Danfoss tp5000 thermostat

brokendoll

Hi, I have an older model Daikin ASHP, fitted with what I believe is a Danfoss tp5000 room thermostat.

I believe that the temperature sensor in the thermostat is not working accurately.

It always seems to think it's around 17 degrees when it's a lot colder.

I was advised to keep the desired temperature to 18 degrees, all day, for optimum usage.

This means the heating will only come on for a couple of minutes before it thinks it's 18 degrees so the house never actually has time to warm up. 

If I manually override it to 22 degrees or so it still leaps to 22 degrees quicker than the actual rooms do, so sometimes doesn't cut it. I haven't managed to find a sweet spot when the rooms have a chance to get warm without it being suddenly a bit too hot (because I've had to blast it to 25 to stop it going off).

When I set it higher it also comes on more frequently in the night waking me up. (internal pipes and radiators, as opposed to the sound of the outside fan) because the house obvs hasn't been holding the heat well. (recently got new windows so hopefully that helps). 

 At one point I set it to 15 degrees trying to be thrifty and it just never came on even tho it was well under 10 degrees (thermostat said it was higher). 

I know that sounds like I've messed around with it a lot but it was only 3-5 changes in the last year trying things out. 

I have replaced the batteries and pressed the restart button. The online manuals are not useful for this scenario. 

It is located in the hallway at the recommended height near the front door, it's not particularly draughty or close to a radiator. 

I gather the temperature sensor is inside the thermostat and would need a professional to check it for dust/wear etc? 

I did have my annual boiler check in February but I'm not sure they did anything with the thermostat. I'm new to ASHP too so just trying to figure it out. They told me to not touch the actual control panel for the ASHP as it messes it up and they'd set it to the optimal settings. 

What would you recommend as a next step? (Obviously I can ask them to come out and check but I want to be as informed as possible, in case they don't see anything wrong and don't offer any sensible solutions).

Thanks. 

vacheron

You mention that the thermostat says it is "X" degrees when it is actually "Y" degrees.

Where is the thermometer that you are using to compare the thermostat to? Is it located right next to it? 

Also where is the thermostat physically located, just above a radiator, or near a window?

Have you had this issue since it was installed, or just recently?

Reed_Richards

You could buy a replacement, with a quick look the cheapest one I can find is here: https://www.grantandstone.co.uk/danfoss-tp5000-si-prog-room-stat-7day-or-24hr-087n791000

It's generally thought to be bad for a heat source (a heat pump or a boiler) to run for very short periods as you describe that yours is doing.  But I presume that it has only been misbehaving recently, indicating that something has indeed gone wrong.

NedS

Reed_Richards said:

You could buy a replacement, with a quick look the cheapest one I can find is here: https://www.grantandstone.co.uk/danfoss-tp5000-si-prog-room-stat-7day-or-24hr-087n791000

Or for the same money, I'd highly recommend this programmable wireless model (I have) which works well with ASHPs:

https://www.ephcontrols.com/section/cp4/