Grant Aerona r290

[Beelbeebub]

Grant have released details of their r290 heatpumps

 

https://www.grantuk.com/professional/products/air-source-heat-pumps/r290/

 

As before I think it's a rebranded unit from another manufacturer but I don't think itvs Chofu, who make the current r32 units. 

 

At first glance the performance seems to be about the same (unsurprisingly as r32 and r290 units have very similar performance characteristics)

 

The biggest difference apart from the units being black (yay!) seems to be the size. The r290 units are significantly wider. 

 

Still. Nice to see another entrant in to the fray. 

[sharpener]

3 hours ago, Beelbeebub said:

As before I think it's a rebranded unit from another manufacturer but I don't think itvs Chofu, who make the current r32 units.

 

They have taken their time! I saw the new R290 model on the Grant stand at the NEC in summer 2023, and was told like the R32 model it was made by Chofu and would be on the market winter 23/spring 24.

[Beelbeebub]

2 hours ago, sharpener said:

 

They have taken their time! I saw the new R290 model on the Grant stand at the NEC in summer 2023, and was told like the R32 model it was made by Chofu and would be on the market winter 23/spring 24.

It might be a Chofu unit, but Chofu haven't got it on their website yet (which I would expect). 

 

It's interesting it seems to be bigger (power for power) than the chofu r32 units - which were nice and compact. 

 

They do seem significantly quieter though so maybe the extra size is sound insulation. 

Edited September 24, 2024 by Beelbeebub

[JamesPa]

1 hour ago, Beelbeebub said:

They do seem significantly quieter though so maybe the extra size is sound insulation. 

Notably both the Daikin R290 and the Samsung R290 units are larger and quieter than their predecessors.  I think its reasonable to conclude, as you suggest, that the extra volume is to accommodate sound insulation.

 

Unfortunately in the case of the Samsung unit for certain (not sure about the others) this pushes the volume over 0.6cu m which is the max allowed under permitted development.  Hopefully this figure may be raised soon, as suggested in the consultation carried out by DENZ earlier in the year (before the election). 

[GSV3MiaC]

The Grant r290 models appear to be rebadged Exinda, eg

 

https://exindagroup.com/collections/r290-air-to-water-heat-pump

 

Though the smart controller may be a home brew, can't find details of that on the exinda site. 

 

Has anyone actually used one yet? The spec looks good, especially the potential turn down ratio (under 30%), noise level, and power outputs at stupidly low ambient. 

[andyj007]

i have found  the grant ashp's  really fail to work very well  at anything under 6 degrees , they mostly go into defrost much more frequently than other brands  of same sizing , same conditions house types  .. also the current controller is pretty naff. i have stopped fittinh them in in the houses we build 

[JohnMo]

17 minutes ago, andyj007 said:

they mostly go into defrost much more frequently than other brands  of same sizing , same conditions house types

Defrost is a bit of a physics thing rather than brand thing. Really depends on location, but driven by the humidity in the air and it's dew point plus the amount of energy you are trying to pull out of it.

 

We near the coast (6 miles) and can also get defrost at around 5 degs sometimes. But we generally flow at higher temperatures to batch charge instead of WC at much lower temperature.

 

Try turning you weather compensation curve down a little, that will make the frosting take longer to occur.

 

Or is the unit undersized?

[JoeBano]

My grant anerona3 hardly goes into defrost, it is sat on my garage roof gets plenty of circulation up there. I hope the new ones have a modulating water pump rather than a fixed one on mine.

 

[LeeVanCleef]

Any further experience with the Grant Aerona 290? 
 

I’m just sizing the 15.5kW one up for our current place and there doesn’t look to be too many alternatives at that output that I can compare against. Maybe Viessmann and NIBE. Any other suggestions?

[JamesPa]

12 minutes ago, LeeVanCleef said:

Any further experience with the Grant Aerona 290? 
 

I’m just sizing the 15.5kW one up for our current place and there doesn’t look to be too many alternatives at that output that I can compare against. Maybe Viessmann and NIBE. Any other suggestions?

15.5kW is a lot, are you certain?  Surveyors got the loss for my retrofit wrong by a factor of 2 (16kW 'surveyed' 7kW actual), just saying!

