Haier R290 Monobloc

[JohnMo]

Forgot to mention DHW, this was to be by immersion only. Have rethought this, as all the hardware and cables are in place, to switch the 3 port valve. But gone a much simpler layout than previously. Immersion is standalone and not connected to heat pump at all. Any issues with heat pump, just flick immersion on.

 

Routing was always difficult to sensor probe from heat pump to cylinder but that has been solved by repurposing a cable or two not in use, that running through the house. But includes the cable I was going to use for the smart grid switching. One problem solved, one created.

[JohnMo]

Decided after all to stay simple, DHW by immersion, will have plenty of excess solar in summer that will not be generated due to export limits. So better to use it via immersion than loose it.

 

So wiring is complete. Have retained the smart grid switching to allow flow temp boost if I need it for the summer house, have retained the open source monitor system (energy and performance monitoring). So wiring actually done by me, power cable, SG switching 2 core cable, which then connects to inside house via existing trenched SWA cable (already in place for existing HP), this connects to UFH controller, so I have remote (hardwired) manual temp over-ride for summer house temperature. 

 

Once outdoor unit in place it's just power cables and shielded comms cable. A some basic pipe work mods.

 

Image below left to right, isolation switch wiring center and performing), electric meter for heat pump, heat meter for heat pump, Hiaer controller, below that, simple wiring center, then the main control/wiring center for Hiaer heat pump.

 

[JohnMo]

So will be keeping the volumiser, it's in the return line, but after the diverter valve due to because retrofit. So it also had an ESBE diverter, which allowed the volumiser to be bypassed during the production. That bypass isn't needed, so actuator removed and all the insulation tidied up.

 

Before

After

 

Not perfect but much better than it was.

 

Still a filling/flushing valve to sort out, but in the difficult basket 

 

[JohnMo]

Been scratching my head how to set WC curves, one for heating the other for cooling, however I found because the unit was set to auto (auto switching between heat and cool) the menu wasn't visible. However switch to heat or cool and WC menu pop up. Very easy to set, so set a flat curve for cooling 16 deg (well above dew point) flow temp and heating the more normal curve.

 

Will most likely need some adjustment once up and running.

[JohnMo]

On 17/01/2026 at 12:48, JohnMo said:

 

I heat the summer house as part of the same zone as the house, it runs at 18 to 19.5 normally, but sometimes we need it warmer, so I normally use a thermostat to trigger a second setpoint for the heat pump, which works fine and floor just buffers the heat. The Hiaer unit, I will utilise the smart grid connection, and set a 2 Deg uplift in flow temp when the connections across terminals for SG2 (EVU signal) are closed. The same connection can reduce the cooling flow temp should I need it

I decided to change this wiring and use zone 1 and zone 2 control via 3rd party thermostat control. This gives a few advantages

Heat and cooling is switched manually, so use a simple light switch to trigger seasonal changes, it's connected to ASHP and UFH controller, so both are always in exactly the same mode - this is hardwired.

Hydraulically the system runs fully open, zones is purely for different running points and flow temps.

Zone 1 terminals are fitted with a jumper wire, so always on pure WC, so runs in heat or cool depending on seasonal switch position.

Zone 2, is a wireless switch controlled by UFH controller, in winter it allows me to boost summer house temp (only if needed via manual setpoint change on UFH controller), increased flow temp being buffered in to house slab (been doing this for the past year, works well). In summer it allows two set points for cooling, 19 degs flow background via zone 1 temp, if house goes above 23, it moves the flow temp to 17 via zone 2 setpoint. It also includes control set point for humidity, so if house goes above 60% it removes boost function via zone 2 (this will require tuning).

 

A further advantage is zone two has its own WC curves for heating and cooling. Certainly for heating it allows me to fine tune the boost temp uplift required at different outside temps, for summer house which runs a fan coils and not UFH.

[JohnMo]

That's the heat pump up and running 4.5 hours from switch off to switch on. Been running for a couple of hours. It seems to testing how the heating system responds. It's keeping return temp, rock steady stable but adding and reducing load, first hour slowly ramped down to 1700W output, then ramped up to 3000W. Now its got a cycle time between peaks of around 30 mins. Pump flow rate is also slowly being decreased at about 8L/mine it was at 20L/min when it first started.

 

Before and after, Haier unit quite a bit bigger and heavier.

 

Issues during switch on, an error code E12 - Zone 2 mixing valve temperature sensor Twzone_2 
abnormality.

 

So zone 2 switch off for now. May revert to my first idea of doing smart grid switching for second set point. Will sleep on it 

[ProDave]

7 hours ago, JohnMo said:

Pump flow rate is also slowly being decreased at about 8L/mine it was at 20L/min when it first started.

Interesting.  I like the idea as it reduces power it also reduces flow rate.  My LG is set on needing 15L/min otherwise it shuts down with a low flow error.  This variable flow seems so much more sensible.

 

I have no plans to change at the moment, but if my present HP fails, this is the sort of thing I will be looking at when choosing a replacement.

[JohnMo]

8 hours ago, ProDave said:

low flow error

I had a flow meter error over night, so it stopped the heat pump, but interestingly the circulation pump continued to run on off every 15 mins. Checked the strainer all clean, reset the controller and it all restarted fine. Maybe some air still kicking about.

