when the UFH system was installed in the summer, whenever the UFH system ran, it would open the zone valve of the radiator heating system (as well as the UFH zone valve). The house would be roasting which showed the main heating system was working perfectly! At the time, I had the Tado heating control system and in consultation with Tado, they said it was a limitation in their product to be able to separately control 3 zone valves (1 for the heating, 1 for UFH, 1 for hot water). Last month, this engineer came to replace the Tado heating control system with a Heatmiser system. This entailed removing the Tado extension kit and 2 Tado room stats (one wireless stat which controlled the heating system and one hard-wired stat which controlled the UFH), and replacing these with 3 Heatmiser wired stats (one as a program stat for hot water, one therm stat for heating, one therm stat for UFH). This may be a pure coincidence but ever since Heatmiser was installed, I've been having this s.53 problem and rads not getting hot. I mentioned this to the engineer but he said introducing Heatmiser would not be causing the issue I am facing. Could there be any wiring issue that may be affecting the Grunfos pump from running properly and therefore not pushing the water fast enough through the system?
I will run the UFH system on its own to see if this brings up s.53 on the boiler. If it does, I am assuming the problem lies either with the boiler (which is 13 years old), the 6-month Grundfos pump, or a blockage somewhere between the pipework from the boiler to the zone valves/Grundfos pump.
Is there anything else I can go before the engineer returns to carry out a power flush on the main heating system?