@derek-m I had tried just turning off at the display power button but that didn’t work and I was panicking as we’re about to have the external volumiser retrofitting. I was just thinking “this is going to be an absolute faff now if this controller is knackered”. 

after what you said I went to the consumer unit and flicked the switch to turn the whole thing off and then after 10 seconds and a short little boot up, it worked. Phew! 😮‍💨 

@derek-m The human race is screwed if ever "turning it off then turning it back on again" stops working 😀

Good Evening, not been on for a while since the EHG sorted our system out. 
Well, control side of things. 

I'm at peace now, Well not quite as I think there’s more to wring out of the 17kw beast yet. 
Did anyone have the homely installed to run there systems more efficiently?

Old barn we are in but totally stripped out and plenty of insulation. Starting to cool off a bit now in Lincolnshire. 2.5c this morning. 
19c inside which is fine
resisting cranking those thermostats up to start the pump off. 

Anyone else caved in?

Run ours 24/7 when we do start again. Think FT is at 32c atm. Not looked since April tbh. 

Posted by: @roamingbull

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Anyone else caved in

We went from cooling mode to heat mode the next day, let the heat run for the last week, but I am in NE Scotland and the temps started to drop quite quickly.

@mikefl could you post the link for this please. I don't realise this could be monitored.

Hi All, 

New member here. I have a 6kw Grant Aerona 3 unit installed when I built the house 3 years ago. House is 1900sqft, high standard of insulation (200mm in cavity and floors, 400mm in attic space), 1.1 air changes per hour, MHRV, and underfloor heating up and downstairs. 

Like most I was handed over the system with the instructions to TFA (touch feck all). After 2 winters of wildly varying house temperatures and high costs in the cold months I started researching these units and  came across this forum and the theory of weather compensation. I had the unit serviced this year in July (waiting for the engineer since November last year). While he was here I had him talk me through the controller and lo and behold the weather compensation was switched off. He was reluctant to enable it as they had a lot of issues with people calling them back when the houses were still cold. When I explained to him that I had an idea on how it was to work he did. The first curve we set up was LWT of 23deg at outside temp of 15deg and LWT of 40deg at outside temp of -4deg. Fast forward to a few weeks ago when things started cooling down, Slowly the inside temp started to drop, thermostats both sending demand to the unit but no compressor running. The flow temp in the system was 19deg and I couldn’t understand why the compressor was not starting. After much research I still couldn’t find out any reason why the system wouldn’t kick into life, I spoke to the engineer whose only suggestion was to turn the weather compensation off, I was not keen to do this and I eventually realised that there is a hysteresis in the set point in the system (group 21-41) which was set at 8dec. I have dropped this to 2deg and the system is now working, I am continuing to tune the curves but it’s been unseasonably warm here, however I am really happy with how the it is now operating. My question is what are your system hysteresis setting, was I right to lower it to 2deg? 
Thanks

BAJJ

Hi there @bajj, you've cracked it I think with setting parameter 21 41 to 2degC. UFH will have a very slow hysteresis response as the mass of the floor will mean the circulating water only cools down very slowly. The cool down is much quicker with conventional wet radiators. Here's a WC ready reckoner I knocked up, to play around with the Grant settings and fine tune. I've never had to worry about the latency of the hysteresis setting as the minimum water temperature for conventional radiators in my case is 30degC, so it cools down quite quickly with typical room temperatures at 21degC. For what it's worth I set my hysteresis to 3degC down from the default 8degC.

Grant not setting up WC is a common issue, you're not alone. It seems they and/or their installers had [but no-one has yet admitted it] a policy of deliberately not enabling it to avoid call-backs with the 'my radiators are not getting very warm' query. Of course that crucifies the running costs, as does using on/off 3rd party thermostats in lieu.

@allyfish We hear this backside covering technique being used by so many installers so that they might avoid call-backs don’t we?! Almost always, the ‘default’ settings these installers tend to adopt are ones that ensure the customer faces a heftier bill for consumption than they might otherwise need to. Perhaps this might be a good topic for a Q&A session please @editor? Regards, Toodles.

@allyfish @toodles , thanks for taking the time to reply , and thanks @allyfish for the WC ready reckoner.

here in Ireland I think we have a bit of an issue with the installation of the units, they are just not being commissioned and operated correctly, with the home owners footing the bill, the guy who installed mine had no idea , he just set it up as a boiler and told me everything was fine. The government have set into law that all new homes must have heat pumps, the idea is great, renewable energy, but in the long run with these in ‘boiler’ mode it’s increasing energy consumption not reducing it, typical government policy, enact a law but have no infrastructure in place to ensure correct operation.
Grant only have two registered ‘engineers’ in my area, one never got back to me and I had to wait 9 months for the other guy and when he arrived he was not that confident with the WC, when I found out about the hysteresis I messaged him to tell him, he thanked me for sharing the valuable information and said, we’re still learning😳🙄. Grant obviously knocking it out of the park with their training. Anyway, rant over. 
Thanks to this forum the system is now operating just the way I always thought it should, house maintains a fairly steady temperature and none of the sawtooth fluctuations of before and, so far it is very efficient, power consumption usually between 200-400 watts, although I expect this to rise as it gets colder. 
cheers