Underfloor flow temperature too low?

[Squonk]

We have underfloor heating throughout the ground floor of our 1980’s timber framed house. It’s double glazed and reasonably insulated. 10kw  ASHP with underfloor heating on a suspended timber floor, with cement board and engineered wood flooring throughout. We only bought the house a few months ago, so this will be our first winter. When I got up this morning the living area was at 18 deg, OAT was about 14. I set the thermostat to 20 but, despite running all day, the room temp never got above 19. This is not even winter yet (even in the north of Scotland) so I’m a bit concerned. Last few days have been the same issue, before that it was warm outside so I didn’t notice.
 

I’ve been keeping an eye on the system all day and the actual pump seems to have done very little heating. The flow temp target is 31, when the pump kicks in the actual temp goes up to about 35, and then seems to drop eventually to 25 once the ASHP shuts down. We did have a power cut recently, so I’m wondering if some settings have got corrupted or reset maybe? Everything seems to work ok individually, and the DHW is as hot as it should be. Alternatively, I’m wondering if the flow temperature needs to be higher? I don’t know what temperature the actual floor gets up to, but it never really feels warm. The system says it’s used 1kwh of electricity today for the heating to yield about 4kW of heat.
 

Any thoughts / suggestions much appreciated. 

Edited September 3, 2022 by Squonk

[JohnMo]

If your needing heating you should be looking at way more insulation.  I am in NE Scotland and our house is at around 21 with no heating on.

 

Couple of questions how long is the heat pump running, is it going on and off a lot?

 

How many zones do you have and how many are calling for heat?

[Adsibob]

I suggest you buy a laser gun thermometer, with which to take temperature readings of your floor. These cost about £15 from Amazon. Get one that has an emissivity setting so that you can set it for wood, given your floor is wood. I found this quite useful for making sure the floor was set to the maximum temperature that did not harm the oak engineered floor. We found that with UFH water set to 35C we got a floor temp of about 27C which was good as floor manufacturer didn’t want us to exceed 28C.

@JohnMo is right about insulation, but that is hard to upgrade without spending lots of money and planning how to deal with various issues. It is much easier to fit draft excluders to make sure your doors and windows are fairly airtight. So do that, if you haven’t already. 

[ProDave]

Did you install the UFH?  Do you know how much insulation is under it?  Was it fitted when the house was built or a later addition?

 

Agreed no heating should be needed yet, I am further north and still cosy warm inside the house.  But this is a 1980's build and they are not well know for being good.

[ReedRichards]

The people saying no heating is needed yet are talking entirely from their own perspectives.  It's your house and you know if it needs to be a touch warmer.

 

It's probable your heat pump is set to do Weather Compensation.  This will reduce your maximum water flow temperature if it is warmer outside.  It is possible that the high end settings are wrong so when it is relatively warm outside, as it is now, then the target flow temperature is not hot enough to give you 20 C.  Perhaps the previous occupants were content with 19 C at this time of year?  So check if Weather Compensation is on and what the settings are.