@benson thank you.

My t4autohmax is also set to 17 so once the weather gets towards that consistently I'll decide what to do.

Part of me think it must be beneficial to keep the primary circuit running periodically to maintain it even though the DHW will be coming on daily. But assume this is not really required and it could stay 'off' all summer?

Personally I would turn it off as I wouldn't necessarily see much if any benefit of keeping the circulator pump going during summer months. The only possible advantage I can think of is that it will keep the system water running through the magnetic cleaner perhaps as I think you are alluding to? Probably marginal gains though...

Plus, in summer the OAT is going to drop below 17 at night but you still aren't going to need any heating so you will probably find it will be coming on when you really don't need it.

Posted by: @benson

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Personally I would turn it off as I wouldn't necessarily see much if any benefit of keeping the circulator pump going during summer months. The only possible advantage I can think of is that it will keep the system water running through the magnetic cleaner perhaps as I think you are alluding to? Probably marginal gains though...

Plus, in summer the OAT is going to drop below 17 at night but you still aren't going to need any heating so you will probably find it will be coming on when you really don't need it.

I believe some heat pumps have an anti-seize function whereby they start up the circulator pump once a week or thereabouts if there is no call for heating or DHW.  Obviously that will only work if you dont cut the power!

@jamespa interesting. Did not know that. That said- I meant just turn the space heating off rather than turning it off completely at the isolator switch obviously.

Hi guys, just further to the question about whether to turn off the space heating side of things over summer, am I to assume it's as simple as switching off the 'left side' of the Modes controller? Will this still mean the hot water schedule comes on daily as planned?

And should the pressure in the system pressure gauge remain the same even with space heating turned off for months?

Posted by: @painter26

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Hi guys, just further to the question about whether to turn off the space heating side of things over summer, am I to assume it's as simple as switching off the 'left side' of the Modes controller? Will this still mean the hot water schedule comes on daily as planned?

Assuming you have a room thermostat, the easiest way to turn the space heating on and off without affecting the DHW heating is to set the room stat to something high eg 26 degrees C to have the heating on, with actual room temp determined by the weather compensation curve, and something much lower, say 12 degrees C, to have the space heating off.

Posted by: @painter26

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And should the pressure in the system pressure gauge remain the same even with space heating turned off for months?

Pretty much so, though mine doesn't! I must have a tiny invisible leak somewhere. I just top it up from time to time. Performance does not appear to be affected - indeed, I have never really established why systems need to be pressurised to what are car tyre pressures in in the first place. As long as the system is full with no air, should it not just be OK? 

Posted by: @cathoderay

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Posted by: @painter26

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Hi guys, just further to the question about whether to turn off the space heating side of things over summer, am I to assume it's as simple as switching off the 'left side' of the Modes controller? Will this still mean the hot water schedule comes on daily as planned?

Assuming you have a room thermostat, the easiest way to turn the space heating on and off without affecting the DHW heating is to set the room stat to something high eg 26 degrees C to have the heating on, with actual room temp determined by the weather compensation curve, and something much lower, say 12 degrees C, to have the space heating off.

Posted by: @painter26

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And should the pressure in the system pressure gauge remain the same even with space heating turned off for months?

Pretty much so, though mine doesn't! I must have a tiny invisible leak somewhere. I just top it up from time to time. Performance does not appear to be affected - indeed, I have never really established why systems need to be pressurised to what are car tyre pressures in in the first place. As long as the system is full with no air, should it not just be OK? 

 

Thanks @cathoderay . If I understand you correctly setting the thermostat / weather comp curve at either extreme will still mean the circulating pump works through the summer but it'll never call for heat? And this is possibly preferable to actually switching the space heating side of things off completely (i.e. the circulating pump becomes silent)?

Posted by: @painter26

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Thanks @cathoderay . If I understand you correctly setting the thermostat / weather comp curve at either extreme will still mean the circulating pump works through the summer but it'll never call for heat? And this is possibly preferable to actually switching the space heating side of things off completely (i.e. the circulating pump becomes silent)?

The room stat and the weather comp curve (WCC) are two separate things, though they can both affect what the system does. The use of the room stat as the main on/off switch comes from the Freedom/Midea Handover and Maintenance log book. Used as described above, it really is just an on/off switch, and when it is set to off, stat set to well below current room temp, the space heating should be off, including the secondary (radiator) circulating pump. As it happens I turned my space heating off yesterday morning (room stat set to 12°C) and the secondary (radiator) circulating pump is currently off.

The WCC controls the actual room temperature when the space heating is on. When the space heating is off, the WCC is not in use, and does nothing. 

• Ahhh thank you, i probably used the wrong terminology as I have a Hive room thermostat which is always set to 23 degrees to avoid over-shooting during winter. The Hive also acts as the on/off switch for the space heating (so when I turn it off it switches off the circulatory pump as well). 
• Ar the moment the space heating only comes on briefly at night of the temp drops below c.12 degrees as my WCC is set super low (25 degrees / 45 degrees).
• I could keep my settings as they are but even at night I get a lot of residual solar gain as the house is directly south facing so I would not need the space heating to kick in on a cold night 

Posted by: @painter26

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Ar the moment the space heating only comes on briefly at night of the temp drops below c.12 degrees as my WCC is set super low (25 degrees / 45 degrees).

I'm still not sure you have fully grasped how WCC works. In a standard setup, no fancy room stats, when you want the heating to be on, you set the room stat to something considerably higher than the room temp you want. This means the room stat is always 'calling for heat' which in a way it is, but the WCC limits the amount of heat delivered by changing the flow temperature according to the outside air temperature (OAT). The WCC is a linear relationship between the two end points, outside that range it flat lines. It looks like this (taken from the Freedom/Midea Installation Manual):

With the setting shown, when the OAT is 15°C (and above), the flow temp will be 37°C, when it is -2°C (and below) it will be 55°C (for rads). In between those set points, it is set by the intersection on the sloping line.

Thus as 12° OAT, the flow temp will be something around 40°C (the slope is roughly one degree change in flow temp for each degree change in OAT over the sloping part).

Posted by: @painter26

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my WCC is set super low (25 degrees / 45 degrees).

This isn't quite right. I assume it means 45°C flow temp at 25°C OAT. If so, the OAT setting is too high (not 'super low'). If it is 25°C outside, you do not need to add extra heat with a flow temp of 45°C! A more common right hand set point might be 30°C (flow) at 15°C (OAT).   

@cathoderay sorry I was using my own shorthand to explain the low/high points that my curve is set to:

25 degrees flow temp at OAT 16 degrees

45 degrees flow temp at OAT -4 degrees 

Thus my space heating is only ever activated at night as the temp drops below 16. During the day it's pretty much always off, although the circulatory pump continues to run (as one would expect).

Posted by: @painter26

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Thus my space heating is only ever activated at night as the temp drops below 16. During the day it's pretty much always off, although the circulatory pump continues to run (as one would expect).

Yes, because it is on, in the full sense, but the flow temp is very low (25°C). Do you have an IR thermometer? If you do, I think you will find the rads have a tiny bit of warmth. Or put the back of you hand on a rad, and then an adjacent metal object, or bit of wall.