 

Checked the control status log and it shows actually flow rate against an internal estimate of flow rate when it thinks it should be doing 20L/min it's actually doing 19L/min. Which also aligns well with the heat meter. So don't think there is an issue with the flow meter.

 

Heat pump now playing catch-up and running flat out flow rate up to just under 20L/min.

[JohnMo]

Photo showing rear of unit and piping, lagged with primary pro insulation. 2 x antifreeze valves (warranty requirement) and 2x isolation valves, then flex hoses and then 28mm pipe.

 

Final wiring scheme

Seasonal switching between heat and cool. Reused light switch, hardwired to UFH controller and ASHP wiring centre, located by UFH controller.

 

Single zone with jumper across zone terminals, so always on.

 

Secondary set point, wired from UFH controller via an EPH TR1-TR2 Two Way Wireless Switch. A call for heat or cool selects Smart Grid SG terminals, and give a demand for 2 degree uplift in heating or a reduced flow temp of 2 degrees in cooling. (Manual had wrong wiring diagram for this, wiring terminals and functions didn't match, so trial and error approach taken). This function uses the humidity sensors within the UFH controller to give a cooling safety shut off. It allows background cooling setting (19 degs flow temp) and then when house increases in temp it steps to 17 Deg flow temp. In heating mode, summer house stabilises at 18 degs with normal WC settings, so boost is used to increase to 21 when we use it.

 

Communication cable to outdoor unit.

 

Pretty simple wiring overall. If I didn't do cooling there would be no additional wires, just a Comms cable.

 

DHW is still being done by immersion.

 

Overall heat pump just seems to run, no on off cycling.

[JohnMo]

I have now been running for a couple of days, and have now got it running in a stable manner.

 

Out the box settings are fixed speed pump and 100% speed setting. There is also a selection to be dT controlled and variable speed circulation pump. If you set to dT control the default being dT of 5 degs.

 

Initial run was on a setting dT of 4 and variable speed. Problem I found was floor return temp was a very stable 23 degs and I had a target of 26 flow temp. So the controller was trying to get return temp to drop while maintaining a target flow of 26. 

A bit of a mess, plenty of overshoot, then undershoot outside was between 5 and 3 in the 4 hours window, CoP 4.17, ok but not great. Tried fixed pump speed similar results.

 

This morning house was warmer than I wanted, so lowered WC curve and set to dT control and lowered dT setting to 3.

Last 6 hours of running - 3 hours spent bring floor temp down a degree, think the spike maybe the energy integral adding energy to floor to catch up. When you zoom in, it's very controlled and deliberate. Then 3 hours running steady state and a CoP 4.96 over the 6 hours. Actually outside temp over the 6 hrs was between 2 and 4 degs.

 

Defrosts, seems very resistant to freezing, only one defrost cycle so far. Took 4 mins and used 0.27kWh of thermal energy.

 

 

[JohnMo]

Just went back and looked for a similar period of running for the Maxa heat pump, similar outside temperature,

CoP here is 0.86 lower, doing the same heating. Flow temp was up to 30 degs to compensate for cycling. Haier is flowing between 25 and 26.

 

 

 

[SteamyTea]

4 hours ago, JohnMo said:

seems very resistant to freezing

It has a larger fan and heat exchanger (radiator) area I seem to remember you saying.

 

[JohnMo]

1 minute ago, SteamyTea said:

It has a larger fan and heat exchanger (radiator) area I seem to remember you saying.

 

Way bigger per kW. Velocity through heat exchanger certainly seems a lot lower.

[SteamyTea]

8 minutes ago, JohnMo said:

Velocity through heat exchanger certainly seems a lot lower

Now I would have thought that would increase the icing as the air is cooled more.

That is counteracted by the greater area though.

The true metric is dT/kg.s or in English, how much is each kilogram of air cooled in a second as is passes though.

Throw in the SHC of nitrogen, oxygen, argon and water vapour and you get the power being extracted.

Edited 22 hours ago by SteamyTea

[JohnMo]

Woke this morning, after thinking I had a stable system, with flow temps bouncing about. The bouncing occur soon after a temp drop overnight.

 

System currently looks like

4kW heat pump at min modulation 1kW, UFH with single fan coils (60L), volumiser (50L). UFH is within 100mm slab.

 

Previously 6kW heat pump and at min modulation 4kW, the rest the same as above.

 

For my previous heat pump volume was king to cycle control.  Current setup not sure the volume adds anything positive, it adds to system inertia and leads to slow feedback to heat pump.  Think the control system is looking for a more timely feedback to changes to running parameters. The thick screed, big water volume (via the volumiser) adding too much delay to changes, such as return temp staying stable for too long after a controller input, so control throws out a further command, feedback comes back (late), so the controller keeps over compensating. We get a yo-yo as witnessed.

 

Luckily the volumiser is easy to bypass, so this was done earlier. Within 5 mins of the change, the flow/return and power input became very stable.  Looking at yesterday and todays day time temps they are almost the same, but CoP has jumped from 5.2 to 5.4 during steady running.

 

Will see overnight as temps swing about outside, if this has calmed the down.