@allyfish 

Hi and welcome to the forum. Is your system installed and running?  What make/size is it?

@kev-m Thank you for the welcome. Grant Aerona 3 10kW ASHP.

I have a 'by the book' install with a Grant low loss header, secondary pump, 250L pre-plumbed cylinder. Hive interface with smart control to 6 radiator TRVs. 12 rads upgraded in the house for higher heat emitters based on 50degC maximum supply temperature. 9 panel 3.6kW solar PV with Solar iBoost to water cylinder.

@allyfish, welcome to the forums. Is your heat pump a newish install and is this your first winter?

You mentioned you were a sceptic. What prompted you to take the plunge?

Hi @Mars, yes, a brand new install. First winter off kerosene. I either needed to replace a 25yr old oil boiler, with a newer condensing oil burner, or go down the renewable option. I've taken the plunge into renewables with a Grant ASHP installation. We all need to try and do what we can to combat climate change. I'm fortunate to be in a position to invest in the property even though I'm unlikely to see much if any saving on my electricity bill and the ROI date will be well into the next decade! However, I will be using substantially less energy, due to an ASHP with COP of 3.9 for max 50degC supply and also 3.6kW solar PV installation including Solar iBoost. The solar is battery ready, so I may add a 6.5kWh battery next year.

I had looked at ASHP previously, and discounted it due to the negligible energy saving it would return (compared to kerosene), system complexity, and reading of poor installs and customer service support. Also, earlier ASHP systems were not overly reliable and not as efficient as current generation models. I decided the way to alleviate my fears was to do a lot of research, choose a well-renowned European manufacturer with local customer support and good spare parts logistics (my local Grant engineer lives 30 miles away), and educate myself about what a proper installation entails in order to specify and purchase something that will be reliable and work for me in my 1992 EPC C home. Graham Hendra's "50 things" book was very informative. I work in building services so I was able to prepare my own home heat loss and system sizing calculations and then cross-examine the installer's MCS calculations (the latter were way out, so it transpired!)

So I look forward to my first renewable winter. But the secondary heating, my 5kW log burner, is still my preferred heating in an evening. 🙂

One negative I've already noticed is that the Grant system & cylinder is so well insulated that the airing cupboard it is installed in barely gets warm. It's no longer any use to dry clothes in. The stove does that rather well however in the winter months when natural outdoor wind and solar drying options are not so plentiful.

@allyfish

Is your system set up for weather compensation control?

@derek-m Yes. 50degC to 30degC heating water supply temperature  depending on outdoor temperature. Weather compensation active from 20degC to -4degC. There's a possibility the parameters will want tweaking in the winter and a bit of trial and error needed. It's at the factory WC default settings at the moment and I'll see how that goes.

Grant rebadge a decent unit, the Chofu (Japanese) unit. Shame their install seems to treat it like a boiler and they fitted a hive, the worst 'smart' stat you can possible get 🙂 

@hughf The HIVE was by the installer, not Grant. It works for me as I can zone various rooms in the house on smart TRVs to boost temperatures to suit our usage pattern from a general low level background heating. The main Hive control stat is set high so as to remain calling for heat. Modulation is by using the weather compensation in the Grant ASHP and return temperature sensing, plus TRVs to all emitters save one.

General comments on this forum about installers and plumbers not understanding the difference between boiler CH and DWH controls and ASHP controls are spot on. The weather compensation was not enabled on my unit as installed, the primary and secondary flow rates were too high, both pumps on max flow/head when the middle curve matches the circuit better and provides a better delta T for the ASHP to work more efficiently. The weather compensation will need some tweaking as I go, but seems to be working well. The ASHP is pulling 1-1.25kWh to keep a background 18degC in most rooms in the house (140m2). I'm old school and like cool bedrooms, so I've set it back to 15degC at night, the morning boost up takes under an hour during which time the ASHP is guzzling about 3kWh initially before modulating down on frequency control.

Most importantly, the trusty but dirty and smelly oil boiler has gone and we're doing the right thing [in my view]