marshian

Whats the difference between a smart TRV and a manual one - they do the same thing Always happy to learn something new

Yikes - that's a seriously hot boiler HE core to trigger that............

I know this an old post and I agree with the point made about using Viessmann controls I don't think there is a huge saving to be made. I've fully invested in the Wiser system and since Sep 22 I've replaced all the rads and optimised the sizes to allow me to run much lower flow temps. The individual room temp settings and the scheduled heating times are now spot on for what I need. I don't have any UFH just rads and one heating zone. However with a house heat loss of 4.5 kWh at -2 and a 24 kW glow worm boiler with a min output of 10 kW it's rather over sized for the house and I don't have weather compensation on the boiler so I currently manually set the flow temp for the weather conditions - I run anywhere between 42 Deg C and 58 Deg C flow temps but for HW requirements I have to manually increase the flow temp and turn off the CH whilst HW requirements are met. Later this year I will replace the boiler with a Viessmann 100 W in DHWP mode, Allow the CH Temp controlled by a Viessmann Weather Compensation module and leave the Wiser system and all the smart TRV's in place. I'm pretty confident that this will work nicely provided I get the curve right. If I find that it doesn't work as well as I expect I'll dump all the TRV's and run fully open system but I think my plan will work just fine. I don't see that the Viessmann Controls for CH give me any advantage over the Wiser and I have no intention of trying to use the Wiser OT to control the boiler flow temps as I don't think it's as accurate as a WC temp sensor on my house wall.

I agree it's very clear what the issue is............ Establishing if the issue affects CH is quite easy - just park yourself in front of the boiler when the house is up to temp and most of the TRV's have shut down. Observation is often the key to seeing whats happening - it's almost certainly doing the same - it's just with a massively elevated flow temp the recovery time for the boiler from the fault timer isn't taking a long enough time to cause the house to cool down because the rads that are still in use have to cool down from 82 deg flow temp and that'll take a while....... So the engineer has given an option that has been demonstrated to stop it happening - you don't want to take up that idea. The "agreement" of the engineer that is shouldn't need you to change your house heat behaviour and the boiler should be able to cope with how you want/need to live is because he recognises you aren't going to change no matter what he says, You are convinced it's the boilers fault - it's his "get out of the situation" because he is unable to educate you out of the issue. He knows full well WB wouldn't entertain replacement of the boiler for the situation you force the boiler to work under. To be blunt - it's a situation of your own making.

Abso-f*cking-lutely this It's like choosing an F1 car for a city commute or a Bicycle for an F1 race it's just nuts and because it's so nuts the boiler doesn't like it and says thank you - goodnight

I'm frankly amazed that any house needs 82 deg flow temp for rads - your heat loss must be horrific Even 70 is high for spring, summer and autumn - the boiler is barely into condensing mode. Does the HW issue occur when you are running at 70 deg flow temp for the CH in spring/autumn I'm currently running radiator flow temp at 55 today I only need maybe 2 hrs of heating this evening - I could run it longer at lower temps but 55 gets the house up to temp a little quicker.

Appreciate the pedantry - thanks

Our electricity usage is pretty constant (Gas Central Heating/Water not ASHP) 4 bed detached - 2 occupants Our background overnight usage is 250w per hr (2 fridges, 1 freezer, CCTV, skybox, router, signal repeaters, microwave clock and a load of smart items that all consume a little) Daily consumption overall varies from 7.0 kW to 13kW at the weekends (washing days, tumble drier and oven usage are all quite large consumers) Point I'm making is usage overall will mirror ASHP as for most houses the usage is pretty constant and I can see why you would put the case that it seems to be double the declared ASHP usage. Summer time when space heating is not required should give you a good guide to your base line usage?

I don't want to be antagonistic here but have you attempted to see what the house actually needs flow temp wise for CH for a reasonable speed warm up and at a steady state? Your old 34 year old boiler would have been fixed output, no modulation and minimal temp control - it would have also been chucking energy out of the flu. Yes they do heat houses quite well but are very inefficient compared to modern condensing boilers - I'd have a guess that you've seen little or no saving in terms of gas consumption since the new boiler was installed.

I've just watched the video and seen that............. And agree with earlier comments that is bloody high for a CH flow temp - have you got tiny rads with no convector fins? Mine is an 82 build house, std CWI and 100mm of loft insulation and 30 year old double glazing and even before improvements to the original rads 68 deg was more than enough CH flow temp for the 13 rads in the house only in a prolonged period of minus 5 did I raise it to 72. 82 is boiler flat out?? It's a condensing boiler and you are running it like an 80's non condensing boiler and at 80's efficiency levels - return temp must be 56 at best so only in the initial warm up phase (which will be bloody short) will it even condense.

