EinTopaz

Hi all, Noticed something I thought was odd on our bay windows, and wanted to check for sanity. Wasn't sure if this was best in the roofing or Window sub category so will delete and re-post if this is in the wrong place, apologies if so. Anyway, Two of our ground floor bay windows are this sort of setup, where the brickwork beneath them projects out from the property with the window, but the brickwork above the bay window does not. I was looking at having the Windows,fascias and soffits replaced and on inspection earlier today I noticed the area directly above the window appears to be a recess, where the brickwork just stops. Its hard to see clearly without ripping off the soffits etc. But my question is, if I was to remove the soffits and fascias and all the little 'roof' section above the bay window here, if it was 'built' properly should I expect to see a lintel on the inner skin and the rest just solid brick work? Or is it correct to have a big recessed void between the brickwork above where the baywindow is? Tried to draw what I'm describing on my phone on the image below. Red is where the bricks carry on, blue void. Cheers Ged

Ok, so First things first, when The boiler is set back to factory defaults, my defaults are not the same as what's in the manual. My defaults are 2-A1 = 0 2-A2 = 1 In this configuration I don't get the option for 2-A3 or 2-A4. 2-A1 makes sense, I don't have a LLH. But 2-A2 have manually set to 0 because i dont have any hot water linked up to this boiler, no cylinder, no DHW, just central heating. When I set 2-A2 to 0, Magically I get the option then of 2-A3 being available. But it only gives me the options 0 and 1 in there. Which is completely inconsistent with the manual. in the manual there isnt even an option for setting "1" in 2-A3 Also, in 2-A2, i get the options of 0, 1 or 3..... which again is inconsistent with the manual, no idea what option 3 is in 2-A2 2-A4, no matter what I set in 2-A1, A2 or A3.... I can never get 2-A4 to appear, so I simply ignore it. SO yes, its a complete and utter mess. WB have told me to just try different configurations with it. And I have. But its never made any sense to me any of this. I've tried these configs below A1 - 0 A2 - 1 ------ A1- 0 A2 - 0 A3 - 0 ------ A1-0 A2-0 A3-1 None seemed to make a massive difference.

Hey guys, sorry ive been away for a few days. Yes one more update, i've been running it at different pump speeds to see which I like best. First set of data logging I tried was pump speed 6 (400mbar constant pressure). This was the setting it tripped on on Xmas day. I since tried pump speed 4 (300mbar constant pressure) it didn't trip out on this setting and didn't seem to take much longer to heat the rads up. Though the dt was 5c greater for most of the operation compared to pump speed 6. Yesterday I tried pump speed 3 (250mbar constant pressure), the flow still got to 60c in 25mins, but the radiators did take notably longer to get hot. Like a good 10-15mins longer, and even more so for the triple column ones. It did not trip out on this setting either, got to 65.5c, and modulated down at a slightly quicker rate than the tests previous. So it is still overshooting target massively, and sometimes tripping out, but mostly taking 30-45mins of time to get from its overshot of target, back to target. With regards to the L2 settings, it's a bit of a saga. I'll make a separate post of it, because its a head scratcher. Though TLDR is i've tried all the obvious configurations in there and it hasnt appeared to make too much of a difference. Will post below.

What would be reasonable next steps then guys? get WB out again and show them that it's going way beyond target and fingers crossed I can get it to trip out on the day? As it stands they have swapped out the pump, sensors, Hex, and they did the board last Monday too. Not sure what else to do other than keep running it with slower pump speeds and seeing if that fixes anything. I have noticed a whole bunch of weird inconsistencies in the manual, particularly in the L2 hydraulic settings, the settings on my boiler are not consistent with the ones in the manual. But WB told me because i simply have flow/return/Gas and no cylinder or diverter etc, then it doesnt really matter about L2.... again not sure if im being palmed off there again or they're right on that one.

https://www.worcester-bosch.co.uk/support/literature/download/release/6720883858/45568 Goes into the settings from around Page 51.

