marshian

I had my 100W (Heat only) fitted by a Viessmann trained Gas Engineer at the end of July I was really specific about what I wanted and how I wanted it set up (not specific enough in hindsight) Hopefully the HW demand box, the Wifi Module and the NO CH zone valve (to replace the NC zone valve that was fitted) will all get fitted very soon then I can turn on the weather compensation and the CH can do it's CH thing based on a the WC curve and the HW I can set up to do it's thing at an elevated flow temp in a reasonable time frame. Once it's all sorted I might do a little thread on it. It does amaze me how low the Viessman can go in terms of flow temp and output.

Reminds me of my neighbour - He had a Viessman 100W Heat only boiler fitted - with weather compensation but not DHWP - consequently his flow temp is fixed for CH at 68 deg (Because any lower than that and his HW is not heated in a reasonable time) totally negates the point of weather compensation because the boiler isn't actually using it despite there being an outside temp sensor on the north facing wall. At the end of the day he's got a nice boiler but he's not taking any advantage of what it can do when the temperatures aren't -2

I'm bang on the Norfolk/Suffolk Border but I'm Suffolk born

This was my solution We never had a problem with pigeons on the close I’ve lived for 33 years till recently….. 3 years back English Heritage repointed up a local church ruins - all the nooks and crannies were filled up and all the ledges covered in spikes - so the population of pigeons and doves decamped 50 yards to the nearest houses Each house got 4 to 5 new roof top occupants The first year they decimated all the fruit trees and so we pruned them back the second year they destroyed every single young plant in the veg patch the other half does every year The other half tried feeding them to save her veg patch this year - they pulled the young plants up and left them The territorial males constantly fight for the right to f (party) - they s (defacate) over everything - windows cars patio decking it’s everywhere and I have one modern car with water based paint and the laquer coat is utterly ruined in places The doves I leave alone - the feral pigeons unfortunately I don’t - there is a “bird table” in the garden now that has a substantial back stop (6 inches thick) They soon get used to feeding from there They get a weeks worth of free food then they get despatched Downside is that as they seem rather territorial more move in But numbers are going down…… about 4 a fortnight

I think that tells you all you need to know - they are working to a one size fits all script and complies with the BUS grant criteria I’d find someone who actually will design a system that meets your criteria which I don’t think is impossible at all No local “heat geek” trained installer???

That is the value for the wall but for the section below it looks like averages the wall Window and Door area by the U value for each by area then divides it by the total area

I honestly think you need to find another supplier - if they aren't listening you are almost certainly going to get what you don't want I am assuming here that you are going for the BUS grant?

330 m3 is a big house - are you really going to replace all that air in the house every hour? Seems a bit high? 21 Deg for all rooms also seems a bit high - if the house is relatively well designed and sealed then a target temp of 19 is fine for me

3.1 Oversize factor (from the Heat Emitor Guide) They are trying to improve the Heat pump efficiency by ensuring the operational flow temp is 45 deg is my guess so 3.1 x oversize for the room heat loss https://zlcenergy.co.uk/wp-content/uploads/2013/08/MIS-3005-Supplementary-Information-2-Heat-Emitter-Guide-v2.0.pdf

That expansion pipe is full of water until it rises above the level of the cold store (Funny story I know this becuase I wasn't thinking straight one day and cut into it to change it's route without drain down - luckily I had a bucket nearby and some self amalgamating tape to temporarily cover my error) Anyway heat rises and it will be a source of losses (I am very tempted to fit a london loop in mine to see if it makes any difference)

I think of it like that too - Loft temp in the spring/summer/autumn in daylight hours can regularly be above 30 Deg C for most of the day and has occasionally hit low 40's I have a data logger recording temp and humidity up there because I was concerned about pipes freezing in the winter after I moved the cold water tank to a better location and increased the length of all the pipework by 3m This winter (when temps are cooler) the plan is to increase the level of insulation up there which will lower the cold temps further

We have a 114 Litre tank (Ish) we heat water once a day between 7am and 8am to around 50 deg (this fluctuates a bit because the water heating is timed rather than to a set temp point) This gives us enough water for 2 showers AM and 2 showers PM - I have data logging temp sensor at top of tank and another at the bottom However this means our graphical representation looks a little weird but fundamentally once the morning showers are done the water at the bottom of the tank is replaced with water from the cold store in the loft above Our energy usage in summer for water heating is much lower than the winter where the cold store tank (cold loft) is at a much lower temp

Assuming S or Y Plan - How close is that rad to the HW tank return to the boiler pipework? (is it just pipework stealing heat by convection?)

