EinTopaz

Yep, though I can definitely rule some of them out already. Mag Filter - was checked by a plumber last week. Said it was clear. Strainer - dont think we have any of these on the system Gate valve - haven't seen one of these and assume if we had one it'd be above floor level for easy access etc? Piping - plumber confirmed last week no short cycles, i've been down myself and drew the layout myself. That said, re: blockage, 28mm flow/return pipes that runs from the boiler... I havent seen it myself but the plumber said those 28mm pipes each has a Y pipe that splits each into the 2 parallel runs of 22mm.... Do those Y pipes have a valve on them? Or is possible that the 28mm copper pipes could be blocked before the the Y pipe? Like maybe when they were solder welded or something?

Yeah, well to sanity check I did do a quick tote up of the kw/btu of the rads fitted. I worked it out at around 27kw or so @ t50..... Now whether that is overkill for the house, or indeed whether the 22mm pipework is enough to accomodate for that kilowattage if im running the boiler higher than 70'c (despite the WB guy saying the target temp set on the boiler doesnt mean the system will go that warm.... bizarre)

Hey @JohnMo It's a 1955 built property. Has cavity walls (75mm cavity) they're insulated, and it has a suspended subfloor which I insulated myself (awful job)...That said the house has been extended many times. Was originally a bungalow so a large single story footprint, it's now 3 stories. This boiler solely does the rads on the ground floor. For the rooms - Lounge, Hall, Bathroom, Dining Room, Study, Kitchen, Family Room, Utility room. Regarding the calcs it was done by the installer 2 years ago who's no longer contactable. Thats interesting to know about the gradient limitation. Regarding the raising rate of the boiler's flow temp. It's pretty quick and consistent, it doesn't seem to pause for anyminutes as it raises to 70 within 10mins. But as above my biggest concern is that the flow pipe and subsequent rads are no where near raising at the same rate / getting hot as quick. The video I put above of it going between the 20/80% output that is a new symptom. I suspect because we've put it to 80 target, im gonna drop that back down to 70 and see if it still does it. I've considered the blockage aspect too... Sorry if a silly question but what is the easiest way to check this? i've tried all the rads on the front of the property TRV's turned down, leaving only rads 1-6 open, and then done the inverse, 1-6 closed and 7-15 open. Same symptoms of massivey differential of boiler temp to flow pipe temp. So if there is a blockage or gate valve... I surmised it must be close to the boiler before the 28mm splits into the 2 x 22mm parallel runs. If that makes sense? That said I had a plumber here last week down the sub floor inspecting the piping i assume he'd have mentioned if he seen a any sort of odd valves down there.

I know, it was either that or replace the original upstaiirs one with something massive, like a commercial. it is a property on the larger side.

Agreed. I've got a Senior Wb engineer coming out on Monday. What would reasonable next steps be? I believe he's bringing a new control board with him. And I was going to run him through all the symptoms. The last guy said there are zero problems with the boiler and it must be the system. But it really did feel like they were passing the buck.

Yes, on the pump side, it's set to setting 0 (the mode that unlocks the pump mapping) this also puts it relative to the burner rather than constant Mbar, i've tried all the settings with not much difference. Currently its on setting 0 relative to burner mode, but with the min % set to 80 and the max set to 100. WB Advised that was a good setup to ensure the pump is not being lazy. As their initial suspicion was the pump wasn't getting rid of the hot water fast enough hence the differential between boiler and flow pipe. But it hasn't fixed the issue. I will try loading it down when im back home and see if that makes any difference.

Mag filter was stripped and cleaned last week, when the boiler was serviced. From memory it's never run correctly no. It's always seemed to cost a lot this boiler but all the rads on it's system never seemed to get as hot as what the LCD was displaying, until i recently starting actually measuring the flow temps... it confirmed what it 'felt' like living with it, if that makes sense? The boiler only went in 2 years ago when we did the extension, all rads new, all pipework new, boiler new. It's a problem that only presents itself in the colder months as I don't use CH at all until maybe mid-october-ish!

