Post and beam

We have just had a planning department concern about our planned install of a 7kW Vaillant. They have siad we dont have permitted development rights because it was not included in our submission. It was clearly shown on the drawings as located on the south side of the house. Regardless, the only question i cannot yet answer from the Class G requirements is the size of the compressor. I have seen this written down somewhere and am currently scanning all the Vaillant literature i can find. But does anyone have a link to where i might find this parameter please? Thanks as always keith

You were not there and you are incorrect. I did not express to him the views that i have here. He offered his own opinion that we should not need to alter our home to suit the boiler. Whether this is a good or bad strategy is another question.

I believe it is clear what the observed issue is. I believe that to all practical standards it is not likely to be possible to detect if the CH water experiences the same pause to heating. And in any case the engineer has confirmed what he does observe and why. He said himself that opening TRV's ( at least one) does stop the issue at the hot water taps. He also agreed that changing our house heat behaviour, while effective, is not the answer to the problem and that the boiler should be able to cope with how we want/need to live. But that Worcester Bosch would not be offering to replace the device for this scenario.

The 'error' is me having cold shower water. Whether or not the central heating is being presented with no hot water supply on some occasions is, as previously stated, invisible to me and probably to anyone. This is true. Engineer demonstrated this when he was at our house. By opening the bathroom towel radiator TRV fully the issue did not occur during tests.

I maintain that it is indeed unsophisicated. Becuase... The control algorithm cannot cope with this. Remember, nothing i am doing is outside of the published operating parameters of the boiler. Forget whether or not my house is poorly insulated ( it is). or i have too many TRV's, or i dont want to run at a higher temperature in the house to mitigate the over production of hot water.

Agree But that means us having to modify our chosen living conditions to suit an unsophisticated combi boiler. Mind you, i doubt Worcester Bosch are going to do anything about it so perhaps that is what i will have to do. One thing is for certain, there wont be a combi in the new build.

Of course. In the winter if it goes below zero then it needs to be 82 degrees. Funnily enough thats why i had it set at 82 Degrees. Today 76 degrees is probably too much and i will be returning it to 70 until probably November. John: i appreciate your efforts but i dont understand why the long sentence above. We have already discussed at length that Worcester Bosch cannot explain or fix the fact that in the winter months at least they cannot reliably deliver both CH and DHW without sometimes leaving us with cold water for washing. We know what is happening. They cannot fix it.

No. To be honest i think the boiler that it replaced 3 years ago, at 34 years old, heated the house better than this one. But until we build our new house this is what we have and it has the issues described.

Currently 76, was 82 through the winter because its a 1986 house.

Not sure if 'after' is the condition we experience. Most obvious and annoying is when we turn on the shower. It also happens when we open any hot tap in the house. The water remains cold. So ' after using DHW constantly' does not fit our experience. Remember this is only every few weeks it might happen, it is not an everyday or every occasion condition. I do not know what the actual flow temperature out of the tap is. i will measure it. It is set for 55 degrees.

I have very definitely stated that it is blocking code 2965. And it does clear after about 4-5 minutes. There has never been an actual 'error' code on this boiler that would require a manual reset.

I doubt i would ever be aware of it, dont even know how i could be aware of it. If the radiators were not receiving hot water for 4 minutes the effect would most likely be undetectable.

As an untrained punter( and, the customer ) this is my view. I repeat what i said previously. The boiler documentation says it can heat to 82 degrees if required. It should be able to give hot water for bathing in parallel.

No its 15mm. But the PID algorithm controls the physics. My contention is that if the boiler cannot do what i need it to then it is deficient. I am not after all asking it to do anything odd. Specifically, heat a 1986 vintage 3 bed semi and deliver hot water when asked. The boiler manual does say that in older houses it might be necessary to set the temp to as much as 82 degrees C. There by recognising the need. It does not say ' but we wont always be able to give you hot bathing water if you do'

Not to me. The engineers can see them. The previous engineer in january denied that they are time stamped, which i find unbelievable. Mondays engineer said that error codes and blocking codes are time stamped but that it is ' days since last reset' in some format. so not easy to decipher. Probably why the january engineer said what he did. By the way the boiler is a Greenstar 4000 rated at 25kw. Mondays engineer did say that when it fires up it will be at a % of max that makes the modulation very difficult when engaged water is low. Low as far as the boiler wants to see anyway.

With respect i disagree. The boiler should be able to deliver the needs of my house and its occupants. In fact the engineer agreed and said that we should not have to bend to the will of the boiler. If the house is warm enough by the criteria we set that that is how the house operates. Stone cold showers every now and again are not part of my expectations.

Yes, basically. It appears the boiler overshoots its upper limits and goes into a blocking mode for perhaps 5 minutes. My thoughts are that this is a failure of the P.I.D algorithm not being very sophisictaed, well not sophisictaed enough. The code is very specific '2965' to be precise.

All but 2 yes

This is a traditional 1986 house with a gas boiler and radiators.

I agree which is why i made the comment about software engineers. Little point in me demanding a replacement boiler under the warranty. But i will use this to try to get some kind of software update. However, i think we are on their latest and if they dont have a better algorithm then i am screwed until/unless they do.

Knowledgeable Worcester engineer visited this morning. Nothing to do with cross bleed via the mixers ( didn't believe it was) and apparently nothing to do with flow switch ( i thought it likely was). Basically it comes down to the PID control of the heater when water temperature is falling just below the set point from an already high winter set point temperature. It does not appear to be able to modulate enough to prevent overshoot of the target. A greater engaged water volume in the radiators would allow the excess temperature to have somewhere to go. Upshot is a high temp 'blocking code' that needs about 3-4 minutes before it will allow any more heat to be produced. Bloody software engineers.

I do have a reported crossover bleed issue. Have you watched the video? I cannot see how a bleed over can reduce the boilers sensed temperature down to the same as what comes in directly off the street. And, why that low temperature does not induce the boiler to fire up. This makes no sense to me. I can imagine the possibility of an affect on the shower supply temperature via a bleed over to a lower than desired delivery temperature. But the onserved scenario i cannot imagine.

Really. We are hoping to start our Potton home soon and that is SIP's with a brick skin ground floor and Cedral cladding on the upper. No other insulation anticipated.

Hi John Mo Central heating temp is this high becuase i have not turned it down from the winter. This is still in our current house of 1986 Vintage, not a new build. Yes when it plays up it is all outlets its just that the shower is the most obviously annoying place for it to leave us with freezing cold water. When my furious playing around with everything on the boiler display eventually gets it to fire up it will be good for perhaps a couple of days or weeks. The flow switch was replaced a year ago on a previous engineer warrany visit. Pressure is very good so i doubt its flow related but who knows. The most recent engineer tried to claim that it the boiler was behaving perfectly normally, ( on watching the video) because ' you called for heat and it fired up'. Seriously? Dont know anything about a 'combi save device' Thanks keith

Youtube link: = https://youtu.be/GuhOogbQo5o I am having an argument with Worcester Bosch about this boiler that has misbehaved almost since day one. Occassionally it refuses to fire up when asked to give hot water. I believe the nonsense their technical people are giving me is them trying to wriggle out of their warranty obligations. So i would very much appreciate the opinions of people that know what they are talking about. If i am wrong please feel free to shoot me down.