Yep makes sense, I couldn’t get it to trip this time. I have a feeling the trip is +6c on this boiler. It went up to 65.6c in today’s test. When it does trip again though I’ll be able to confirm the 3-b3 setting above. I’ve set it to -2now. So I’m expecting the behavior to be… if/when it next trips above target, it’ll drop to 58 then fire up again. Where’s at -10 I suspect it waited all the way down to 50 before firing up again. That’d explain the gap where I wasn’t monitoring yesterday. But yeah the larger concern is… why is it exceeding target by nearly 10% at all?! Perhaps I should range rate it down too to maybe like 85% max and see if that affects heat up time / and / or helps this over shooting issue.

id have thought so. But looking at the data I logged side by side with the previous test. It reached target temp around about the same time. All rads felt hot. The only difference was the dt was mostly around 25 rather than 20 in the test previous. Whether that’s better or worse. I couldn’t say. edit: previous test was pump setting 6 at 400mbar, this test was pump setting 4 at 300mbar

Image didn't attach, its this one, i thought that meant "target can be exceeded by this many degrees before it turns the burner off" but on reading and testing again I dont think it means that. I think that threshold is hard coded to the boiler and what this option means is "after the burner has turned off from overshooting, how far do you want the temp to drop before the burner re-ignites?" I'm fairly confident it means that now.

HIVE. Just using the boost function it. As far as I know it doesn’t do any modulating itself. Just on/off im running the heating again now with a lower pump speed. It hasn’t tripped off this time which is annoying. Target still 60. It over shot to 65.5 and is still at 65.5 now 20 mins after reaching target With lower pump speed the flow / return dt was closer to 25 than 20 for the most part. It’s now at 18. Or so.

Hey, hope you all had a lovely Christmas. Ours was lovely despite the boiler still playing up after all this. I ran it yesterday with exactly the same settings as previous, got to target of 60'c in 25mins like last time. I had to nip out to go get the family, came back 10mins later and the boiler was down at 51c again, and a really low output % on the burner. I never got to witness it happen but in the past this is because it's exceeded the target temp by > the set threshold and turned the burner off for 2mins. It's annoying I never was logging the data for that run but i'll do another today and see if I can replicate it. If it did do that then the issue from my last post where it was taking a while to modulate down despite going 5c over target...appears to be getting worse, as in its going higher and higher over target each time, i'll confirm that today. EDIT: Infact looking at the settings, I did change one thing, I raised what I thought was the threshold before it would trip out, from 6c to 10c. I think that's what this setting is for anyway in the image below. Maybe I misunderstood it.

thanks for the data again on that John. RE: the 25mins to 60'c yeah Im happy with that. It's more the fact its going so far beyond target and still not modulating down for a while that's concerning me. It has took a turn for the worst again on Christmas day, will make a separate post below as it's a bit meatier.

Ok, gave it a whirl and logged the temps and burner/pump outputs at each interval too. TLDR it did run well but overshot the target by 5c and stayed there for a while whilst modulating down slowly. Some things worth noting before looking at the data below. I set the pump setting back to pump 6, the highest constant pressure setting, rather than setting 0 (which makes it relative to the burner). Now that the HEX is fixed, I did want to try that to see if it ran well and still got everything hot etc. Also worth noting the target temp on this run was set to 60'c On for 5minutes Flow 30.6 return 15.6 Burner 62% Pump 93% On 15 minutes Flow 50.9 return 29.0 Burner 100% Pump 100% On 25 minutes (target temp reached) Flow 60.1 return 39.1 Burner 100% Pump 100% On 30 minutes Flow 63.2 return 42.8 Burner 95% Pump 100% On 35 minutes Flow 64.8 return 46.4 Burner 85% Pump 100% On 45 minutes Flow 64.8 return 50.2 Burner 65% Pump 100% On 55 minutes Flow 61.9 return 50.7 Burner 49% Pump 100% big time gap now as I stopped measuring till it settled to actual target temp of 60'c On 1h35mins Flow 59.9 return 47.8 burner 49% pump 100% Lastly, I did two lots of measures on the meter, first set when the boiler was at 100% and second set when it had settled to 49% 100% meter readings (in m3 meter cubed) 0mins - 7293.39 3 mins - 7293.56 6mins - 7293.74 49% meter readings ( in m3 meter cubed 0mins -7296.14 3mins -7296.22 6mins -7296.31 What do you guys think? To me im not sure why it's staying above target for so long before it starts modulating down. If the greenstar 8000 has no return sensor, i wonder what is making it think it needs to stay so hot at such high % long after target is achieved?

