Would a bigger pump compensate for small pipes?

[SteamyTea]

3 hours ago, J1mbo said:

All this manual configuration is representative I feel of the manufacturers not being software companies, it's a bit like the challenge the established automobile manufacturers are facing when compared to the new-entrants.

Is that why the challengers are poaching from the big automotive  companies.

Still, if the new people can, via software, stop wipers smearing damp dirt over a windscreen, stop headlights dipping when they spot a reflection, brake lights coming on when speed creeps over a set speed (followed a truck yesterday that did this, really annoying) and if Tesla can stop their cars doing emergency stops when the AI picks up on a speed limit sign on the back of a vehicle in front, then I will start to trust software engineering.

 

I think all that is needed is power, temperature and CoP control, with simple overides i.e frost sensing and ToD control.

 

Edited November 17, 2021 by SteamyTea

[Hogboon]

Well, having spent a few more fruitful minutes in the broom cupboard, the current settings for your suggestions are:

 

Outdoor temp for auto mode: min -10º max 15º

Indoor temp for auto mode: min 16º max 21º 

LWT for auto mode: min 20º max 50º

 

These are obviously different from your suggested values, but what I have no understanding of is whether the differences are significant or only minor? 

[J1mbo]

Progress! Since outdoor temp for auto mode min is -10, it will almost never reach the max flow and the general flow temp will be lower. Change it to -1.

 

Indoor temp probably shifts the whole curve up and down. Try 18/23.

 

LWT are the flow temps themselves. Change the min to something higher eg 30.

[Hogboon]

I adjusted some of the settings as per your suggestions as follows;

 

Outdoor temp for auto mode: min -10º max 15º changed to -1º/15º

Indoor temp for auto mode: min 16º max 21º changed to 18º/23º

LWT for auto mode: min 20º max 50º changed to 30º/50º

 

The house temperature at the time, according to the Hive, was 19.9. Having made the changes the system fired up and I took an image [below] of the LG controller.

 

 

Moments later the system had evidently executed whatever it had been set to accomplish as stopped and I took another image.

 

 

The Hive showed the house temperature = 20º

 

The first 'real' test will be to morrow a.m. when I will note times and temperatures as per my initial post for comparative purposes.

 

Thanks again for all the help. 

 

[J1mbo]

Set the hive to well above where you want the room as well.

[Hogboon]

Only just seen your last message about the Hive setting J1mbo, so the following is as per the original set-up: target temp of 20ºC required starting at 07:00hrs. Here's the data.

 

17 Nov 2021	00’	30’
07:00	18.4º	18.3º
08:00	18.8º	19.3º
09:00	19.7º	20.0º

 

Outdoor temp was about the same as for the original data set, about 10ºC at a guess. Household usage was also about the same but whereas no shower etc was run during house heating the water heating was already in progress at 07:00. And I confirm that the house temperature appeared to go backwards during the first half hour. However, today's performance seems to me a considerable improvement and I await with interest the promised cold spell!

 

Below are 4 images of the controller; the first was taken at 07:00hrs, second and third at 08:00 and 09:00 and the last about 09:30 once the target temperature had been reached and the system powered down. 

 

     

 

 

 

 

I'm not sure why the room temps. according to the LG controller [images above] are shown as higher than the Hive temperatures [noted in the table] unless it is because the LG Controller has its own temp sensor in which case the difference is probably accounted for by the controller being in a smallish 'cupboard' in which the hot water tank is located and thus a degree or so warmer than the bulk of the house.  

 

 

 

 

[Hogboon]

On 16/11/2021 at 20:09, J1mbo said:

The final consideration is the Hive controller. I suspect this is a big part of the problem. Anything with a TPI program is unsuitable for a heat pump with weather compensation as the TPI program will introduce short-cycling by design, which is the worst possible operating condition for a heat pump. My advice would be to replace it with LG's native controls. However, for now, just set it to something really high like 30°C all the time which will effectively eliminate the TPI as the room temperature will be so far from the target and let the heat pump weather compensation control the living space.

