Vaillant Arotherm Plus Heat Pump VRC720 SensoCOMFORT Settings 

Thanks for the comment. Hope it's going well for you!

I hope that a wide rollout will improve the education and implementation of commissioning these systems. No heat pump should be heating radiators and hot water at the same time. You should have a 3 way diverter valve that be default allows the heat pump to flow around the radiators and when that is energised it should stop all flow to the radiators and direct it through the coil in the hot water cylinder. If yours doesn't act like this, then you must contact your installer to have something corrected.

Thanks for that. I shall be contacting the installer (Aira)

You're welcome. I realise now that the video was a bit scatter brained as it was targeted at helping one individual that was struggling to find certain settings. I may record a more comprehensive and better thought out video going forward!

I use these in the rooms to roughly monitor room temp. amzn.to/3TMyaJ8 You can pay more for Bluetooth or data logging thermometers if you want. I started with getting the heat curve set correctly to heat our living room which is the coldest in the house and then worked backwards from there. If necessary, adjust the room TRVs to limit overheating in some of the other rooms, especially if you often leave doors closed. I found that because the heat pump is pretty gentle in the way it heats that the rooms and the house were naturally quite well balanced and I didn't need much intervention, especially once I lowered the heat curve to where it should be. The old gas boiler was many times worse with hot and cold spots all over the house.

@@UpsideDownFork thanks! I’ll look into those monitors Good idea to work backwards from coldest room We’ve just extended the house and had the task of insulating every internal wall which was fun We have solar, Tesla pw , two evs and now ashp so need to see if octopus offer a better option to octopus go that we are on Gives us 5 hours off peak at 8.5p and I like that it’s simple and we never use peak so that’s nice Can’t get intelligent yet as cars aren’t compatible and smart Hypervolt isn’t yet either Thanks again

@@AnotherBoring43yearold The best tariff will likely be directly linked to how many miles you do in the EV, unless you're happy to switch at least once a year. With your PW, you will probably be best served by the Cosy tariff when it gets really cold and the heat pump is consuming a lot of energy. But then again if you do a lot of miles in the EVs every day then you may be best sticking with Go and just trying to load shift as much as you can to the cheap energy window. Good luck, I quite enjoy the game of tariff hopping! Consider trying the Octopus Compare app as well. It will take your smart meter data and show you how much it would cost on various tariffs. Difficult for you to get a perfect picture because it will be influenced by the load shifting.

The panels themselves will not change your running costs, but the settings will 👍

Is your room mod set to inactive?

@@UpsideDownFork expanded I think..

@@MikeGleesonazelectrics So your pump will not be running on pure weather compensation. My guess is that your room temp is higher than your target temp and the sensocomfort has turned the pump off because of that. You will only find your true weather curve by turning it to inactive, but beware, any changes you make to the curve will take 24-48 hours to become clear.

@@UpsideDownFork Ok many thanks, I shall have a little play. The target Flow temp does come back on once its switched to inactive, as yours is but to me the target temp shouldnt read zero at any time at any setting but maybe its just me not understanding it..

@@MikeGleesonazelectrics Yes, it's a totally different approach once you set it to inactive. Low and slow, but you should see your CoP improve by doing that.

Is this a new system or an existing system that has developed a fault?

This seems to appear frequently when the heat pump is overpowering the cylinder coil / heat exchanger. Vaillant flow rate is high to try and help this issue, but it just can't shed the energy quick enough.

@@UpsideDownFork Thanks. Will see what flow rates I can adjust.

Hello Simon, thanks for your comment. Yes, i've covered this in some of my other videos. I'm monitoring my current performance throughout this winter and i'll decide what we do with the buffer later on. My preference would be not to entirely remove it but to re-pipe it as a volumiser on the return leg of the rad circuit. As my 7kW unit requires 20-55L for a defrost cycle (dependant on water temp), the buffer tank plumbed as a volumiser on the return would mean that it shouldn't initially draws heat from the radiators themselves during defrost. Your 12kW unit will require more volume for defrost I would imagine but you can check that in your manual. I don't believe there are any disadvantages to using as a volumiser. The theory that a buffer decreases operating efficiency is definitely based in science and engineering understanding but some of the claims of a 25% decrease seem somewhat exaggerated. There are so many variables when it comes to distortion that it could in reality only be a 5 or 10% decrease in efficiency. I've tried my best to match the flow rate on our rad circuit with the flow rate of the heat pump itself to minimise any distortion which will keep our efficiency as close to a non buffer system as possible. My most up to date running figures were just published a couple of days ago if you look on my channel.

