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My house is annoyingly hard to heat throughout despite being quite small. In order for the hall and bathroom areas to stay warm, the flow rate needs to be 5c higher than the rest of the house needs. Its not too bad, i have smart trvs throughoutnso no room overheats, but it means i still have to run at 60c if its below 3c outside. 60c will then cope with that area down to -3, but below that id have to turn up to 70c. Vexing. I know the problem: bathroom radiator is undersized and sucks heat out towards that side of the house, and the landing above has no radiator. ...but theres no room to put a bigger rad in the bathroom or one on the landing! My hallway rad is oversized now which has helped - last winter i had to run at 60c below 7 and 70c below 0, but the bathroom remains stubbornly between 16 and 18. Bah. I think im going to have to get an IR panel or something in there. If it wasnt for that bathroom i think i could run the house at 55c flow rate or below all the way down to -3, which would be at least heat pump ready, if not heat pump perfect.

Still liking more load compensation than weather compensation. It's way better for my lifestyle and "comfort".

This was very well explained. However, you never took into account how the house is used. In my house, other than the bathroom, none of the internal doors is ever closed.

This is top notch, now I understand. I will be moving homes soon to a traditional boiler /radiator system, this helps me to ensure that when we move I will need to consider the current installation, trial using the boiler at the optimum temperature etc at the same time work out my heat losses per room and take what I’ve discovered here and put it into practice. Not at the ASHP stage yet. Regards Mike

To increase heat transfer, what about having blown air on the radijators, aka fancoil

Only just found your channel. It’s a shame that you don’t seem to be publishing much content as you explain things simply & clearly 👍👍

perfect explaination

12:19 DT for the boiler should be 12 not 11

Horrible boilers, Grant much better.

I've done a few of these over the years especially on a long bungalows or very large properties, They've been a design for decades. I learned about them in the 1980's, Interestingly enough though, a lot of new plumbers have never heard of them

Very helpful . Love from pakistan

That’s the best presentation I’ve seen on it. Subscribed 👍🏻

The bonus content at the end is good 24:06 I'd like know if this is applicable to heating via a heat pump. I'm looking at the reheat time for heating a 230 litre unistor to 50 degrees using a 7kw heat pump that has a 40Kw output coil.

Another great video. I have two questions on the content. 1. So at 15:46 Would you design bedrooms for 18°C and then they always have to be used as a bedroom, or at 21°C and add TRV's as a limiter so it's warm during the day but with a 3°C set back at night it would become 18°C anyway. This way the bedroom can be used for other in the future? 2. At 20:03 you say to try & stick to the same MWT throughout. Does having UFH ground floor with radiators 1st floor make a difference to this because the UFH will be blended down via the mixing group and would be a lower MWT?

Great content throughout. The only part I don't understand was 15:03 With an 11Kw boiler and a 16Kw coil, why do you get to condense through 95% of the cylinder heat up? Where does the 95% figure come from and why does 11 into 16 keep things within condensing mode with the return below 55°C?

Interesting that Part L specifies flow of 55 when a return temp of 55 is the start of the condensing phase. Did they get confused?

That’s a great explanation on how to run them in. I struggled big time when I tried to install one for the first time, many years ago. I dreaded commissioning it as I was sure I cocked up something 😂. (It was fine 👌🏻)

Without heat loss calcs ,it must be guess work .

Great video, clear and precise explanations on how heating works and how sizing needs to be done. Many thanks.

Very interested in the comment about radiator piping. In the illustration of the "European Way", you have hot entering at the top. Does it make a difference if hot enters at the bottom (which feels more logical to me)?

I'm trying my combi flow rate set at 56 degrees. I have heating at 18 degrees when on and turn it down to 16 degrees when off or out. I'll see how goes through winter.

Fantastic explanation and detail. I've been trying to lower my flow temperatures on my Baxi Plat combi as low as possible but can only get as low as 61oC as Im probably hitting the boilers minimum output for my system design.....yet my boiler still cycles as my heat loss is obviously lower than the boiler can go to (manually). My return temps are around 50oC so my boiler is only just condensing. Is there anything I can do to lower this further with my current boiler? I'd love a modern load comp boiler but cant justify it considering my boiler works perfectly.

great video and clear explanation, thanks. It seems like the best way to get the most from WC is a hot water tank - not a combi? that way you can size the boiler so your modulation can go low enough for average temps, and the lower size of the boiler needed should still be enough to heat a HWC? A combi like we have would need to be sized for instant HW and unlikely to modulate down for low enough flow temps? eg at the moment we’re running at 12-13c outside, heat loss 6kw in the house, we can run at 30c flow temp and the house is lovely and warm, but the boiler still cycles because it can’t maintain 30c. Vitodens 050-w 30kw for HW and I think can modulate down to about 3.2kw? 1:8.