There is a separate much older WB CDI boiler upstairs that does the hot water for all the property and some rads up there too. It's a conventional type that one. And the flow pipe coming out of it (using the same measuring tools) is always within a degree of the LCD display on that boiler.... I only wish the one downstairs was as straight forward. The boiler we're discussing here with the problems solely does the CH for the ground floor, as to not complicate the older system.

For a while that's true, though if I leave the boiler on for maybe a few hrs, the delta drops to 11'c sometimes even single figures. But either way this made me think its unlikely that the system is too restricted. Otherwise that delta would be enormous, right? That's a good question, haven't tried that. But you are correct that the differentials so far have been fairly relative. I'll need to try it when im back home im away for a couple days now. argh. The max can be reduced down yeah. To as low as 50%....though when It's firing up at the moment it is going as high as 90% output. So won't this just make everything take ages to warm up?

I've thought about that too. I don't know the lockshield positions off by heart but i know atleast 4 of the 15 are all the way open as they've struggled to get hot in the past. Also when i've tried different configs of which trvs are on and off the boiler has always done this, so a blockage or a closed valve close to the source seems more likely. That said there are no zones on this system or anything like that. Just 1 CH only circuit directly piped to the boiler. Probably a silly question but how does one make sure the valves under the boiler are open, should they be all the way open or is it potentially dangerous for a nontechnical person like me to fiddling with that stuff? Edit: I forgot to mention, generally speaking I have about half the radiators TRV's set to /4 and the other half all the way open. So they're certainly not closed down.

They do, eventually. The type 22's get warm within maybe 20mins, the triple column designer rads get warm after maybe 40mins. When I say warm, their temperature is consistent with the flow pipe reading, all around low 50's.... whereas the boiler ofcourse is showing much higher. Towel rad does get hot yes. I've tried it on and off, didn't seen to make a diff.

Hey @Nickfromwales thanks for the reply. I put a video on Vimeo of the valves under the boiler, and the mag filter etc, those are the only valves I can see physically. It is overshooting yes. In normal operation, it sometimes goes as high as 6'c over target and flicks the burner off for a minute or so. The temperature rapidly drops during that minute. Then when it comes back on its a very low% burner output and creeps back up to target temp then stays there pretty stabley. But still with the 20'c differential between LCD display and flow pipe. I hope you're right. Let me know if anything looks untoward in the video link above. Sorry if i've not given a clear picture on the situation. it is turning into a bit of a saga and apologies for that. I will say see my other post above this one with the update from the WB guy, it is now showing a new symtpom too after he did a software update and told us to set the target tempt to 80 rather than 70. The problem still does persist with big differential between boiler and flow pipe. But its now also showing a new symptom where the boiler is getting to 80 target, then going into this weird mode for an hour or so where its constantly alternating between 20/80% burner output while the target temp stays around 80. Flow pipe is showing around 60 during this time. But this is now a new problem after the WB guy updated the software, replaced the pump and sensors. As above. before it was doing this new symtpom, yes it'd get to 70 within 10-15mins and often overshoot it by upto 6c

Hey @SimonD thanks for the reply. It does short cycle when I run it in chimney sweep mode. When it exceeds 88'c it clips out. Even when not in sweep mode, it does overshoot the target temp by 6'c sometimes, causing it to turn the burner off for 2mins. As a safety thing I think. Also in my last post above, i added a video of a new symptom it's doing. After the WB visit, it's now getting to target temp of 80 (as suggested we do that by WB guy) then constantly changing between 20/80% burner output. You can hear it loading up and loading down as many as three times per minute. Its not cycling the burner off during that time, but definitely does not look or feel correct or normal in any way. There is no ABV on the system. The boiler doesn't have one internally.... and externally the fitter back then (2yrs ago now or so) said as we have a towel rad with no TRV, it's fine to use that with no ABV. Good question. The flow pipe at 53/54 the return tops out at around 42. Generally speaking the delta stays at 20 ish or so for a while, then after the first hour once the flow stops climbing, the return closes the delta down to 12ish, worst case sometimes as low as 9ish if I leave the boiler on for ages.