Hi, thanks for responding so quickly. Which video of yours covers this subject? The only downside to turning the buffer into a volumiser might be that you'd reduce you return temperature a little bit but I'd imagine that would be fairly minimal. My 12kW unit requires up to 150l but I have 11 large column rads and they add up to at least over 280l, plus I then have some underfloor. My worry with my system is whether the primary pump will work when I take the secondary one and buffer away. I was told by Vaillant that I need 2000l per hour, currently I'm only getting around 1500l. I'm not sure why and if this is really an issue. I was going to take away the pump on my UFH as well. Any thoughts? Also, how did you match the flow rate of your two pumps, are pumps easy enough to play with? Maybe as you said it's not worth all the fuss anyway. Thanks again

@@simongooden63 in your case with all that circuit volume it's probably not worthwhile to use a volumiser. I have 4 large radiators but the other 10 are all medium size, although I do have well over the minimum system volume, an extra 45 litres will only help the thermal mass and my pump will easily reach the 1200lpm it needs. I balanced my heating circuit pump to the heat pump itself by setting the heat pump to a fixed flow temp and measuring the DT across the flow and return. I then measured the DT on my heating circuit which was much smaller as left by the installer. Dropping the constant curve on my grundfos pump from 3 to 2, got it to almost match within 1 degree. Once I put it back onto full weather compensation, the DT between the HP side and the rad circuit side remained pretty closely matched as I monitored those temps for about a week at various times. Ultimately, it will never be a perfect match unless the heat pump could control the heating circuit pump modulation. I'm sure the real experts will also factor in the balancing of rads to achieve the correct DT on the rad circuit side. I did measure all of them and got them.all pretty close after a few days of back and forth. A clamp thermometer or at a push an IR thermometer are your best friend if you want to monitor and/or tweak 👍

​@@UpsideDownFork thanks again for your help. One last set of questions... I've bought a clamp thermometer as you suggested but I see there is a temp probe on my primary return, do you know if this temp can be found in the SensoCOMFORT settings? I can only find the flow temp, not the return. Secondly, in regards to balancing the rads, do you mean you measured the flow and return temp at each rad and adjusted the lock-shield valve to get the same flow and return temps for each rad across the circuit?

@simongooden63 Return temp isn't in sensocomfort, but in the main controller. I ignored those temps for my measuring so that the same meter was used for both and don't have to worry about calibration. Yes, the rad balancing was measuring the flow and return across all radiators. Once those are correct then I measured all the ambient room temps and had to go back and adjust a couple of lockshields to try and get the right balance between room temp and DT across rads. Hope that makes sense.​@@simongooden63

Yes, you're correct. I thought I had covered that in the video but apologies if I didn't. It wasn't a planned or scripted video, just a quick recording aimed at one member in the Facebook group who was struggling. Uploaded here too as thought it might help others on their journey.

@@UpsideDownFork you seem to know it well. the curve can be tricky to understand. in the end you just want to lower it until its no longer keeping up with your house. enjoy the journey to better cops.

@@joewentworth7856 thanks for taking the time to comment!

You need to set them for individual zones. For most efficiency you want the HP to be using as much volume as possible which means multiple zones open at a time, unless you have very large zones of Underfloor heating or radiators.

Thank you very much for your reply. What does multiple zones open at times mean? 😊

if you can, have the zones timed to match each other as much as possible. An open zone is one that is connected to the heat pump because the timers are showing that it is on. Good luck 👍​@@lakshmikumar21

Now I got it, really appreciate the time and advice . Thank you again

Yes, the flow temperature can go lower than 30 degrees. Adaptive heating curve may automatically be disabled when you select room. Temp mod. Inactive, but it's good to disable it if you want full control 👍

@@UpsideDownFork If i'll use gas boiler ecoTEC than i'll can setup the calculated by heat curve target flow temperature lower than 30C ?

