Adsibob Posted January 15, 2022 Share Posted January 15, 2022 We have a Vaillant Ecotec 637 system boiler that is about 7 years old. Was working fine until last night when a leak at the local water main caused Thames Water to switch the water off for the whole street without warning. It was off for about 16h. When they turned the water back on this morning we noticed our boiler wasn't working. We tried turning the tap that feeds it with water, that didn't seem to do much. When we switch it on, the blue LED screen just flashes with the word "loading" coming up on the screen, as it makes an intermittent whirring sound. It doesn't progress beyond this and just keeps doing that until we switch it off. No actual error code, nothing in the trouble shooting area of the manual. Any ideas? Link to comment Share on other sites More sharing options...
ProDave Posted January 15, 2022 Share Posted January 15, 2022 Turning the WATER off would not normally stop a system boiler. You would of course get no hot water out of the tap. Did the electricity go off? did you turn anything off? Link to comment Share on other sites More sharing options...
Adsibob Posted January 15, 2022 Author Share Posted January 15, 2022 25 minutes ago, ProDave said: Turning the WATER off would not normally stop a system boiler. You would of course get no hot water out of the tap. Did the electricity go off? did you turn anything off? I agree, but No, we didn’t do anything. Link to comment Share on other sites More sharing options...
ProDave Posted January 15, 2022 Share Posted January 15, 2022 17 minutes ago, Adsibob said: I agree, but No, we didn’t do anything. My suspicion is the boiler just stopped and the malfunction has nothing to do with the water turned off. If contacting plumbers just say it has stopped don't confuse the issue. Link to comment Share on other sites More sharing options...
Radian Posted January 15, 2022 Share Posted January 15, 2022 Vaillant eco tec plus 837 continuously 'loading'... Quote +2 for pcb, don’t think I’ve known it to be anything else. I seriously Doubt that. Link to comment Share on other sites More sharing options...
Radian Posted January 15, 2022 Share Posted January 15, 2022 1 minute ago, ProDave said: My suspicion is the boiler just stopped and the malfunction has nothing to do with the water turned off. Maybe but what a coincidence! Just can't think of anything relating to water supply loss that could cause any kind of problem with a system boiler. Link to comment Share on other sites More sharing options...
Radian Posted January 15, 2022 Share Posted January 15, 2022 58 minutes ago, Adsibob said: When we switch it on, the blue LED screen just flashes with the word "loading" coming up on the screen Had you switched it off when the water went off? I mean - was it working, you switched it off, then the next time you switched it back on it wouldn't start up? Link to comment Share on other sites More sharing options...
Adsibob Posted January 15, 2022 Author Share Posted January 15, 2022 9 minutes ago, Radian said: Had you switched it off when the water went off? I mean - was it working, you switched it off, then the next time you switched it back on it wouldn't start up? No, we didn’t switch it off. We didn’t think to switch it off as the water went off without warning. Link to comment Share on other sites More sharing options...
Radian Posted January 15, 2022 Share Posted January 15, 2022 So what was on the display when you first noticed it wasn't working? Was it showing the "Loading" message? Link to comment Share on other sites More sharing options...
Adsibob Posted January 15, 2022 Author Share Posted January 15, 2022 6 minutes ago, Radian said: So what was on the display when you first noticed it wasn't working? Was it showing the "Loading" message? Not sure. I wasn’t in, the landlord popped in to take a look at it. He said he couldn’t fix it. I guess we will just freeze until Monday now. The flat is part of an 1890s block. Never been upgraded insulation or glazing wise. Link to comment Share on other sites More sharing options...
Radian Posted January 15, 2022 Share Posted January 15, 2022 Feel for you. Always happens on a weekend.? From what I've seen online tonight and from experience it's probably the switch-mode supply on the main PCB. These are often the weakest part - specifically the large 400VDC reservoir capacitor which often have a rated lifetime of as little as 2000 Hours. In practice this is a de-rating that continues over its lifetime so some margin is designed in to keep the thing going over its warranty period. But past that, the power supply becomes too erratic and odd faults like this crop up. The controller isn't even managing to boot the firmware that would identify and display a fault code. I've re-capped a few of these kinds of controllers before and there's a healthy market in refurbished ones like this as the fix can be done for as little as a couple of quid. Link to comment Share on other sites More sharing options...
CotswoldDoItUpper Posted January 15, 2022 Share Posted January 15, 2022 We had something similar with a similar boiler and it was something like the pressure switch. Simple £25 part from a decent plumbers merchant and a diy (with YouTube!) fix in about 15mins. We had an error code of f.75 I think. Hope it’s a simple fix for you! Link to comment Share on other sites More sharing options...
