I’ve found leaving DHW temp correction set to 5C works well. This is a confusingly named setting, it’s the flow temp rise above target. If your cylinder is not hitting target, double-check the cylinder sensor is making good contact with the tank pocket. If the cylinder sensor is positioned low on the tank, then the temperature will be higher.
You’ll notice a significant increase in COP with a lower DHW set point e.g 45C, also allowing at least half of the tank to cool down before reheating makes the cycle much more efficient, e.g set a hysteresis of 5 or more.
I’ve not found a way to adjust the speed of the circ pump, but you can use Silent mode scheduled to limit the compressor output, I found this increased efficiency:
This works the same as Vaillant DHW ecomode which @Zarch has written about extensively :
Silent mode was added in firmware S024.25.
I’m not sure where the exinda rumour has come from, but as far as I can tell comparing the datasheets it has no resemblance to the Grant unit: 9KW R290 full DC inverter heat pump
I think the Grant R290 HPs may well be re-badged Axen units. I note that “AXEN” appears in parameter names in responses from the ecoNET local API and the specs (heating outputs etc.) of the 5 models in the Grant R290 range match the specs of the 5 single phase models in the Axen range:
Hey Glyn,
Have you managed to update the firmware on your unit? I’ think it’s only possible to get hold of latest firmware with a grant support hub installer account. My current firmware is showing as 2023.14 on the Controller and 2023.20 on the ecoTouch.
Many thanks,
Matt
Mine is also 23.14 and 23.20, so well out of date.
In response to earlier question, I did not pay the £x00 for emon, I am accessing the local api, which gives most of the required data, and even some local control, via home assistant ‘rest’ command access.
I have 15 temp sensors around the house, and 3 on the dhw cylinder (plus Grant’s), plus two weather stations, so I have much better idea of what is going on than the heatpump does. I reheat the cylinder when the ‘not warm enough for my liking’ reaches 50L down from the top, by sending a boost command. Dhw hysteresis is set to 18c (max), so reheat is up to me. Single sensor dhw control is stupid idea.
Yes, they could well be rebadged axen units, though I saw some exinda units which looked rather similar. Axen does appear in local parameters (though controller is PLUM /econet, so some of axen spec doesn’t apply). I guess dumbness of water pump control is built in to (firmware in) the hydraulic board in the heatpump though.
How to get upgrade to at least 24.x??
I am using dhw temp correction of 10c right now, since electricity is basically near free at night (ev tariff) and that completes a reheat in 30 mins, during which time house temps fall less than 0.1c, a slower reheat means bigger drop, and the wc curve is such that it takes forever to recover from a drop in house temp. Still collecting data though, such a high LWT might cause defrost issues when it gets colder.
Near as I can tell circuit temp correction just boosts the LWT in central heating mode, which is pretty much the same as applying ‘shift’ to the WC curve, although the C1 target temp doesn’t move, but the LWT does.
I am not on open energy monitor, but for reference I have ~200 sqm bungalow, in shropshire (1000 ft up), pump was installed by Josh Stead (who I can recommend), using existing vented rapid recovery DHW tank (2sqM coil, all copper) and saving 20 of the 21 rads (massively over radiatored for the previous oil boiler). Design is 50c flow at -3.8c, which aint going to happen but once in a blue moon, according to my weather data history.
The Grant external sensor is influenced by being screwed to tons of brick wall - always lags the real outside temp (as per weather stations). I am still fiddling with the WC curve, currently 0.8, +3. Yes, I have a model of heat loss vs ambient .. see below. Problem with computer scientists with nothing better to do.
I suck all the interesting Grant data from the local API into Home assistant. The spikes below are where the compressor starts, and the oil recovery (every 4 hours in theory but mine is more like 3 and a bit). I do get a lot of solar gain when there is some actual sun .. several kW.
The overnight gap, and one other on most days, is when the system switches to DHW.
Ah, it turns out even hysteresis of 18c was not enough to stop an unnecessary reheat after two showers.. Cold water coming in got up to the dhw sensor the heatpump thinks matters. Guess I need to actually set work mode to off for dhw, and only reheat on boost.
OK, I have been playing with the settings, and my best guess so far is ..
First the heatpump picks a target temp, based on WC curve, and shift, Presumably adjusts at some interval, as outside temp changes. Call this ‘T0’
The compressor then adjusts itself to try to achieve a flow temp of T0 + circuit temp correction, subject to the minimum value set in the heatsource (25c or higher) plus the correction.
When the return temp exceeds T0 + ‘setpoint temp correction’ the compressor shuts down, on the basis of it can’t adjust the flow temp any lower.
I am still fiddling with the numbers to try to prove this (and causing lots of short cycling, when output was set to minimum of 30c, and ambient of 15c caused T0 to be 28c, with the two corrections both at zero - basically the compressor ramped up until flow temp hit 30c, and when the return hit 28c (didn’t take long!) the compressor shut down; rinse and repeat).
That makes sense - basically a way to finetune setpoint/target temp beyond WC curve.