Hey all, thanks for all the replies. I didn't expect it to be this popular. I'll start replying now in order. Massively appreciate the responses. I'll start working through them now. Before I do though, quick update, I had a WB engineer here today to swap the pump and sensors to rule those out. He has, and the problem has persisted. He also said something which I completely disagree with albeit me not being technical. He said there should be a different between LCD display target temp, and actual system temp. I said by as much as 20degrees?! he said the boiler target temp isnt you setting the temp for the system its just the internal temperature of the Hex. he advised we simply turn the target flow temp on the boiler up to 80. Which also sounds bizarre to me, but giving it a try. The same problem persists, 20odd degree differential between boiler temp and temp on flow pipe. (BTW i've measured the flow pipe now with 4 different instruments, including a rental expensive one, and the one Wb brought with them) they all say the same number. and that number is consistent with all the flow pipes on each of the rads. They're all within a few degrees of each other. But the boiler is the one that's 20 or so above everything else. Anyway, the stuff the WB guy did was, software update, factory settings, replacement pump and sensors, checked the hex and said it was clear, and also set the target temp to 80. Same problem persists, and a new problem has arisen now too which i'll put a video below of. After half hour the boiler gets to target temp of 80, then from half an hour to an hour afterwards it then constantly alternates between 20/80% burner output. Gradually with that window getting smaller 30/70 - 35/65 etc, then eventually settles on 45% stabley. Im not sure if this is the massive flow temp now, or the factory reset, or the new parts. But it definitely is a new thing that wasn't happening before. Would this help suggest to any of you what the problem is? Its not cycling the burner off per sae, but almost as if it cant decide what to do with the heat etc. video below.

Hi all, This one is turning into a bit of a saga... but, I've been having a hate / hate relationship with a boiler we had fitted a couple years back. Now it's getting colder again and we've started to use this boiler again, it still has issues. I'm hoping to get some help diagnosing what the problem/s are with it and perhaps some guidance on good next steps to take and focus my efforts. Boiler / System Info This is a 36KW system boiler and CH only. It powers 15 radiators, 11 x type 22 and 4 x triple column which sum total around 28kw total @ T50. It's 28mm pipes for the first couple meters, then splits to two parallel runs of 22mm (each around12Meters or so) then down to 15mm for the last meter or two to each rad (i've added a topdown image of the system design below). The pressure is 1.3Bar when not on and raises to 1.8Bar when on... Also worth noting; the boiler, pipework and all radiators were fitted at the same time around 2yrs ago, all new at the time. Operational Issues The most notable issue is that is the boiler seems to be reaching (and actually slightly overshooting) target temp of 70'c within 10minutes of it firing up from cold. This is displayed via the boilers LCD display . Yet despite this, the flow outlet pipe and all radiators take longer to get hot to the touch, and the flow pipe and radiators never seem to get higher than around 53-54degrees, which ofcourse is way cooler than what the boiler LCD display is showing. So there seems to be a fairly large temperature differential between what the boiler thinks the flow temp is and the heat of the stuff outside the boiler. Almost as if the boiler can't get the heat away from itself...? I've added a photo of this too showing the LCD display and thermometers I put on the flow/return pipe. Questions based on the above Would upping the 12 meter 22mm runs to 28mm help in my case? Could there be a blockage in my boiler, and would this show an error code if so? (it's clear of error codes) Could there be a blockage in my system? and if so what's the best way of finding it? If I open all the lockshields on the rads and the problem persists, would that rule out bad balancing? System design image (thick lines 28mm, medium lines 22mm, thin lines 15mm, black square outline is the 4 x triple column rads) Lcd readout image (left thermometer is flow, right is return) As well as all the above, it'd be great to know if anyone else has this boiler so we can compare notes. Lastly, i've got a plumber and someone from WB coming out this week to try and rule things out. But it'd be good to arm them with as much knowledge as I can so any and all suggestions and help here are massively appreciated. Thanks Ged