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Grant ASHP


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Hey group,

 

My builder has been telling me for months of our build he is purchasing us a vailliant or daiken heat pump.... now this morning he has said its going to be a Grant aerona or something....(fiest i heard)  has anyone heard of this manufacturer? 

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Grant is a UK manufacturer; they gave me a quote when I was looking for heat pump in 2020.  They were also the favoured choice of two Scottish companies that (over?) sell heat pumps with teams of fitters to do the installation.  Possibly Grant heat pumps are not terribly sophisticated because oil boilers are not terribly sophisticated.  They also make aluminium radiators (of which I have two).

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14 minutes ago, ReedRichards said:

Grant is a UK manufacturer; they gave me a quote when I was looking for heat pump in 2020.  They were also the favoured choice of two Scottish companies that (over?) sell heat pumps with teams of fitters to do the installation.  Possibly Grant heat pumps are not terribly sophisticated because oil boilers are not terribly sophisticated.  They also make aluminium radiators (of which I have two).

Did you go with them if bot why and who did you go with

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Here is some info about Grant ASHPs from a user on another forum.  I've just cut and pasted it so no guarantees...

 

 

I was in exactly the same situation 3 months ago - lead times on the Ecodan cylinders were out to 12 weeks and we couldn't wait.  So we went with the Grant 13kW. House is about half the size of yours, radiators, TRVs, oil boiler, Cambridgeshire.

The installer recommended the 10kW Grant but I went for the 13kW as it's double fan and supposedly quieter (and the actual spec sheet says they are respectively 10.5kW and 11.4kW at 55C, which is more realistic since we have radiators - so the 13kW isn't actually massively more powerful, although the flow rates are higher).  It remains to be seen how it copes in spring and autumn when only a little heat is required, but in winter it seems to be coping fine.

Now, the Grant heat pump seems to be a good unit.  It's made in Japan by a company called Chofu Seisakusho Co. Ltd - Grant buy them from a European distributor and rebrand them. From what I've seen of the unit and the documentation it seems to be good build quality.  I've been curating some documentation here - the Chofu installation manual, service manual, etc and marketing information from other countries.

The problem is that Grant is really an oil boiler company, and they want a heat pump to behave like a boiler, which it isn't.  My install is absolutely by the Grant book, the problem is that Grant took the perfectly good English installation instructions from Chofu, deleted lots of stuff (it should do cooling, which they don't admit to.  I enabled the cooling button, but can't really test it in winter), and added a relay box to interface it to UK on/off boiler controls.

The trouble is that on/off thermostats aren't good for heat pumps - my installer provided a Honeywell Lyric controller which does TPI.  TPI is a way that, by default, it looks at every 10 minute period and decides how much the boiler should be on. Result is that it turns the boiler on for say 3 minutes, then off for 7 minutes, repeatedly throughout the day.  You can set that back to 20 minutes, but can't turn off TPI. This is terrible for heat pump efficiency. With some great help from a heating engineer who installs these, we managed to reverse engineer the Modbus protocol, which is a way of logging data from the heat pump, and I'm now logging this into Home Assistant.  That shows me how spiky things are:

image

I have, just today, figured out how to revert to the Chofu room controller (ie cutting out the Honeywell and using the heat pump's own room thermostat) and am doing some experiments as to what difference it makes. Removing the Honeywell out of the loop completely is going to require some minor rewiring of pumps and valves, but I have just tried things temporarily as a test for now.  I should get a better feel over the coming days.

We also have some noise issues which might be being caused by TPI's constant switching on and off, or might be something else (there was terrible noise to begin with, because there was loads of air in the system). The heat pump is currently mounted next to the kitchen, so about a metre from the kettle with a window adjacent, which means it is audible inside. A family member is very noise sensitive so the contingency plan is to move it to the bottom of the garden, if my tinkering can't improve matters.  From measurement the noise is in spec, but there are certain points in the spinup curve where it buzzes (another thing to investigate).

Another thing is that Grant have switched from installing a buffer tank (that we have) to a low loss header.  I'm sure some more plumbing-knowledgeable folks can comment on this, but I know plumbers familiar with the units are not impressed (read the Twitter replies) - I defer to more experienced folks, but seems to be just another thing Grant doing backwards to make it look like a boiler.

One other thing is that the way Grant plumb in the buffer isn't good for doing cooling - it should work, but be less efficient.  Investigating that is for another time of year...

The Honeywell does have the ability to be controlled by an app, the Chofu natively doesn't*. Since I have Modbus up and running on Home Assistant I'm thinking of doing something in that area too, not sure quite what. I gather some of the other heat pump vendors are better in this respect.

* Chofu the company also sells oil boilers and those can have controllers with apps which look very similar to the ASHP controller - maybe they will talk to it? But they would probably be in Japanese...

On the flip side, it works, it heats, the hot water is great.  On a cold January day (daytime maybe 3-5C) we're probably using 30kWh per day for heating, on a warmer one a lot less.