 

What is TPI? and by the same token what is short-cycling? We are presumably not talking about a bloke on a bike in lycra! Does it mean the 'system' will be starting and stopping all the time? If so I can't say I have noticed it doing so. I don't know what sort of drop in house temperature is required to trigger the heatpump. Would that be in the controller's settings somewhere? I'll see if I can catch it in flagrante next time it starts up and make a note of the temperature.

[J1mbo]

TPI is an algorithm used to reduce overshoot by on-off thermostats. Basically it cycles the heating on-off periodically as the set point is approached, thereby reducing the average surface temperature of the radiators.

 

Heat pumps with weather compensation are always controlling the surface temperature and hence the two conflict.

 

Short cycling is the compressor running for short intervals. Since there are losses in the pre-run and as the pressure builds, each compressor start costs efficiency. Running the compressor for less than about 10 minutes each cycle will reduce COP and therefore increase running costs.

 

The TPI programme probably only takes effect within 1 degree of the set point (either side). Therefore you want the Hive to be at least two degrees above your actual desired temperature to eliminate the short cycling risk.

 

The house temperature dropped initially because the heat pump was heating the DHW.

[Hogboon]

While I scratch my head over this, wouldn't setting the Hive 2º about my desired temperature simply result in the house being 2º warmer than I want it? And wouldn't the system simply continue its bad behaviour but 2º higher? Is the TPI 'in' the LG Controller? the heatpump itself? or the Hive?  Sorry to be so dim! 

Edited November 18, 2021 by Hogboon

[J1mbo]

It’s a nightmare tbh with all these “smart” controllers being hooked up to simple contact inputs on heat pumps. It should not even be allowed in my opinion, for whatever that is worth. I feel sure that it is precisely these controls that will further hurt heat pump reputation as unresponsive and having poor output.

 

Anyway, the hive won’t start doing the TPI thing until the temperature is within 1 degree of the set point. Yes the room will overshoot, and that’s what you need to find out so that you can tune the weather curve to your particular home by turning down the min/max temps based on observations. For now obviously making sure it heats enough is however the priority.

 

To minimise running costs, the heat pump compressor ideally would run continuously and the radiator temperature be just enough to keep the temperature up. If either are not true then the COP is impacted and the running cost increases.

 

Obviously there are too many variables (how much the property is heated, amount of hot water demand, how much solar heat gain ie sunshine, how much other thermal output in the house like cooking, just people being there etc) to have a perfect setting at all times but right now the heat pump is very likely set much too hot. So you need to monitor it for a few weeks and see how much the settings can be tweaked to reduce overshoot whilst providing adequate warm up.

 

If you get to the point that you’re  happy with it with the Hive controller and aren’t trying to squeeze every last percent of efficiency from the system then fine. You might even be able to log a ticket with Hive to have them turn off TPI for yours if the setting is not in the app.

 

I suspect that the system will cost less to run and be more responsive with LG controls though, but will need yet more configuration.

[Hogboon]

It all seems massively over-complicated! How do I "tune a weather curve" ? Surely the weather does that ? The only tuning I understand is my cello - and that is pretty hit or miss. However, I am on good terms with the installers - who 'specialise' in heatpumps as opposed to being just glorified plumbers - and have a nodding acquaintance with a couple of people at LG so I will see what they make of it all. Whoever set this system up - whether LG 'default' settings or 'tweaked' by an installer - seems to have got it wrong judged purely by comparing my original heating data with that of today after the alterations you suggested.  

 

All I want, or rather all my wife wants,  is a house at 20º in cold weather. As you suggest [I think!] fancy thermostats are an irrelevant complication but I can see they have their attractions; by making the process apparently intuitive and more 'plug and play' the average punter [me] does not need to get his hands dirty with TPI, heat curves, set points, overshoots and so on. But the set-up here is far from PnP nor is the LG controller at all user friendly. 