Will give it a try tonight. It’s going to be hard to get an accurate reading from start up as it’s output % does change quite for the first 10 mins from start up. It goes higher and higher. I’ll wait for it to settle at a high % then do the 3 min tests.

Thanks John, does the boiler need to be at target temperature when I do these tests or does that not matter?

Gave it another run last night. Still on pump setting 0 (relative to the burner setting) and locked in a range of 60-100% min/max for the pump too. It got to target of 60'c within about 30mins. All rads hot by then and measuring around the same on the flow pipes for each of them. So all fine. The not fine bit is it stayed at a max output on the burner for 30mins after reaching target temp. Then took another 30mins after that to very slowly modulate down to 60%. So that feels like its not modulating down soon enough. Or that the system really needs the boiler to be on 100% even to maintain the target temp of 60'c... which i'd be very surprised by. So to test the latter, I tried it again but range rated it down to 75%, it took longer to get to target, but then frustratingly didn't drop from 75% once it got to target, it did exactly the same as it did when it was rated to 100%, just stayed on 'max' for half hour after hitting target, then dropped. So in conclusion, if it can raise the temp to target at 75%... why would it think it needs to stay at 100% to maintain the target? What exactly is telling the boiler to modulate down on the greenstar 8000 life?

He never did no, they brought a new board with them. But he said that replacement is for the older version of my boiler that suffered from a different set of problems, mainly something to do with the boiler idling for long periods of time when there's a clear demand, mine never had that as it's the newer physical version of the same boiler. So he only changed the HEX. I will do some logging now that the boiler is reading 1:1 with the flow pipe. I can try all the different pump settings which previously due to the issue I was having made it unclear which was the correct set of settings. I should easily be able to monitor and decide on that now though.

We're closer to the former of those two, but honestly we just boost it if and when rather than on a schedule. When the house feels chilly we boost it for a few hrs.

Yep could be. Though It is strange there is no increase there, as the flow pipe and rads were all measuring 10'c hotter than before the HEX was changed. So its definitely outputting hotter water than it was before.

What would that suggest for next steps? Certainly the rads are getting hotter than before the HEX was replaced. So that’s good. Wil the rest be down to trying diff pump settings and balancing?

Edited the post

It has started to modulate down now. Just very slowly. Maybe it is supposed to be like this and it just seems weird to me now with living with it broken for so long. Readings boiler / flow target 65 boiler / flow actual 66.5 return actual 52.3 burner output 54% pump output 87%

Does anyone know how long it’s supposed to take after reaching target temp before it modulates down? It’s been at target temp now for 15 mins or so. And only modulated down by a few % the target and flow pipe stopped rising for those 15 mins but the return pipe still risen

Certainly will. The flow pipe has never been hotter than mid 50’s before. I think because I’d gotten used to the rads being 53 ish. They feel so hot at 60 now. this means I can set the boiler target temp down to 60. So a huge cost saving too I’m sure. 👍

New HEX in. Flow and boiler LCD within a degree of each other.

Senior WB technician here with me now. Will update all findings once he’s done and gone but in 5 mins of being here he said that he thinks the HEX is blocked. Based on an inconsistency between what the read out was saying vs what he could feel on one of the internal pipes. Said it may be blocked due to too much inhibitor etc. either way he’s ripped it out and popping a new one in. Let’s see if it deals with the temperature delta any better! Also said the target temp should be very close to the flow pipe temp. Within a couple degree and said the previous technicians advice of setting it to 80+ is “incredibly poorly thought out advice” so I’m glad I’m not going crazy, atleast!