marshian

Perfect summary

House is 1/3 of yours 113m2 however it is a stupid T shape with many rooms having 3 external walls which in a 1980’s house hurts. what I would say however is heating 24/7 with or without setbacks for me is actually not much of an increase on heating via a schedule with much higher flow temps for shorter periods morning and night - house temp swings were dramatic - far too easy to overheat the house and it never felt as comfortable as it does now. (Less than £50 a year from memory) what really triggered the move to 24/7 was that I would run the CH at the weekend all day and Monday would always be really low usage compared to the rest of the week - simple when I thought about it - I’d warmed up the internal fabric of the house over the weekend and on Mondays it gave it up again…..

WHS ^ I did manual WC for nearly 2 years on scheduled heating - it worked quite well - not as good as WC but really only a few days a year when you really need to wind up the flow temps rest of the time a happy medium works well

From my non technical viewpoint and I'm going to phase it as such For the burner to be running at 100% then the water flowing thro the boiler must be taking that heat input - which means the return temp water is cool enough to enable the boiler to "have at it" Only when the heat capacity of the return flow is less than the full power of the boiler will the boiler modulate down (OK it may rise above target set point before it does that but that will be in the programming of the boiler MBU) Basically you have a circuit of water (Pipes and rads) and it's taking a fair old time before the return water starts to warm up enough to cause the boiler to modulate down.

I'm pretty OCD when it comes to pipework/wiring now - If I've had a floor up I normally take a photo of pipework/wiring while the floor is up Then I'll mark out the "unsafe" zones with permanent marker on the floor - the photo is especially useful if you then go and tile the floor and cover the "unsafe" zone markings (Always handy to be able to refer to it if you ever need to put a fixing in) Of course I haven't always done the above - I don't have a picture of the master bedroom floor before it went down - when it was laid I also didn't mark the floor for any pipework or wiring. There is one section that always has a little creak - wakes up Mrs Alien if I've come in late having had a few beers She wanted new carpet so we ordered carpet and arranged for a fitter - day before we emptied all the furniture, cut up and removed all the old carpet and underlay - the morning of the carpet fitting I walked on the creaky bit and it reminded me to throw another screw or two at it - as I looked at the floor it was bloody obvious I'd missed two screws out Creaky floor resolved - new carpet and underlay laid OK you all know what happened next.......... well not actually next as water takes a little while to escape if you've put a self cutting screw thro a copper heating pipe and plasterboard is pretty good at holding water - screws that held it to the ceiling joist not so much

I’d stick with the boiler until end of life (or close to it) just from an environmental perspective (not replacing something that is still functional and effectively a very bloody good and efficient boiler).

I can go one better (or worse depending on viewpoint) Utility room sink waste was slow to drain - not unusual as Mrs Alien has a small tendency to slightly overdose on the washing powder so over a period of time it tends to clog up the drain so a strip down and clean out was required Having learnt from previous occasions the last time I rebuilt the section I put a couple of strategic compression joints in what is mainly all solvent welds. sections removed and then rodded/scraped/chiselled out and rinsed thro in the sink. The plan was drop all the muck and water into a bucket under the sink…… Off course only a complete idiot would pull the plug out without having placed a bucket in the cupboard under the sink……. oh how I laughed!!!!!

Ouch what caused that - clearly not a dart?

Christ - that sounds painful but progress looks good

I have Wiser - went down the whole micro management with 13 smart TRV’s (one for every room/rad) complicated schedules, heating only the rooms when they were needed - it worked but was horrible to manage. All now removed and replaced with PICV and dumb TRV heads the Wiser hub remains with one roomstat - running 24/7 with WC - if I ever get round to connecting it to the boiler it will give me remote access to turn off or turn on the boiler and that’s all I need - however the boiler has it’s own app and it’s easier just to use that when I need to.

I have very similar one - have you tried powering it down Mine always re-gens if the power is accidently turned off Bottom of the screen on mine normally shows 4 blocks which is the state of the resin and then it re-charges overnight unless you catch it out with abnormal usage. Only other advice I can give is keep a careful eye on the pipework - Mine decided to weep over a few months - the crimp had started to fail

What are your L2 settings? I would have thought it was pretty important to have the correct parameters??

Seen that before - my take away is that above 60 mins cycle time there is no efficency degradation - anything below that there is and the shorter the cycle the greater the eff loss

