Vaillant boiler coming on then dying

[TheGirl]

With all due respect, it is not the tenants problem to deal with. It's the tenants job to simply report it to the landlord and leave it to the experts to deal with. There can be nothing worse than an ill informed tenant, peering over the shoulder of someone with expertise, and advising them to try this, that or the other, because they have read up on it, on the Interweb and know better than the expert.

This tenants time would be better spent pulling a list together of the symptoms, and handing it to the expert to deal with.

Good morning Harry, the list of symptoms is unfortunately not being taken into consideration. The most recent experience is of this past week when the junior contractor came out. This has unfortunately become my problem. I would like it not to be.

 

[TheGirl]

Yes!

Thank you, Harry.

 

[TheGirl]

For the record I think @Mottie 's response is the correct one. I find it irritating enough to go back to a customer's house to find problems caused by well meaning but incompetent relatives or neighbours; and that's even though I'd be paid to correct them. Your landlord may not react well if he/she believes you to have contributed to a problem. You may have read somewhere that such and such a boiler is better than a.n.other, but a simple Google search of 'such and such boiler problems' will no doubt contradict this in just about every case.

Leaving that to one side, and dealing with your landlord's heating problem, there appears to be a number of symptoms which have a common element to them, and that is low flow through the boiler.
Low flow can be caused by a poor pump performance; despite its newness, all circularing pumps are designed to pump water, not air.
If the loft (header) tank has run dry there will be a lack of water to pump.
If the feed pipe between loft tank and heating system is blocked the water from a fully functioning header tank can not get into the system, therefore leading to a lack of water to pump.
If the heating water if full of s.h.1.t.e (sometimes called sludge, or debris) then the pump will not pump it effectively, leading to low flow.
If the pump impellor is substantially blocked with debris released by a cleaning agent then it will not pump effectively; no prizes for guessing what that leads to.
If the hydraulic circuit that the pump is connected to is restricted there will be low flow.
The slower speed the pump runs at, the lower will be its flow output.
A pump impellor may become unbalanced by debris, and an unbalanced impellor will cause excessive vibration/noise.
If the boiler has a semi-blocked heat exchanger this contributes towards a restricted hydraulic circuit.

Do you need more convincing?
Read up on the specific heat capacity of water, and the relationship between Joules and Watts; then you can work out why low flow through the boiler leads to a rapid rise in boiler water temperature.

Now to the only piece of evidence that contradicts the low flow theory: the boiler display shows a slow temperature rise on first firing, but on subsequent firings the temperature rises rapidly.
Why doesn't it rise rapidly on first firing? Could it be that you (or the control system) turn the boiler power OFF overnight? This would invoke the boiler's slow start-up routine (if it has one, and here my knowledge of the Vaillant system is limited), which would effectively give it minimum power output (small flame size) for several minutes. This would not be the case for subsequent firings.
Could it be that loose debris falls away from the pump or boiler overnight, but re-collects at a narrow point once circulation re-starts (highly unlikely, but possible).
Could it be something else?

If you are determined to go on an evidence gathering exercise then I suggest the following actions:-

1. At first start-up feel (or better, measure) both the incoming water temperature (return temp) and the outgoing (flow temp).
Does the return temp warm up as the flow temp warms? Does it remain cool/cold?
2. Feel the temperature on the pipework between the pump and the 3-port valve. Does it also get hot rapidly as the boiler fires?
3. Bleed a little water from a radiator. Is it like coloured water, or more like mud?
4. Read up and learn how to change the pump speed. Does the vibration/noise correlate to pump speed? Is the pump set on a fixed or variable speed?
5. Read up on how to open a pump isolation gate valve, then make sure both pump valves are fully open.
6. Find the neutral point, where the cold feed from the header tank meets the system (usually just upstream of the pump). Will a fridge magnet attach itself to the copper pipe at that point?
7. Is there water in the header tank, and does it resemble mud? Is its level a couple of inches above the cold feed outlet pipe?
8. Is the water surface in the header tank lower than the level in the (larger) domestic cold water storage tank?

These are all relevant actions, and should lead to good evidence gathering for your landlord or his contractor, though I reiterate that @Mottie was right, and there was absolutely no need to rear-up at his advice (given freely in his own time).

MM

Good morning MeldrewsMate,

Thank you for this very detailed response, it's very welcome and I know it would have taken time to write.

I am not a professional tradesman or even an amateur one, just to assure you that nothing is being touched by myself or anyone else other than a tradesperson. This means that I would not be able to carry out most of the checks myself and will have to rely on the tradesman.