Still not sure how it differs from Circuit temp correction - perhaps that just adjusts the displayed temperature on the Panel? but I would imagine panel temperature correction does that. Maybe one of them adjusts how far over target temp the circuit goes before the compressor shuts down?
Sorry for the slow reply. Grant send out the firmware update on an SD card, but it’s possible to put the updare files on an SD card and flash it yourself. I’ve attached the firmware update files to this post. There are instructions for how to update in section 11.3 of the latest V2.2 user guide:
Here’s are some more detailed instructions:
Determine which version of the touch controller you have. On the back of the controller there will be printed either “T50” or T50 and then some additional stuff below, usually HW2.0X (The X is the important bit). My controller is the T50 varient, the other varient is the “X” varient
Select the correct FW version: There’s two different firmware versions, one for “T50” and another for “X”. Make sure to select the correct one to match your controller:
Extract the .pfc files into the root of a freshly formatted FAT 32 SD card (max 32GB)
Once the files are on the card, insert it into the bottom of the smart controller touchscreen display (with the gold pins facing you). It should then pop up with a prompt to update the two firmwares.
Select PANEL first, let it update and complete
Remove the card for and reinsert it and select CONTROLLER.
Grant recomend doing a factory reset after a firmware update with service code “7586” then "RESTORE DEFAULT SETTINGS’ then power cycle the wiring center. However, I didnt do this. The only issue I had is that I had a AHS (additional heat source) error. To fix this I had to go into Service settings code “0000” and switch off AHS additional heat.
This is what the update screens looked like for me:
Hey @glyn.hudson,
You mentioned previously that certain features were introduced with particular firmware revisions, I don’t suppose there is a change log available? Just trying to work out if the July revision will sort out my high flowrate issue.
Sorry for additional question, it’s good to have someone with access to the installer side info.
Many thanks,
Thanks Glyn, I’ve just installed the updates and have access to the silent mode - will try that for hot water to see if I see the same impact.
I don’t have access to the new pump speed settings (you show above) through my user or service parameter menus, you may have additional access. I spoke to my installer and he’s still chasing Grant for an update.
Looking at your stats, your pump does seem to be modulating (14-30l/m) and similarly the recently installed 4kW model in Norwich (3-28l/m). My 4kW shows constant 26.5l/m for HW and 24l/m for heating (from my flow meter), the systems own data shows 83l/m but lets not worry about that.
Either way, I’m totally happy with the pump except for the flow, due to low heat demand the pipes aren’t oversized, which means the system is pretty noisy and tends to get turned off.
I think you should contact Grant and ask why your circ pump is not modulating, your flow rate looks totally different from all other Grant R290 systems I’ve seen. The flow rate makes no attempt to modulate down. I think this could be a fault.
I think someone mentioned the issue, but I can’t find it, so I post here.. My r290 unit is giving quite a loud double ‘clunk’ when it starts dhw heat, IFF it was doing heating at the time. I suspect it is the grant supplied 3 way valve trying to change over with the water pump still pushing 1.3 bar thru it at high speed. Is this a known issue, maybe fixed in later firmware, or maybe only seen (heard) with particular chageover valves?
I do have a solution, since my dhw reheat is always triggered by home assistant calling for a boost, so I can easily tell it to turn off heating first (which is how I control it from the mass of temp sensor data I use), but this won’t work for the Joe average install where reheat decision is down to the controller and hysteresis value.
Someone (Mart?) asked how to get data from the econet controller into Home assistant. This is a work in progress for me, but maybe the attached .yaml file will help. You need to insert the line:
rest: !include rest.yaml
into your configuration.yaml file, and you need to put the attached rest.yaml file into the same folder, after you have used notepad or similar to ‘replace all’ instances of the ip address (mine is 192.168.1.25) with whatever address you heatpump lives at. Hint: you need to tell the router to assign a fixed address to that MAC (object) because if it moves, the rest commands won’t work.
You then use developer tools, yaml, to reload rest entities (or you can just restart HA). Good plan to ‘check configuration’ first, incase you messed up.
After that you will have a set of shiny new entities telling you more than you could want to know. Some are commented out (#) because they contained (as far as I could tell) nothing useful. Some are duplicated, since I added a new name when I figured out what they were, but never deleted the old one.
If anyone is interested, there re also some ‘RESTful’ commands to set things, turn things on/off, etc. Some of this may have altered with the new controller firmware, will let you know if/when I get it.
The REST commands just read data, and should not cause issues (but don’t poll too fast), the RESTful commands which set things probably need be used with care, though I haven’t fried anything yet.
Note the file name needs changed to rest.yaml from rest.txt .. I am apparently not able to upload yaml files.
All heat pumps keep the circ pump running during the change over to DHW. The diverter valve specified by the installer should be capable of handling the flow rate. Most installers choose to use an ESBE style valve, which is designed for this. If it’s making a loud clunking noise then it’s an indication that maybe the incorrect valve has been used e.g sprung return.
