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- 25 Oct 2019
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Hi Everyone,
I have a Viessmann Vitodens 100-WB1B 26Kw combi boiler in a 2 bed flat with 1 shower. Hot water in taps and shower used to fluctuate and was never quite hot. In Jan of this year it triggered a F2, so I had a plumber in who said the DHW heat exchanger was blocked likely due to sludge in the CH side. So I got it replaced and had a mag filter and lime scale reducer installed at the same time. Things were ok after that.
Then last week, the hot water temp started fluctuating again, where it would get hot in the shower for 2 min then drop to lukewarm for a min and then back up. I went over to the boiler and could see it firing at 65C then going up to 85C. At that point it would shut off but the temp on the screen kept going up to 104C. It would then drop to 65C and refire. And this morning it finally caused the F2 lockout. Engineer came by and said 2 hrs later the internal temp in the heat exchanger is still 117C.
My mains pressure is 4 bar, and I had the boiler set to 1.7 bar. Could it be the DHW heat exchanger is gone again this quickly? Or an issue with the pump or PCB? Am wondering if its worth fixing or do I need to just take it on the chin and look at getting the boiler replaced? I suspect its 7-8 years old (previous owner didn't leave any documentation).
Thanks
I have a Viessmann Vitodens 100-WB1B 26Kw combi boiler in a 2 bed flat with 1 shower. Hot water in taps and shower used to fluctuate and was never quite hot. In Jan of this year it triggered a F2, so I had a plumber in who said the DHW heat exchanger was blocked likely due to sludge in the CH side. So I got it replaced and had a mag filter and lime scale reducer installed at the same time. Things were ok after that.
Then last week, the hot water temp started fluctuating again, where it would get hot in the shower for 2 min then drop to lukewarm for a min and then back up. I went over to the boiler and could see it firing at 65C then going up to 85C. At that point it would shut off but the temp on the screen kept going up to 104C. It would then drop to 65C and refire. And this morning it finally caused the F2 lockout. Engineer came by and said 2 hrs later the internal temp in the heat exchanger is still 117C.
My mains pressure is 4 bar, and I had the boiler set to 1.7 bar. Could it be the DHW heat exchanger is gone again this quickly? Or an issue with the pump or PCB? Am wondering if its worth fixing or do I need to just take it on the chin and look at getting the boiler replaced? I suspect its 7-8 years old (previous owner didn't leave any documentation).
Thanks