I have a c/h system with a Vaillant Ecotec Plus 418 system boiler. The boiler has one water circuit which is externally divided for rads and water by 2 motorised valves. The system is open vented.
Most of the system is pretty old, was here when we moved in about 12 years ago, and probably dates from the 60s or 70s. We had to replace one radiator about 4 years ago when it started leaking along a seam.
The boiler was installed 2 years ago, and the installer flushed all the rads except the relatively new one by taking them outside and hosing them. He didn’t power flush it.
It seemed to run OK at first, then it started to have problems, the boiler kettling and shutting down, which was traced to the pump having deteriorated. Replacing the pump got it going again. The heating engineer said the pump had got a lot of muck in it (and I think he implied some of it might have been from the pump itself breaking up).
After it had been in about 6 months, the boiler started shutting down again (either with status code S53 on cold start-up, or anti-cycling when hot). The heating engineer cleaned out part of the system around the pump, and fitted a new pump, and it fixed it again. He also fitted a Y filter, but this got clogged up pretty soon and stopped the system working, so I had it replaced by a magnaclean filter.
The filter picked up a quantity of grey metallic flakes, but there doesn’t seem to be much fine sludge.
The magnaclean filter was fitted horizontally, which another engineer was later dubious about. It’s hard to tell from the installation instructions, but the filter is the highest point in the system, and the bleed valve is on what would normally be the top, which is therefore halfway up the side of it.
About a year later (i.e. 6 months ago), the symptoms returned. In addition the system was making a noticeable humming noise, present even when the boiler had switched off and only the pump was running, and I called out a Vaillant engineer who said he thought the heat exchanger might be scaled up, and that it needed some kind of scale remover left in it for several days (or maybe weeks?) to get it clean again. My understanding (from the Vaillant engineer) of the S53 status failure is that the boiler switches itself off because the flow temperature rises too high relative to the return temperature because of poor flow through the heat exchanger. The Vaillant engineer turned the (Grundfos) pump from 2 to 3 to improve it a bit.
He recommended a heating engineer. The heating engineer power flushed the system, saying that the power flush would do a better job than leaving scale remover in.
This got it working again. He turned the pump back to 2, saying that it overpumped through the header tank if set to 3 (although the header tank is in the attic).
I was quite happy that this had fixed it, as I’d always thought it should’ve been power flushed in the first place. I was a bit surprised 3 weeks later and again a month later when I cleaned out the filter and found those grey metallic flakes again.
Unhappily, now, 6 months later it is back as it was, giving S53 and stopping on anti-cycling – implying the flow is poor – and humming.
Can anyone diagnose what is wrong, suggest a way forward, or recommend a good heating engineer near Huntingdon, Cambs, UK? Clearly I want a definite fix, otherwise I’ll be anxiously waiting for it to stop working again. I’d be grateful for any advice.
Sorry this has ended up being a long story, but it probably helps having all the details.
Most of the system is pretty old, was here when we moved in about 12 years ago, and probably dates from the 60s or 70s. We had to replace one radiator about 4 years ago when it started leaking along a seam.
The boiler was installed 2 years ago, and the installer flushed all the rads except the relatively new one by taking them outside and hosing them. He didn’t power flush it.
It seemed to run OK at first, then it started to have problems, the boiler kettling and shutting down, which was traced to the pump having deteriorated. Replacing the pump got it going again. The heating engineer said the pump had got a lot of muck in it (and I think he implied some of it might have been from the pump itself breaking up).
After it had been in about 6 months, the boiler started shutting down again (either with status code S53 on cold start-up, or anti-cycling when hot). The heating engineer cleaned out part of the system around the pump, and fitted a new pump, and it fixed it again. He also fitted a Y filter, but this got clogged up pretty soon and stopped the system working, so I had it replaced by a magnaclean filter.
The filter picked up a quantity of grey metallic flakes, but there doesn’t seem to be much fine sludge.
The magnaclean filter was fitted horizontally, which another engineer was later dubious about. It’s hard to tell from the installation instructions, but the filter is the highest point in the system, and the bleed valve is on what would normally be the top, which is therefore halfway up the side of it.
About a year later (i.e. 6 months ago), the symptoms returned. In addition the system was making a noticeable humming noise, present even when the boiler had switched off and only the pump was running, and I called out a Vaillant engineer who said he thought the heat exchanger might be scaled up, and that it needed some kind of scale remover left in it for several days (or maybe weeks?) to get it clean again. My understanding (from the Vaillant engineer) of the S53 status failure is that the boiler switches itself off because the flow temperature rises too high relative to the return temperature because of poor flow through the heat exchanger. The Vaillant engineer turned the (Grundfos) pump from 2 to 3 to improve it a bit.
He recommended a heating engineer. The heating engineer power flushed the system, saying that the power flush would do a better job than leaving scale remover in.
This got it working again. He turned the pump back to 2, saying that it overpumped through the header tank if set to 3 (although the header tank is in the attic).
I was quite happy that this had fixed it, as I’d always thought it should’ve been power flushed in the first place. I was a bit surprised 3 weeks later and again a month later when I cleaned out the filter and found those grey metallic flakes again.
Unhappily, now, 6 months later it is back as it was, giving S53 and stopping on anti-cycling – implying the flow is poor – and humming.
Can anyone diagnose what is wrong, suggest a way forward, or recommend a good heating engineer near Huntingdon, Cambs, UK? Clearly I want a definite fix, otherwise I’ll be anxiously waiting for it to stop working again. I’d be grateful for any advice.
Sorry this has ended up being a long story, but it probably helps having all the details.
