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The central heating on my Baxi DuoTec Combi 28 HE A has stopped working but the hot water is fine. I have also discovered a leak from somewhere on the lower isolation valve to the Fernox TF1 Compact filter, it may just need tightening up. I'm guessing that it could be the diverter valve but could it just be the TF1 filter is blocked and needs cleaning. I have a British Gas repair appointment booked but they cant come until Saturday, so if its just the filter I could clean that myself. The water pressure is between 1 and 2 bar.

TF1.jpg
 
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The TF1 is renowned as a leaker there is a service kit available i get mine from plumbase merchants , isolate the the valves drain out the filter then it can be removed and cleaned in hot soapy water and rinsed off dry it replace all the rubber seals from the service kit with a smear of silicone grease , reassemble . Is there a fault code on the boiler if you pull down the front flap you will see examples of fault codes that occur ? . Kop
 
No fault codes and many thanks for the advice. Am I correct in thinking the TF1 could be the problem rather than the boiler.
If I do drain and clean etc, can I add Fernox to the filter or is that best left to an engineer.
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UPDATE: Just took a look at the TF1 and found some sludge around the magnet sleeve as you would expect but not as bad as some of the videos Iv seen on YouTube. I tried to flush by turning on the bottom valve but no water pressure at all. I checked the bar meter on the boiler and it is 0 so all the water has drained. I tried to refill but no water pressure anywhere. It now has an error code E19. Also no hot water form the taps which there was earlier this morning before I messed with it. Looks like Ill have to wait for CH engineer after all.
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OK so here is what I found. I gave the filter another clean and this time fitted a new main seal ring to the lid which came with the original installation pack. I coated with Vaseline as I don't have silicone. I opened the top and bottom TF1 inlet valves, (which is why I could not repressurise before) and the boiler filled as normal. The leak on the lower valve is as bad as ever and is why the boiler visibly looses pressure. No pressure at all means no hot water either. Unfortunately I do not have a large enough spanner to tighten the valve and see if that fixes the problem. If the boiler senses a leak and slow drop in pressure would that stop the CH from working.
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Also, the boiler will light for a few seconds but then shuts down.
 
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Yes read inside the flap of the boiler you need 1 bar cold pressure with no leaks for the boiler to operate as i said the washers in the valves also need replacing .
 
The info says if pressure drops below 0.5 boiler will not operate. The pressure is currently 1 bar and the heating still wont work. Its been leaking for a very long time, years but this is the first time the heating has stopped working after refilling. I managed to reduce the leak from the valves to almost nothing by taping the brass nut with a screwdriver, but I really need a spanner the right size to do the job properly. Do you know the size of the spanner I need to remove the valves so I can fit new washers.
 
UPDATE:
British Gas fixed it back in December 2019 and it was the diverter valve. He replaced the insides with a kit of parts from his van. Also re-pressurised the expansion tank and tightened up the filter. Worked fine until today. Looks like the PRV is faulty and my boiler insurance has just expired. Looking at fixing it myself.
 

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