marshian

I freaking love the internet for stuff like that - well found sir It certainly clarifies the position

I missed this edit because I quoted before you'd added it but can I just say I 100% agree with this - I think my long reply says pretty much same thing TRV's can save energy but badly used they can drive up energy usage and smart ones can do far more damage whilst apparently being sold as the next best thing.

Snotgobblers I call them One thing I did like about Covid was it showed the world how good a childs developing immune system was and how it could take on a novel pathogen (CV-19) and just bloody laugh at it like all the other colds and coughs They didn't need vaccinating and there never should have been any attempt to do that all the data screamed that!!!

Ahhh OK but it's not a flow it's just a rise and fall of the level - water level increased due to expansion and drops due to cooling However if the system is pumping over constantly into the F&E tank then potentially it could be creating a circuit where the F&E tank is acting like a very poor radiator...........

I think for me there is an educational step missing in the industry, the manufacturers, Installers and the end users Go back to before TRV's were a thing - your control over the rad was a valve that could be opened or closed at one end You didn't use it to trim room temps unless you had to because the result the next day could be the opposite so as a result most of the time there was an element of "overheating" Then TRV's come along with their fancy numbered scale and all of a sudden room temp could be set or trimmed with some degree of repeatability - as a result energy saving - trouble is if one TRV in one room works well then fitting them to all rooms must be 100 times better Then system becomes over zoned and cycling screws up the boiler efficiency but as you are already saving energy a little loss here doesn't hurt right?? Then comes along "smart" TRV's - they aren't really smart as such they just have a better level of control than the old waxstat variety and they can really screw with boiler efficiency because these TRV's can call for the boiler to fire............ Yes one room drops below the setback temp and the boiler fires up running a circuit size of maybe as little as 30 litres so burns are super short but the room temp is recovered Now fit a house with a bunch of those and you can have all the rooms individually calling for heat at different times - I've been there with Wiser - 8 hrs overnight 53 boiler fires - fifty bloody three times in 8 sodding hours!!!! TRV's have a place but it needs to be a place of "balance and control" and people need to seriously consider a strategy for their implementation, operation and level of control they are allowed. Manufacturers want to promote what they sell TRV's Good - More TRV's better - Smart TRV's must be better than "dumb" TRV's therefore more smart TRV's must be even better when in real life too much of anything can be bad. Installers need to explain the risks of over zoning and giving smart things control of dumb things............. 99.9 % of the "General Public" are not going to have the understanding needed to make even a remotely educated call JM2pW PS I know 2/10 bloody poor rant and lack of variety in expletives

Because the level doesn't change in the F&E tank?

Bloody ingenious - I wish I'd have thought of that before I fitted a replacement pump - still got the info anyway now but it would have been nice to compare the old grundfos 3 speed pump - pretty sure the new one uses less electrickery but pumps harder. Actually I still have the old pump but the speed control is broken - if I can get a second hand pump with a working speed controller I could swap it over and refit it - perhaps I should sling a wanted post up.

They should be able to sort it I was with Scottish Power - took me a lot of effort to get tariff changed to std rate for all hours with my old E7 meter but got there in the end - however when I moved to Octopus they took a similar amount of effort to get them to agree to a single rate tarrif with an E7 meter. When I had the "direct communication meters" fitted (I refuse to call them "smart" as there is nothing smart about them) I hoped to go to a single daily consumption but no when I look in the app I still see day and night rate readings recorded even though the meter only has one reading - bloody weird but at least it means I can still make the calculation if E7 type tarrif would work for me. (It did until electricity costs sky rocketed and the suppliers loaded the day rate far higher than the night rate saved (£200 a year was my saving in ditching the E7 rates)

Regression tool is on this site - dead easy to use if you have data in xls or similar table format https://www.degreedays.net Only caveat is do your best to exclude HW energy usage or you'll get a funny answer (ie a lot more than your true baseline temp) Eskimos had the right idea then

16.5 is my base - slightly higher than the normal 15.5 but the HDD site has a regression tool that I used to establish it after the last round of improvements and I’m pretty happy with the base line You have to bear in mind it’s a stupid shape house with a lot of rooms having 3 external walls which means it’s not a std box with two levels

Nice work Here's my favorite From top to bottom Elec kWh for 2019 to 2024 Gas kWh for 2019 to 2024 HDD data for 2019 to 2024 Bloody labels disappeared for some reason!! Yes 2024 is an increase on both elec and gas but electric was driven by my hobby (welding takes a fair chunk of electrickery) and Gas is a result of going 24/7 this heating season. Data For a 113 m2 (290 m3) 4 bed 2 storey detached house with 2 occupants (one of which makes a lot of noise if it's cold) Oh and just to say when we moved into the house in 1991 we were using 25,000 kWh of gas a year - but the house had single glazing throughout the house, 25mm of loft insulation, no jacket on the uninsulated copper HWC and a non condensing glow worm boiler from 1982 that needed to run at 80 deg on the flow temp all winter to allow the 10 undersized T11 rads to be able to get the house warm.......... Now I'm running 30 deg flow temps at Zero outside!!!!!

I was under the impression that once air had been removed from the system the heating was working again but I could be wrong?