 

Vaillant do a 12kW and I believe now a 16kW and actual output, according to the datasheets, tends to be more than sticker value (although there is some evidence that output during defrost may be much closer to or even slightly below the sticker value.  They likely will be cheaper than Nibe, Viessmann and personally I like the way the Vaillant controls work, its a much more intelligent interface to weather compensation than many because changing the set temperature, whether programmatically or manually, shifts the WC curve so you aren't reliant on a thermostat, with the inevitable performance penalty, to have setbacks etc.  Also adjusting the WC is just a single dial, not 4 parameters common in many others.

 

I should state that I dont know about Nibe, Viessmann controls and, as they are European and manufactured boilers for countries where WC was compulsory, they may have a similarly well though or even better interface to WC  Ditto Grant although their R32 models were the usual, not terrible good, interface.

Edited September 3 by JamesPa

[Beelbeebub]

I believe the r290 grant units use their newer interface and control box. Quite how good it is, i don't know, but it looks OK and is a step up from the functional but not very user friendly old ones. 

[LeeVanCleef]

Good question @JamesPa. Based on the MCS calc approach, about half our losses are due to ventilation. I know there has been much postulation on this point already. I can’t easily quantify it unless I do an air tightness test. If the calcs are an over estimation at least we will be warm on the coldest days. The potential poor efficiency on the shoulder seasons might need some management.

 

For arguments sake let’s assume it is correct for a moment. I’ll need a heat pump that covers the top end for the coldest days but can also modulate low enough too.

 

Doing a bit of digging, it at least looks like the heating curve in the newer Aerona Smart controller is non linear and editable (to a degree) now. I think that was a problem some folks had with an older iteration of the Grant controls.

Edited September 3 by LeeVanCleef

[JohnMo]

2 hours ago, LeeVanCleef said:

If the calcs are an over estimation at least we will be warm on the coldest days

That is not necessarily always true.

 

2 hours ago, LeeVanCleef said:

can’t easily quantify it unless I do an air tightness test

You can take a common sense approach to air leakage. 

1. Do you have open fire places?

2. Are rooms drafty, can you feel a breeze around closed doors, both internal and external.

3. What sort of build is the house.

4. @JamesPa favourite, what was or is your current operating regime for your heating system? What are your gas/oil usage. Use that to back check your likely heating requirements.

[marshian]

33 minutes ago, JohnMo said:

4. @JamesPa favourite, what was or is your current operating regime for your heating system? What are your gas/oil usage. Use that to back check your likely heating requirements.

 

Also my favorite (works well unless you tolerate a house kept to temps far below accepted norms in which case all bets are off)

 

Example - I used 8701 kWh of Gas in 2024

Of that 1758 kWh was for HW and cooking

 

So for my space heating needs (ie the heat loss element of the energy usage) I used 6943 kWh of gas. we heat the house for effectively 8 mths of the year so 240 days a year so 0.82 kWh heat loss over the heating season but that's not representative of the true heat loss in the depths of winter.

 

If I take Jan as my worst month from a heating perspective I used 1854 kWh of gas divide that by 30 days x 24 hrs and you get 2.6 kWh heat loss but as the average temp for Jan was just 4 Deg again it's not a true measurement of heat loss in the coldest period

 

For that I need to go to the 8th to 12th Jan where night time temps were consistently well below freezing and day time temps only just above it giving an average of -0.7 Deg C

 

That period I used 397 kWh in 120 hours or 3.3 kWh heat loss

 

I'm pretty confident as a result that my Heat Loss calcs of 4.5 kWh at -2.5 Deg C are validated

 

For Heating season 2025/6 I've improved/increased my loft insulation as well as a few ventilation related improvements and I think this will bring me at or just under the 4.0 kWh heat loss at -2.5 Deg C

 

 

[JamesPa]

4 hours ago, LeeVanCleef said:

For arguments sake let’s assume it is correct for a moment. I’ll need a heat pump that covers the top end for the coldest days but can also modulate low enough too.

Unfortunately if the heat pump is grossly oversized, thats impossible.  Heat pumps have a practical modulation range of about 3:1, sometimes less.  This means that about the best you can expect is that they will run steadily up to about 11-12C then cycle.  if its a factor of 2 over it will cycle at all temperatures, either because of defrost or because of oversizing.  The sole exception I know of is the Mitsubishi 8kW R290 which has 2 compressors (2kW fixed, 6kW variable.   There may be others but 3:1 or thereabouts is very common.

