mk1_man

What heat pump do you have? We have Vaillant Arotherm + 7kWh unit with UFH. We have it running solely using weather compensation and its been running great, even with the temp dropping last cuple of days internal temp stays constant. The flow temp rises and falls automatically dependent on external temp. Has been running at around 27 degrees flow (same at manifold) but today with 0.5 degrees outside this morning it rose to 32 degrees and then later this afternoon dropped back to 29.

I am using a 5kWh Sunsynk inverter. I have two Sunsynk batteries with comms to the inverter so charge / discharge is all good. The additional AOLithium batteries I am adding are being added in 'dumb' mode so are only connected electrically in parallel via the +ve & -ve 48v terminals. There is no active comms between them or to the existing Sunsynk batteries. As they are all same 16S architecture they charge and discharge in harmony. £649 ind free delivery and the cables (normally around £50 - £80) is an absolute bargain and too good to resist 🙂 the plan is to charge overnight and run the rest of the day on batteries. Payback circa 2 - 3 years. I have just been looking at the Tomato Lifestyle tariff, this gives 00:00 to 06:00 at 5p /kWh and a couple of other cheap periods a little like Cosy.

Hi all, I am currently using Octopus Cosy alongside 10 kWh of battery storage (no solar yet) it means we have been running our heat pump and the rest of the house at 12.72p kWh 24x7 I am currently looking to increase my battery capacity to 20kWh by adding an additional pair of 5kWh rack storage batteries due to an amazing deal of £649 each inc delivery ( https://www.amazon.co.uk/AOLITHIUM-Lithium-Battery-LiFePO4-Lifespan/dp/B0BS9BL6M9/ref=asc_df_B0BS9BL6M9?mcid=2881ba6285a83c6f9a20979621681b40&tag=googshopuk-21&linkCode=df0&hvadid=697230221025&hvpos=&hvnetw=g&hvrand=3251995294949021747&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9046567&hvtargid=pla-2198438482546&gad_source=1&th=1 ) I am now considering moving to the Eon NextDrive tariff that offers 00:00 to 07:00 at 6.7p /kWh and running off the batteries for the rest of the day. Just wondering if anyone was doing similar?

Hi, I just ran the primary pro insulation straight through the cavity wall. Its a nice tight fit and creates good seal. I have seen the plastic tubes and finishing bezels? Don't think they are required myself.

The insulation is Primary-Pro, brilliant stuff and possibly the best for external use. I am however going to be putting a sort of lid over it made up of some 40mm xps foam board I have. Conscious of need to maintain air to the anti-freeze valves.

Same here, using batteries on the Cosy tariff. Charge them during the off peak periods and run the house, heat pump etc from the batteries during the other periods. Works really well. DIY install of Sunsynk 5kW inverter and two of their batteries. Just need to get some solar panels now

I don't entirely disagree with you re the £7.5k grant, however its available so why not use it. What they need to do is reduce the grant to say £3-4k but remove requirement for it to be installed by MCS certified companies. They are simpler to install than gas boilers so why tie the process up in red tape which a limited number of companies profit from. Its the same with removing vat from insulation as an incentive, you can only access vat free insulation if you then pay through the nose for a certified company to install it. Why can't I simply purchase 10 rolls of insulation myself from say B&Q and not pay the VAT on it.

Could there be such a thing as a simple hybrid boiler. I looked at hybrid approach prior to going the BUS route, although feasible it would have been far from simple. Time will tell but really happy with my heat pump and performing brilliantly so far. Miles cheaper than my gas boiler. Also, as per topic query. There is no requirement to remove the gas supply, although unless you were wedded to gas hob why would you keep it. I am just in process of getting my gas meter removed via Octopus as they do it for free.

@JohnMo : What make / model is your heat pump? Your traces are very similar to mine. I get the initial spike followed by a period of modulated output then after a period of less than 1hour heat pump turns off, waits about an hour then does same again. Mine is an Arotherm 7kW :

Thanks, that's a really interesting article. I have just checked and I look as though I have the latest firmware 351.09.02 at least the article answers my question about how do you update the firmware, I just assumed you could do it as long as it was hooked up to the Internet ! As for the on off behavior I suspect I was running it a little warmer than the house needed, yesterday it did get a bit warm even though it was showing 10 degrees outside, this morning I changed it from 0.40 to 0.35 curve and the system has been off all day after the initial 04:00 - 08:00 period. It has only just fired up again at 18:00 Crikes, we never paid this amount of attention to the old gas boilers !

Apologies, yes my Sensocomfort is set to Inactive. I will do some reading up on the Expanded mode and see if it brings any benefit. Thanks

No, those were all space heating. I have a sensor on the diverter valve that tells oem when I am doing dhw so it then plots it with a blue background and keeps a separate tally of COP etc which is cool. That way dhw which is always lower cop doesn't distill the space heating cop. I have my water set for 50 degrees. I have an additional sensor in oem that tracks my cylinder temp - the black line : Overall it looks like this. Its nice to see the two separate cop figures also :

DHW : Eco mode, space heating is set to Inactive

Thanks all for the feedback, its a fascinating journey, wife thinks I have gone mad though. All the Vaillants appear to have this weird initial spike before it settles down. The open energy monitor is great, my advice would be have a look on Ebay for the heat meter element itself as there are some great buys. I managed to get a brand new Superstatic 440 with 11/4" connections so no impact on flow rate for £100 instead of £650, chuffed to bits.