 

As a first step I will dig out the [utterly useless] so-called 'smart meter' so that I can at least keep a vague track on electricity consumption and run comparative days with the controller on the original settings compared with the revised settings you suggested. B.t.w., I don't have solar thermal here, only PV. One of the reasons the 'smart' meter is in a drawer is that it takes absolutely no notice at all of the contribution the PV array makes to the grid or my own consumption. 

 

Anyway, many thanks again for the help and advice and if I think I have anything interesting to report resulting from future tinkering I will post here. All the best - for now!   

[Hogboon]

Another piece of the jigsaw: electricity consumption. At present, grid power consumed is the only way I have of monitoring 'efficiency' of the heatpump and its configuration. Today was another mild morning [about 10º at a guess] and below is the heatpump's performance with kWh consumed.

 

18th Nov 2021	00’	30’	40’
07:00	18.6º	18.9º
	6113.622	6115.733
08:00	19.6º	19.9º	20.1º
	6117.268	6118.659	6118.685

 

Total power used: 5.063 kWh. No hot water heating in the above but a couple of kettles boiled plus 'background' domestic consumption by fridge, freezer etc. so knock off say ½kWh means power used to achieve the above increase in temperature was probably about 4½kWh. At current price of 19.74 p per kWh = ca. £0.90p which strikes me as pretty good. I do have PV roof panels but what they contributed, if anything, I don't know as the very unsmart 'smart' meter doesn't log it/them.

 

When the promised cold weather arrives I will re-run the above using the new settings and the old default settings for comparison.      

 

[SteamyTea]

5 hours ago, Hogboon said:

When the promised cold weather arrives I will re-run the above using the new settings and the old default settings for comparison.  

If you plot imported energy usage against temperature, you will see where the the line intersects the y-axis.  That is your non heating electrical usage (roughly).

[J1mbo]

The heat pump should also have meters either built in or connected to it assuming it was installed under the RHI.

[Hogboon]

Thanks SteamyTea - but where would I plot this data? Is there a 'standard' graph in one of the manuals to use or is it a question of d.i.y. ? And J1mbo; yes, installation was under RHI but no idea if there are separate meters. Should I take a spanner to the case of the pump to peer inside? There is nothing in the cupboard with the tank.

 

Meanwhile, here is the Data Log taken from the LG Controller for yesterday. It suggests to me that the machine is not endlessly switching on and off, but only doing so when a drop in temperature demands. 

 

DATE	TIME	OPER.	SETTEMP	IN/OUT
2021.11.20	06:57	Heat	50º	17º/17º
2021.11.20	07:24	Heat	50º	42º/51º
2021.11.20	07:28	Heat	50º	38º/38º
2021.11.20	07:40	Heat	50º	44º/51º
2021.11.20	07:43	Heat	50º	40º/40º
2021.11.20	07:56	Heat	50º	44º/51º
2021.11.20	08:00	Heat	50º	41º/41º
2021.11.20	08:11	Heat	50º	45º/51º
2021.11.20	08:15	Heat	50º	41º/41º
2021.11.20	08:27	Heat	50º	44º/51º
2021.11.20	08:31	Heat	50º	41º/41º
2021.11.20	08:40	Off	-	43º/48º
2021.11.20	08:40	Off	-	43º/48º
2021.11.20	08:40	Off	-	44º/48º
2021.11.20	09:08	Heat	50º	36º/36º
2021.11.20	09:28	Heat	50º	59º/62º
2021.11.20	09:41	Heat	50º	29º/29º
2021.11.20	09:58	Heat	50º	42º/51º
2021.11.20	10:01	Heat	50º	38º/38º
2021.11.20	10:06	Off	-	40º/44º
2021.11.20	10:47	Heat	50º	29º/30º
2021.11.20	11:02	Heat	50º	42º/51º
2021.11.20	11:06	Heat	50º	38º/37º
2021.11.20	11:10	Off	-	39º/44º
2021.11.20	12:01	Heat	50º	28º/29º
2021.11.20	12:19	Heat	50º	43º/51º
2021.11.20	12:23	Off	-	39º/38º
2021.11.20	12:23	Off	-	38º/39º
2021.11.20	13:19	Heat	50º	28º/28º
2021.11.20	13:26	Off	-	33º/39º
2021.11.20	14:07	Heat	50º	26º/26º
2021.11.20	14:02	Off	-	37º/45º
2021.11.20	15:15	Heat	50º	27º/27º
2021.11.20	15:35	Heat	50º	43º/51º
2021.11.20	15:38	Heat	50º	38º/38º
2021.11.20	15:38	Off	-	38º/38º
2021.11.20	16:47	Heat	50º	26º/27º
2021.11.20	17:04	Off	-	41º/48º
2021.11.20	18:07	Heat	50º	27º/28º
2021.11.20	18:32	Heat	50º	59º/62º
2021.11.20	18:43	Heat	50º	26º/26º
2021.11.20	18:58	Off	-	39º/46º
2021.11.20	20:13	Heat	50º	25º/26º
2021.11.20	20:24	Off	-	35º/42º
2021.11.20	21:13	Heat	50º	26º/26º
2021.11.20	21:28	Off	-	38º/46º

