@pooneil

https://renewableheatinghub.co.uk/what-is-weather-compensation-and-is-it-important

Thank you. 

As you can probably tell, this is starting to stress me out. 😊 

As you and James have said, it looks like I've picked the worst possible circumstances to sort this out -- just below 17° outside and sunny. 

But, by that principle, for example, if that 17° was reduced to 10°, shouldn't it not turn on when it's above 10° outside?  This is what I thought I was aiming to do. 

Posted by: @pooneil

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This is the current status. 

There is something odd going on.  It says water outlet 34 yet if it is running on WL1 with the parameters you showed us earlier it should never get to that assuming that the OAT is above 10.  What does it think the Outside temperature is?

Posted by: @pooneil

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But, by that principle, for example, if that 17° was reduced to 10°, shouldn't it not turn on when it's above 10° outside?  This is what I thought I was aiming to do

Maybe.  The alternative behaviour is that, above 10 outside, it keeps the flow temperature at the value for 10.  Not sure which the Samsung odes.

See also my post above - there is something odd going on, were both of these shots with the settings you showed us earlier?

Posted by: @pooneil

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As you can probably tell, this is starting to stress me out. 😊 

Im presuming you are under time pressure.  Have you got an external thermostat.  At this time of year it wont cost much extra to use that to turn the heat pump on and off and it may just be worth deferring the matter until a more suitable opportunity.  

@jamespa 

I can't remember exactly, but I think when I was there and took that picture it said outside temp was 16°. I noticed because it was the same as whatever my car was reading.

@jamespa You have got me thinking now, I think it turns off above the top value as I used to have my controller in the hall and Im pretty sure it switched off.

@pooneil post some of the other relevant FSV values and I will check them against my system.

Posted by: @pooneil

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@jamespa 

I can't remember exactly, but I think when I was there and took that picture it said outside temp was 16°. I noticed because it was the same as whatever my car was reading.

Sorry but without more complete information its impossible to tell what is going on.  Screen shots of the controller when its operating (making sure as much is displayed as possible and if necessary scroll - I dont know if Samsung turns off part of the display/some information is only visible on scrolling) and screenshots of all of the 10xx and 20xx parameters are probably sufficient.  I apologise I cant be more helpful but there are obviously a couple of parameters that are set differently to what might be expected.

I am sorry I cant be more helpful but its quite difficult with limited info.

@pooneil It sounds like the settings are all over the place and you are maybe misunderstanding some things. Let’s get back to basics at the risk of teaching you to suck eggs. The temperatures I will use are illustrative only.

Say the room target temperature is 20C. When it is 15C outside (OAT), heat will flow outwards (5C delta-T), the amount per C dependent on insulation level. The heat emitter must compensate for this, therefore could be at 25C (+5C dT to room also). If OAT is -2C, then dT rises to 22C and room heat loss increases. The emitter must then rise to 42C to compensate if the heat relationship is quasi-proportional (e.g.UFH). So settings for WC would be 42C @ -2C and 25C @ 15C. Radiators are non-linear and emit less heat at low water temperatures, therefore the setting at 15C should be higher, e.g. 30C. If your flow temperature is 34C @ 16C OAT, it sounds like you have set 33C @ 17C OAT - too high. Samsung defaults are 40C @ -10C and 25C @ 15C, I think. Adjust your settings according to these principles, starting with the temperature required to meet your heat loss at -2C which should have been given in your design. A 10C OAT setting makes no sense.

@heatgeek 

Hi. I appreciate your help, but none of that really makes anything clearer, specifc to the problem I have. Which is part of my frustration in general. I probably have a better grasp of domestic heating than the average person. The vast majority of homeowners probably don't know how their gas systems work, but have no problem operating them.

The settings are all over the place because I'm desperately trying to reduce the house temperature down from 26°. My tenant will want to do the same. It doesn't seem right that either of us 'need' to have a technical understanding of weather curve settings and deltaT values (or whatever terminology each different manufacturer confusingly decides to use). 

