Posted by: @derek-m

Posted by: @mike-patrick

@derek-m 

Derek,

Sorry for the delay  but I've now read the  remote control

My instruction manual is May 2016 but I think table 10.3 is the same.

Here are the numbers:

00 Circ Water temp    29 deg

01 Compressor freq    0

02 Discharge temp      35 deg

03 Current consump    400

04 Fan Control      480

05 Defrost temp   9 deg

06  Outdoor temp   11 deg

07 Water pump rotation   2900

08  Suction temp    9 deg

09  Circ water flow    38 deg

Mike

 

Hi Mike,

Thank you for providing the data. It is probable that your system is working on weather compensation, but it may be necessary to fine tune the settings for optimum operation.

How familiar are you with adjusting the settings on your controller? The other question would be, are you controlling the indoor temperature using thermostats and/or TRV's?

An easy way to check how well the weather compensation is functioning, would be to increase your thermostat setting by 1C. If the indoor temperature increases by 1C, then the weather compensation curve is incorrectly set and requires adjustment.

Derek,

The system has individual thermostats in each room, which are independent of each other so can each have their own timing schedule.

I've not tried adjusting the controller as I'm wary of changing something in error and then not being able to get back to the original setting.

The Grant engineer who visited, gratis, in the spring adjusted the time controller so that the heating is off when the water is on. I've not had a problem with cold water since.

However this was done by using the Honeywell timer such as you find on any central heating system. He set the heating to literally turn off when the water is on (3 times a day) which cuts the power to the room thermostats (so they never show the right time). It fixed my immediate problem so I've been reluctant to change anything. However I think that the heating should be left on when the water is heating, but with the room thermostats set to a low temperature during those periods so they are not calling for any heat.

I can try adjusting the room thermostats to see what the result is of increasing the setting by 1C

Mike

@mike-patrick I am in the view of everyone else here. You should do away with all the timed heating and do the whole house. If you zone it there is a good chance your ASHP will be on all the time providing heat to individual rooms. I don't think it'll be very efficient at all.

@mike-patrick 

Hi Mike,

The important thing is to note the original settings before making any adjustments, so that you can always revert back to the original ones.

What I find quite amusing, is that it clearly states in the manual the following:-

If the installation is receiving an RHI payment, do NOT set
the outgoing water control to ‘fixed set point’ as the weather
compensation function MUST be operational.

Whilst your system may be set for weather compensation, I suspect it is not fully operational and is being overridden by the thermostats located within your control system. Raising the temperature in one of the rooms by 1C should soon prove that to be the case. Whilst it is still possible to operate your system using thermostats combined with weather compensation, it may not be as efficient as weather compensation as the main controlling element.

@mike-patrick 

Mike,

I forgot to mention that systems are set up so that the ASHP is providing heat energy to the heating circuit or the DHW, but not both at the same time. In the first place, the DHW will normally require a higher water flow temperature, but also providing heat energy to both systems at the same time would require the heat pump to work much harder, and hence less efficiently.

The normal way to do this would be to have a diverter valve, which directs the warm water coming from the heat pump to either the heating circuit or the DHW, or by using two separate on - off valves to carryout the same function. All of this is normally achieved by the ASHP controller, and not by some additional timer switching off the power supply to the thermostats. Very strange.

Posted by: @derek-m

@mike-patrick 

Hi Mike,

The important thing is to note the original settings before making any adjustments, so that you can always revert back to the original ones.

What I find quite amusing, is that it clearly states in the manual the following:-

If the installation is receiving an RHI payment, do NOT set
the outgoing water control to ‘fixed set point’ as the weather
compensation function MUST be operational.

Whilst your system may be set for weather compensation, I suspect it is not fully operational and is being overridden by the thermostats located within your control system. Raising the temperature in one of the rooms by 1C should soon prove that to be the case. Whilst it is still possible to operate your system using thermostats combined with weather compensation, it may not be as efficient as weather compensation as the main controlling element.

 

Derek,

I increased the room thermostat by  1C in one room (all 13 would have been too much) and left it for an hour. It did appear that the temperature in that room had then increased by 1C.

My electricity usage is at a record low compared with the same period in each of the last three years but this may be mostly due to the mild weather. So I'm happy to give making changes a try.

Mike

@derek-m 

A big reason why, 5 years after installation, I'm still trying to optimise the system is my lack of confidence in local heating engineers. Our original installer no longer does heat pumps and the two I have tried for servicing (both on Grant's list) clearly didn't really understand the set-up. As I mentioned, the guy that Grant sent then set the time switch to mediate between heating the house or the water.

I would happily pay someone who properly understands these systems to come and configure mine, even if it was more than the usual minimum of a £200 call out charge.  But it's only after they have been that you learn whether or not they really knew what they were doing.

Mike

@mike-patrick 

Would it be useful if I explain weather compensation and what we are trying to achieve before we make a start?

What are you like with Skype? 

@derek-m 

Yes, that’s very kind of you.

I can do Skype. 
I’m next working from home on Friday so that would be a good day. Next week I’m home on Tuesday and Wednesday also.

Mike

@mike-patrick 

This coming Friday sounds good, around 10 am? What are your Skype details?

Where are you located?

I suggest that you familiarise yourself with the controller as shown in section 9 of the manual, and also section 8 which details weather compensation.

Think of weather compensation like creating a straight line graph within Excel. By setting the co-ordinates for the lower end and then the upper end, a straight line is produced connecting the two points. So when you are setting the required slope for your weather compensation, you may set the required water flow temperature to be 50C, when the ambient air temperature is -5C, and the required water flow temperature to be 25C at an ambient air temperature of 15C. As the ambient air temperature varies, the controller will move up and down the slope of the graph to select the required water flow temperature.

@derek-m 

Derek,

I'm based near Witney, Oxfordshire.

Skype account uses same email addrres as here mjpatrick@protonmail.com

10am tomorow will be good.

I'll study my bedtime reading before then!

Regards,

Mike

@mike-patrick 

Looking forward to speaking tomorrow.

Posted by: @derek-m

@mike-patrick 

Looking forward to speaking tomorrow.

Derek,

Sorry for not following up earlier on our conversation, but I have only just had an opportunity to have another look at my ASHP controller settings. Since then we have of course had a brief (here in the south) cold spell and my  electricity consumption went through the roof. It spiked at 75kWh one day, having averaged about 35kWh daily during the earlier part of the month (which were my best November figures for 3 years)

Firstly, as you suggested, I took another set of readings when the pump was running:

00 Circ Water temp 32 deg

01 Compressor freq 76

02 Discharge temp 50 deg

03 Current consump 2800

04 Fan Control 680

05 Defrost temp 0 deg

06 Outdoor temp 4 deg

07 Water pump rotation 2900

08 Suction temp -10 deg

09 Circ water flow 39 deg

I also checked parameters:

31 01  is set to 1

51 19 is set to 1 (DHW has priority over space heating)

Now on to Weather compensation

21 00 set to 1

21 02 45 deg

21 03 30 deg

21 04 10 deg  (I've changed this to -5 deg, quite a difference)

21 05 25 deg

21 41 8 deg

Apart from 21 04 they are not too different from your suggested figures so, for now, that's the only one I've changed

Thanks for your help - I'm now more comfortable making changes on the control panel. It's far from consumer friendly but I've got the hang of it. Just got to remember to record any settings before changing them so I can revert if necessary.

Mike