@sand 

welcome to the forum.  Don't be afraid of weather compensation.  All it does is change the flow temperature according to how cold it is outside.  Even if you find 40C works one day, if/when it's colder that might not be enough to heat the house, even if your thermostats are telling the ASHP to keep heating.  

Another point is that radiators don't have to feel that hot to heat the house, especially in a well insulated new build.  They work mostly by convection, ie. warm air coming out the top rather than radiating heat from the front. Unless it's really cold, 40C heat my house very well.  You need to try and forget the piping hot gas/oil heating radiators you're probably used to.

If you need help with the Ecodan settings please ask as there is a lot of knowledge here.  

Thanks for that Kev M. Yeah the rads never get red hot, but when I turned it to 40 it struggled to get to 19 degrees upstairs no change with ufh. Thats why I'm going to check with the builder to see if the rads are K3. When we first moved in we had issues with rads as system had not been on, pressure had dropped so we had to realign pressure gauge on water tank and bleed them. Today it feels toasty warm at 44c but will keep lowering it, because I think I read for every 1 degree reduction we will save money. Also we have only been here 3 weeks we have no blinds/curtains or carpets so that will also be a factor, so glad to hear 40c is achievable.

Posted by: @sand

Thanks for that Kev M. Yeah the rads never get red hot, but when I turned it to 40 it struggled to get to 19 degrees upstairs no change with ufh. Thats why I'm going to check with the builder to see if the rads are K3. When we first moved in we had issues with rads as system had not been on, pressure had dropped so we had to realign pressure gauge on water tank and bleed them. Today it feels toasty warm at 44c but will keep lowering it, because I think I read for every 1 degree reduction we will save money. Also we have only been here 3 weeks we have no blinds/curtains or carpets so that will also be a factor, so glad to hear 40c is achievable.

 

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Hi Sand,

Welcome to the forum.

Kev is perfectly correct, that for better efficiency you should be utilising weather compensation, though if your FTC controller is located in a suitable position you could use auto adaptation, which would keep the indoor air temperature more constant. They are predicting a warmer spell in the near future, so you could probably find that with weather compensation or auto adaptation the water flow temperature would be lowered to the mid 30's.

K3 radiators have 3 heating panels, K2, obviously two, so it should be easy to check what you have.

Do you have any heat loss calculations and do you know that total heating capacity of your radiators and UFH?

Do you have a buffer tank or low loss header?

If the radiators are the correct size and have been bled, but you are still not getting sufficient heat to the bedrooms, then it could be that your system is not correctly balanced. That is that you are not getting sufficient water flow to the upstairs radiators.

Hi Derek sorry no heat loss calcs system already in place when we moved in the epc rating was B. Other than that i wouldn't know where to start.

Not sute re buffer so see attached images, think rads are K2 then, size wise they look big. Not the most aesthetically pleasing rads but we hoping to change them in future will look for K3 now. They have all been  bled and pressure gauge aligned.

This is our default compensation curve set by installers, what should we set it too. Because we still learning about the system we just reduced flow as that seemed the easiest thing to do, quickest win re economy as it had been set at 60.

Ta for help.

@sand 

Hi Sand,

It is impossible to tell from the photo if you have a buffer tank or low loss header. It could be incorporated within the bottom section of your hot water cylinder. If you Google the manufacturer and model you should be able to find out the details.

Do you know if your system has been zoned?

Since your home should be quite well insulated, I would suggest trying a weather compensation curve of 50C water flow temperature at -10C ambient air temperature and 25C water flow temperature at 20C ambient air temperature. It is then a matter of monitoring the change in indoor temperature with changes in outdoor temperature, and making adjustments so that the indoor temperature remains reasonably constant with variations in ambient air temperature.

You will of course need to turn up your thermostats by 1C or 2C, so that they are not interfering with the weather compensation.

@derek-m 

That tank, in fact pretty much that install is nearly identical to mine.  My installers informed me no buffer or low loss header.

Thanks  for replies.

Yes Derek the system has been zoned zone 1 is downstiars zone 2 is upstairs. I'll have a go and will let you how the weather compensation changes go.

@sand 

Do you have any water pumps external to the ASHP?

Also what is the arrangement of the control valves?

1. Hi Derek I don't think so, see images re what I think are the control valves, I have a manifold too in cloakroom thats always lovely and warm. 
   

   

   

   

   

    

    

@sand 

They look more like pressure relief valves. If you cannot identify an item of equipment then get the manufacturers name and model number and consult Dr. Google. If you are still not certain then send me the details and I will try to identify it.

The red item in the fourth photo is a water pump, which appears to be connected to the bottom section of the cylinder, it therefore may be the buffer tank.

There should also be a set of control valves for your UFH, and probably a 3 way diverter valve for DHW or Heating control.

@sand 

My mistake, on closer inspection the pipework from the pump is going through the wall and not connected to the cylinder.