Can I improve my COP?

Exiled_Tyke

It's exactly a year since install and I've taken a set of readings from my Daikin set up.  I'm slightly disappointed at DHW is only 1.9 and space heating 2.9.   So any ideas on how to improve these would be appreciated. 

Heating is set to 21 degrees. At night the set back is 18 degrees.  I have it come on in the early hours (on cheap electricity) to wam the house for the morning. By day it sets back again until mid-afternoon.  I think the water temperatures are set up just about right: it takes a few hours to get the house to temperature.  For the early morning schedule the heat pump is set to run on a quiet setting. I could probably change this without upsetting the neighbours. 

Hot water heats to 43 degrees but I do run a Legionnaire cycle once a week. (There's two with poor immune systems in the house).  For this I run the heat pump to maximum hotwater temperature and then run the legionnaire cycle, the hope being that the immersion heater has the minimum of work to do.  

Thanks! 

Netexporter

What emitters do you have; radiators or underfloor heating? What's the flow temperature?

Exiled_Tyke

radiators throughout.  undersized ones were changed.  

Flow temperature is determined by the outside temperature.  It's still set to the default curve from install.   But I notice the app allows me to amend this up or down by 10 degrees each way.  

Netexporter

Have the rads got thermostatic valves?

Exiled_Tyke

Netexporter said:

Have the rads got thermostatic valves?

Yes and rooms that we don't use often have got the Hive ones so I can programme them around our schedules 

Netexporter

That's your problem. Get rid of them/leave them all fully open. Then use the lock-shield valves to achieve the desired temperature for each room when the main thermostat reaches its target temperature setting.

It will take a fair bit of fiddling if you do it by "eye". You can speed the process up by getting a two-channel electronic thermometer so you can read the delta-t (difference between input and output flow temperature) of each radiator in real time. I've got mine set at at around delta-t of 5 degrees on a 30 degree flow temperature.

I got a thermometer like this https://www.amazon.co.uk/dp/B0CBBRHK8Q but I see the price has gone up a lot. A couple of clip-on pipe thermometers would probably be cheaper. You just have to do your own sums to get the delta-t.

Exiled_Tyke

Thanks. But I don't think this is the issue. There are 15 radiators on the system.  Of which twelve are permanently fully open.  I've also seen no evidence of the system cycling. ( I can monitor consumption from my phone apps).  Also this doesn't account for the poor HW COP.  Any other ideas would be appreciated.  

QrizB

Re. HW, was your tank replaced as part of the eat pump installation?

Exiled_Tyke

QrizB said:

Re. HW, was your tank replaced as part of the eat pump installation?

Yep.  State of the art, heavily insulated cylinder.  

QrizB

Who installed your system, one of the nationals or a local firm? (I'm mostly asking out of curiosity, I don't think it's going to lead to any breakthroughs on COP.)

Is there a buffer tank?

Do you have a system diagram you can share?

Exiled_Tyke

QrizB said:

Who installed your system, one of the nationals or a local firm? (I'm mostly asking out of curiosity, I don't think it's going to lead to any breakthroughs on COP.)

Is there a buffer tank?

Do you have a system diagram you can share?

Thanks for taking such an interest.   Octopus fitted it and they are coming to service in a couple of weeks so I will also ask them.   

There is a buffer tank.    I don't think They gave me I  a diagram