marshian

We posted at the same (or similar times) thanks for the further explanation even before I'd asked the question

ahh OK so in doing that you "hopefully" minimise the distance to travel and with the pipe size minimise the volume of water that needs to be displaced before you get HW at the tap No pump?

OK and radials - a loop of pipework without a pump (so reliant on convection currents?)

Any chance of schooling me in what a TMV is? Long time bug bear of Mrs "Alien" is the amount of water she has to run off in the kitchen before she gets hot water - despite the VC being directly above the kitchen the Hot feed takes the long way round via bathroom first in 22 before reducing to 15mm going 2.4 m down a boxed section to feed first the downstairs toilet then utility room and down 1.0 m and then 6m across the house under the floor to get to back up to the kitchen sink All the pipework runs are insulated.......

Much better 11.2 kW - will it go down to the absolute min? Different ways of doing things - room struggling to reach target temp - my first reaction is to increase flow thro that rad ACT probably pays to be a bit mathmatical ACT of 5 mins means a max number of fires in 60 mins is 60 / 5 = 12 now of course the burn time is going to reduce the number of cycles but even if the burn time is only 1 min each time it'll drop the number of cycles to 10 per hour so idealy you want a burn time of 5 mins or more to get below 6 cycles per hour. If you aren't achieving that then consider increasing the ACT Hysterisis 15 deg might help - boilers only tend to get fussy when the delta between flow and return goes over 20 deg OK it's handy to have that understanding Normally I'd say do one thing at a time but in your case - throw everything at it to see what happens - it's an easy step to reset to factory settings Not a problem at all If I could comment some of this detail would have been good to have known in the first post of the thread - yes it would have made it a bit wordy but it might have saved a bit of time. What I really am interested in is if the purge and initial burn is still at an elevated boiler kW output...... My current boiler hits the circuit with 60% of the boiler max for 90 secs - it range rated to 5.86 kWh - so it's still smashing ~10kW at the circuit for the first 90 secs My old glow worm was 75% of max for 30 secs trouble is that was 18 kW - pretty damn hard for the circuit to deal with that if the overshoot is only 14 deg away

It's a 30kW boiler for CH so 40% of 30kW is 12 kW - do you really need 12kW to cover your heat loss and allow a little for a reasonable recovery time - Im surprised you can't range rate it down to minimum - the manual seems to indicate that you can range rate to the minimum?? Anti cycle time - decreasing it makes no sense - longer is what you want It's the time the boiler waits out before restarting On some boilers once the flow temp and return temp get down to 10 deg below set point they fire anyway I'd also look at the Anti-cycle flow temperature differential and consider increasing that to give a longer coast period via a lower restart temp. I don't know your boiler like I know Glow worm but GW/V pump over run gets first call followed by ACT so I'd start with adjusting PORT - it didn't have the Anti-cycle flow temperature differential adjustment so never got to try that OK I did wonder if it's always been like this or something new. It's only 4 allen bolts to take the pump assembly off the body (oh and an isolate and drain - you don't need to take the pump out of the boiler - just remove the motor and impellor from the pump body

Went googling - installation manual was rubbish, user manual equally so that you tube video gave me a big clue Turns out all the interesting set up stuff you can do with boiler parameters range rating Anti cycle Pump speeds and modes Pump over run time Greenstar_CDi_Classic_Engineer_Service_booklet.pdf

One more thing - has the boiler been range rated down for the CH side of the boiler?

Never have an issue with that - wind them in and if you feel the board lift - back em out and then bang them in again. I'm sure I will

I'm not concerned about rooms over shooting Evohome can do what it likes but if you still have a situation where the flow temp spikes when the boiler shortly restart overshoots and shuts down quicky then clearly the circuit still has a restriction to flow that the boiler is not happy with. You also say the system is noisy - now normally that would indicate a strong flow thro the circuit and I wouldn't be looking there but now I am. Let me show you my issue when for a reason I didn't understand I had to wind up the pump to speed 2 in order to stop the boiler short cycling due to temp overshoot. This massively increased system noise Now admittedly the pump had been in there 15 years and there was a magnaclean installed a couple of years before I found this but it was installed after the pump......... The system noise kept SWMBO awake which is sub optimal and also annoyed me as the system had always been whisper quiet on the lowest pump speed Cleaned out (and there was a lot of stuff in the vanes you can't see) I was able to drop back to speed 1 and the short cycling stopped Not say this is your problem but whilst Evohome is almost certainly cycling the boiler the over shoots aren't down to Evohome

They don't look sodden but then you've not got to the one near the drain? I was trying to work out if the floor is ply or OSB but either way I would not expect tile grout on wooden floor to be acceptable as a wet room...

looks at location - thinks "Blimey your are a quick driver.................."

Yes it’s still cycling but the important bit to consider is if the boiler still overshooting the set point with more open rads?

