Posted by: @allyfish

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@roamingbull You running on weather compensation? If the house is too cold when it's milder and warmer outside you may need to flatten the WC curve a little and increase your minimum flow temperature. Customising the WC is trial and error as every house is different and how your heating responds is influenced by UFH vs rads or combination and how long each day it's switched on for, etc. 24/7 would give chance of the most stable control of course, but I find that's a little too warm for us overnight. Check these parameters for settings, values are the defaults:

2102 Maximum Water Temp °C 45 (default by Grant, set to 35°C for your system?)

2103 Minimum Water Temp °C 30 (don't set too low, for UFH +wet rad combined this is probably about right)

2104 Minimum Ambient Temp °C -4 (I was advised by Grant commissioning engineer to raise this to 0, which works for me)

2105 Maximum Ambient Temp °C 20 (above this value your heating will be disabled)

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Apparently we are running on weather comp from what the EHG set up as it wasn't when commissioned. Upstairs it doesn't come on as the thermostats are set to 18.5c which is more than enough. 

Will check the defaults out but always a bit skeptical about changing these but saying that like you state it's a trial and error, but didn't realise it would be too much of an hassle to have a piece of mind with these systems. Anyway EHG is coming back end of November. 

Some amazingly helpful information on this thread for me as a heat pump newbie with a 17kW Grant Aerona! One thing I am tearing my hair out to try and work out is how to set the times for the hot water to come on as I'm wanting to take full advantage of any solar power available and it seems to have been set to come on at 7am. how do I change this? @allyfish can you help with this one?

Hi @shadowfax - I’m sure we can help. First, what device controls your hot water timing? Do you have a timer unit like the one on the left here somewhere near the Grant unit controller? It's fairly easy to adjust, else the hot water will be controlled by some other external timer. Unlikely it will be by the Grant unit controller, it can do it, but Grant tend to use external timer controls.

Early morning isn’t a good time to generate hot water, you probably want your space heating on then, and when the ASHP is generating hot water it is not heating. Early afternoon around 1pm is much better when the daily outdoor air temperature is highest. It’s these little things that Grant often overlook, but maximising the efficiency of the ASHP is key to reducing the running cost.

Posted by: @shadowfax

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I'm wanting to take full advantage of any solar power available

1pm - 2pm daily is a good time 🙂 I have a small 3.6kW solar PV+battery. In summer hot water is free via any morning solar generation stored in the battery, plus any instantaneous solar PV energy powering the ASHP for hot water. I also have Cosy Octopus, so if there's no solar generation, I generate hot water during the low rate tariff afternoon tariff time of 1pm-4pm, taking advantage of the early afternoon being the warmest daily outdoor air temperature year-round. The warmer it is outside when you generate hot water, the better your ASHP efficiency = lowest energy consumption. The Grant pre-plumb cylinders are very well insulated and keep a tank of hot water plenty warm enough from 2pm all the way to 7am next morning for us.

Posted by: @allyfish

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Hi @shadowfax - I’m sure we can help. First, what device controls your hot water timing? Do you have a timer unit like the one on the left here somewhere near the Grant unit controller? It's fairly easy to adjust, else the hot water will be controlled by some other external timer. Unlikely it will be by the Grant unit controller, it can do it, but Grant tend to use external timer controls.

Early morning isn’t a good time to generate hot water, you probably want your space heating on then, and when the ASHP is generating hot water it is not heating. Early afternoon around 1pm is much better when the daily outdoor air temperature is highest. It’s these little things that Grant often overlook, but maximising the efficiency of the ASHP is key to reducing the running cost.

 

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Amazing! I do have a screen like the one on the left of your pic and had no idea what it did! Sorry if I sound like a complete idiot, we have been left with a "working" system but no proper handover yet as we are waiting for a faulty radiator to be reordered and replaced and I am fed up of seeing too much electricity getting burned while I wait for them to come back.

@shadowfax good. You have a 4 channel digital programmer, but only one channel, 1, will be used for hot water timing. It's a unit badged up by Grant based on this unit.

