British Gas Heat Pump installations

matt_drummer

Looking at my data today.

The temperature in my house has varied by 0.4c since midnight.

Basically nothing.

It is just set to run and I haven't touched anything.

There is no thermostat controlling the heating and I haven't adjusted the flow temperature, it is as simple as it gets with no zones or trvs.

It has been 587% efficient for the last 20 hours and used on average 449W of electricity.

It will have cost £1.16 to heat our house today.

I doubt the heat pump will rarely if ever end a day being less than 450% efficient and I expect the annual SCOP to be around 500% efficient now I have got to grips with it.

Since it was installed in February it has been 492% efficient.

There is no reason why you or anybody else can't do the same as you have the same heat pump as me.

oliver1951

matt_drummer said:

I haven't changed anything other than radiators so there is no affect on my warranty.b

I don't have a target temperature for the house if that is what you mean.

It's a heat pump, it runs best if you just let it run without stopping and starting.

Room thermostats may suit some people and I understand that, but it is an idea linked to gas and oil boilers.

I just set a fixed flow temperature.

If it is too cold I turn it up by 1c, if it is too hot I turn it down by 1c or turn the heat pump off if it is really too hot.

I also monitor the efficiency, not all the time, but regularly, either on a computer or my phone. It is easy to see if an adjustment is necessary.

I don't need a weather curve as my heat output regulates itself enough to keep us comfortable with only the occasional adjustment necessary

This is possible probably because of the size of my radiators but you may need a curve.

This will take time to set up but just take notes of what flow temperature you need at differing outside temperatures.

Then just let it run.

You can make adjustments as necessary from the Onecta app on your phone.

You only need the Hive, or maybe I should say the Hive only turns the heat pump off,  because your flow temperature is wrong. Once you get that set with a wdc your home should stay at whatever temperature you find comfortable without any intervention from any sort of room thermostat.

Ok, I’ll have a look at the manual and see how one might do that. You said “ once you get that set with a wdc”, feel I ought to know what you mean by that, but I don’t. I’m having a problem finding my flow temperature, without any monitoring kit it’s difficult. Also I suspect my Daikin MMI is on the blink, it seems to do some odd things, but BG isn’t listening.

matt_drummer

WDC is weather dependent curve.

The flow temperature varies according to the outside temperature, normally lower when warmer and higher when colder.

The app shows your flow temperature as does the MMI.

The manual goes through how to set up different types of WDC.

oliver1951

Yes, that’s very different from mine. My temperature has varied thru two valleys from 16c to 18c and back again. It takes about 5 hrs to get to 18 c and the outside temp is quite high about 15c! ( yes it got warm again) and it’s consuming about 1.5 kw per hour , so very different. 

You may be right that anyone can achieve it, but I have to figure out how to do it! I’m good at reading stuff but if something can break, when I get near it, it usually does.

so did you make all the adjustments thru the MMI?

matt_drummer

Where are you getting the 1.5 kWh from?

Are you sure it's correct?

I assume your house isn't very big with a 4kW heat pump?

At 15c outside 1.5kW of direct heating would heat your house if your heat loss at 0c or less is only 4kW

I don't see how you can be consuming that much electricity and struggling to get your house to 18c.

All of the set up is done through the MMI and now I never touch it.

I just adjust my flow temperature when needed through the Onecta app on my phone. I also use this to turn the heating on and off. I can change my DHW schedule here too but not the DHW temperature, that has to be done in the MMI.

oliver1951

I have the same thoughts as you. Which is why I’ve queried it with British Gas. So I run my house quite frugally ( yeah well the heat pump is an outlier) so I know what my base load is and when I’m running the heat pump I’m not usually placing any further demands on the system. I have a smart meter and can see what consumption I have. I can see that when I put the heat pump on the demand goes up and to a decimal point the usage. I can see that in the first hour the demand is higher then drops a little in the subsequent hour and then seems to rest at that level for the rest of the session. However and curiosly to my mind, the temp gain seems to drop off sharply. And today was doubly curious because throughout the day and into the evening the outside temperature has been rising. With regards to the ONECTA app , as far as I’m aware I’m not supposed to use that for anything because of the hive! But when you say you adjust your flow temp via ONECTA, and you’re talking about the leaving temp I assume, I can’t see anything on the app that would let me do that. I only have two functions, climate control , which is the thermostat and is not used in my config, and the hot water tank, also not used in my config, there is nothing else? Oh and as you noted before I have the same heat pump as you an 8kw.

oliver1951

….but I have to add, I don’t understand why it is , or appears to be struggling. After all the design is 21c at -3c! Go figure! And I have only one zone and all rads are fully open, ie set to max, so the water can rush around undeterred to its h2O molecules desire. Also, and maybe this is a feature, but the rads warm up at the beginning but then they cool down, even though the system is still running and drawing all that juice!

matt_drummer

oliver1951 said:

I have the same thoughts as you. Which is why I’ve queried it with British Gas. So I run my house quite frugally ( yeah well the heat pump is an outlier) so I know what my base load is and when I’m running the heat pump I’m not usually placing any further demands on the system. I have a smart meter and can see what consumption I have. I can see that when I put the heat pump on the demand goes up and to a decimal point the usage. I can see that in the first hour the demand is higher then drops a little in the subsequent hour and then seems to rest at that level for the rest of the session. However and curiosly to my mind, the temp gain seems to drop off sharply. And today was doubly curious because throughout the day and into the evening the outside temperature has been rising. With regards to the ONECTA app , as far as I’m aware I’m not supposed to use that for anything because of the hive! But when you say you adjust your flow temp via ONECTA, and you’re talking about the leaving temp I assume, I can’t see anything on the app that would let me do that. I only have two functions, climate control , which is the thermostat and is not used in my config, and the hot water tank, also not used in my config, there is nothing else? Oh and as you noted before I have the same heat pump as you an 8kw.

You said you had a 3.8kW heat pump so I thought you meant 4kW, but the 4, 6 and 8 are all the same.

Have you looked at graphs of heat pumps running?

Daikins start at a high flow rate and that reduces after the first 20 to 30 minutes of running.

The heat output is the difference in temperature between flow and return and volume of water.

The flow rate reduces so the heat output reduces, it gets a bit more complicated at the flow and return temperatures change also, but you should see by looking at data.

My MMI is set to fixed flow temperature, no room control, that is why I can adjust flow temperature in the app.

The HIVE system you have is not great, it's up to you what to do about it.

You need to do some research and make sure you understand how a Daikin heat pump works.

You also need to check all your settings.

1.5kW of power should be producing the maximum output of your heat pump at 15c outside. You should have been baking!

I don't think MSE is the best forum for this as I think I am the only person here with a Daikin heat pump.

oliver1951

@matt_drummer , I have a daikin altherma 3 ………..8 kw. Hence the confusion . Altherma 3 is the model number. Agree with all your points. Thanks 

oliver1951

matt_drummer said:

oliver1951 said:

I have the same thoughts as you. Which is why I’ve queried it with British Gas. So I run my house quite frugally ( yeah well the heat pump is an outlier) so I know what my base load is and when I’m running the heat pump I’m not usually placing any further demands on the system. I have a smart meter and can see what consumption I have. I can see that when I put the heat pump on the demand goes up and to a decimal point the usage. I can see that in the first hour the demand is higher then drops a little in the subsequent hour and then seems to rest at that level for the rest of the session. However and curiosly to my mind, the temp gain seems to drop off sharply. And today was doubly curious because throughout the day and into the evening the outside temperature has been rising. With regards to the ONECTA app , as far as I’m aware I’m not supposed to use that for anything because of the hive! But when you say you adjust your flow temp via ONECTA, and you’re talking about the leaving temp I assume, I can’t see anything on the app that would let me do that. I only have two functions, climate control , which is the thermostat and is not used in my config, and the hot water tank, also not used in my config, there is nothing else? Oh and as you noted before I have the same heat pump as you an 8kw.

You said you had a 3.8kW heat pump so I thought you meant 4kW, but the 4, 6 and 8 are all the same.

Have you looked at graphs of heat pumps running?

Daikins start at a high flow rate and that reduces after the first 20 to 30 minutes of running.

The heat output is the difference in temperature between flow and return and volume of water.

The flow rate reduces so the heat output reduces, it gets a bit more complicated at the flow and return temperatures change also, but you should see by looking at data.

My MMI is set to fixed flow temperature, no room control, that is why I can adjust flow temperature in the app.

The HIVE system you have is not great, it's up to you what to do about it.

You need to do some research and make sure you understand how a Daikin heat pump works.

You also need to check all your settings.

1.5kW of power should be producing the maximum output of your heat pump at 15c outside. You should have been baking!

I don't think MSE is the best forum for this as I think I am the only person here with a Daikin heat pump.

Matt, working through my MMI and thinking about what you said. Without tinkering with anything I was thinking that If I set the thermostat very high I’d get a similar effect, because at some point the RWT would equal the LWT, or get within parameters that would cause the pump to turn off. However I also wondered how it works for you with solar gain? So for example today, with solar gain just through the windows the temp in my living room, which is also where the thermostat is, got up to 22c, with no heating. So if I’d had the heating running, it would have contributed to that rise in temperature and maybe I would have ended up with even a higher temperature, without any intervention. So when does your pump stop churning out heat? And one other question I’m still trying to get others experience on. My radiators warm up when I run the pump, but by the end of the cycle, while they are slightly warm, they are not as warm as they are earlier on and I’m assuming the LWT is a constant, or does it drop? I’ve got the install team coming to have a look next week see if they can address some of the issues. But when one’s not quite sure how things should be it’s difficult to know how what you’re experiencing is either within or outside the norm. Your input has been very helpful.