For me I can't make cosy work out as a cost effective tariff for our lifestyle. Ours is set at 20 degrees 5:30-8am and again at 3:30-9pm. Setback set to 17 degrees between those periods 👍

I think octopus recommends setting the heating slightly higher during the cheaper periods, so that the house is warmed up somewhat when it reverts to the peak period, so using less juice. I'm on the intelligent Go tarriff so I do that by setting the room temp to 22C for an hour 04.30 - 05.30am, when the off peak period ends (7.5p/kwh) , then setting it to come on again at 20C at 07.30am. This should cost less than heating from 6am say.

@@MikeGleesonazelectrics Unfortunately this just doesn't work with systems that are running true weather compensation because they will typically only warm up at a rate of 1-2 degrees per hour. Also, who wants to avoid cooking etc between 4 and 7pm. I know it's a different story if you have a decent home battery and inverter but I think the marketing and targeting towards heat pumps is misleading as for most people it will not work out cheaper because of how hard you will need to run the pump before and after the period to make up the difference.

@@UpsideDownFork I guess thats where different home situations arise.. in my case I have retained gas (reluctantly and for now) just for cooking as we have a full gas cooker. It also helps to heat the house for the evening in winter and is (at the moment) relatively cheap. Used just for cooking its cost £4.67 so far for the month incl standing charge. I do have solar pv and a small battery and now that elec prices gone/going up further I am about to replace/add to the battery with a larger one which is able to charge up for 6 hours @ 7.5p/unit. This is the ultimate and then prob can disconnect the gas completely. No wonder the take up of ASHP has been so low in the UK with the cheap cost of gas, its such an anomoly and needs to change. I should have held off for a bit, I only got the £5k grant!!

@@MikeGleesonazelectrics Yes, you raise many good points! Our gas is now gone and with it the £100 per year of standing charges. Our gas hob has now been removed but waiting for the Induction hob to be installed so right now we are in limbo and making use of the oven, slow cooker and microwave to get us by for a few days. I'll put together a whole video about getting rid of gas.

Thanks for raising that point. My adaptive heat curve is disabled 👍

My adaptive heat curve was set to disabled on installation thankfully.

Why?

@@m23605 It's only really applicable if you have the room temp mod set to expanded. If you have room temp mod set to inactive then Vaillant says that the Adaptive Heat Curve shouldn't interfere with your set curve. I think most of us disable the adaptive curve just to be sure we are in control!

@@UpsideDownFork Thanks I'll have to look into what expanded means. This is for a rental so I want the system to look after itself. if it doesn't work, do you think I can make adjustments remotely? I've specced the internet gateway into the install job.

Hello, this one is the VRC720f/2. I didn't touch on that in the video as the core functionality is the same across the models and the biggest difference that end users will notice is if their system is not schematic 10. They will likely have additional options that mine does not show if that's the case. Thanks for taking the time to comment 😊

That depends on lots of factors, but manual is not the right solution for most people, most of the time. 1. What is your lifestyle? Are you mostly home or mostly out? 2. How well insulated is your home? Being a newbuild it should in theory be quite good. Rule of thumb: - If you are away most of the day time for work, then use the timed setting with a 2 degree setback. - If you work from home then leave it at a constant temp all day long but you still really want a 2 degree setback at night as it is better for our bodies to sleep in a slightly cooler temp.

@UpsideDownFork thank you for your help, the engineer advised how he set it up is most effective 🤷‍♂️ we're home most of the time, it was set on 18 on timed and setback was 16. I changed it to 17- 15 set back. I asked him which is cost effective, not sure if having it on constant or having a set back, not sure if costs more for it to climb back up the 2° once the morning comes. I just hear the fan on on a night and hoping it doesn't cost a fortune.

@@what-lies-in-your-skies In terms of running efficiency (CoP), it is probably better to leave the same temperature 24/7 but in terms of running costs, a 2 degree setback will definitely work out cheaper to run on a standard electricity tariff. If you have a cheaper night rate then it's a totally different story.

Different approaches for different homes but inactive will give you more consistent heat throughout the whole home as it's not susceptible to solar or other heat gains in the room where the sensocomfort is placed.

Yes, that seems to be an issue. I've read about a few well insulated or smaller homes that suffer with this. Do you have the myVaillant app? Does it show you how many operating hours Vs cycles?