I have 13 rads - all have TRV's What you describe in terms of leaning on the WC and using the TRV's as temp limiters is exactly what I am doing This is the dining room showing a little solar gain this morning If it his the temp target the TRV will reduce the flow to stop overshoot The dip and recovery was due to water heating stopping the CH for 21 mins (PDHW setup)

Isn't that where you have to accept it as a compromise? I don't want perfection and I can tolerate swings of less than 1 deg (well I say tolerate but what I mean is I can't notice them) I get a small amount of solar gain in Winter in 4 rooms (2 bedrooms, Dining room and Living room) - if the impact warms the room up beyond the TRV set point the rad gets shut down. I'm only running my TRV's now as limiters set approx 0.5 deg above the target room temp. My room to room heat transfer is minimal as the majority of rooms are heated 24/7 (OK to slightly different temps but with say one bedroom at 18 deg next to a bathroom at 21 the delta between them is just 3 deg - there isn't going to be a huge movement with a delta of that size. Heat loss calcs said 22 w gained by bedroom and 64 w lost from bathroom.

Why does do you think it tries to go up the vent The level of water in the vent is the same as the level in the tank - it has to be The only reason the vent pipe (and the cold feed) get warm is convection It will pull water from the cold feed under certain circumstances - when you have a leak in the system or bleed a radiator that has a lot of air in it. Rest of the time it's a static head above the pump Water expands when heated - the tank provides a safety element allowing water volume changes due to temp to be accepted without causing system pressure changes When the system cools the volume increase in the tank is given back to the circuit

So the problem is either blockage in circuit or Pump Head exceeds system design As you've recently changed the pump my money is firmly placed on the Pump "Settings" being the cause of the pump over PS I was hoping @John Carroll would join this thread - he was very helpful in explaining my system issues and as soon as the spring is here I'm moving to a combined vent and fill

I can understand the concerns but studies have shown that the risk of catching Covid from physical items is very low - the risk is mainly airborne and close contact with someone who has the virus is probably the biggest risk Transport for London have long since abandoned the hand sanitiser stations https://tfl.gov.uk/transport-accessibility/cleaning-and-air-quality You do you but if you haven't had Covid 19 already I'm amazed and you've done very well to avoid it. I seriously doubt that wiping everything you come into contact with with sanitiser is going to make the slightest bit of difference to your chances of catching it. I had Covid in November 2019 - an unintended consequence of a holiday in North Vietnam on the border with China or migrating thro two large airport hubs I was never sure where I caught it It (the original strain) was proper nasty and I wouldn't recommend it to anyone but a virus that kills it's host doesn't tend to last long - it's evolved into a much less aggressive strain over time Not had it since either - the human species is quite amazing in it's ability to deal with pathogens that it's had to meet.

With HW demand box it's not possible to cap the boiler output on HW mode (Viessmann Technical told me this when I asked how to stop the boiler throwing 19kW at a 3kW HW coil) I know on CH it is possible and I know 10.6% is my boiler min (3.2 kW in low temp operation) because I've measure consumption at that rate in long stable burns. I did a little study a while back on HW to see what the boiler was really kicking out 100% is 19 kW (on a 16kW rated boiler - go figure) 50% is 10 kW 33% is 7.4 kW So I've set it to 20% and see if that stops the issue but still gives me some head room on restarts

How bloody right you are - today was 11.5 Deg C - flow temp target on the WC curve was 26 deg Cycling wasn't great - rooms maintained temps but at the expense of frequent short burns over 30 burns so far today I think the driver is the flow temp rises too fast for the boiler to modulate down rather than the circuit being too small I increased the room temp target to 25 which skews the WC curve to be 34 at 10 deg C and got a couple of decent length burns at the expense of room temps bouncing of the TRV temp ceiling I'm going to range rate the boiler to 5kW (or whatever % that works out to be) and see if that fixes the issue

Here's my math for my rad sizing In a nutshell what I had was a calculated heat loss at -2 and a rad kW output at T50 - what I wanted to see was where as I stepped down flow temps was I likely to have a problem with rooms not meeting the target temp (ie the rad was borderline) In truth I think my heat loss parameters for ACH and loft losses were a little pessimistic and so my heat losses for some rooms are a little higher than reality. But it does show clearly that I am likely to have an issue with three or four rooms

It's actually I think hard to match rads to exactly the room heat loss requirements and not get them oversized (OK I did in one room) For 95% of the year they are oversized by virtue of the outside Air Temp being above the worst case outside temp. Pretty much agree with that

My other half and her mate bet on every single horse in the Grand National once......... 2009 was a lucky year for that process 100/1 winner

If rads are also oversized then you can reduce the flow thro that rad at any given temp and basically make it behave like a smaller rad Quite hard to go the other way mine except winding up the flow and sacrificing the return temps I can definately save some gas by turning the heating off when I'm not in the house but the re-heat process means I have to start quite early before I get home and I'd rather have the house heated a little lower all the time than burst of high energy heating I think there is a lack of clarity in the discussion but you only get clarity by discussion so lets keep it going in the good natured way it is World is too damn polarised now Exactly what I mean by polarised viewpoints - there is no right and wrong only different approaches (with the UK's housing stock - there is an awful lot of grey and I'm not talking about the fashion trend for windows and cladding)

If I hadn't done the math @SteamyTea would have but he'd have used Joules or some other unit of measure 😉

Quick bit of maths 300 L tank heated to 85 Deg C You only use 250 Litres so 50 litres remain at 80 deg after 14 Hrs (Assumption is minimal losses) That 250 Litres has been replaced by 250 litres at 10 Deg temp (It's winter average delivery temp) So you've got 250 litres at 10 deg and 50 Litres at 80 deg If you mixed them you get 300 Litres at 21.6 deg C The mixing occurs when you turn an immersion on that's in the side or the bottom of the tank