No shank for the boards to rub on - threaded from head to tip 😉

Interesting but my set up never did that - it would just intervene when rads were close to temp - knock the boiler off for anywhere between 2 and 8 mins and then call for heat again like nothing ever happened. That was enough to annoy the heck out of me hence the various approaches I took to limit it's influence over the heating circuit I'm almost 100% sure it hasn't intervened at all in the last 2 months since I've been heating 24/7 with TRV's set to elevated room temps (that the weather compensated flow temp from the boiler cannot hope to achieve) If it had intervened then I'm very sure I'd be removing it all and going back to a simple clock timer set to a heating schedule for the shoulder months and switched to constant "24/7 On" for the winter months

I think that's what he is doing - he's running it at the minimum elevated temp he can - he wants to run the boiler at lower flow temps but can't because it cycles like heck (more than it's doing now) Marginal?? The difference between the red arrow and the green arrow is marginal?? That's like saying the difference between running a heat pump at 55 versus 45 is marginal in terms of COP!!! On this we agree

I would not be happy with that if I'd done it myself!!! I'd be really Expletive unhappy if I'd paid for it to be done like that!!!

Can I have a bit more detail on this end of the graph please??

Yeah 13 TRV's managed by the hub and when a number of them get close to target the system goes into save energy mode and actually uses more For me on the old boiler (Glow worm) I'd dialed in 10 mins of pump over-run and in the shoulder seasons nearly 30 mins of anticycle time at the lowest flow temps I could realistically run (So as the POR runs concurrently with ACT a max of 30 mins between burns) This was down to 10 kW min of the boiler and a heat loss requirement of max 1.5kWh - I wanted to do everything I could to maximise the burn time and allow the system to coast for as long as possible And then when the boiler finally fires up Wiser says "oh no you don't" It nearly went in the bloody sea!!!

Whoa!!! You witnessed it doing that?? That's bloody nuts!!! I never got those symptoms - it would always switch off the call for heat (like a single house room thermostat reaching temp) - you would see the CH light go out on the hub - the pump over run would kick in and then 2 mins later the CH light on the hub would come on again and it would re-fire if the return/flow temps had dropped enough to call for heat.

So in a nutshell "smart" can be "really bloody dumb" - Anyway this is OT for the original post and I'm damn sure it's been discussed elsewhere

OK let me help @Nickfromwales The Wiser Hub has some "smart" functionality inbuilt into the software where it tries to save energy It's looking at the delta between "actual room temp" the TRV is feeding back to the hub and the individual target temp set point if the delta between them both is a very small the Wiser hub can turn off the call for CH. The boiler as a result shuts down and waits for the return temp to reach a point where it can fire again Trouble is this "smart" approach can result in additional cycling where none would actually be required so maybe "not so smart" It's bloody annoying to have a few rooms not yet up to temp and the boiler switching off as soon as it's just fired just because one or two rads as saying they are close to target. If it's installed in a house with a traditional higher flow temp (60/70/80) this sort of intervention will actually work quite well - it did when I was using higher flow temps and scheduled heating However in a lower flow temp system 30/40/50 it's very much an unwanted interruption to the boilers normal cycles There are a number of ways you can limit the impact 1. You can tell the Hub it's managing an oil boiler - that should drop the hourly cycle limit from a gas boilers 6 to an oil boilers 3 per hour (other options include telling wiser it's connected to an "Opentherm" managed boiler - it really cops the hump with that one and gives you a warning triangle on the app but it worked for me 2. You can restrict a couple of rads in areas not used all the time to never achieve the target room temp (thereby ensuring that there are always a number of rooms where the set point hasn't been achieved and this minimises interventions for the hub 3. You can set some rooms to have a higher target temp than can be achieved - your room temps in the app will go bright red cos of "overheat potential" but this is the "(expletive deleted) you wiser" option but in reality has same impact as 2.

OK so how close are the rooms to target temp? Is it wiser trying to minimise overshoot in room temps?

Some progress - the barn that it was stored in burnt down around it - front end was so soft I had to cut it away Shell has been shot blasted and etch primered - gathered an awful lot of parts for it over the last few years but retirement is still a few years away and other cars* keep me busy Oh that will go well * Other cars.....

I can understand why that would keep you awake at night but as you say if the job is creative and rewarding I hope the number of sleepless nights are minimal I'm with you on the fun bit - I work in manufacturing in a slightly weird role (started in manufacturing management - moved sideways into logistics and then sideways again into finance before my most recent role as a the sole business analyst but linked closely to operations As a result I deal with everything from automation optimisation, scheduling, costing (lab, RM and OH recovery) as well as capital projects - That might get me a a label of "A jack of all trades" and probably the back ground I have mean the std "master of none" doesn't actually apply 😉 For me it's a consequence of text or rather the English language being easily miss interpreted - emails can be even worse!!! I do try to see any comment as "meant in a good and constructive way" I find that helps avoid issues or poorly worded responses that result in tensions The Design guide was very useful and yes gave me food for thought The roof bracing is exactly as it was built - where boards intersect with the bracing - the boards get cut to suit 🙂 Anyway - I'm pleased to say last night I completed phase one - 1/3 of the accessible area is fully insulated and boarded - I can already see the difference in the ceiling temps of the rooms below (with an IR thermometer - only 2/3rds of the rooms below are covered by the improved insulation right now)