ASHP plus small condensing gas boiler Hybrid Experience?

You won’t be able to get the BUS grant for a hybrid system. Full info here: https://www.gov.uk/apply-boiler-upgrade-scheme/what-you-can-get

Thank you Juliamc, yes I can see this now, so I shall revert to my original plan, namely to get a small maybe 3kWh to 4kWh ‘balanced flue’ gas fire installed in my living room for instant ‘on demand’ heating during any cold snaps, because this is an independent room heater and can be switched on at any time regardless of how the Heat Pump is cycling.and is typically one third to one quarter of the cost per kWh of heat generated when compared to one of my excellent, but relatively expensive to run 2.5kW, De Longhi Dragon 4 oil filled electric convection-radiator heaters..  

​@juliamc has basically hit the nail on the head. Why wouldn't you just install an ASHP? Under the MCS/BUS Grant you have a survey that identifies the whole house heat loss and the heating requirement for each room. From that the size of the HP is calculated and also the size snd type of the radiators in each room. That's it! The only down side is that there may be a fundamental issue with your property that prevents you going ahead with the install but apart from that it is a well trodden path. Is there a reason why you don't think that would work?

We would be happy to talk through any issues that you may think would be a problem.

Peter 

ADDENDUM:  I had overlooked an important aspect here clearly, namely that with the ASHP installed, my home could be kept warm or at least not have any dramatic cooling down over night, unlike my current situation where we have only Oil filled portable convection - radiators to heat our home and they are necessarily progammed to switch off from midnight to 8 am every day.And therefore, with an ASHP running 24 x 7, my little family will not wake to be greeted by a cold house in the winter as is my current experience using only two De Longhi 1.1 + 1.4 kW Dragon 4 Oil filled portable convection-radiators (positioned in the middle of my reception rooms), to heat my lounge and dining rooms, running on their built in 24 hr electro-mech timers and programmed to switch off at around midnight and only switch back on at say 8am the next morning. (We had to do this as a ‘temporary’ measure when our Corvec Maxi Flame Gas C/H boiler finally gave up on us after nearly 40 years of carefully curated maintenance and repair and we did not want to embark on the very costly and very disruptive replacement journey, where a modern, high efficiency, condensing gas central heating system is ‘mandated’ by  UK Govt order and strict regulation)...Thus we  (I) have become habituated to this ‘self imposed’ daily heating and cooling cycle over several years now, and I had forgotten that with proper gas fired C/H, running over night, the impact of a sudden cold snap is felt far less dramatically inside the house than if the whole house is allowed to cool down over night.!  Thus we have been 100% electric now for over 2 years and our annual energy consumption has fallen to just around 9250 kWh per annum using just 3 off De Longhi Oil filled room heaters for all our space heating, two downstairs with the lounge and dining room doors open to allow the rising heat to freely escape and rise up the stair well to keep the chill off the bedrooms and bathroom upstairs and suing the 3 kW (super alloy) immersion heater in a poorly insulated copper cylinder in the central airing cupboard, running on another electro-mech daily timer, provide hot water for showers every morning and ordinary domestic kettles (Excellent, robust and reliable, 3 year warranty versions from LIDL) to heat water for washing up the crockery in the evenings when the water in the immersion heater has cooled down somewhat. This routine quickly became ingrained in my living human experience and hence I developed (incorrectly) significant doubts about the adequacy of a say 7.5kWh ASHP, with a potential COP of 3.5 to 4, with its gentle, persistent heat output available, presumably, 24 x 7 hours per week, to keep us more comfortable than we have recently become accustomed to, with our ‘temporary all electric stop gap’ solution !  Thus the need to have an extra, more powerful and instant ‘heat on demand’ requirement formed firmly in my mind. YES, the De Longhi Dragon 4 Oil filled room heaters DO warn that they are NOT designed for long term, unsupervised space heating but with their unusual 10 year warranty we have come to rely on them and they have performed surprisingly well as a replacement, temporary’ heating source and have allowd us to effectivley characterise the heat demands of our modest home with just my wife and I occupying only one of the upstairs bedrooms, (two sons all grown up and married) and a smaller De Longhi 2 kW Radia S  - fully digital in our bedroom for those occasions when room temperature falls below 15 to 16 degrees over night with no wasted warm air coming from downstairs over night. Therefore the OVO Forum Community has encouraged me to try running with the properly sized ASHP BEFORE even condisering the addition of a ‘luxury’ gas fired room heater in our lounge. THANK YOU ALL for your very helpful responses.! “Engineeer, mend thyself” springs to mind!  Cloudliner79, C.Eng, MIET, Electronic engineering, LUT 1979 signing off for now <-_->   

If you do get an ASHP you will be so comfortable you’ll look back at these ‘oil filled room heater’ days and wonder.

You might find this YouTube video interesting: Glyn and his colleague Tristan developed a brilliant monitoring system (which I have on my heat pump). https://youtu.be/bHsp7fDw_bg?si=Kungfhd-VSYmJL6Q

This is the appropriately name HeatPumpMonitor system. If you put Fetcham in the filter you can see my system.

https://heatpumpmonitor.org