HEATMISER.COM "https://www.heatmiser.com/en/download/211/english/10798/tm4_v2.pdf"

Fairly easy to adjust the programme times. Press 'Zone1' and you should see the programme status and a time when it's next on or off, then follow in the link from page 11. You'll probably need to adjust them for Mon-Fri then also for Sat-Sun. You only need to do this for Zone 1, Zones 2,3 & 4 probably will not have anything programmed in them and will show a blank screen.

Thank @Allyfish, you're a star! Although I changed the times to have it come on at 1pm today and had a cloud come by and floor the solar generation neatly for almost exactly the same time as the water was heating 😭 🤣

Posted by: @shadowfax

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Thank @Allyfish, you're a star! Although I changed the times to have it come on at 1pm today and had a cloud come by and floor the solar generation neatly for almost exactly the same time as the water was heating 😭 🤣

Maybe you should complain to your MP to do something about those pesky clouds. I thought that is why they keep installing all those 'big fans', to blow the clouds away. 😋 

Hi again, I'm afraid I need more help! It was initially programmed to come on at 7am which I changed to 12 to make best use of the solar and thought I had it going perfectly. However, I went up to the attic yesterday evening to do another tweak on my weather comp settings and discovered the hot water on! Checking the settings I could see a second time period had been scheduled from 4pm to 8pm but when I changed the second time to go both on and off at 4pm it then showed as on until 12, so effectively it was reversing the controls. So I changed the time to come on at 7pm then off again thinking that would reset it but it just said off til 7 and came on and wouldn't go off! So I turned it off and left it. I went back to it today and turned it back on during its scheduled on period and though it was ok but when I came upstairs to bed I could hear it on and it was showing as on until 2pm. I'm sure I am doing something stupid here but can someone please put me out of my misery and explain how I fix this!!!

Can you see the make/model of the programmer used to control the HW?  Or can you upload a picture of it? I have a Timeguard 7-day 1 channel for my HW which says things like "on until ..." "off until..." so it might be one of those?

Timers these days seem to be 'helpful' (overly complicated) and adjust other times when you adjust one of the time slots to ensure they all make sense (to it). 

@allyfish hey AF,

So finally home and checked some settings as what you asked me to check. Low and behold the water was actually set to 52c for some reason!! 

So changed to 55c (Thought 55c was standard set up?). If still not warm enough will increase. 
tbh I still think there’s still an issue with our htw as it seems to be lottery if we have a hot shower. 
Timings for HTW are 04:30-05:30 and 16:30-17:30.  Only two of us fyi  250l tank. Think you stated to have one setting mid afternoon ? Are we wasting our time/money with two htw settings?

And re the ufh I have it set to 35c flow temp WC. Got up this morning and it was 18c downstairs and our system runs 24/7. Now 20c. 
Other day when I got home it was a quite warm for us 21.8c. 

Don’t really get it tbh it’s a frustrating system  

Any other settings I should look at?

BRGDS RB.

Posted by: @roamingbull

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@allyfish hey AF,

So finally home and checked some settings as what you asked me to check. Low and behold the water was actually set to 52c for some reason!! 

So changed to 55c (Thought 55c was standard set up?). If still not warm enough will increase. 
tbh I still think there’s still an issue with our htw as it seems to be lottery if we have a hot shower. 
Timings for HTW are 04:30-05:30 and 16:30-17:30.  Only two of us fyi  250l tank. Think you stated to have one setting mid afternoon ? Are we wasting our time/money with two htw settings?

And re the ufh I have it set to 35c flow temp WC. Got up this morning and it was 18c downstairs and our system runs 24/7. Now 20c. 
Other day when I got home it was a quite warm for us 21.8c. 

Don’t really get it tbh it’s a frustrating system  

 

Any other settings I should look at?

BRGDS RB.

I would suggest that you check the location of the temperature sensor on your hot water cylinder, since if it is fitted too high up the cylinder you may not be heating the full tank.

If you have your flow temperature set to 35C, is this the upper limit of WC, or is it set to a fixed flow temperature? Dependent upon the heat loss as the outside air temperature falls, you may need the flow temperature to be higher than 35C.