So I think you can get a better outcome if you can avoid some of the installation problems (buffer not LLH, use the room controller or put in a smart thermostat that will run the heat pump for long periods not pulse it), use the heat pump to control the pumps and valves rather than the thermostat.  I understand the price wholesale is quite good, which might be why installers like them.

According to the Grant person on that Twitter thread:

We are more than happy to let installers like yourself install how you want to and to get the best out of the systems they install. In fact we have embraced many more installers with our new offerings which include 3 port direct systems using our controller to maximise efficiency

Just to be clear - you Don’t have to fit the units this way. If you are an experienced engineer and are sizing systems correctly we have no issues with you fitting it to your preferred suitable method.

so it is something they are happy with, but your regular plumbing and heating engineer is going to install it like a boiler, and that's not so good.  It works and all, but it could be better.

Bottom line: would I do it again?  Depends how much money is at stake.  In our case we didn't have a lot of other options (the oil boiler had been condemned a year before and finally expired a few weeks before installation), and I think I probably would. Basically it was a calculated gamble, with various things I didn't know (noise, controls, cooling enablement) but thought were worth the risk, and some within my competence to address. I don't have final answers on those yet, but they are looking promising - I don't think there's any showstoppers.  (In the worst case, moving it will be most work, but we get to rearrange the garden which needs doing anyway). On the other hand it has become a bit of a 'project' - if somebody was offering me an Ecodan for a few hundred quid more I probably would still take it (although it's possible noise etc issues would still apply)

 

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7 hours ago, Mike_scotland said:

Did you go with them if not why and who did you go with

 

I thought the companies offering a Grant heat pump were being over-optimistic about savings that this could achieve by comparison with my oil boiler.  Nor did I like their impersonal service using teams of fitters roaming Scotland.  And I wanted more than just a heat pump and radiators, I also wanted to re-route a lot of my heating pipes.  So I went with a contractor that could offer me a personal service, quote for all the work I wanted and was prepared to admit that it was a close-run thing to save on running costs.

 

By the way I see nothing wrong with TPI per se but you have to be able to limit the number of cycles per hour.  I was just helping a relative set up an oil boiler controller with TPI and I set it to 3 cycles per hour because an oil boiler is another type of heater that you don't want to be on for just a few minutes at a time. 

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Soooo im speaking to my builder and his mcs registered contact and there now suggesting a 10kw grant heat pump, i asked for the hear calcs and was told there going by a basic 45w per m2.... this is making me feel a tad uneasy

 

Any advice

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On 06/02/2022 at 14:26, Kevm said:

Here is some info about Grant ASHPs from a user on another forum.  I've just cut and pasted it so no guarantees...

 

 

I was in exactly the same situation 3 months ago - lead times on the Ecodan cylinders were out to 12 weeks and we couldn't wait.  So we went with the Grant 13kW. House is about half the size of yours, radiators, TRVs, oil boiler, Cambridgeshire.

The installer recommended the 10kW Grant but I went for the 13kW as it's double fan and supposedly quieter (and the actual spec sheet says they are respectively 10.5kW and 11.4kW at 55C, which is more realistic since we have radiators - so the 13kW isn't actually massively more powerful, although the flow rates are higher).  It remains to be seen how it copes in spring and autumn when only a little heat is required, but in winter it seems to be coping fine.

Now, the Grant heat pump seems to be a good unit.  It's made in Japan by a company called Chofu Seisakusho Co. Ltd - Grant buy them from a European distributor and rebrand them. From what I've seen of the unit and the documentation it seems to be good build quality.  I've been curating some documentation here - the Chofu installation manual, service manual, etc and marketing information from other countries.

The problem is that Grant is really an oil boiler company, and they want a heat pump to behave like a boiler, which it isn't.  My install is absolutely by the Grant book, the problem is that Grant took the perfectly good English installation instructions from Chofu, deleted lots of stuff (it should do cooling, which they don't admit to.  I enabled the cooling button, but can't really test it in winter), and added a relay box to interface it to UK on/off boiler controls.

The trouble is that on/off thermostats aren't good for heat pumps - my installer provided a Honeywell Lyric controller which does TPI.  TPI is a way that, by default, it looks at every 10 minute period and decides how much the boiler should be on. Result is that it turns the boiler on for say 3 minutes, then off for 7 minutes, repeatedly throughout the day.  You can set that back to 20 minutes, but can't turn off TPI. This is terrible for heat pump efficiency. With some great help from a heating engineer who installs these, we managed to reverse engineer the Modbus protocol, which is a way of logging data from the heat pump, and I'm now logging this into Home Assistant.  That shows me how spiky things are:

image

I have, just today, figured out how to revert to the Chofu room controller (ie cutting out the Honeywell and using the heat pump's own room thermostat) and am doing some experiments as to what difference it makes. Removing the Honeywell out of the loop completely is going to require some minor rewiring of pumps and valves, but I have just tried things temporarily as a test for now.  I should get a better feel over the coming days.

We also have some noise issues which might be being caused by TPI's constant switching on and off, or might be something else (there was terrible noise to begin with, because there was loads of air in the system). The heat pump is currently mounted next to the kitchen, so about a metre from the kettle with a window adjacent, which means it is audible inside. A family member is very noise sensitive so the contingency plan is to move it to the bottom of the garden, if my tinkering can't improve matters.  From measurement the noise is in spec, but there are certain points in the spinup curve where it buzzes (another thing to investigate).