@@UpsideDownFork Yeah, it shows that I have 680 cycles in some 811 hours which is acceptable. I am trying to mitigate the cycling issue somewhat. My newest idea is using a Shelly Plus 1 connected to port S6 on the VR71 unit. This would turn the heating off (called externe Wärmebedarfsanforderung in German) when it has significantly overshot the desired room temp in the Bathroom. I will see how that affects things. Overall, it's not really a problem so far, but it is annoying that even one of the smallest Heat Pumps can't modulate well enough to always provide the appropriate flow temps for our building.

@@rolandrohde yes, for now the modulation ratios on these heat pumps appears to be 1:4 from what engineers say, hopefully they can improve that in the future and get closer to 1:10 and then heat pumps will work incredibly well under partial load. Good luck with your experiment! Although you don't have anything to worry about with less cycles than hours 👍 My buffer tank certainly helps the system in my house with reducing the cycling.

Thanks for contributing 👍

Where is a COP displayed? Thanks

Pretty much all the same. I've gone round and round trying to gain a little efficiency by tweaking to the max but what's shown here is pretty much perfect for my property. The only thing I need to actively be aware of is setting my DHW temp a bit higher in the winter and a bit cooler in the summer.

Thanks. That's a great point that Vaillant is very eager to make users aware of the fact that their figures are estimates. That said, there have been a handful of users who have fitted the whole open energy monitoring kit and they found that after a couple of months of monitoring, the figures estimated by Vaillant and measured by the openenergymonitor heat meter kit, was pretty much in the same ballpark. Ultimately like you say, a good baseline to work from when trying to optimise the system 👍

@@UpsideDownFork I only say as i do not have independent measuring, and my working figure for the last year of use was 5.2 which although i have worked hard to get it as high as possible and the flow are only 40 degrees at -2. this figure is better than the data sheet suggest so maybe I just have a more inaccurate unit than those you are referring too.

@@joewentworth7856 have you considered combining your design temperature with degree days to calculate what your SCoP should have been according to the Vaillant specs?

​@@UpsideDownFork that sounds interesting could you point me in the right direction to do this?

@@joewentworth7856 I haven't figured out the exact details but I am planning to do that once I have a bigger data sample, probably after a full year. I would like to present 1. My recorded consumption data according to Vaillant controls. 2. Estimated consumption based on MCS calculation formula 3. Theoretical consumption based on degree days, design temperature and extrapolating the flow temps based on my compensation curve. It should be theoretically possible and of course hopefully the 365 degree days are enough data points to level out over the year.

You'll have to ask Vaillant technical about that, I'm not familiar with your unit I'm afraid.

Hello there, do you know what your design temperature is? Was the UFH installed at the same time as the heat pump?

@@UpsideDownFork UFH? What is this ?

@@swedishkev under floor heating.

@@UpsideDownFork no this is a new pump install 4 months ago. I still have lots of air noises in the system though. Before was a sanyo eco from new 2008. Never ever had all these noises in the pipes. Obviously, it will not run to the best efficency. I am going to get this looked at soon. But this does not have so much to do with why system was struggling at minus 19.

@@swedishkev I would make sure that the flow rate is set correctly according to the spec of your underfloor heating pipework/manifolds and of course the Vaillant heat pump itself. Flow rate is critical. 👍

Hello, I can't advise you on your system I'm afraid but in the video the actual temperature is higher than the target temperature because it is just going onto the setback And i had also taken the controller into my home office to make this quick video. My home office has large south facing windows so regularly experiences some solar gain throughout the day. Take care!

@@UpsideDownFork thanks,l only wanted to understand,heat curve and flow rate, and if you had any thoughts on why my system was slow at keepingcthe heat,when it got to minus 17. You seemed very knowledgeable.

​@@swedishkev the website energy stats UK has a good section about the compensation curve that might help.

Good, sounds like your commissioning was done properly.

That's the way to do it 👍

Yes, this is recommended but based on my personal risk assessment, it's unnecessary for us.

@@UpsideDownForkI honestly don’t think I need the legionnaires cycle as we use up most of the water everyday with bathing the kids and showering etc.

@@KoochiKoochi That's the exact reason for us too.

Just a word of warning, flushing the tank every day doesn't eliminate the risk of legioneers, it lives in the biofilm and sludge in the bottom of your tank, strongly recommended to steralize the tank at least once a week.