I set the OAT to 10° to test if the system would send heat to the rads even though it was above that temp outside. It did. Whether it's set to 10 or 17, I still don't know if that's normal. Hence my question about whether it's still going to be running mid summer when it's 28° out.

I understand how the system is supposed to work. It was originally set by the installer (who presumably does understand the technical issues), but the house is still about 8° hotter than the target temp of 18°. 

And as an ignorant homeowner I seem to have no control over that. 

From advice here (which I really do appreciate) apparently the installed TRVs shouldn't be used, the actual measured indoor temperature is irrelevant to whether the system continues to pump heat to the rads and there's no roomstat anyway.

I have just called the installer to come and have a look at the settings, which I wanted to avoid because he's been back once already for the same issue and I feel like I should be able to control the temperature in my own house. I'll let you all know how that goes.

@pooneil I have a Gen 4 Samsung. The setting on mine is 25C @ 15C. 25C is the lowest base temperature and the flow at 16C or 17C will still be at 25C. It does not cut off. Some heat pumps don't like going below 25C.

Posted by: @pooneil

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I set the OAT to 10° to test if the system would send heat to the rads even though it was above that temp outside. It did. Whether it's set to 10 or 17, I still don't know if that's normal. Hence my question about whether it's still going to be running mid summer when it's 28° out.

Obviously without knowing how it is set up its impossible to comment on this.  It seems your installer left it with settings that didn't work for you.  Normally they try to leave heating with settings that will work, but may not be optimum, because that reduces call outs.

Posted by: @pooneil

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Hi. I appreciate your help, but none of that really makes anything clearer, specifc to the problem I have. Which is part of my frustration in general. I probably have a better grasp of domestic heating than the average person. The vast majority of homeowners probably don't know how their gas systems work, but have no problem operating them.

I appreciate your frustration.  On this forum people tend to be focussed on getting best efficiency out of a system, which may not be what you need at this stage and something we dont mostly bother doing with boilers - modern examples of which have just as many options as heat pumps.   Weather compensation in particular can be a little challenging to set up, which is probably why we didn't enable it on boilers in this country (unlike several others which made it mandatory).  Because we didn't implement it we in a poorer position when it comes to the transition to heat pumps, and many of us have paid 10% more for our gas heating than we needed to and were less comfortable.   It was a choice that we in the UK made.  

Unfortunately quite a few heat pumps, particularly those made by companies that did not previously sell boilers, have a user interface which is not really designed in a way that the average user can easily get the best out of it (some are much better).  This is probably why some installers hide it away in the cupboard and issue dire warnings not to touch it.  Samsung is one of the heat pumps with such an interface.  For that reason I would probably, if I were putting a Samsung (or any other heatpump with a UI that isnt easy to explain), in a rental property, do one of two things

1. Install Homely to present a friendly UI that people will understand (I am told its friendly - I havent actually seen the UI)
2. Adjust the WC curve to a couple of degrees above the maximum desired temperature, fit TRVs in the bedrooms, fit a thermostat in the living room (or use the inbuilt sensor in the controller)

The second will likely be less efficient (roughly 2-3% for each degree above the desired room temperature) but doesnt involve purchasing hardware.  It might lead to complaints about house being insufficiently warm if they keep changing the temperature expecting it to respond quickly

Your installer will likely set it up for (2) if you are lucky, in fact thats what I would have expected them to do in the first instance.

Hope that helps

@pooneil Hi. I do understand that this can be confusing at first and as a landlord myself I understand your need to get this sorted.

Your idea of setting the upper weather compensation limit to 10C to test if the heat pump turned off was logical. In my mind it should have done so.

I think you have several options:

1. leave it to the installer, this is a two edged sword as they rarely set things up most efficiently

2. See if your new tenants are interested in minimising their bills and getting involved (surprisingly some people are)

3. Move the thermostat/controller into the main room and use it as a temperature limiter as I do. It just requires extending with two strand wire, mine is shielded but I dont think its essential. This is a quick, cheap fix to get things useable quickly.

4. Install Homely or something similar which will take over and optimise the settings for you.

5. Take the role on yourself and spend time getting your head around this stuff (not for everyone I know)