Switching a Cool Energy ASHP between heating and cooling - on the actual unit as opposed to with the app or the internal control/display

[Bramco]

DI-6 works the same way as DI-4. So connecting to GND (8) sets the unit in 'Hot Water + Cooling/Heating'  depending on which one is connected.

 

Given we don't use the Hot Water modes, only Cooling or Heating, I'm going to have to find out how to switch off Hot Water....

[dpmiller]

DHW is called based on cylinder temp, so just put the setpoint to below ambient?

[Bramco]

Could do that and tbh, in the summer the tank is hot to overflowing with all the solar divert. I'd just have to remember to go back to heating only before the winter.

 

Although at ambient it wouldn't come on anyway...

Edited Monday at 12:18 by Bramco

[JohnMo]

32 minutes ago, Bramco said:

summer the tank is hot to overflowing with all the solar divert

Just stating obvious - if you get paid for export, a diverter may not be best for your pocket, with a heat pump. In summer heat pump will generate DHW with a CoP of around 4. Leaving you 3 units of PV kWh to export and be paid.

[Bramco]

1 hour ago, JohnMo said:

Just stating obvious

It's been stated many times......   😄

 

Sadly we have a DHW tank with an ASHP coil (3m2) BUT it's corrugated which leads to a lot of noise from air trapped in the corrugations. Manufacturer says - your problem mate. The fix is to replumb with a deareator etc to try to get rid of the air. So given we lose a bit on using the diverter rather than the ASHP, we have some way to go before it cancels out the cost of the replumbing - I'd also add a heat meter and the kit to be able to monitor the CoP, so it's not a cheap solution fix - and it may not work!

Edited Monday at 14:29 by Bramco

[JohnMo]

18 minutes ago, Bramco said:

I'd also add a heat meter and the kit to be able to monitor the CoP

You to fix the air in the system first, as any makes the flow meter of the heat monitoring system stop working. You also need to fix to stop corrosion in the system.

 

Mine just has an auto bottle trap where the red circle is. Including Tee was less than £20.

 

 

[Bramco]

22 minutes ago, JohnMo said:

You to fix the air in the system first, as any makes the flow meter of the heat monitoring system stop working. You also need to fix to stop corrosion in the system.

I know I do....   🙂     Long discussion here -> https://community.openenergymonitor.org/t/water-hammer-noises-and-heat-pump/26263

 

22 minutes ago, JohnMo said:

Mine just has an auto bottle trap where the red circle is. Including Tee was less than £20.

And you've been short changed - mine has a couple of those.  😄        and they haven't worked on the air trapped in the corrugations in the DHW tank.

Edited Monday at 15:22 by Bramco

[JohnMo]

1 hour ago, Bramco said:

And you've been short changed - mine has a couple of those. 

Not really - no air in mine, always comes out very easily - have one on cylinder very top of system, one on flow and return near ASHP at a high point, two on UFH manifold, and one in ASHP. All are closed off after initial filling and once no more air being caught. Then a week later go around and make sure no more air coming out.

 

1 hour ago, Bramco said:

and they haven't worked on the air trapped in the corrugations in the DHW tank

@Nickfromwales may be able to help. He fits Telford cylinders.

 

But have you tried to increase system pressure, this will dissolve any air bubbles. Run for an hour or so then slowly decrease system pressure and then air trapped air will have been transported, and could back out suspension and hopefully come out of auto vents.

 

"UFH buffer tank has 2 coils which are connected serially"

 

That is a strange configuration?

[Nickfromwales]

1 hour ago, JohnMo said:

2 hours ago, Bramco said:

 

@Nickfromwales may be able to help. He fits Telford cylinders.

AAV on the flow and another on the return, no issues from any I’ve fitted.

 

 

[Bramco]

Thanks for the suggestions guys - I'd put solving this on the back burner as we had a workable if slightly more expensive solution - think I probably need to give this a bit higher priority on the to-do list....