Regarding the investigative list above- the contractor is in and out, usually. I am certain they will not do most of these checks. But it is super information for me as it means I can independently understand what is happening. It is my preference to keep the existing boiler even with its limitations. Why? Because from my experience with this contractor, something will likely go wrong if they install a new boiler and that will be a new headache to deal with. And it will be myself that will have to deal with it.

To answer your question: the Drayton console does not come on at set times throughout the day. I switch it on and off when I need it and so that means that it is switched off from the console overnight.

If the cause is low flow, what is the remedy? And would it be more time/cost effective to replace the boiler rather than carry out the remedies?

 

[TheGirl]

Good morning all.

I think what is not being understood is that because of inattentive workmanship on the third party's side my time and energy is being consumed chasing up bad advice, followed by bad work, followed by more costs to the landlord because of the bad advice and bad work.

My motivation is: to look after the property to minimise unnecessary work and as a result of this care save myself crucial time and energy. This time and attention on my part benefits the landlord.

The landlord is less informed than myself and from the answers I have received from the valuable responses on this portal the past few days, I can see that the junior contractor is giving me incorrect input and also carrying out the work substandard. His superiors are not stepping in and the landlord is none the wiser as to what is going on. Or maybe the landlord is. And is okay with the contractor taking cheaper short cuts. This is information I am not privy to. But as with all shortcuts, the road leads to nowhere good.

It seems that had a power flush been carried out in a correct manner, I might not be on this forum at all. I am a team player and want to work with both the landlord and the contractor to get the best and most cost effective result. If the contractor is not diligently doing their job and my time is being wasted in chasing up, this results in extra work having to be carried out. Which serves neither myself nor the landlord.

 

[Mottie]

Let the contractor do their job. If it doesn’t work, tell the landlord. Get them back again. Keeping on paying for visits is not the cheapest option for the landlord. You could perhaps suggest to the landlord they get another contractor if this one is unable to do the job but as a tradesman myself, I’d be inclined to give the royal runaround to a clueless customer that asks me to do a job and confronts me with how it should be done as advised by strangers on an internet forum.

 

[Justin Passing]

Ooof.
I can think of a number of things which could be causing this problem which haven't even been mentioned here. That's without getting into the obscure things which can happen. Oldish installations are likely to have more than one thing sub-optimal.
Your "tradesperson" will not have discussed everything they've thought of and checked, with you, because they'd then have to go into a round of explanations.

Anybody can be stumped, but it's pretty unlikely the problem will be isolated by internet forum. I mean eg if you've got a swollen squidgy rubber ball .... it would take a paragraph to explain and it's rare, but can be checked in seconds on site.

If your man/woman hasn't found it, and the landlord actually listens to you, you could suggest a Vaillant engineer comes out to it. They would rule in/out a high percentage of possibilities in minutes. By all means make a list of what's been done like the pump change and whether it helped, but after offering tea and biscuits, tell them you're intetested to know but then leave them alone!

Good luck .

 

[TheGirl]

Ooof.
I can think of a number of things which could be causing this problem which haven't even been mentioned here. That's without getting into the obscure things which can happen. Oldish installations are likely to have more than one thing sub-optimal.
Your "tradesperson" will not have discussed everything they've thought of and checked, with you, because they'd then have to go into a round of explanations.

Anybody can be stumped, but it's pretty unlikely the problem will be isolated by internet forum. I mean eg if you've got a swollen squidgy rubber ball .... it would take a paragraph to explain and it's rare, but can be checked in seconds on site.

If your man/woman hasn't found it, and the landlord actually listens to you, you could suggest a Vaillant engineer comes out to it. They would rule in/out a high percentage of possibilities in minutes. By all means make a list of what's been done like the pump change and whether it helped, but after offering tea and biscuits, tell them you're intetested to know but then leave them alone!

Good luck .

I think the challenge is that, as an example, other than the pump being checked on the tradesman's recent visit when the boiler issue started, no other checks were carried out. In and out. Less than 10 mins. Which means none of the observations I've catalogued have been noted and none of the investigative tests MeldrewsMate suggested were carried out (other than looking at the pump). It would be wonderful if that was not the case.

I appreciate the Vaillant suggestion and as I am interested in learning would be pleased to hear the other issues that have not been mentioned. Thank you for the good luck wishes.

