Just a brief update, following 10 months of discussion with the developer and the other third parties, some progress is now being made.  Roof space insulation was deficient in several areas and this has now been re-layed. The buffer has been re-piped so both UFH and radiators flow from the top connection. All accessible pipework and exposed manifolds have now been reinsulated. Vaillant now need to come and replace two radiators that were under specced. Will be looking forward to see whether we have a) a warm house b) a more efficient system... although there is no need for the heating yet given its almost 20 degrees outside but temperatures looks to fall over the coming days. 

Have also bought a few builders tonnes of hard wood for the log burner for the cooler days. 

@webcmg 

thanks for the update.  It will be interesting to see how your system performs when the colder weather sets in.  Fully stocked woodstore here too!!

@webcmg I've just joined this forum, just to reply to this. We have had the same heatpump fitted on the 5th of October this year and have the same astronomical costs. Between £20 and £25 per day. Please tell me that you've managed to make some headway with reducing the costs from where you first started? And more importantly, please tell me how?! It's causing us endless stress and sleepless nights.

@alexelk

Hi Alex,

Welcome to the forum and I am sorry to hear about your high costs.

For the forum members to be able to help could you please provide as much detail about your home and system.

Also provide details of how it has been set up and is being operated.

@alexelk Hi Alex, sorry to hear you're having problems too. In our case, I don't actually think it is the heat pump, but the house insulation, overall airtightness, and the design and commissioning of the system.

We're slowly making progress but it's so hard to tell whether it is going to really improve efficiency until it gets really cold. I've provided details of some things that have been done to improve below, but as your system is different I wonder if you might start a new thread (tag me) and we can all contribute there?

We're in a 300m² new build and we have:

• Loft insulation was found to be very poor and had to be relaid and topped up
• Upstairs radiators were underspeced and need to be replaced (downstairs is UFH) 
• Pipework on buffer tank had to be reworked to change outward flow to UFH and Rads to the top connection and return into the bottom connection
• Our heat exchanger, hot water tank and buffer is in a garage store room so I insulated them all. 
• The pipework ran through the garage roof space that was uninsulated and has now been insulated
• Pipework in this area was also poorly lagged, radiator manifold was exposed, but is now boxed in with celotex.
• We're still waiting for the developer to reseal around windows and doors and to resolve some issues with significant draughts. 
• We also found the hot water tank was autosyphoning via the secondary return resulting in significant water heat loss from the tank. A non return valve was fitted which stopped the problem (but introduced a new one that means the secondary return doesn't currently work - this just means we have to run a tap longer at extremes of the property to get hot water - I know, first world problems we can live with). 
• Purchased and installed a homeassistant server to monitor energy usage and flow temperatures so that I can understand exactly what the heatpump is doing
• We've put all our thermostats on 30 degrees (to basically stop them from working) and are now running the heatpump 24/7, using pure weather compensation. The setback temp is being used at 17 degrees when we're typically not in and all night and 20 degrees at other times as required.
• Current daily cost for all electricity use is under 30kwh per day (November). Do you know how many kwh you're using, we're fortunate to be on a very low fixed tariff so around £4-5 per day (will be up to 4x as much more when our fixed rate ends). The kwh usage will also increase as the temperature drops. 
• I'm in the process of doing some calculations to try and understand what cost will be throughout the year because in the summer we were only using 10kwh per day, with 2kwh for heating the hot water. It was scary seeing the kwh usage last year, so hope the changes will mean the system performs more efficiently. I was however surprised how little it cost to run over the summer months. 

Assuming you have a VRC700 (rather than ambisense? ), one video relevant to commissioning our systems that I did find very useful is here:

Happy to help you as much as I can, I've been very grateful to everyone who has helped me here to date. 

@colin Hi Colin looking at the frient monitor. If using with HA will I still need a compatible Zigbee hub? I have loads of hubs (philips hue, tado, amazon echos, neomeister, eufy, somfy) and don't really want any more!

Information on compatible hubs seems limited. Depending on whether any of these are compatible, I might go for the Hildebrand IHD instead...

Can you offer any advice? Thanks

@webcmg Hi, brilliant news you've made good progress. I'm using ZHA with works well with the Frient monitor. You need a device (Coordinator) that's on the ZHA compatibility database. Hopefully you can do something with one of your existing Zigbee hubs. In theory, if you have one in HomeAssistant, you won't need any others because it can control all the other manufacturers so it might be a good opportunity to consolidate it under the one home automation solution.

https://zigbee.blakadder.com/coordinators.html  

@colin

Insulation has been improved (still more to do), we've had 2 of 3 rads changed to K3s yesterday (last one on back order) and some check valves swapped for a more appropriate type.

I had been running the system as above (consumption around 50kwh per day before these changes), but the unstaller has reconfigured our system back to rely on room thermostats and a higher flow temperature with narrower range. I'm happy to try this for a couple of days, but prefer the idea of full weather compensation with set back because downstairs has been nice and warm all the time using that approach and with the larger emitters upstairs suspect this will also be the case upstairs. 

My concern is that if the stats are set to 30 in order to stop them operating and allow full weather compensation, I think the pumps on manifolds (x2) and Grundfos pumps (x2) upstream of the buffer tank will run 24/7. Even when the ASHP is not active. Is this likely to be OK from a safety perspective? If so I think I'll follow heat geeks advice and go with full w/c.

Does anyone have a view? 

@webcmg Weather Comp. is the way to go and find the heat curve settings for your zone(s) that works best for you. Our Heat curve works well at 0.35. The lower the flow temperature, the more efficient the heat pump is. If you're using thermostats, the Ambisense radiator valves are probably the best choice for Vaillant Pumps as they can adjust the flow temp for the zone. I hear that Tado can do similar with Vaillant Heat pumps. I imported the Ambisense stats from Germany via ebay because they were a good deal cheaper than the UK. We've been averaging 20-30 kw/h per day over the last week. Our worst day was 40 units. Hope these comparisons help.😀 What flow temps did they set and which stats are you using?   

@colin the room stats are from an independent manufacturer (Heatmeiser). There are basic TRVs on the rads upstairs.  They set the day temp to 23 deg and heat curve to 0.75.  The house was warmer and more efficient before these mods when had 21/18 set back and 0.55 and system was running 24/7. We used 90kwh yesterday at minus 1, what's your daily rate at that temp? I'm getting an independent assessment of the system design and installation because this isn't what we were sold when we bought the house.

@webcmg

Hi, we're not even using half of what you're using. It's been -6 here for some nights and most days this week are around zero.

Are you monitoring your flow temperature? Have you got any data? If it's costing you 90 units per day at -1 ºC, then it sounds like your flow temp is quite high e.g. >40 ºC

My total house power usage this week.

 This weeks flow temp:-

@colin will come back to you with some more data when I have a few mins to plot the graphs in HA. Just a quick question, what setting is your wilo pump set to in the heat exchanger box? I, II or III?