 

   

[SteamyTea]

42 minutes ago, Hogboon said:

but where would I plot this data? Is there a 'standard' graph in one of the manuals to use or is it a question of d.i.y.

Read this

https://www.degreedays.net/

Fairly simple to DIY it all.

[J1mbo]

@Hogboon - possibly on the main controller there is an 'energy' menu with the electric consumption data: Information Of Meter Interface - LG Therma V series Owner's Manual [Page 36] | ManualsLib

 

 

[Hogboon]

SteamyTea: Thanks for the link. Looks like a lot of heavy lifting involved to me.

J1mbo: I have already hunted for anything resembling the 'Energy' symbol and menu shown on p.36 on my controller and concluded that it is a feature that for some reason is not included. However, a cursory read of p.35 suggests I may have to initiate it through the installer menu so will have a closer look tomorrow and see if I can goad the thing into revealing itself.   

Thanks both. 

[Hogboon]

I stumbled across the Meter Interface Settings in the LG Controller last week when tweaking the temperatures and shied away having no idea as to what Modbus or Port settings might be in use etc. I am in much the same predicament now! Apart from the Hive thermostat there are PV panels which supply power a] direct to the heat pump, b] to hot water heating and c] assign any spare capacity to the grid. That side of things is controlled by something called iBoost. And for all I know there may be other bits of kit hogging a modbus or port.

So my questions are:

1.   Does it matter what modbus address and port settings I use? Nothing is recorded in the LG Control Panel which resembles https://www.manualslib.com/manual/1511067/Lg-Therma-V-Series.html?page=35#manual

2.   If getting the correct modbus and port settings is critical have you any suggestions? Or can they be gleaned from somewhere in the controller or elsewhere?

 

My objective in this being to have a ‘real time’ record of energy consumption by the heatpump.

 

Many thanks.

[J1mbo]

It sounds like the meter monitoring is dependent on some external piece of hardware.

 

Contact the installer as having some form of metering for the heat pump is a requirement for the RHI. They should have shown you this as it is part of the RHI annual declaration.

[Hogboon]

Apologies but my brief reply to your last post J1mbo has gone awry. But fear not; you didn't miss anything. More to the point you are right in assuming "some external piece of hardware." I had this from LG today. 

 

"In order to monitor or read energy consumption watt-hour meters must be fitted in the power supply of each of the following.

·         Immersion heater

·         Boost heater

·         Heat Pump Unit(s)

·         The Outdoor package in the case of a Monobloc AWHP Unit

·         Both the Outdoor Unit and Indoor Unit's in the case of a Split-Type AWHP Unit.

