I was hoping for some advice after reading about people having issues with their 9kw Diakin unit. Octopus are also installing an Eddie and a 300l Diakin water cylinder.
My heat loss survey came back of 7.74kw and they are wanting to replace all but one radiator in the house. All piping to the rads is 10mm which they didn’t seem to have an issue with.
They are wanting to install it at the end of the month, is there anything which stands out as being wrong?
We currently have a 4kw solar array and an ev.
I’m rather new to all this so seeking some third party advice!
Not enough information for us to know the accuracy but for a 4 bedroom house your heatloss seems a little high but it will depend on the build and the insulation you have installed.
Do you have cavity wall insulation, how deep is your loft insulation?
The 9kW unit is a beast and I would personally recommend double checking the heat loss survey (even if it is just on upgrades.heatgeek.com) to make sure you are not under 7kW (the limit for the smaller 8kW unit (actually Modulates and seems to run a lot better during the shoulder months).
If you do not yet have 400mm of loft insulation, cavity wall insulation or internal wall insulation and double glazing I would highly recommend these first (cheaper to insulate than to keep letting the heat out).
Eddie is the solar diverter immersion heater? Is that useful these days? I thought you were generally better off importing cheap-rate overnight then selling solar back to the grid during the day. That’s certainly what I do.
I’m in a similar sort of place, but post-install. 3 separate heat loss surveys all said heat loss around 7.5kW, though heat geeks predicted much less. There’s a heuristic based on degree-days to calculate based on gas usage - I think there’s a link in the learning resources topic?
It’s a little early for me to report on 9kW performance. Have not been impressed by its defrosting behaviour, but I’ve been making tweaks and may have got it tamed.
Very unimpressed by poor reporting of consumption/generation. I repurposed one of my Zappi’s CT’s to measure energy consumption.
In my case my Octopus journey took months while finding the most suitable solution. I think it was time well spent.
In my view, I think you should spend more time researching whether you need the larger Daikin. My heat loss was first surveyed at 9kW and I was allocated an 11kW heat pump.
After a lot of to-ing and fro-ing ( including having figures from a blower door test replace the MCS assumptions) my heat loss was adjusted to 7.5kW and then I had an 8kW Daikin fitted.
As it happens, in this present cold weather (which is about at the design outside temp). I am finding that about 4kW of heat from the pump is enough to hold the house at a steady internal temperature.
So, my impression is that MCS calcs over estimate heat loss and lead to larger-than-needed heat pumps being fitted.
You will have read in these pages that there is a world of difference between the 8 and the 9kW Daikins, so in your place I would ask for a delay in the install schedule while you do more research.
Having a heatpump is way better than heating by gas boiler, and all of us here want you to get it right from the start.
If you have smart gas meter readings for the past week and you have maintained a fairly stable house temperature that would be a good start to sanity check the estimated heat loss is in the correct range.
