Not warm enough! Is it wind?

valiant24

I have a Samsung AE120RXYDEG air source heat pump, with underfloor heating controlled by a Heatmiser system.

House is well insulated.   Generally the heating, per Heatmiser app, runs for a few hours each morning and keeps the downstairs rooms at 21C.

Today the heating has been running all day in all rooms, and rarely gets above 19C in some rooms.  Yet it's not very cold outside.   What may have gone wrong?   It is very windy.  And we did have a power cut earlier ...

Any suggestions greatly appreciated!

Thanks
V

Reed_Richards

Well it could be that the wind blowing over the outside of your house is cooling it much faster than normal so the rate of heat loss is a lot bigger than usual.  But if you are using weather compensation then that is only paying attention to the outside temperature and so doesn't boost the heat output from your heat pump to cope.  But if you generally get by on just a few hours worth of heating and now continuous heating isn't doing the trick, then it's a bit of a stretch to believe my possible explanation is correct. 

valiant24

Reed_Richards said:

Well it could be that the wind blowing over the outside of your house is cooling it much faster than normal so the rate of heat loss is a lot bigger than usual.  But if you are using weather compensation then that is only paying attention to the outside temperature and so doesn't boost the heat output from your heat pump to cope.  But if you generally get by on just a few hours worth of heating and now continuous heating isn't doing the trick, then it's a bit of a stretch to believe my possible explanation is correct. 

What else could I check?

zxzxzx

valiant24 said:

Reed_Richards said:

Well it could be that the wind blowing over the outside of your house is cooling it much faster than normal so the rate of heat loss is a lot bigger than usual.  But if you are using weather compensation then that is only paying attention to the outside temperature and so doesn't boost the heat output from your heat pump to cope.  But if you generally get by on just a few hours worth of heating and now continuous heating isn't doing the trick, then it's a bit of a stretch to believe my possible explanation is correct. 

What else could I check?

RR, Just curious…what temp does it work by? Does its positioning have an effect?

 My outside thermometer in a sheltered position currently say 11c, the local weather app says 7c with a wind chill down to -5c that’s quite a spread and ‘might’ support your theory?

michaels

Interesting I was about to post the same thing re wind load, over the last month our house temp has been pretty steady at between 21.5 and 20.8 but it dropped to 20.3 today. The heat pump is running the normal time/temp for the outside temp but the house is losing more heat.  Not sure if it is the trickle vents and the cracked bathroom window, whether we have draughts, or it is simply the wind (plus rain) makes the fabric lose heat more quickly..

matelodave

We are in an exposed position and  get a lot of evaporative cooling when its raining and blowing and sometimes I need to tweak the flow temp a bit to compensate especially if its not as cold and the weather compensation has turned down the wick

valiant24

zxzxzx said:

valiant24 said:

Reed_Richards said:

Well it could be that the wind blowing over the outside of your house is cooling it much faster than normal so the rate of heat loss is a lot bigger than usual.  But if you are using weather compensation then that is only paying attention to the outside temperature and so doesn't boost the heat output from your heat pump to cope.  But if you generally get by on just a few hours worth of heating and now continuous heating isn't doing the trick, then it's a bit of a stretch to believe my possible explanation is correct. 

What else could I check?

RR, Just curious…what temp does it work by? Does its positioning have an effect?

 My outside thermometer in a sheltered position currently say 11c, the local weather app says 7c with a wind chill down to -5c that’s quite a spread and ‘might’ support your theory?

Pic attached.

Reed_Richards

I understand that "Water Law" is Samsung's own name for weather compensation so it looks like you are using that.  Except that 56.4 is a ridiculously high temperature for the leaving water temperature, especially if you are using underfloor heating.  And 5 C is what it thinks the outside temperature is?

valiant24

Reed_Richards said:

I understand that "Water Law" is Samsung's own name for weather compensation so it looks like you are using that.  Except that 56.4 is a ridiculously high temperature for the leaving water temperature, especially if you are using underfloor heating.  And 5 C is what it thinks the outside temperature is?

So what should these numbers be, and what do I adjust to get there?

Reed_Richards

I'm not an expert on UFH but I would have thought that you can't possibly need water hotter than 40 C, even in the coldest weather.  What are your Water Law settings?

matelodave

As @Reed_Richards suggests, 56.4 degrees is excessively high for a heat pump, even with radiators . Underfloor heating would generally be around 40-45max.

In fact be careful that, as most heatpumps max out at 50-55 degrees, that you dont have an auxiliary immersion boost heater switched in as well - it used to be a big complaint with EcoDan heatpumps that they were set too high and the aux heater was coming on.

At five degrees outside, ours would be about 33-35 increasing to 40 at -5 outside. Most of the time its nearer 30 degrees.

You really do need to understand how your system is set up and how all your controls are set (both the heatpump controller and the heatmiser controls) have you got zones and timers set.

Generally an underfloor system works like a storage heater at a continuous gentle low heat rather than being blasted for a couple of hours twice a day. More controls can end up making the system less stable and very expensive to run especially if its being run like a gas or oil boiler.

Have a shufti here for how to tweak weather compensation on the Samsung controller and suggestions for temperature settings for u/f heating - 
https://www.bing.com/videos/riverview/relatedvideo?q=Samsung+AE120RXYDEG&mid=0B9B617AD841EC3A5B510B9B617AD841EC3A5B51&FORM=VIRE

Having a look at this video and the piccy of your controller showing 5 degrees, it looks like someone has also cranked up your temp to 5 degrees above its normal setting - https://www.youtube.com/watch?v=kqfbvjb-ZTY&list=PLa_cY4oQlxWtQcP8WLJ1KuZQZ41wDqV67&index=7 so has some random fiddling been done?

As a rule of thumb, every degree above nominal on a heat pump will increase its energy consumption by around 2.5% where nominal is 35 degrees. So running yours at 56 could be increasing your energy consumption by nearly 50%. Not sure if that's the same with a high temperature unit but heatpumps are most efficient when running at the lowest possible temperature, even if that means running them for longer.