Well for the last three days the boiler has been a very naughty little pixie (Note - It is not range rated at all) Despite falling outside temps the cycles per day have steadily increased - the cycle lengths have shortened Date - No' Cycles - Avg Cycle Length 23/12 - 27 - 21.9 mins 24/12 - 32 - 34 mins 25/12 - 34 - 22.7 mins Boiler behaviour is basically intitial purge and burn up to 58% and then modulate down to 10.8% - it'll sit there for a while before starting to ramp up to 25 -35% even tho the flow temp is already at the WC setting - it'll hit temps of 4 or 5 deg higher than the target temp before shutting down - the return temp would then drive a restart 10 mins later. Once the boiler gets into this spiral of increased cycles with shorter burns it's always defeated my efforts to get it back in line but I don't always have the time to try different things. Normally it goes away with a sudden change in outside temps - either a warmer day or a cooler day. Yesterday I took the boiler off weather compensation mode and set it to a fixed temp setting - boiler did the same thing, I range rated it to minimum - boiler ignored the RR'ing and continued to randomly ramp up. I've powered the boiler down - several times - made no difference I set it back to Weather Compensated flow temps - still the same In the end I turned the whole system off for an hour and then restarted it late yesterday evening. Overnight normal behavior is resumed...... It hasn't missed a beat all day As of 16:30 today Date - No' Cycles - Avg Cycle Length 26/12 - 15 - 40 mins Should end the day at 22 or 23 cycles (one of those would have been HW) Which is exactly as it should be. So I think it's time to schedule some stops into it's activities as opposed to an overnight setback temp My Wiser controller isn't currently linked to the boiler (it has a link wire providing power to both perm live and switched live but a single core cable from the Wiser Hub will fix that and then I'll schedule two hours of downtime for the boiler 1 hour overnight and 1 hour in the daytime I appreciate that the above sounds a bit mental for a WC system but I'm not always at home to see and hear it ramp up but as the Boiler App provides me the total number of hours run and the number of boiler starts I've been noting down the readings every day at the same time so I can see when it's either cycling more than normal or cycle length is shorter than normal

The issue there is the dumb controls are all @EinTopaz requires for the way he uses the heating system

I think I've said this before - be careful if you end up with a DT greater than 20 Deg at the boiler most modern condensing boilers really don't like this much and will do all sorts of things to try and protect themselves. If you are getting a wide DT with a slower pump speed then you could probably lower the flow temp to tighten the DT (at the expense of slightly cooler rads but I wouldn't think the difference in rad temp between 60 and say 55 would be detectable by touch)

I wouldn't expect range rating it down to impact the overshoot unless it was RR down to less than the circuit can accept in which case the temp wouldn't over shoot for a long time - equally the house would be also slower to warm up. Plus your "85%" might be fine for now but when it's -2 outside and you want to throw a bit of heat at the house it could potentially result in a lot slower warm up. IMO the only time you can be justified in RR a boiler is where the boiler capacity is massively in excess of the house heat loss and even then with a scheduled heating (or as and when you think it needs it in your case) you are going to need plenty in reserve to bring the house up to target temp so probably not much point RR'ing the boiler

The other interesting thing is the DT at the boiler On initial start it doesn't apply full power to hit target temp because the DT would be greater than 20 Once the DT is at 20 Deg it applies full power Once the DT starts shrinking it modulates down (it's not doing that by knowing the return temp it doing it based on the flow temp rising above target and then it modulates down At the end of the day you are intermittently heating - your circuit temp at the start is less than 15 Deg C (now the rads will normally be at the same temp as the room when the system has been off for a while so clearly your tolerance for cooler temps is greater than mine or rather Mrs Alien) I do wonder if you would be better of heating low and slow rather than blasts of heat, cool down, blast of heat etc If your flow temp was say 45 deg C and initial circuit temp was 15 the boiler wouldn't have to throttle back and wait for a DT of 20 before hitting the circuit with full power. The return temp would rise and the boiler would modulate down sooner and probably much more........ However with a flow temp of 45 you'd need to have rads that were big enough to emit the heat the rooms needed.

I would think it's managing the modulation based on flow temp target Anyway kWh usage below for the for the two sessions 100% being the first one shows the boiler is really chucking everything it can at the circuit 49% being the second one shows it's modulation percentage is not far out

Similar boiler on third heat exchanger

Not answering for @John Carroll but I'd do readings from start up Logic is I'd want to establish that what the boiler is stating it's modulation state actually was. My 16kW Viessmann modulates from 100% to 10.8% - 100% is 19kW 10.8% is 4.2 kW the % values between the two aren't very linear or put another way if 10.8% is 4.2 kW 100% should be 38 kW

Another thought Read the gas meter at the start and then say every 20 mins noting the modulation claimed Post the readings lets see what it's really consuming

That does appear to be rather odd behaviour How big is the circuit volume?

Then you probably want to give the boiler the ability to run at whatever kW it can or potentially your warm up time will be extended. We used to run a similar process with the old boiler - Summer to Autumn transition - boost for a couple of hours when you feel the house needs it. Moving thro to fixed scheduled heating in the winter months increasing the scheduling period to ensure the house was at target temp when we got in from work Mrs Alien is a stupidly light sleeper and mornings were an issue because if I set the schedule earlier in the morning it woke her so we had to compromise on heating early in the mornings. Then back to boosting whenever required for the spring transition But I found it very unsatisfactory, temps swings, rapid cool down because you aren't putting any warmth into the fabric of the building (so it can't give it back to slow down the temp drop) Needed to heat rooms to a much higher temp to feel the warmth. Moving to weather compensated flow temps enabled me to run lower target room temps - with a little bit of set back on the boiler overnight - house is just so much more comfortable all the time and the additional gas usage compared to scheduled heating isn't worth worrying about (for us it works out to £60 extra a year)

Well despite having a number of hedgehogs thro the garden during the evenings we've only had one take up residence the other one is being ignored. I'll leave it where it is over winter and then maybe relocate it next year as it's probably the location that doesn't suit (no kerb appeal probably)