I think this is one for Mr. Ecodan himself, @ashp-bobba 

@editor Fingers crossed 🤞 

I've tried to turn down the pump speed since they were maxed out. 

The thing i really cant understand:

1. Why do the circulation pumps turn off soon after the compressor stops? 

2. Why does a freeze stat keep occurring? 

The flow temps are set to:

12°c = 20°c

-2°c = 32°c

I appreciate these are low but any higher and the house gets to warm, any higher it means having to use the room thermostats to knock off circuits (wasting energy), at the moment they are calling for 23°c but the rooms are balanced to 20~21°c. 

This is a screenshot from this afternoon: 

Thanks for any help 🙏 

@patch321 did this just start recently? Clearly a control issue, and maybe @pirate-rich might have some thoughts.

@patch321 HI, I will try to jump on later tonight as I can see this will need some thought, but for now can you tell me which pumps stop, we need to label them as it looks like you have 7 pumps so I assume you have a zoning setup, most heat pumps prefer simple layout less zoning.

Try to work out which ones stop and which do not, in heating the left 2 Mitsi pumps should be running and the right not as this is the plate HX pump for hot water.  

Posted by: @ashp-bobba

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we need to label them as it looks like you have 7 pumps

OMG, I never even spotted that. Why are there so many pumps? Yikes!

@editor zoning and more zoning, @patch321, don't panic yet, I will try to help later.

@ashp-bobba hey Bobba+Mars, thanks for jumping on the thread. 

Indeed, the two pumps which switch off are:

Heat Pump Circulating pump + Heat Zone 1 Circulating pump

That's was my understanding also, seems a lot of pumps, my understanding was you only needed extra pumps for >2 zones. 

I think zone 1 is the ufh and zone 2 is the upstairs rads. 

From what I can tell the white vertical pump is on the flow for zone 2.

Green vertical pump is for hot water in the upstairs bathroom (hot water recirculation system).

@patch321 

1. Why do the circulation pumps turn off soon after the compressor stops? 

In compensation curve or fixed flow, the result of a flow temperature overshooting the flow setpoint (i.e. not enough heat dissipation or not modulating low enough) results in the ecodan operation mode becoming Off.

When the operation mode is off, as are the pumps.

When you are in Auto-Adapt, this occurrence will result in an outdoor unit pause. Until the thermo. Diff limit temperature limits are satisfied. Pumps do not stop as the operation mode remains 'heating'

2. Why does a freeze stat keep occurring? 

When there is no demand for heat (operation mode is off) and the outdoor temperature is low, then if enabled, freeze stat will circulate water to prevent freezing.

Typically enabled only when Glycol is not present.

@f1p thanks for the post.

interesting, I wonder in that case its modulating down, I think the ashp is massively oversized for the heating demand for our house, I think it looses about 3-4kw but have a 11.2kw ashp. 

Seems mad but do you think I need to increase my flow temps on the tcc to give it an “artificial demand” and then limit the room temp with room thermostats? Or is there any other way to prevent the modulating down? 

Still non the wiser to why the pumps are laid out like they are though 😩

Here is the current chart:

@patch321 

You are going to have a bit of a fight on your hands I'm afraid if you are oversized and particularly in warm weather.

the Ecodan logic is to ramp up compressor speed to recover a difference between setpoint and actual, its not very quick at reducing it again - in many cases you will overshoot by the time it's ready to settle and then the 'cycle' (often short) begins again 

You have one of the options, higher flow temperature 

Auto adapt can work better often than fixed or compensation curve

There is another but it's not perfect either and complicated to implement 

Posted by: @patch321

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Hi, 

I think I’m having some issues with my Ecodan ashp and the pumps, details are as follows:

11.2kw Outdoor Unit (PUZ-WM112VAA)

300L Indoor Unit (EHPT-UKHDW)

Flow Temp Controller (PAC-IF073B-E) 

New Build Property

UFH downstairs

Rads Upstairs

Running on Temp Comp Curve (tcc)

I’ve attached some photos showing the current set up.

So the issue (I think) I’m currently having is that, when the compressor comes on the circulation pumps switch on - Happy days, but when the compressor shuts down so do the circulation pumps with a flow rate of 0.
The flow rate rises but then drops when the compressor shuts down, which then the return flow is higher than the flow rate, which slowly drops, only then does the compressor switch back on to increase the flow temp.

Am I correct in thinking that the most efficient way to run the tcc is for the circulation pumps to continuously run including the compressor but just at a low level? 

Also I’m worried that because the circulation pumps down seem to be running that the t1+t2 sensors (they are on the correct way)

are just detecting stagnant glycol, hence the slow drop in return until it then switches back on? 

Also does anyone know the optimum flow rates for my ashp?

Any help/guidance would be appreciated.

 

Thanks

Can you  tell me if you have an FTC6 or FTC7

If you have muti zone system and the floor is off the 11.2kw system will not inverter effectively down to 3 or 4 rooms to this will cause some short cycling or over shoot, can you tell me if (FTC6 the PLAY Symbol) goes out (FTC7 if the home goes black or stays red) when the pumps stop

Lets find this out 1st.