Air Source Heat Pumps

albyota

probably because they are adding the element current 4kW + 2kW Plus the load of the heat pump anywhere between 2 kW and & 7 kW depending on COP at delta T, possibly nearer 7 kW at minus 7...what do you think Men?

Cardew

albyota wrote: »

probably because they are adding the element current 4kW + 2kW Plus the load of the heat pump anywhere between 2 kW and & 7 kW depending on COP at delta T, possibly nearer 7 kW at minus 7...what do you think Men?

Agreed = assuming the 7kW should read 3kW?

albyota

Im just thinking that if both elements are on i.e total 6 kW as well as the work the heat pump is having to do... probably flat out..i.e 7 kw therefore
6 + 7 = 13 kW

Cardew

albyota wrote: »

Im just thinking that if both elements are on i.e total 6 kW as well as the work the heat pump is having to do... probably flat out..i.e 7 kw therefore
6 + 7 = 13 kW

I think the max load(input) of the ASHP is 3.5kW

I think as Hermann states the 13.5kW from an immersion heater(s)is what it could cope with, but in this configuration it is a 4kW and a 2kW.

Hermann

For what its worth .....

I think the 13.5kw is total output of combined Heat Pump and Immersions. This is made up of 6kw immersions (probably 2 x 3kw) plus the output of the heat pump, up to around 7.5kw (dependant on COP), thats an input of around 2.5kw.

The literature refers to the heat pump giving, at 2c outside air and 50c flow, 6.8kw output for 2.5kw input.

So set up properly it shouldn't be using the immersions other than very occasionally (Factory default is once every 14 days) to give the 60c plus boost. This would mean using no more than around 2.5kw an hour if used flat out. Thats 60kw a day, and theres no way it should need to run 24 hours a day!

So I think there's something wrong in the set up. The immersions are being used when they don't need to be I suspect.

Hermann

eugeneg wrote: »

Definitely averaging 108 KWhrs a day over the last 2 weeks. Largely due to both the 2KW and 4KW immersion heaters kicking in so frequently I think. That does include my lighting and fridge/freezer too, but still seems more than I was hoping for or expected.

The supplier tells me that this is normal and over a year the ambient temperature will see that I am spending less than I did before I received the beast, but that's an aweful lot to catch up in the Summer.

You really need to make sure you're using the right modes and have the correct settings for your circumstances.

Also make sure your set points are correct for this sort of system.
You may only need the CH and HW set at 45c. The heat pump should provide this without the immersions.
The 60c plus Temps are used once in a while (default appears to be once in 14 days) for an hour or two, don't try and run at 60c all the time!

Tell us more about your set points, standards of insulation, windows etc.

I wouldn't be surprised if you could halve that consumption if set it up/use it right!

richardc1983

Hermann wrote: »

You really need to make sure you're using the right modes and have the correct settings for your circumstances.

Also make sure your set points are correct for this sort of system.
You may only need the CH and HW set at 45c. The heat pump should provide this without the immersions.
The 60c plus Temps are used once in a while (default appears to be once in 14 days) for an hour or two, don't try and run at 60c all the time!

Tell us more about your set points, standards of insulation, windows etc.

I wouldn't be surprised if you could halve that consumption if set it up/use it right!

PRetty much as I have said previously... the immersions are coming on when perhaps they dont need to be.

However if you havent oversized the radiators then maybe this is why you have set the flow temp higher because 45C is not enough to heat your home with standard radiators.

Cardew

richardc1983 wrote: »

However if you havent oversized the radiators then maybe this is why you have set the flow temp higher because 45C is not enough to heat your home with standard radiators.

Eugenue(not Hermann) has:

All 14 are new radiators sized 20% above recommended output downstairs and 10% upstairs. I am surprised how much more efficient the new radiators are than the old ones. Perhaps positioning them under windows where possible is in part responsible. What came out of the old radiators was black gunge where once there was crystal clear water.

richardc1983

Im sorry, for some reason the forum is taking me to different posts and isnt indicating the most recent post I should be starting at.

Normally it will take me to the point in the thread that I have not read yet, doesnt seem to be doing this.

richardc1983

Perhaps flow temp is still set too high then without op realising if tere oversized they do not need to be at full pelt!