Another thing is that Grant have switched from installing a buffer tank (that we have) to a low loss header.  I'm sure some more plumbing-knowledgeable folks can comment on this, but I know plumbers familiar with the units are not impressed (read the Twitter replies) - I defer to more experienced folks, but seems to be just another thing Grant doing backwards to make it look like a boiler.

One other thing is that the way Grant plumb in the buffer isn't good for doing cooling - it should work, but be less efficient.  Investigating that is for another time of year...

The Honeywell does have the ability to be controlled by an app, the Chofu natively doesn't*. Since I have Modbus up and running on Home Assistant I'm thinking of doing something in that area too, not sure quite what. I gather some of the other heat pump vendors are better in this respect.

* Chofu the company also sells oil boilers and those can have controllers with apps which look very similar to the ASHP controller - maybe they will talk to it? But they would probably be in Japanese...

On the flip side, it works, it heats, the hot water is great.  On a cold January day (daytime maybe 3-5C) we're probably using 30kWh per day for heating, on a warmer one a lot less.

So I think you can get a better outcome if you can avoid some of the installation problems (buffer not LLH, use the room controller or put in a smart thermostat that will run the heat pump for long periods not pulse it), use the heat pump to control the pumps and valves rather than the thermostat.  I understand the price wholesale is quite good, which might be why installers like them.

According to the Grant person on that Twitter thread:

We are more than happy to let installers like yourself install how you want to and to get the best out of the systems they install. In fact we have embraced many more installers with our new offerings which include 3 port direct systems using our controller to maximise efficiency

Just to be clear - you Don’t have to fit the units this way. If you are an experienced engineer and are sizing systems correctly we have no issues with you fitting it to your preferred suitable method.

so it is something they are happy with, but your regular plumbing and heating engineer is going to install it like a boiler, and that's not so good.  It works and all, but it could be better.

Bottom line: would I do it again?  Depends how much money is at stake.  In our case we didn't have a lot of other options (the oil boiler had been condemned a year before and finally expired a few weeks before installation), and I think I probably would. Basically it was a calculated gamble, with various things I didn't know (noise, controls, cooling enablement) but thought were worth the risk, and some within my competence to address. I don't have final answers on those yet, but they are looking promising - I don't think there's any showstoppers.  (In the worst case, moving it will be most work, but we get to rearrange the garden which needs doing anyway). On the other hand it has become a bit of a 'project' - if somebody was offering me an Ecodan for a few hundred quid more I probably would still take it (although it's possible noise etc issues would still apply)

 

Did you get proper heat calcs carried out? Im getting told a 10kw will do? 

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  • 3 months later...

Haven't been on here for a while, but that's my text cut and pasted from above.

 

Full heat loss was done, came to about 5kW if I remember, which i was a bit dubious about. I did the calcs myself and it came to 8kW.  So I think 10kW would have handled it. But the 10kW Grant is 3dB noisier than the 13kW and noise was a critical factor in our install. Also, we have to have the house dead silent at night so we have to start the ASHP from cold in the morning (we don't turn it off but setback to maybe 13C at night time so it only kicks in when it's really cold) - the 13kW should in theory be able to warm it up faster, although it's no gas boiler.  Probably take a hit for efficiency but it modulates down (by default) based on return temperature, so if the emitters can't emit it won't consume so much power ('normal' electrical power is about 3.5kW when it's on (eg in DHW mode), going down to about 1.5kW based on return temp and weather compensation).  The price delta wasn't very much and am generally happy with that choice.

 

TPI is a problem because it takes the first maybe few minutes of 'on' time spinning up, only for TPI to then tell it to turn off again a minute or two later.  Which makes it noisy and maybe interferes with the modulation.  On the Lyric the best I can set it to is 20 minute TPI periods, which is better than the defaults but still not ideal.

 

I'm happy with it as a unit; it works; I'm happy with the efficiency; it is generally configurable if in not the most user friendly way; the way it has been installed could be better. Which is partly the fault of the 'it's a boiler' mindset rather than a problem with the unit itself.

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2 hours ago, Ommm said:

...the 13kW should in theory be able to warm it up faster...

I'm not convinced that is significantly true.  Once the water reaches its set temperature the speed with which the building warms up is entirely down to the heat emitters, the radiators and/or UFH.  In my case this takes about 15 minutes from cold; I might be able to shave 5 minutes off that with a bigger heat pump but what's 5 minutes?  Whilst the building is much colder than usual then delta T will be a bit higher than usual but with a nighttime set-back it probably won't be more than 20% so I suppose you could size your heat pump 20% higher than you think you need.  After you have reached temperature if you want a building that warns up more quickly you oversize the heat emitters (radiators) and/or you set the water temperature higher than it would be in its steady state.  The former would make your heating system more prone to cycling and the latter would hit your efficiency.  And the latter you could only do if you have Load Compensation or you intervene manually.     

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