What is your flow temp for CH? I assume no weather comp (and you don't manually weather comp by changing flow temp depending on the weather)

I'm sure you are right but just to say about 25-28 years ago there was a push to get more households off rateable value based water rates and onto meters - one of the incentives offered in my region was pipe coverage from the meter to the house stop cock for as long was we were in the house (it expires on change of ownership) We got a saving of 50% of our previous water costs as a result of fitting a meter. I've been very careful to keep the letter in my water bill history file. It would be interesting if I ever did have a leak to see how the water company would react - my money says that they would say from the meter to the house it's my responsibility but that letter might provide an interesting leverage and whilst I haven't needed it yet I think they'd have trouble backing out of the responsibility.

Never seen one but then I haven't looked that hard

Agreed - it takes me a lot longer but I get what I want to the std I'm happy with And the next time I do something similar I do it even better having learnt from the previous

Looks identical to ones I have fitted It's a std button type like this - has a slotted shaft to lock on the cable mechanism and the pusher comes out of the middle https://www.screwfix.com/p/flomasta-dual-flush-push-button-chrome/674fy If you want something different then you may need to evaluate if it will work

Absolutely - My boiler is 5m from the HW Tank - the pipes run inside the heated envolope of the house (between the ground floor and 1st floor) but are not lagged and I lose 2 deg of flow temp between the boiler and the HW Tank When the kitchen gets replaced this year the ceiling is coming down anyway so both flow and return pipes will get lagged then

At one stage I was running 10-12 cycles per hour on manufactures stock settings - it was driving me nuts so I decide to deviate from the manufactures base settings I now only hit 6 cycles per hour when the house is in a steady state condition but most of the time it's around 4 Manufactures base settings are exactly that "base settings" get familiar with your boiler parameters and understand what they do and what impact they have and you can tweak the settings to reduce cycling without impacting warm up or comfort. Biggest impact is getting the flow temp right (if you don't have weather compensation) - next comes range rating to meet the heating requirements (in my case 16 kW on a 24kW boiler is more than enough) - then POT (pump over run timer) and then ACT (anti cycle timer) although both the last two have limitations

When I replaced an old non condensing 1980's boiler with a new condensing boiler back in 2009 I saved 4000 kWh per year so around 10kW per day I reckoned 50% was down to the pilot light and 50% was down to condensing eff improvements (as we couldn't get below 72 deg flow temp due to rads sized for 80/60 so condensing was marginal after the initial warm up phase The pilot light was set up to be robust or it would get blown out on a regular basis when it was windy so I'd say the 3.5 was probably quite representative of pilot light wastage

Absolutely agree but I was trying to make the same point - if you include the heat up phase you are going to over estimate the steady state losses.

I was using the std 15.5 to base HDD data to compare if my improvements were making a difference - however using the regression tool and historical consumption I quickly established that 16.5 deg was a much better base line for my house Currently between 2.7 and 3.3 kWh/HDD but if I make a mistake in setting the flow temp (get caught out by the outside temps changing quickly) then I can easily overshoot. (HW requirement is excluded) I don't have weather compensation - a 10kW min on a 24kW boiler range rated to 16kW so manual adjust flow temps to suit For 10 deg outside I can run as low as 45 deg for closer to zero I need 58 for the warm up phase but then I can drop to 52 to maintain temps (I'm looking forward to a new boiler and weather comp in the spring/summer)

Was the heating on constant (24/7) and the house up to temp before you started measuring gas used?? If you are heating intermittently or using setback temps then measurement of consumption is not going to give you your heat loss as you have heavy usage in heat up but periods when the heating is not on or it's maintaining a set back temp you will lose less as the house cools down. My calculated heat loss is 4.5 kWh (target temp 20 outside temp -2) however I deviated from the default ACH parameters in the assessment used - IMO they were way too high - with the suggested ACH it would be 6.1 kWh. I sense checked mine in a slighty different way in the cold snap we had in November last year (temp was between 0 and -2 during this time) as we do heat intermittently and don't have set backs on a weekend heating so on those days I heated the house up and then only measured gas usage for the hours once the house was up to temp - as a result I was only effectively replacing the heat being lost in that period First day averaged 4.1 kWh Second day average 3.9 kWh As a result I'm comfortable that my heat calcs are reflective of my actual heat loss

Explained well here

Turning off rads can save you very little........... The balance of the circuit on the remaining rads is no longer correct Unheated rooms steal heat from heated rooms so those rads have to work harder The circuit volume is reduced so the boiler short cycles which is bad for efficiency

Extended the garage about 20 years ago (5.5m by 3.5m) matched the original pitched roof (Marley Mendip concrete tiles and roofing caps) - been absolutely fine for years No leaks into the garage loft space but I noticed the other day when cleaning out the gutters some of the mortar on the valley joints and the roofing caps has cracked - some has fallen out and dropped into the gutters (see other post on gutter cleaning Anyone know what mortar mix to use if I get up there and pull out the loose stuff and re-point/repair the areas where it's poor? Soft sand or Sharp sand? I'm quite happy working/walking on a roof - it's only single storey and I over speced the roof trusses because I use the loft garage for storage

Bravo claps hands - nice detail (in some case a smidge too much) but Thank you for showing your workings