 

I have a 1930s house with partial fabric upgrades, some modest modern extensions and originally solid walls.  The surveyors (2 lots of them) ignored any fabric upgrades they couldn't see (mostly IWI but they also well overestimated the double glazing loss), double counted room to room losses and assumed ACH=2-3 depending on room.  Correcting for fabric and room to room losses brought the calculation down to ~10.5kW.  7kW, the measured loss, requires one to assume an ACH of 0.5-0.75.  I have heard several installers say that this is a more reasonable assumption anyway and one who says that he has never measured more than 1 ACH on the occasions when a measured result has been obtained.

 

If you have your annual gas consumption in kWh a very rough estimate can be got by dividing by 2000 and separately dividing by 3000.  The loss is  very likely somewhere in between unless you run a Chinese restaurant so have a wok burner going all day. even in summer (or something similar)

 

I did the attached using 2 years worth of half hourly metering data from my gas boiler.  I had been running the boiler 24*7 so somewhat like a heat pump although its a matter of some debate how much difference it makes.  basically this was used to size the heat pump and the installer 'adjusted' assumptions to fit.  The one I chose was not the only one that was prepared to do this, but many were not.

 

One way or another I would strongly recommend you sense check.  If you need to get an air tightness test its probably worthwhile - £300 or thereabouts I am told.

 

How big is your house and what is the construction?  That might also give a sense check and @JohnMo s set of questions also. .

 

 

Measured consumption - Copy.pdf

Edited September 3 by JamesPa

[Beelbeebub]

Just a though about modulation and over sizing etc.

 

Rather than a single 15.5kw unit, how about a 9kw and a 6.5kw (it would cost a bit more) 

 

If the controls could manage it correctly you would be able to mldulate down to the lowest of the 6.5 up to the max of both together. 

[JohnMo]

58 minutes ago, marshian said:

kWh heat loss

That should read kW. 

 

28 minutes ago, JamesPa said:

annual gas consumption in kWh a very rough estimate can be got by dividing by 2000 and separately dividing by 3000.

Are you sure that's correct - you end up with a very small number. The number I have seen is to simply divide kWh of gas used per year, by 2900 for gas or 290 for oil. This used the assumptions as stated by @marshian. But the rules in addition to that are

 

This assumes your dwelling (flat or house) is in the southern half of the UK (i.e. South of Manchester) and that you set your thermostat to 20 °C.

 

If you live between Manchester and Edinburgh, increase your estimate of heat pump power by 10%.

For each 1 °C above 20 °C that you set your thermostat, increase your estimate of heat pump power by 10%.

[JamesPa]

1 hour ago, JohnMo said:

Are you sure that's correct - you end up with a very small number. The number I have seen is to simply divide kWh of gas used per year, by 2900 for gas or 290 for oil. This used the assumptions as stated by @marshian. But the rules in addition to that are

Same isn't it.  2900 is between 2000 and 3000.  290 is because 1l of oil is worth about 10kW

 

1 hour ago, JohnMo said:

This assumes your dwelling (flat or house) is in the southern half of the UK (i.e. South of Manchester) and that you set your thermostat to 20 °C.

 

If you live between Manchester and Edinburgh, increase your estimate of heat pump power by 10%.

For each 1 °C above 20 °C that you set your thermostat, increase your estimate of heat pump power by 10%.

Fair enough, but I said 2000 and separately by 3000 and the loss lies between the two, which easily encompasses these uplifts.

Edited September 3 by JamesPa

[IGP]

Indeed, just to give another example is that my annual gas consumption is 10,750kWh /year. I know that during summer I use around 5kWh per day for hot water ~ 5*340 days (we go on holiday occasionally!) = 1,700 kWh. So 10750-1700=9,050 kWh of heating, accounting for efficiency of 90% (running at 40c flow temp) = 8145kWh/year. Dividing by the degree days of 2350 for my location for last year =3.46kW heat loss which isn’t far from my modelled heat loss in heat punk of 3.6kW at -3c outdoor. 

 

To be clear I kept my house at 20/21c all day and 19c at night all winter. 
 

So, if you can do a similar calculation @LeeVanCleef you’ll ball park your heat loss (assuming you adequately heated your home in the first place) without having to do anything fancy with air changes. 

[marshian]

4 hours ago, JohnMo said:

That should read kW. 

 

Oh FFS of course it should be - has @SteamyTea hijacked your log in

 

[marshian]

5 hours ago, JamesPa said:

-2 = 17.5 HDD @ 15.5 Base temp 
 

Slight threadjack

 

Can you share how you worked that out? Really Interested in that aspect

 

I've always used HDD with @ 16.5 base temp - for a couple of reasons

 

1. once the average outside temp gets below 16.5 I am pretty much guaranteed to need CH

2. my historical data is all based around that base temp

3. the regression calculation on the HDD site all came back with 16.5 was the optimum base line for this house.

