EinTopaz

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!

Video below from what I saw from being under the subfloor earlier (a great way to spend a Sunday evening... honest). I was hoping to find some sort of valves where the 28mm flow and return pipes divide into the two lots of 22mm. But no joy, its all just copper fixings Teeing off. I could see the filling loop was attached to the flow. But looking at the installation manual, that appears to be correct..... The location of where i filmed this is sort of directly beneath where the boiler is, within a meter of it anyway.

Just trying to think of other possibilities @John Carroll... could the colder temp in the flow pipe be because cold water is coming from somewhere else? like a faulty filling loop. Just been under the floor to have a look at everything and the filling loop looks to be T'd into the flow pipe. Id have thought they usually go on the return. Long shot? I guess if it was letting cold water through i'd see ever increasing pressures? And it'd affect the boiler temperature too?

That was my very first suspicion in all of this. I was most disappointed when I read the boiler does not have an internal bypass. I was hoping i could've just adjusted that and bobs yer uncle. But you are right, when you simplify it down, either something is stopping the flow pipe from getting that hot, or the heat is staying in the boiler. As the return pipe certainly isn't hot. So it cant be that its making its way round the system too easily either.

I'd be happy enough with that! ha. My CDi upstairs has a difference of jus 1 degree between boiler and flow pipe. Maybe i'm spoiled!

Yep, this is a WB Greenstar system too. Do you know if the theres a large delta between your boiler target temp and flow pipe by any chance? I had wondered if this is just an issue all these Greenstar System boilers have, and WB are refusing to acknowledge. You're the only other person i've spoke to online who has one.

Exactly this, hopefully the Senior engineer doesn't try to say that this is normal. a couple degrees, sure, but not 20,

By that time, it will have modulated down to 40% output and stayed at around that.

@SimonD replying to an earlier suggestion of yours of running the boiler at a much lower target temp an seeing if the delta between the boiler and flow pipe is consistent vs running it at higher. Im going to try that tomorrow. But something I forgot to mention is... when the boiler has been off for a while, all 3 displays are pretty close. (boiler,flow,return). As in the photo below. But when the CH is demanded, the boiler one rockets up to a delta of 20-25 between that and flow within a couple mins, then maintains that delta thereafter pretty much.

It's max isn't rated down at all currently. It's something im going to give a try to tomorrow to see if that enhances heat up times and stops the kettling. Do you think range rating to 70% would be a good starting point? I think i've mentioned already but when I add up the KW of the rads we have here, its there abouts 27kw. (11x large double panel) + (4 x large vertical triple column)

They did acknowledge a huge DT between boiler and flow pipe. But tried to tell me that it's normal. Which sounded like BS. Also tried to say it was 100% likely a system issue. Which sounded like I was being palmed off. The boiler is wired up to Hive, and for all these tests ive been running it on boost mode. I dont think that makes any diff to running it normally tbh, but just for clarity.

Ish, it's set to min 80% max 100% on the pump. Though tbh this didn't make a huge amount of difference compared to running it at constant pressure.

If the boiler is set to 68'c target temp, it settles at around 70'c after an hour. At this time, the flow pipe will max out around 54'c and the return 45'c, I appreciate that delta between flow/return is too small for a modern boiler. it does maintain 20'c delta for the most part but really closes down after the boilers been on for a while.

I see an issue, it gets to 70'c on the boiler within 10mins. then modulates down, long before the radiators get hot.

I've WB coming back on Monday, with a new control board. Will show them the issues. I would've liked to go down the sub floor myself between now and then and have a look at where the single 28mm flow and returns each split into dual 22mm ones. If those splitters have valves on em, im wondering if they've been left partially closed. I've mentioned already... but last WB guy, as I stated above very much did try to wash his hands of it and said its normal to have a difference between boiler target temp and flow pipe temp. I challenged that. He didn't really have a good come back. And just said we should raise our boiler target temp to 80. Which has brought the new kettling symptom in now. This is why I've asked for a more senior gentleman to come, this time.

Done all that, WB brought their own too to verify, used 4 different measuring instruments now including clamps. K-type sensors, all within lagging and paste. Whole thing. The flow pipe is 20'c cooler than the boiler is saying. I'd like the radiators to go to circa the value that im setting on the boiler. Like every other boiler ive ever owned does. Then I can easily control everything.

The issue is to get the radiators hotter than 52degrees, the WB technician has told me to set the boiler target temp to 80. When the boiler is set to target temp of 68, the flow pipe coming out of it is measuring 54ish, and all the subseqent radiators are measuring around 52ish. I've checked the gas meter and it is using the amount of gas that the boiler modulation would do. So my concern is two fold. 1 - the boiler is way hotter than the water coming out of it, this is costing me money to heat my house but my house isn't hot. 2 - to get my house hot i've got to set the boiler to a target temp that is now making it overheat and kettle when it gets to the new target temperature recommended by WB of 80'c... for a modulating boiler that sounds crackers to me.

Did anyone have thoughts about this? I haven't had time to check yet, could I be onto something here?

Ours sort of does this. When we had the target temp set to 68, it never went up to 100%, max it went upto was around 70ish. But it also doesn't hit this output straight away, it starts at 20% when the CH is demanded then gradually works its way upto 70, then when hits target (on the boiler atleast!) starts modulating down. Ours does often overshoot, but it's set to only turn the burner off if it overshoots by <6'c... it does do that sometimes but less commonly. If I run it in sweep mode however, it exceeds 88'c and turns itself off every few mins. Which I guess is also indicative of a boiler that can't get rid of heat quick enough, or is reading its internal temperature incorrectly.

I suspect it's a coincidence. I have measured at the gas meter when the boiler burner output says 40%, I did the 3minute measure at the meter and it is using the correct amount of gas at that modulation.