12k + 6k Daikin Atherma 3 HT ASHP user experience?

[magutosh]

Hi everyone,

 

We've been quoted a Daikin unit as above recently, just when we thought our hearts were set on Ecodan. 

 

The price came through about almost a third cheaper than a 14kw ecodan, yet it has a hydro box which stores 6k of backup heat, in case of an eventuality. 

 

14kw might also be an overkill for a 4 bed sip house with UFH downstairs, so 12k main unit plus 6k backup appeals to me better. 

 

I've used Daikin air conditioning unit in the past and know its reputation, hopefully ashp would carry that on.

 

Has anyone had real life experience with them? What about RHI payment for such unit? There is a thread referring to an older model, I don't know if the same still applies.

 

Any feedback would be much appreciated!

 

Regards

Dominic (Stockport, Northwest)

[PeterW]

The 6kW hydro box is just a cylinder in a nice package - they do the 12kW unit without it, and it’s a lot cheaper. 
 

Make sure they have priced the monoblock unit too as the split ones need an F-Gas installer and also can be a bit noisier inside the house.

 

The Ecodan quoted is usually used on standard builds / retrofits so who has done the heat loss calculations ..? 
 

Also doesn’t make sense that you’ve got the HT unit quoted and UFH - they are again normally a replacement for standard radiator based installs and the “HT” on the Daikin is also a fairly poor CoP at high temperatures as it uses R32 refrigerant and also I believe uses an in unit electric boost to get to the top temperature. 
 

Is this a retrofit or a new build ..?

[magutosh]

2 minutes ago, PeterW said:

The 6kW hydro box is just a cylinder in a nice package - they do the 12kW unit without it, and it’s a lot cheaper. 
 

Make sure they have priced the monoblock unit too as the split ones need an F-Gas installer and also can be a bit noisier inside the house.

 

The Ecodan quoted is usually used on standard builds / retrofits so who has done the heat loss calculations ..? 
 

Also doesn’t make sense that you’ve got the HT unit quoted and UFH - they are again normally a replacement for standard radiator based installs and the “HT” on the Daikin is also a fairly poor CoP at high temperatures as it uses R32 refrigerant and also I believe uses an in unit electric boost to get to the top temperature. 
 

Is this a retrofit or a new build ..?

 

It's new build with insulated foundation, so we have already buried the UFH in the concrete.

 

Regarding the heat loss calcs, the first company quoted us the ecodan supposedly has done it, and quoted the 14kw unit, but when we asked to reduce it, they were happy to accommodate? 

 

Which make and model would suit UFH for entire downstairs and upstairs bathrooms, with wall mount radiators in bedrooms, in your opinion? 

[PeterW]

Need to see the heat loss calculations - what are the uValues for walls roof and floor ..?? 
 

14kW is a big ASHP - I would I be expecting half that in a decently insulated and air tight building. 

[J1mbo]

Bear in mind that there is a trade off between hot water recovery and system efficiency mid season. ie 12kW doesn’t go far in hot water recovery speed whereas it’s enough heat for maybe 400m2 at 30 watts per m2.

[magutosh]

34 minutes ago, PeterW said:

Need to see the heat loss calculations - what are the uValues for walls roof and floor ..?? 
 

14kW is a big ASHP - I would I be expecting half that in a decently insulated and air tight building. 

 

We use 142mm Kingspan TEK sip panels with u value of 0.2 for roof and walls, floor has 300mm eps kore insulation with u value of 0.1.

 

We haven't seen any heat loss calculation yet, only SAP report, every party likes to keep that close to their chest until they get go ahead. 

[J1mbo]

You can get an EPC for £50 that will give a guide.

[PeterW]

8 minutes ago, magutosh said:

 

We use 142mm Kingspan TEK sip panels with u value of 0.2 for roof and walls, floor has 300mm eps kore insulation with u value of 0.1.

 

We haven't seen any heat loss calculation yet, only SAP report, every party likes to keep that close to their chest until they get go ahead. 

Ask for the heat loss calculations that support their quotes. 
 

What is your total ground and first floor areas and have you got MVHR..??

[magutosh]

Just now, PeterW said:

Ask for the heat loss calculations that support their quotes. 
 

What is your total ground and first floor areas and have you got MVHR..??

 

Total floor area comes to around 210 m2, we will install MVHR being a very airtight house.

 

I'll fire them an email for the heat loss calcs now.

[magutosh]

8 minutes ago, J1mbo said:

You can get an EPC for £50 that will give a guide.

 

We do have a SAP report, but I can't see any field in particular address heat loss?

[J1mbo]

Look at annual demand then work back.

[A_L]

1 hour ago, magutosh said:

Total floor area comes to around 210 m2, we will install MVHR being a very airtight house.

 

1 hour ago, magutosh said:

We do have a SAP report, but I can't see any field in particular address heat loss?

 

I cannot see your heat loss as being as high as 250W/K and given some gains of casual occupancy a 8.5kW ASHP would be adequate down to at least -3°C. This assumes air tightness around 0.6ach@50Pa (Passive house standard) or 1m³/m²/hr@50Pa (units used in SAP)