I have Daikin ASHP which runs my hot water and underfloor heating. (Put in about 8yrs agro)

In December I had the the unit outside serviced/new refrigerator gas. 

My underfloor heating started to underperform a lot. Wouldn’t heat up above 18 degrees. A mixing valve had got stuck so was replaced but still not working UFH effectively 

If the outside unit gas was removed incorrectly (not using mode21) and the system has to much gas could this be the issue?

I have no clue about this stuff so any help is appreciated.

I understand stand the heat pump can only heat the water or the underfloor heating but it seems the underfloor heating doesn’t hold the heat

1 hour ago, Dcc said:

If the outside unit gas was removed incorrectly (not using mode21) and the system has to much gas could this be the issue?

Yes it could as it would inhibit both the condensing and the evaporation phases.  This is how a heat pump works.

 

But look at the simple things first.

Is your UFH fluid full of crud?

First question:

 

Is the ASHP getting hot enough to heat your hot water? If it is, the fault is nothing to do with the heat pump and it's recent service.

 

Post a picture of your under floor heating manifold and any gauges it has on or near it.

Sry what do you mean by crud? 

I’ve had the heating engineer round and they have checked the system from that side all seems fine. 

 

the issue only really started after the outside unit was serviced so I’ll call them back. At the time they said when changing the gas it only had 2.5kg but the base plate said 4.5kg, so they replaced new gas to 4.5kg (none of it makes sense to me) but I’m thinking if it wasn’t done correctly I could have max have 6.5 kg ?... I may be looking at it all wrong. 
 

I just would have thought an error code would have appeared if you to much. Hot water is up to 50 degrees and no problem it’s just getting the temp into the UFH which is about high 20’s not the 45 it’s set to.

 

Appreciate you coming back to me.

Edited March 6, 20215 yr by Dcc

8 minutes ago, Dcc said:

Hot water is up to 50 degrees and no problem it’s just getting the temp into the UFH which is about high 20’s not the 45 it’s set to.

That points to the blending valve being at fault. Heat pump is getting to temperature. 
 

What did they replace when you say mixing valve ..? I’ve seen them installed upside down before ...!

A week after the service to the outside unit they replaced the following 

 

so the lk unit thermostat as well as the valve

 

 

Edited March 6, 20215 yr by Dcc
Remove pic

Are they all gold plated ..??!!! That’s eye watering prices ..!! I would be getting them back as that definitely is not working correctly. 

It’s just so odd that the the day after the outside unit was serviced the heating drops off. The heating engineer said the valve had got stuck and couldn’t manually turn it so replaced the parts. 

WOW just WOW you spent £1000 on a "repair" and it's still not working.  I would get them back and not let them leave until it was working properly.

 

All at NO extra charge, just getting them to make what they fitted work properly.

 

I sometimes wonder how people have the balls to charge outrageous prices and have no shame or concern if the work they have done works or not.  I am pretty sure if I took that attitude it would not be long before I had no work and people were advising others not to employ me.

You don’t thinks it’s extra gas issue then?

They have been back and both times they get it up to temperature then 12 hrs later it loses heat

19 minutes ago, Dcc said:

You don’t thinks it’s extra gas issue then?

No as the ASHP would throw an error with gas over pressure. 

Thanks for your help

why was the gas "replaced"?

 

The unit was turned about 90 degrees. Some work done in the garden. It still the same distance away from the house and still exposed. 
 

I was having daikin air con fitted to the house so the same company/engineer serviced it, turned it and replaced the gas (r410a)

13 minutes ago, Dcc said:

The unit was turned about 90 degrees.

Is there any difference in performance depending on wind direction?

Previously like this

Turned to face down the flowerbed. 

I am also checking with the engineer who serviced it that they used mode 21 when removing all the gas. 

so it wa degassed & regassed to allow a move rather than "new gas" being fitted as some kind of service?

Yes.

They said it only had 2.5kg of gas and replaced it with 4.5kg as per the base plate.

@Dcc does the heat pump provide the domestic hot water ..?? You said this is getting to 50°C so it indicates an issue with the UFH manifold not the ASHP. 
 

Unless this is split system, there would be no need to take the gas out unless it was leaking. Is this all outside the house - there is no internal unit..?? 

Hot water gets up to temperature with no problem, the pump can only heat the water or the ufh.

 

I have a silver box in the plant room also. (hydro box is it?)

 

The new thermostat/valve gets up to the 45 (temp its set to) degrees but then just drops off to low 20s (even when it’s not heating the water)