"In addition, a Flow Sensor is used to record the water flow rate.

"These provide signals to a 'Heat Meter', and/or the LG Meter Interface [PENKTH000] which in turn sends a Modbus communication signal to the AWHP which can be displayed on the LG Controller. Although the below PENKTH000 Accessory provides a means of measuring and displaying the power consumed, this device is not approved by the RHI for metering and subsidy payments. Whereas the products shown in the previous email were approved for use, and allowed subsidies to be paid.

 

Quote

 

"There is nothing included in the product as standard, which allows metering and consumption to be AWHP equipment."

 

Which doesn't quite make sense but I have the gist of it. Just to be clear; the set-up here is a monbloc unit - no indoor unit. The 'previous' email referred to in the above had information about an installation approved by RHI which looked hugely complicated compared to the above and presumably has a suitably impressive price tag. 

 

So the long and the short of it looks like no energy or efficiency monitoring is possible in my current set-up. The only performance criterion [singular - I can only think of the one!] available to me seems to be to monitor time taken to achieve a target temperature based on primitive trial and error adjustments to temperature settings in the LG Controller.

 

How much lower can the tech get than that?   

Edited November 22, 2021 by Hogboon

[J1mbo]

Get back to the installers. The system must have metering to qualify for RHI (assuming it was installed on or after 22-May-18). Probably you need to be metered for performance and not payment unless there are secondary heat sources installed.

 

Factsheet_DoINeedMetering_RPIIA (ofgem.gov.uk)

[Hogboon]

I am 'in contact' over this with the installer. So far they have contributed this;

Quote

Good to hear from you, hope your well.

 

This is a good example of why forums can be both good and bad.

 

The requirement for the MCS / RHI Metering for Performance Purposes (MPP) to receive your Deemed tariff  – this is why there is a electricity meter fitted for you to monitor – of Ofgem if they so wish.

 

The setting image you have attached is for the connection of the LG monitoring suit (MODBUS is the method of connection to the adapter) This is both costly and unnecessary which is why we don’t fit them.

 

Hope this helps.

 

I have pointed out [with embellishment] that the answer to his concluding sentence is a firm 'no'. 

 

I don't understand the RHI process. The installer provided the forms, some assistance and some of the answers which I then submitted. Payments have followed. However, the bumph that came back contains statements like this;

 

Quote

Installation Requires Metering for Payment: No

 

Their capitalization. At the moment I know no more than that.  

[J1mbo]

The requirements are either metered for payment (meaning you have to submit readings) or metered for performance. All heat pumps require one or the other. The installation only needs metering for payment if there is a secondary heat source fitted (such as a gas boiler or electric heating element external to the heat pump itself). Your installation will require metering for performance per the guide I linked to above if it was fitted on or after 22-May-2018.

 

From the doc,

 

"If you apply and are successfully accredited to the Domestic RHI on or after 22 May , all new applications for air source heat pumps and ground source heat pumps will be required to have electricity metering arrangements alongside their heating systems to be eligible for the scheme. This means that even if you do not meter your heat pump for payment, it will still need at least one electrical meter."

Edited November 23, 2021 by J1mbo

[Hogboon]

'strewth! Have you ever tried to contact Ofgem? Getting to grips with the performance of heatpumps is child's play in comparison. In desperation I emailed them this yesterday. 

 

Quote

Someone said the RHI 'grant' - or whatever it is - is conditional on installing energy metering to monitor the heat pump's efficiency and usage. Someone else told me that metering does not have to be installed. Which is correct?

 

Not had a reply yet.

 

43 minutes ago, J1mbo said:

This means that even if you do not meter your heat pump for payment, it will still need at least one electrical meter."

 

Does this not simply mean that my house needs an electricity meter? which of course mine does. It does not specifically say, although I think it means, that for a heatpump to 'qualify' it must be installed with its own separate meter.