Vaillant boiler coming on then dying

[Mottie]

Dunno why you’re getting so uppity. You mentioned a landlord so I assume you are renting and the boiler is not yours. If it’s not yours, I doubt very much in whether you’ll have a say in whether it’s repaired or replaced. If it’s replaced, again, I doubt whether it will be your decision as to what it’s replaced with.

Just tell the landlord it’s not working and leave it to him to sort out.

 

[TheGirl]

Could discount the pump, but check the pump speed - should be lit up on the front. Also those valves don’t look fully open

This is a better picture. I will check pump speed later- my worry is if it's increased, that very loud vibrating sound which transfers to other rooms will return. I am not sure where the valves are but if they are fully open does this contribute to the boiler firing up consistently without shutting off?

 

[martygturner]

The system gets flushed by draining it down and then refilling it...2 or three times till the water runs clear.

You cannot really go to boiler faults until you have a reasonably clean system...it could be anything...temperature probe, blocked heat exchanger, faulty 3 port valve, pump iffy, faulty tank thermostat.....list goes on and on.

I would stop reading so much...evidently the open vented system you have is not working...so i would start by looking at what can be got in to give you heat and hot water as soon as possible....start screaming fix it. If its not yours its not your issue if it leaks, it will be pressure tested before its connected and lets face it...a new boiler will be saving you a small fortune...don't put roadblocks up for problems you don't even know exist.

 

[CBW]

This is a better picture. I will check pump speed later- my worry is if it's increased, that very loud vibrating sound which transfers to other rooms will return. I am not sure where the valves are but if they are fully open does this contribute to the boiler firing up consistently without shutting off?

If its increased and the noise returns then there’s an issue of a possible blocked system, power flushes aren’t the be all and end all. The valves are the brass connections either side of the pump, if it’s overheating because they’re not fully open then this can result in firing up and shutting down, especially if it’s getting too hot too quick.

 

[TheGirl]

Thank you very much for the advice martygturner. I think I found it difficult that the tradesman was giving me wrong information because my decision making is then based on that and also it means he's not qualified to give the correct advice and so every future work is not carried out well. This means I have to spend more time fixing someone else's errors. Which is why I am here- if I am given incorrect info, I can say 'well, actually, my learned friends have suggested this, this and this...'

I hope this makes sense. I'd love an easier life but I seem to find my time is being spent correcting other people's mistakes.

 

[TheGirl]

If its increased and the noise returns then there’s an issue of a possible blocked system, power flushes aren’t the be all and end all. The valves are the brass connections either side of the pump, if it’s overheating because they’re not fully open then this can result in firing up and shutting down, especially if it’s getting too hot too quick.

Thank you very much CBW. We have had this new pump around 7 months. It is only in the past week the boiler fires up and then turns itself off. I wonder if the pump is fine, otherwise issues would have been apparent earlier?

 

[TheGirl]

The system gets flushed by draining it down and then refilling it...2 or three times till the water runs clear.

You cannot really go to boiler faults until you have a reasonably clean system...it could be anything...temperature probe, blocked heat exchanger, faulty 3 port valve, pump iffy, faulty tank thermostat.....list goes on and on.

I would stop reading so much...evidently the open vented system you have is not working...so i would start by looking at what can be got in to give you heat and hot water as soon as possible....start screaming fix it. If its not yours its not your issue if it leaks, it will be pressure tested before its connected and lets face it...a new boiler will be saving you a small fortune...don't put roadblocks up for problems you don't even know exist.

Thank you very much for the advice martygturner. I think I found it difficult that the tradesman was giving me wrong information because my decision making is then based on that and also it means he's not qualified to give the correct advice and so every future work is not carried out well. This means I have to spend more time fixing someone else's errors. Which is why I am here- if I am given incorrect info, I can say 'well, actually, my learned friends have suggested this, this and this...'

I hope this makes sense. I'd love an easier life but I seem to find my time is being spent correcting other people's mistakes.

 

[martygturner]

I do understand but again I would suggest for your own sake put the pressure where its due...on the landlord. If you step in then the landlord could point to you as having brought the issue on yourself...ie she has been fiddling with it defence. I personally would log all contact with the landlord or agent, email them rather than phone or confirm a conversation afterwards by email.Its the landlord's statutory duty to ensure heating and hotwater....

The trouble is we could be actually doing you a disservice...its not your job to correct the tradesperson, mad as it sounds, its your job to say OI its not working fix it...now...as I am paying for it. Otherwise you will be part of the its not working loop....the only acid test is does the heating work when you need it and does the hw work when you need it....if now OI fix my CH...now. That way you can escalate it....

Start with the basics...ask to see the gas registration of the service chap, make sure there is a gas safety inspection in place, make sure its been regularly serviced. Log all problems with the landlord...if its not fixed complain...us landlords just want an easy life....honest.

 

[TheGirl]

I do understand but again I would suggest for your own sake put the pressure where its due...on the landlord. If you step in then the landlord could point to you as having brought the issue on yourself...ie she has been fiddling with it defence. I personally would log all contact with the landlord or agent, email them rather than phone or confirm a conversation afterwards by email.Its the landlord's statutory duty to ensure heating and hotwater....

The trouble is we could be actually doing you a disservice...its not your job to correct the tradesperson, mad as it sounds, its your job to say OI its not working fix it...now...as I am paying for it. Otherwise you will be part of the its not working loop....the only acid test is does the heating work when you need it and does the hw work when you need it....if now OI fix my CH...now. That way you can escalate it....

Start with the basics...ask to see the gas registration of the service chap, make sure there is a gas safety inspection in place, make sure its been regularly serviced. Log all problems with the landlord...if its not fixed complain...us landlords just want an easy life....honest.