Hi, I have just started off in the exciting world of heat pumps. I have recently completed my diy install of a Vaillant 7kW unit and 250l Vaillant cylinder. Its a very simple setup with single zone covering underfloor on ground and first floors although there is only one active circuit upstairs as we don;t like bedrooms warm. I am monitoring on OEM which gives fantastic feedback so thoroughly recommend anyone doing this on their setup be it not a cheap option. Heating has been on for a few days now and I am getting strange on off periods throughout the day, is this normal? Curve was set to 0.4 but I have dropped to 0.35 as house was almost too warm. Pump has been running at around 3.3kW output and around 590W input, flow temp steady around 30degrees.

Thanks, took a bit longer to install than I had planned, probably due to soldering all of the joints as opposed to hiring a press fit tool. I was doing in in fits and starts but all in probably 4 - 5 man days in total. Hard to see how the companies I got quotes from could quote £12k plus ( excluding BUS grant ) the parts were approximately £6k and that is including vat and purchasing as an individual, surely the bigger companies command a much better discount. In my eyes just proves that the current situation is ripping off consumers and not delivering biggest bang from government investment. My view is that it should be opened up to a much bigger market and simply install to a best practice guide but essentially make something like Open Energy monitor compulsory if you want to access BUS grant with a requirement to score at least a cop of 3 or above to qualify. This would put the onus on installers and manufacturers to deliver the goods and stop it being an MCS monopoly. Thanks for advice on cooling, I was going to look into it and have ordered the following at £11 delivered 🙂 https://www.theheatxchange.co.uk/vaillant-plug-coding-vai0020266328

Chuffed to bits, finally finished my diy install of my nice shiny 7kW Arotherm. Have only used for dhw but working a treat once I realised that my esbe diverter valve was wired back to front and I was heating the ufh ! Just need to finish off wiring the OEM stuff. Old boiler out : New unit : Primary Pro and anti-freeze valves

I have just fitted a Vaillant ashp, a window above the unit and outside of the protected zone is permitted. You can also have a window that extends to the ground as long as it is non opening or at least the element that is located within the protected zone is non opening i.e. split unit.

Also you don't want hot water heating contributing to temps in the house during summer. My view is insulate everything, gives you option then for using cooling function later on also. If I had access to a press fit tool I may have gone that route. Filled up system this very morning and touch wood no leaks as yet, once system gets some heat in i will be happier 🙂

Crikes, some of the those costs are eye watering. I am just in final stages of installing a Vaillant 7kW unit plus new uvc and headline costs have been £4k for heat pump, £1k for uvc and around £1k for sundries Granted it has been a fairly straightforward install with existing underfloor on ground and 1st floors, that said have still removed blending valves and pumps on manifolds to make fully open loop, that was quite and effort to get right. It has taken me 4 - 5 days on my own and that is doing soldered joints not press fit. Seeing quotes of 15 man days makes me think they must drink lots of coffee ... Majority of suppliers appear to use the BUS grant as a nice little bonus instead of it being the fully passed on discount that it should be.

Hi Chris, we are in final stages of build / retrofit of 250m2 house, aiming for as near passive house as we can with attention to air tightness, triple glazing throughout, removed chimney and have mvhr. Also underfloor ground and first floors with 28mm primaries etc. I approached a few MCS suppliers and was being pushed towards 11 - 12kw units. This didn't match my own calcs or how the house behaved when on gas boiler. The route I have taken is DIY install via an MCS Umbrella company. I am doing all my own plumbing and electrics. Headline costs have been £4k for 7Kw Vaillant Arotherm, £1k for Vaillant 250l cylinder and approx £1600 for Umbrella costs. ( All inclusive of vat ) This way you can still install via BUS grant but are not tied to crazy prices or forced into a heat pump that you don't want or need.

Hi all. Stuck on one element of the heat pump interface wiring - the cabling to the diverter valve from the interface connection UV1 : I am using an ESBE diverter that has a neutral, permanent live and switched live for switching to DHW. The interface has connections marked N (assume neutral), Auf & Zu? Anybody point me in the right direction. Thanks.

Hi all, 1/2 way through my self install of Vaillant heat pump and cylinder. I am making an effort to give the flow the best chance it can by using sweeping bends, 28mm pipe for all main runs, 1 1/4" esbe diverter valve etc. I have looked at the 28mm flexible connector pipes and I have to say not overly impressed with the internal diameter, appreciate its only a 750mm run but its a chunk smaller than 28mm copper pipe. My heat pump is 300mm away from utility cavity wall so pipe run is really short, basically straight out of the back and through wall via pair of anti freeze valves. I have read a few comments about not requiring flexi hoses on the Vaillants. What are peoples thoughts?

Thanks for the input. The thing I focus on more than maybe I should is cycling and the risk of oversizing. Currently debating whether to install a 7kW or 5kW Arotherm. The 5kW will probably suffice as majority of time it can generate 7kW My rational is that it won't cycle as much as possible the 7kW unit will. Are you saying that a degree of cycling won't harm as long as its not to often?

But it appears to affect the heat pump size required i.e. the design temp is taken as 21 degrees on both floors at same time. Generally bedrooms are cooler and also not needed during the day, at night downstairs is on setback at around 18 degrees or so. None of this appears to be taken into account. I kept trying to argue that what I see day in day out during the winter with my gas boiler doesn't marry up with what I am being told I need on paper. Also MCS forces you to have a warm house at -2 degrees, majority of time temp is not below zero but you are not allowed to factor in the possibility of a few days of the year where you may be a little down on temperature and have to pout on a jumper etc. What that means is the rest of the winter and the majority of the time you have a heat pump that is to big. Bottom line is that I am now installing a much smaller heat pump than I was originally being forced to do, time will tell who was correct 🙂