I bought a Heat Pump

thefordprefect

Thanks RR,
My Wiser uses weather forecast of area to adjust on/off periods - so not the best! It does have opentherm, but as far as I'm aware the ashp does not require this. the boiler was also too old to utilise this feature (6 years and a water jacket leak)!

Reed_Richards

That's a feature of Wiser I have never tried to use - because the heat pump does it better.  Being situated outside it can measure exactly what the outside temperature is.  It then sets the temperature of the water leaving the heat pump accordingly (based on settings that you can adjust).  So when it is warmer outside my radiators are more tepid - but still warm enough to keep the house warm.  Unlike your oil boiler, which either manages to condense (more efficient) or not (less efficient), the efficiency of a heat pump increases as the difference between the air temperature and the temperature it is heating the water to gets smaller. 

shinytop

thefordprefect said:

@reed_richards or anyone else!!

we are about to have an ashp installed (Mitsubishi ecodan 11kW). The initial plan from the installer shows mitsubishi ftc6 interface and a couple of room temperature sensors.
We are "upgrading" from oil and a semi broken high efficiency boiler (now held together with chewing gum) replacing this and buying a years worth of oil at £1600 (£1/L) is only a few years oil price below having an ashp fitted (with £5k BUS grant)
This system has worked OK with a Wiser controller and 8 radiator electronic valves/thermostats. We would like to keep the system as it controls individual room heating as required. The wiser controller has weather compensation and will learn each rooms heating and cooling times adjusting the boiler on time accordingly.
However I do not understand how this would interface with the ftc6 controller

I believe you said you had a drayton wiser controller? If so could you please enlighten me as to how the Wiser connects to the ASHP to control heat demand.

We also have Myenergi Eddi to use excess solar to heat the domestic hot water. I believe this can be used with a heat pump by using the legionella output of the heat pump controller (power to immersion heater until legionella death temperature is reached) to feed the input on the eddi using a plug in board. The eddi then needs to be set to use boost output (i.e. not solar controlled) to water heater 1 when this added input is at 240v. 

Hi, I have an Ecodan working with its own weather compensation and it works well.  However, the only way the FTC6 can interface with an external controller is to use it as a simple on-off thermostat.  That is, the thermostat communicates a demand for heat to the FTC6 and the ASHP fires up using whatever flow temp it's set at - either fixed flow or weather compensation.  The ASHP will stop when the thermostat stops demanding heat or the set flow temp us reached.  You can't control the flow temp from an external controller, nor can you control what the ASHP does based on room temperature. 

If your plan has 2 room temp sensors they will be looking to use Mitsubishi's own room temperature control function.  I won't try and explain it all here but have a look at p16-17 in the link below for an explanation of how it might be set up

What you could do is use your controllers to work out when your house needs heated and which rooms.  I assume your controller could adjust the valves in each room individually but the FTC6 would only respond to a simple on/off command.  I'm not saying that's the best way to run an ASHP as it's normally recommended to run them continuously for longer periods and avoid using individual TRV-type valves too much. 

https://library.mitsubishielectric.co.uk/pdf/book/Ecodan_FTC6_PAC-IF071-3B-E_Installation_Manual_BH79D843H02#page-16-17
          

Reed_Richards

My heat pump was installed with a dedicated electricity meter so I know exactly how much power it consumes.  Yesterday the outside temperature (that I saw) varied between - 5 and -1 C.  My heat pump consumed 65.8 kWh in 24 hours, that's the largest 24 hour number I have ever seen (I don't read the meter every day, however).  Still that's less than 3kW on average for the whole house and my hot water.  And the house was nice and warm, about 20 C daytime average temperature.

Spies

Reed_Richards said:

My heat pump was installed with a dedicated electricity meter so I know exactly how much power it consumes.  Yesterday the outside temperature (that I saw) varied between - 5 and -1 C.  My heat pump consumed 65.8 kWh in 24 hours, that's the largest 24 hour number I have ever seen (I don't read the meter every day, however).  Still that's less than 3kW on average for the whole house and my hot water.  And the house was nice and warm, about 20 C daytime average temperature.

£21 of electric? Is that right?

Bianchiintenso

Looking at my meter 45kwh, and regular bursts of condensation when it auto defrosts the back of the ecodan (I presume that’s what it is) but like you toasty warm, consoling myself in the knowledge it’ll soon warm up and days that cold are few and far between… I hope!

Mstty

Reed_Richards said:

My heat pump was installed with a dedicated electricity meter so I know exactly how much power it consumes.  Yesterday the outside temperature (that I saw) varied between - 5 and -1 C.  My heat pump consumed 65.8 kWh in 24 hours, that's the largest 24 hour number I have ever seen (I don't read the meter every day, however).  Still that's less than 3kW on average for the whole house and my hot water.  And the house was nice and warm, about 20 C daytime average temperature.

That is an absolutely ridiculous figure.

By comparison I can only provide you with all household electrical use as ours does not have a seperate meter. Have to take off 12 kWh Monday due to extra wash and Tumbledryer day and 10kwh on Tuesday for our daily electricity use in winter.

So that is 24.42kwh Monday for heat and hot water and will work out the sameish Tuesday as a few hours late night missing from the bright app.

Very similar here past 4 days -5 to -1. Last Saturday was a very big projector day with full on Dolby Atmos system running loud hence the big usage

Reed_Richards

Spies said:
£21 of electric? Is that right?

Using exact numbers it's £22.23 at my local version of the SVT for electricity (and before the Government discount).  But you have to remember (or keep telling yourself) that it evens out over the year, for example my average for November was 20.7 kWh per day.

akwexavante

My Daikin ashp has started to work harder this last few days and overall I'm very happy. Small two bedroomed house, cavity wall insulated etc. I'm happy with 16 degrees overnight and 18 during the day. I fire up a multifuel stove between 6pm and 9pm. I'm completely electric for everything otherwise. 

Before the cold snap I was using £2 to £2.50 (10 to 13kwh) a day at 17p kwh. I'm now using £4.20 to £4.60 (22 to 24kwh) a day.

My only minor issue would be that since the cold snap began the pump is much louder and I can hear it through the wall. A minor annoyance that's not keeping me awake at night though. 

My brother who lives 2 miles away tells me he's using £19 a day in gas and electric with heating set at 18 degrees 24/7. He's on the current capped rate. 

Still getting used to the idea that it takes an hour to an hour and a half to increase room temp from 16 to 18 degrees. 

Reed_Richards

Mstty said:

That is an absolutely ridiculous figure.

It's ridiculous in terms of current electricity prices, yes, but it's really not so terrible in the context of my house.  We are all different and we all have different dwellings of different sizes and different levels of insulation in different locations.