Adsibob Posted January 15, 2022 Author Share Posted January 15, 2022 Thanks all. Apparently Vaillant have an approved engineer call out service on a Sunday, so we will hopefully have it fixed tomorrow. Link to comment Share on other sites More sharing options...
epsilonGreedy Posted January 16, 2022 Share Posted January 16, 2022 5 hours ago, Adsibob said: No, we didn’t switch it off. We didn’t think to switch it off as the water went off without warning. My boiler needs to be powered cycled off and on at its mains 240v connection if an LPG bottle runs out of gas before it will fire up again with a fresh LPG bottle. Link to comment Share on other sites More sharing options...
Temp Posted January 16, 2022 Share Posted January 16, 2022 17 hours ago, Radian said: Maybe but what a coincidence! Just can't think of anything relating to water supply loss that could cause any kind of problem with a system boiler. Bit tenuous but it's the only thing I can think of.... Suppose there was some corrosion causing a weak spot between the pressurised side and the mains. Loss of main caused the pressure difference across the weak area to reverse causing failure. When mains restored pressure is then too high. But this would show up on pressure gauge or error code if boiler has over pressure switch. Link to comment Share on other sites More sharing options...
Pocster Posted January 16, 2022 Share Posted January 16, 2022 Diverter valve or solenoid for sure ? Link to comment Share on other sites More sharing options...
Radian Posted January 16, 2022 Share Posted January 16, 2022 2 hours ago, Temp said: But this would show up on pressure gauge or error code if boiler has over pressure switch. The boiler microcontroller appears to be fubar. Not getting past its boot-up and into the state where it can even report its own demise. Wondering if perhaps Thames Water also temporarily cut the local electricity supply either deliberately or accidentally. Power being applied to an SMPS is often the point at which it fails. Link to comment Share on other sites More sharing options...
Adsibob Posted January 16, 2022 Author Share Posted January 16, 2022 (edited) It’s a mystery, but it’s also a Vaillant boiler outside its warranty period, so no real surprises given I’ve never had a Vaillant boiler that didn’t start developing issues shortly after the warranty expired. Glad the new place has a Veissman! Couldn’t get an engineer out today, but we do have an appointment tomorrow. Hopefully being a Vaillant branded engineer, he/she will carry spares of whatever is needed. It is very cold tonight! Edited January 16, 2022 by Adsibob Link to comment Share on other sites More sharing options...
Adsibob Posted January 17, 2022 Author Share Posted January 17, 2022 14.5C in ours this morning. I actually thought it would get much colder with no heating. Link to comment Share on other sites More sharing options...
Happy Valley Posted January 17, 2022 Share Posted January 17, 2022 (edited) Surely the landlord that you mention should be sorting this out and ASAP as has a statutory obligation to provide space heating and hot water. A good landlord will provide a few plug in oil radiators temporarily. Edited January 17, 2022 by Happy Valley Link to comment Share on other sites More sharing options...
Adsibob Posted January 17, 2022 Author Share Posted January 17, 2022 Boiler has now been fixed. PCB and gas diverter valve both needed replacing. We had an immersion heater so we didn't lose hot water. Landlord is actually a close relative, so I can't really get annoyed with them! I guess it was just coincidence that this coincided with the water being shut off. Link to comment Share on other sites More sharing options...
Adsibob Posted January 18, 2022 Author Share Posted January 18, 2022 And it’s broken again. With a new PCB, we can at least see what error it is reporting. It seems to be so excited to have recovered that functionality that it’s reporting two: time to call out the engineer again! What fun it is having a Vaillant. 1 Link to comment Share on other sites More sharing options...
Pocster Posted January 18, 2022 Share Posted January 18, 2022 23 minutes ago, Adsibob said: And it’s broken again. With a new PCB, we can at least see what error it is reporting. It seems to be so excited to have recovered that functionality that it’s reporting two: time to call out the engineer again! What fun it is having a Vaillant. As you say , at least you have errors reported …. A temperamental boiler reporting no error codes is worse . Valiant engineers in my experience of using them for decades are usually pretty good . Link to comment Share on other sites More sharing options...
Radian Posted January 18, 2022 Share Posted January 18, 2022 Probably just needs air bleeding. Must have been drained down to replace divertor valve. Some naughty air still hiding in primary somewhere. Link to comment Share on other sites More sharing options...
MJNewton Posted January 18, 2022 Share Posted January 18, 2022 A Google search suggests that first error might be a loose/disconnected flow temperature sensor. Perhaps that itself might then also cause the second error? Link to comment Share on other sites More sharing options...
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