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Has anyone seen this problem before? Huge anticycling times

cg360 · 2023-11-29T19:55:14Z

Hello, after an incredibly frustrating 18 months with a Vaillant heat pump and facing our second winter without reliable heating or hot water I stumbled across this forum! My problem is I have a Vaillant heat pump which will not function as it should. It reports low water pressure when the pressure seems fine, continually blocks the compressor and throws up the same five faults on every occasion. The first is low water pressure, then sensor input, output etc. But the thing that puzzles me is that when the compressor is blocked (which I understand is not a 'failure'), the pump reports an anticycle time off between 65,000 and 85,000 minutes - getting on for six months! The faults are: F703 - low pressure F585 - sensor fault capac. outlet temp F520 - sensor fault building circuit flow temp F519 - sensor fault building circuit return temp F73 - building circuit water pressure The fault goes away if I turn off the house mains and switch it back on. But how long it will work for is another question. I've reset the mains seven times today just to heat the hot water. I want the heat pump to work, but if even Vaillant can't get it to function properly... It's currently more work than keeping my wood stove going and far more inconvenient! It's a Vaillant Aerotherm, feeding radiators (sized by the installers and appropriately upsized), with a solar power system feeding in during the day. That's on its own distribution board, not the same one as the pump. We have good water pressure here and there are two similar pumps running in the village using the same water supply. I have spoken to Vaillant more times than I count. Engineers from the installers and valiant themselves have visited on more than a dozen occasions, replacing parts, fixing wiring - the same faults always recurs. The engineers are stumped. They've never seen these faults occurring. The regional manager is coming out on Monday and I would just like to have some idea if anyone has ever seen anything similar, for whatever reason. I feel like I'm being fobbed off.

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Air Source Heat Pumps (ASHPs)

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jamesh

(@jamesh)

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Joined: 5 months ago

Posts: 6

20/11/2025 3:07 pm

For the information of others. Vaillent came today, checked everything and decided to change the electronic circuit board in the machine. Hopefully this is a final fix and it's not all good - as winter is just about to hit properly.

🙏

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