Fantastic video. Really done well. Thanks

Bootneck?

I won’t be calling, didn’t see a dam thing in that airing cupboard.

You are all gone pear shaped.ypu have and are being pulled into climate hysteria. Sure the world is warming we don't need heat

Very informative and helpful information. Are the spreadsheets you show in your videos, custom made or are they a resource we can obtain from the internet or from a paid service?

Sorry a silly question: why is my plumber saying tjhat Opentherm is old and is not worth it and wont make difference? I got TADO thermostat supporting it and Ideal Vogue max s18 supporting it yet the electrician and plumber disagree and have no idea how that is support to help because boilers have regulators and do that by itself. Am I loosing my mind?

When it comes to zones you would need two lines ?

Hi, does this leave the 4 time flow rate now needing 28mm pipes installed all around ?

🤘😎🤘

Great video. I have an open vented 250 ltr direct Thermal store, McDonald Water storage, that gives me mains pressure hot water and central heating which is piped from nearer the bottom of the Tank. CH controlled by a Tado controller and pump. No zone valves required. The boiler is controlled by Tado and a tank stat with a separate pump. Works well as LPG boiler, old non condensing, has a long run heating the water only when required and you can shut off boiler at night. One thing I like is that you can set Tado to have towel rails come on when rest of heating off as the tank always hot. I was considering updating the heat only boiler and was interested on your view as to whether a new boiler would run in condensing mode properly and on using weather compensation. Tado can operate open therm boilers as far as I know. Keep up the good work.

Very interesting. Do you recommend any courses for learning about heatloss when considering low temp systems? Do you have to be MCS registered?

When would you take into account the BTU of the radiator?

Great video. Concise and easy to follow. You do mention a 10 degree difference on the stelrad site but then go on to use a 20 degree difference between flow and return later on, why is this?

Great video. Just wondering how you tied the pipe stat into PIRs on the secondary. Didn't quite understand?

Great presentation that has saved me some work! It's clear and concise and something I can point customers towards when we tell them that times are changing.

Just subscribed - what a great job you are doing at putting this across in a way that is easier to understand. I really look forward to seeing more presentations from your channel. Out of interest is the spreadsheet you are using available or is it taken from the Cibse guide?

How do you convert from a dt of 50 once I’ve worked out the wattage needed to what wattage will be needed with a dt of 24/25?

What a fantastic in depth explanation of weather compensation. You are a natural at these explanations and so on the money technically. Fantastic. I'll be sending your videos to my customers.

Great to see another great source of learning on utube.

We compliment you on your presentation on this subject, after reading or watching many articles on this same subject yours is the most comprehensive. Whether customers can fully understand or even agree due to installation costs is the major problem, so far installers are suggesting a suck it and see approach to keep heat pump install costs down, customers go along with that. I totally agree you have the correct approach, congratulations.

At last someone who is giving a true explanation of heat loss and what you need regarding system design. It’s not all about the heat source you must fully design a heating system. Great stuff very well done 👍

Answered a lot of my questions I had on radiators. Thanks for that Black Mountains

really good video! I'm glad someone is going indepth with this kind of stuff! keep them coming mate!

I would love you to install mine but I'm based in Cambridge

I love my 15/19 works fantastic and is always serviced. Had all new rads fitted around the house with some nice chrome valves and all the old fluid drained and system flushed. Runs super quiet and a lot more effecient now with a digital room stat.

Learned a lot from your installation videos.I like the idea of putting isolation valves all over the system to reduce drain down times.Learner question:You have put two 2 valves in series on the hot water side to the unvented cylinder,one honeywell? the other danfoss?.Is their a reason for this, an extra level of safety perhaps? in case the first one fails ( in the open position), But why two different makes?Maybe thats all you had on the van or is their another reason.I assume you wire them the same in the wiring centre.Thanks again .Great job.

good to see a cup of tea being provided to the tech ..