 

17 hours ago, JohnMo said:

"UFH buffer tank has 2 coils which are connected serially"

 

The UFH buffer tank is a smaller Newark tank (140l) - earlier when I contacted them, they said they put either one or two coils to get the 3m2 surface arear depending on the size of the cylinder. So I guess they always put two in on one that is 140l.  Our 300l DHW tank has only one.

[JohnMo]

On 11/07/2025 at 14:06, Bramco said:

And there's a downstairs bedroom which needs less heat than the rest of the house, so we do need some zoning

Couldn't you just trim the flow rate down, so the dT goes up on that loop and it naturally gives less heat to room?

 

Then dump the buffer and additional pump(s) and use a single thermostat timer, to control batch heating?

[Bramco]

13 minutes ago, JohnMo said:

Couldn't you just trim the flow rate down, so the dT goes up on that loop and it naturally gives less heat to room?

 

Then dump the buffer and additional pump(s) and use a single thermostat timer, to control batch heating?

Could do but...

 

In our setup, we only need to run the ASHP at night to batch charge the insulated slab. When it is cold, all the rooms need the full 6 hours or so. When it is less cold, the thermostats will cut off the flow when the set temperature is reached.  So for the downstairs bedroom it cuts the flow off earlier than the other two living area zones - the set point is lower.

 

I do set the thermostats in 1 hour intervals starting a couple of degrees higher than needed and decreasing the setpoint every hour. This makes sure that the thermostats don't dick around with the ASHP by tuning it on and off at short intervals.  Again this seems to work fine.

[JohnMo]

48 minutes ago, Bramco said:

So for the downstairs bedroom it cuts the flow off earlier than the other two living area zones - the set point is lower.

If you reduce the bedroom flow rate the mean flow temperature for that loop reduces only. It adds less heat, so over the 6 hours will add just enough to get that room to the temperature without any need for a thermostat. But if only this room is using a thermostat to limit room temperature rather than call for it, you just don't need the buffer, especially if batch charging the floor.

 

I just used a single window for batch heating floor, but used a 0.1 hysterisis thermostat to stop overshoot. Could do the same for boiler and ASHP. Both would run a single cycle (so start at start of time and run continuously until the end), only ASHP having to defrost when required. Once outside the running window the thermostat was set a couple of degrees below actually room temp. But don't bother with any thermostats any more.

[Bramco]

2 hours ago, JohnMo said:

But don't bother with any thermostats any more.

 

You're making the assumption that someone in the house (you know who I'm talking about) can guess the temperature without looking at the app - ain't gonna happen.....

 

😄

 

[JamesPa]

1 hour ago, Bramco said:

 

You're making the assumption that someone in the house (you know who I'm talking about) can guess the temperature without looking at the app - ain't gonna happen.....

 

😄

 

Why do they need to know the temperature, surely all they need to know is if they are too warm or too cool.

 

Anyway if you want to measure temperature, get a thermometer!

[JohnMo]

All my room temps are in an app, all the rooms have a thermostat, but the boiler output isn't connected. Anyone could change any set point but it doesn't actually do anything. It's just a monitoring tool.

[JamesPa]

1 hour ago, JohnMo said:

All my room temps are in an app, all the rooms have a thermostat, but the boiler output isn't connected. Anyone could change any set point but it doesn't actually do anything. It's just a monitoring tool.

Ah, placebo controls, don't you just love them.  Absolutely ideal when you have people fiddling with things who don't think about what they are doing. 

 

I once considered implementing placebo controls in a community centre where successive users whacked the thermostat either fully up or fully down (but of course the building didnt actually respond materially before they left, and they didn't bother resetting it.  In the end I opted for locked controls.  Im not sure to this day if that was the right decision.

[Bramco]

14 hours ago, JamesPa said:

Why do they need to know the temperature, surely all they need to know is if they are too warm or too cool.

 

You obviously live alone...

14 hours ago, JamesPa said:

Anyway if you want to measure temperature, get a thermometer!

Where thermostats have a display, isn't that what the display is?