 

With recent improvements that may well change this winter.........

 

PS the data presentation is good I very much liked the scatter plot of energy used v HDD tempted to do similar with my 30 min data from Octopus

[JamesPa]

16 hours ago, marshian said:

Can you share how you worked that out? (15.5 C base for degree days). Really Interested in that aspect

I didn't, I just used the default.  It doesn't make much difference to the plot other than at the high oat end which doesn't matter much.

 

I did once try a best fit to my data exercise on degree days.net and I think the best fit was if the base was 16 or 20.  The latter is obviously silly and 15.5 is close enough to 16 which gave me confidence to use the default.

 

As you see from the plots I came at the answer in more than one way further increasing confidence.  I had also clamped boiler output at 8.5kW (house remained warm) further increasing confidence.  The time average plots seemed to me to confirm that anything above 7kW was rare and transitory, so house would just 'ride it out'

 

I did have a bit of a concern that the loss might be as high as 8kW, but concluded that if it was (a) the heat pump may well quote as the data says it does and (b) for the couple of days per year where it's this cold all day and night, I could use supplementary heating.  The need to use supplementary heating hasn't arisen yet.

Edited September 4 by JamesPa

[marshian]

27 minutes ago, JamesPa said:

I didn't, I just used the default.  It doesn't make much difference to the plot other than at the high oat end which doesn't matter much.

 

I did once try a best fit to my data exercise on degree days.net and I think the best fit was if the base was 16 or 20.  The latter is obviously silly and 15.5 is close enough to 16 which gave me confidence to use the default.

 

OK makes sense - I was just trying to work out how you came to the conclusion that 17 in terms of Heating Deg Day number was equivalent to -2 OAT

 

27 minutes ago, JamesPa said:

As you see from the plots I came at the answer in more than one way further increasing confidence.  I had also clamped boiler output at 8.5kW (house remained warm) further increasing confidence.  The time average plots seemed to me to confirm that anything above 7kW was rare and transitory, so house would just 'ride it out'

 

Range rating boilers I'm a fan of - mine is currently range rated to to min on CH

 

The actual min is slightly higher output than manufacturers info would imply (because Min output at 50/30 is 3.2 kW and at 80/60 is 2.9 kW - as I run 34/27 as an absolute max I think the min output is closer to 4.0 kW so pretty well aligned to my house heat loss at -2.4 Deg C OAT

 

DHWP has full fat output so RR'ing has no impact

 

And if heating 24/7 then I agree the house has the ability to "buffer" sudden changes outside @SteamyTea will shoot me if I start talking about thermal mass so I won't but the house can give back - maybe it will lose a but of room temp but as soon as conditions outside change it's going to recover. If that became a problem I can always increase the RR value to give the boiler a bit more wiggle room

 

27 minutes ago, JamesPa said:

I did have a bit of a concern that the loss might be as high as 8kW, but concluded that if it was (a) the heat pump may well quote as the data says it does and (b) for the couple of days per year where it's this cold all day and night, I could use supplementary heating.  The need to use supplementary heating hasn't arisen yet.

 

Yeah I can agree with that.

[JohnMo]

1 hour ago, marshian said:

@SteamyTea will shoot me if I start talking about thermal mass

Not sure why they such a bee in their bonnet about it. This is what building regs says about

 

https://www.gov.scot/publications/supplementary-topic-notes-review-domestic-non-domestic-energy-performance-certificates-scotland/pages/3/

 

The thermal Mass, or the heat capacitance, of a material reflects its ability of a material to absorb and store heat. It's basically the internal heat capacity of the building. Timber frame and PIR insulation has a low thermal capacity, block work and plaster applied directly it's huge. Pretty simple really.

[marshian]

7 minutes ago, JohnMo said:

Not sure why they such a bee in their bonnet about it. This is what building regs says about

 

https://www.gov.scot/publications/supplementary-topic-notes-review-domestic-non-domestic-energy-performance-certificates-scotland/pages/3/

 

The thermal Mass, or the heat capacitance, of a material reflects its ability of a material to absorb and store heat. It's basically the internal heat capacity of the building. Timber frame and PIR insulation has a low thermal capacity, block work and plaster applied directly it's huge. Pretty simple really.

 

Now you've gone and done it