 

[MeldrewsMate]

I don’t know why this topic has annoyed you so much, but clearly it has....The OP has already reached the point where she knows the problem is low flow, without the need for comments which are supercilious, patronising and overbearing.

Dear @JonathanM , it is often difficult to gauge the mood of the writer in a forum, so it was not clear how clearly I was annoyed; I was not annoyed at all, but going over the same list of subjects repeatedly, and asking for definitive answers from people who are not gathering evidence/symptoms first hand means that many here are wading through prose unnecessarily. My (long!) response was to give the OP some good reasons for the main symptoms she (or he!) was describing; there are many possibles, and elimination of the possibles which don't fit the symptoms is one quick way to home in on the actual problem.
Annoyed? No. Slightly irritated at the distractions from the obvious? Yes....and that's all.
My supercilious, patronising, and overbearing (your interpretation only) comments were merely to help concentrate the OP's thoughts towards the right path, including the last suggestions that he/she could help by gathering accurate and relevant data for whomever is charged with the repair. The skilled gas fitter will reject and verify as appropriate, the numpty repairer will ignore all external help in favour of his/her own diagnosis.

COME ON ENGLAND!!!

 

[MeldrewsMate]

...If the cause is low flow, what is the remedy? And would it be more time/cost effective to replace the boiler rather than carry out the remedies?

The remedy is to increase the flow through the boiler. The method used to achieve this depends entirely on the fault which causes the low flow.
I think you read my detailed list, giving my opinion on the possibilities, it is the contractors job to determine which of the many faults HAS CAUSED your low flow.
It is not for me on an internet forum to suggest that a new boiler is the solution, because there are many reasons why it may not be the boiler.

I have read here that someone suggested your landlord gets Vaillant in to check it. The outcome of that may be equally frustrating if Mr Vaillant leaves after determining that 'it's not our boiler's fault'. You and your landlord need someone who will deal with the whole problem to determine the best course of action to restore your heating system.

 

[TheGirl]

The remedy is to increase the flow through the boiler. The method used to achieve this depends entirely on the fault which causes the low flow.
I think you read my detailed list, giving my opinion on the possibilities, it is the contractors job to determine which of the many faults HAS CAUSED your low flow.
It is not for me on an internet forum to suggest that a new boiler is the solution, because there are many reasons why it may not be the boiler.

I have read here that someone suggested your landlord gets Vaillant in to check it. The outcome of that may be equally frustrating if Mr Vaillant leaves after determining that 'it's not our boiler's fault'. You and your landlord need someone who will deal with the whole problem to determine the best course of action to restore your heating system.

Update: without carrying out any checks, they- not exactly sure who 'they' are- have decided that the heat exchanger will be replaced.

Thank you for the information about the low flow. It's very helpful.

 

[TheGirl]

Dear @JonathanM , it is often difficult to gauge the mood of the writer in a forum, so it was not clear how clearly I was annoyed; I was not annoyed at all, but going over the same list of subjects repeatedly, and asking for definitive answers from people who are not gathering evidence/symptoms first hand means that many here are wading through prose unnecessarily. My (long!) response was to give the OP some good reasons for the main symptoms she (or he!) was describing; there are many possibles, and elimination of the possibles which don't fit the symptoms is one quick way to home in on the actual problem.
Annoyed? No. Slightly irritated at the distractions from the obvious? Yes....and that's all.
My supercilious, patronising, and overbearing (your interpretation only) comments were merely to help concentrate the OP's thoughts towards the right path, including the last suggestions that he/she could help by gathering accurate and relevant data for whomever is charged with the repair. The skilled gas fitter will reject and verify as appropriate, the numpty repairer will ignore all external help in favour of his/her own diagnosis.

COME ON ENGLAND!!!

I was very grateful to JonathanM for sticking up for me. He understood why I was here and my purpose and was very respectful towards me and one of the first responders who provided helpful assistance. I also appreciated your very detailed response MeldrewsMate which I have found immensely useful. I thank you both, alongside a few other responders, for assisting and guiding me.

 

[jeff the gasman]

My money’s on magnetite.

 

[TheGirl]

My money’s on magnetite.

Could you please expand Jeff the gasman?

 

[TheGirl]

I was thinking about when this issue started. Throughout the seven month period with the new pump the weather was warmer. Only the hot water was on for thirty minutes every morning. It is since the weather has got colder and the heating has been switched on, too, that the boiler has started shutting down and not firing back up.

 

[CBW]

Could you please expand Jeff the gasman?

Magnetite