Old topic but I got our water bill today and we used 97 Litres per person per day (70,500 litres per year) Previous years have been consistently around the 110 Litres per person per day The one outlier was 2021 when I'm pretty sure a leaking cistern (that I hadn't noticed) drove up the usage to 160 Litres per person per day

A - Restrict the feed with an isolation valve? B - Add a small length of capped pipe vertically before the cistern connection - creates a pressure absorber with no mechanical parts to worry about Upstairs in my house the toilets are all gravity feed so no issues with shut offs causing pipe work noises - downstairs I have one on mains pressure I tried A but it was still filling very quickly and causing pipework noise so I did B and that made the pipework silent

Stick your postcode in here https://www.degreedays.net/?gad_source=1&gclid=EAIaIQobChMIsoL13PmohAMVG7CDBx27swedEAAYASAAEgJ_bPD_BwE Will find the nearest weather station to you and if you want you can download the temps by hour for up to 36 months or HDD data as a value by day Excellent data resource for me as I have 3 weather stations within 10 miles of me The HDD data I find really useful to compare if improvements (Boiler/insulation etc) are working or not - my base line target is 3.7 kWh per HDD - if I use more than then I've left a door open or I've got my boiler set up wrong!!!

The other tip I got years ago to stop wood splitting when nailing close to the end was blunt the sharp tip of the nail (turn it upside down - sharp side up on a hard surface and hit it once with a hammer to flatten the point) - it's always worked for me (I think the theory is it crushes it's way thro the wood rather than forcing the wood around the nail which then forces it to split if close to the end)

No idea but once I'd got the basics right and refined the ACH to a more sensible level it was pretty damn close in terms of heat loss - Annual usage was probably a little higher than actual but I did make a couple of errors - one room somehow I screwed up the wall heights and it's heat loss was huge compared to the adjacent room. My only advice is check and check again until you are 300% happy with everything before generating the final report. I didn't know there was a free version but I was very happy with the detail provided from the paid version - it produced a 25 page report broken down in sections covering lots of aspects.

Sorry for threadjack - it happens it's not meant to Sign up here https://heat-engineer.com/home Pay £12 and use their online tool - all you need to know is house dimensions and u values for the fabric of the building It will give you your heat loss at pre-determined external temp and annual energy demand

Happy to take one for the team so to speak 😉 OT - Which Viessmann did you go for??

Trying to optimise an unsuitable boiler to be as efficient as possible on Ch as well as HW - I went down a rabbit hole looking for Alice and was doing DHWP manually With new boiler I'm back to once per day - once I have DHWP and Weather comp working I'll run with once per day as the start of the heating period and then happy with the results/efficiency I'll go back to monthly (I hope)

Do you want the full sad story or the precis? I'll stick with the precis I think but in a nutshell I've been a smidge OCD with meter readings (for smidge you can expect very OCD * See Note) Summer water heating is easy to measure no CH to worry about and our daily kWh usage averages out at 4.2 kWh Winter water heating needs a bit more input energy wise - mains water is colder - loft tank is colder and boiler starts from a lower ambient temperature but a bit of math has that as a factor of 15% increase so 4.8 kWh as a daily average Roughly 182 days a year at 4.2 = 766 kWh 182 days a year at 4.8 = 876 kWh Annual Gas usage 7800 so HW (766 + 876) is 21% of the total used Cooking whilst a small percentage is also easy to work out when you aren't using CH or HW Only two people in the household typically 2 showers each daily and Mrs BC likes a long hot bath once a week - ~112 Litre Hot water tank heated to 50 every morning and normally lasts 18 hrs *Note - Just to clarify how OCD - During the course of 2023 from Jan 1 to Dec 31 I have 1,658 meter readings tabulated in a spreadsheet (cross referenced against HDD and House/Water temps and boiler parameters)

I did a similar activity when validating my heat loss calcs - compared it with heat input once all the rooms were at target temp on the coldest day we during winter and it was pretty close. Enough for me to be confident that my replacement boiler didn't need to be 24 kW. We traditionally heat only before we need it (mornings and afternoon/evenings) I wasn't confident enough to purchase an 11 kW boiler so settled for a 16 kW version (min output for 11, 16, 19, 25 or 32 kW all have the same 3.2 kW minimum)

Old Pump - Grundfos 15/50 Selectric 3 Speed (it was 25 years old to be fair - purchased in 1999 for £47.99 as a direct replacement for the previous 15/50 which was fitted when the house was built in 1982) This has been replaced with DAB Evosta3 60/130 DAB PN - 60193271 Max Flow rate - 3.6m3/h Max Head 6m

When I did my heat loss study it used -2.3 based on location (Norfolk) -10 is a little bit OTT for East Anglia The Heat study came out at 14,500 kWh per year for CH and HW (HW was assessed at 3285 kWh of that overall figure) However they use a really high ACH rate due to the age of my house which I disagreed with (it has quite an impact) Our overall gas usage per year is down to 7800 (CH and HW) CH is 77.5% of our usage, HW is 21% of our usage and cooking is 1.5%