Thank you for your considered response, Marty.

From my end, I would like there to be less issues that I have to deal with and that usually means saving the landlord money. I have found that the more new works are carried out, the more errors I've had to fix. Which ends up costing the landlord more money.

By having more knowledge of how a system is supposed to work, I can spot bad advice and prevent costly mistakes and at the same time save myself time. That's all I want: to free my mind, my time and be better informed. The landlord is slow but not so bad- it's the third party advisors who tend to be the kink in the cog. The landlord relies on them for good advice. And because I'm a girl and look young, they tend to think they can get away with a lot.

I will do as you suggested regarding email communication and OI!

But please, everyone, keep all your messages coming. Knowledge is wonderful.

 

[TheGirl]

As an update: The reason the boiler can't remain on when it tries to fire back up is because on the display you can see the temperature rapidly rise from say 40 degrees Celsius to 65/66 within 5 seconds and so it shuts down immediately as it thinks it's reached the set temperature. It seems it can't understand what the temperature of the room is.

 

[JonathanM]

As an update: The reason the boiler can't remain on when it tries to fire back up is because on the display you can see the temperature rapidly rise from say 40 degrees Celsius to 65/66 within 5 seconds and so it shuts down immediately as it thinks it's reached the set temperature. It seems it can't understand what the temperature of the room is.

It's actually unrelated to the room temperature. The boiler can only measure the temperature of the water passing through its heat exchanger. It sounds like the water passing through is getting hot very quickly. This can be because not enough water is passing through. When only a small amount of water passes through, it heats up very quickly, and reaches the set temperature, and the boiler turns off, because it thinks its done its job. (Some people say this issue can be exacerbated on your particular boiler model, because they can take longer than some other boilers to modulate, or throttle down, to a lower burn level.)

If the reason is poor flow through the boiler, the answer would be to find out why. And why has it just started happening. It can be because the pump speed is too slow, but that speed was changed months ago. Or it can be that the heat exchanger is partially blocked. And there might be other reasons.

When the tradesman put the F3 in 7 months ago, what did he actually do? Did he just pour it into the tank in the loft, and leave it?

 

[TheGirl]

It's actually unrelated to the room temperature. The boiler can only measure the temperature of the water passing through its heat exchanger. It sounds like the water passing through is getting hot very quickly. This can be because not enough water is passing through. When only a small amount of water passes through, it heats up very quickly, and reaches the set temperature, and the boiler turns off, because it thinks its done its job. (Some people say this issue can be exacerbated on your particular boiler model, because they can take longer than some other boilers to modulate, or throttle down, to a lower burn level.)

If the reason is poor flow through the boiler, the answer would be to find out why. And why has it just started happening. It can be because the pump speed is too slow, but that speed was changed months ago. Or it can be that the heat exchanger is partially blocked. And there might be other reasons.

When the tradesman put the F3 in 7 months ago, what did he actually do? Did he just pour it into the tank in the loft, and leave it?

Thank you for connecting the dots JonathanM. To answer your question: yes, he came in with the F3. Poured the whole bottle in the water trough in the loft and left. He said it would take between a week and one month for the noise to reduce. It did but the boiler still kettles.

That's right the pump was changed 7 months ago and a few days later the speed reduced. It was two months after the F3 was added to the water trough that the pump was replaced because the kettling sound still existed. And the supervisor who visited said that if that didn't work, the next step would be to change the heat exchanger. That still hasn't been done as I didn't chase it up.

Regarding not enough water passing through and so it heating quickly: when I first switch on either the heating or hot water, the temperature very slowly increases. So this morning, it took the hot water ten minutes to get up to above 60 and then it switched itself off, tried to fire back up, couldn't. This evening, when I turned on the heating, I stood in front of the display for the entire hour (ouchy!). It took 27 mins to slowly, slowly climb up to above 63 degrees C. At this point, it turned itself off, temperature went down to around 40. It tried to fire back up- it did- and under 5 secs it had reached 67 degrees and immediately turned itself off. Same thing happened one more time. So that's 30mins of the boiler not being on out of an hour even though it's switched on from the console. I'm assuming the same thing is happening with the hot water. So, I wonder, if there is not enough water passing through, wouldn't it behave the same way the first time either the hot water or heating is switched on?

 

[JonathanM]

So, I wonder, if there is not enough water passing through, wouldn't it behave the same way the first time either the hot water or heating is switched on?

When it fires for the first time, it's starting from a much lower temperature, so the water going through it takes longer to heat up to the set point. The other thing which will probably be happening, is that the boiler will be modulating down to its lowest setting. So, it will be heating the water much more slowly. When it fires for the second time, there isn't time for it to modulate, before it cuts out.

 

[TheGirl]

When it fires for the first time, it's starting from a much lower temperature, so the water going through it takes longer to heat up to the set point. The other thing which will probably be happening, is that the boiler will be modulating down to its lowest setting. So, it will be heating the water much more slowly. When it fires for the second time, there isn't time for it to modulate, before it cuts out.

Thank you, this is a little more technical but I will think it over to try and understand.

What I understand, though, is that potentially not enough water going through the boiler could be the problem. How should the water going through the boiler be increased to prevent this? And if this doesn't work, do you recommend the heat exchanger being replaced before any other big changes?

You also asked about the tradesman and whether he did anything after pouring the F3 in the water trough. What did you interpret from my answer?

I hope my questions are not annoying, I'm really interested in all this stuff.

 

[Mister Banks]

Is the feed and expansion tank in the loft full of water and if it is have you checked the pipe feeding the heating system isn't blocked. If there isn't any water then has the ballcock failed.